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Effects of velocity loss during resistance training on athletic performance, strength gains and muscle adaptations
Abstract
We compared the effects of two resistance training (RT) programs only differing in the repetition velocity loss allowed in each set: 20% (VL20) vs 40% (VL40) on muscle structural and functional adaptations. Twenty-two young males were randomly assigned to a VL20 (n = 12) or VL40 (n = 10) group. Subjects followed an 8-week velocity-based RT program using the squat exercise while monitoring repetition velocity. Pre- and post-training assessments included: magnetic resonance imaging, vastus lateralis biopsies for muscle cross-sectional area (CSA) and fiber type analyses, one-repetition maximum strength and full load-velocity squat profile, countermovement jump (CMJ), and 20-m sprint running. VL20 resulted in similar squat strength gains than VL40 and greater improvements in CMJ (9.5% vs 3.5%, P < 0.05), despite VL20 performing 40% fewer repetitions. Although both groups increased mean fiber CSA and whole quadriceps muscle volume, VL40 training elicited a greater hypertrophy of vastus lateralis and intermedius than VL20. Training resulted in a reduction of myosin heavy chain IIX percentage in VL40, whereas it was preserved in VL20. In conclusion, the progressive accumulation of muscle fatigue as indicated by a more pronounced repetition velocity loss appears as an important variable in the configuration of the resistance exercise stimulus as it influences functional and structural neuromuscular adaptations.
... 26 Going deeper into VL than 30% causes a lot of neuromuscular fatigue and causes a shift to a slower phenotype. 27 This, of course, does not help the selective inhibition and atrophy following ACLR. With the PBT, clinicians tend to create too much VL and fatigue in sets with the goal of inducing hypertrophy. ...
... 33 The greater the VL, the closer the individual is to muscular failure. 33 Several authors have demonstrated that determining the set volume using a low percentage of VL (between 5% and 10%) enhances athletic performance, such as sprinting or vertical jumping, more effectively than a set volume with a high percentage of VL. 27 It has also been demonstrated that a low-to-medium %VL yields similar 1-RM improvements as a 40% VL, despite requiring only half the exercise volume. 35 These observations confirm that it is not necessary to reach muscular failure to achieve significant neuromuscular improvements. ...
... 30 Several authors have studied the impact of determined VL thresholds, measured as a %VL, on the extent of gains in muscle volume and strength. 27 33 34 50 Their conclusion is unanimous: the higher the VL threshold, the more neuromuscular adaptations are directed towards the development of muscle trophicity. This is in line with Open access traditional hypertrophic training recommendations, which are in favour of high training volumes to increase the total time the muscle is under tension. ...
Resistance training is critical for strength development and physical recovery after anterior cruciate ligament reconstruction (ACLR). Traditional percentage-based training (PBT) methods, which often focus on maximal strength and training to failure, are not able to objectify rapid force development. Velocity-based training (VBT), using movement velocity as a metric for training intensity, offers a promising alternative. This article promotes the use of VBT in ACLR rehabilitation, emphasising its potential to enhance neuromuscular recovery and return-to-sport outcomes. A narrative review of current literature focuses on mid-and late-stage rehabilitation to examine how VBT can address PBT limitations and improve functional recovery and sports performance. VBT provides several advantages, including real-time feedback, individualised load adjustments and better alignment with daily physiological variations. It facilitates the accurate training load prescriptions, enhances motivation and reduces unnecessary fatigue. Monitoring load-velocity profiles and velocity-loss thresholds enables more effective strength and hypertrophy adaptations without reaching muscular failure. In midstage rehabilitation, VBT not only helps to restore muscle strength and hypertrophy using submaximal loads and individualised velocity profiles but also addresses unwanted neuroplasticity following ACLR by providing augmented feedback and facilitating an external focus. In late-stage rehabilitation, VBT focuses on improving explosive strength and power, crucial for sports performance. Despite its benefits, VBT application in rehabilitation is limited by a lack of data on injured populations and specific exercises, such as open-chain single-joint movements. Integrating VBT allows practitioners to enhance traditional rehabilitation protocols, potentially leading to better clinical outcomes and providing a more personalised rehabilitation process.
... Consequently, %VL in the set serves as a reliable indicator for assessing effort levels during a set. In summary, the optimal approach for prescribing, programming, and dosing training load during RT exercises appears to involve the velocity of the initial or best repetition of the set (reflecting relative load) and %VL in the set (indicative of volume) [76][77][78][79]. ...
... Currently, scientific evidence does not conclusively demonstrate that exercises emphasizing greater specificity lead to superior transfer to specific sport actions. Notably, a recent systematic review [21] and other studies [77][78][79][80] have indicated that training programs based on performing so-called basic exercises, such as back squats, offer substantial transfer effects on critical actions in soccer, including linear sprinting, vertical jumping, and directional changes. Moreover, similar findings were observed across studies involving soccer players of different age groups [22,23,[55][56][57][58][59][60]. ...
... In terms of load indicators or fatigue assessment, determining the minimum effective dose for performance enhancement is crucial. Several studies [59,[77][78][79] have investigated the impact of training programs employing full squat exercises at different relative loads on athletic performance. These studies compared the effects of moderate-to-high relative loads (>60% of 1-RM, or MV lower than 1 m·s −1 ) with moderate-to-low relative loads (40-60% of 1-RM, or velocities between 1.28 and 1.00 m·s −1 ). ...
Soccer is an intermittent sport characterized by periods of high intensity interspersed with varying levels of recovery. During the game, soccer players are required to perform numerous determinant actions, such as accelerations, decelerations, pace and directional changes, jumps, and strikes, which demand high levels of strength, speed, endurance , and mobility. This review aims to examine the current scientific evidence on velocity based training (VBT) in order to assess its role in optimizing key actions in soccer players and to provide practical applications for its implementation. A narrative review of the scientific literature was conducted, focusing on velocity-based resistance training and its application in soccer, identifying relevant studies on its effectiveness in improving specific physical capacities and sports performance. Velocity-based resistance training is an effective strategy for enhancing key skills such as linear sprints, vertical jumps, and direction changes. Additionally, this methodology allows for the real-time adjustment of training loads, optimizing outcomes and minimizing muscle fatigue. Velocity-based resistance training represents an innovative and practical tool for soccer coaches and strength and conditioning professionals. Its application can contribute to optimizing physical performance, reducing injury risks, and improving sport-specific capabilities.
... Notably, training to failure is associated with increased perceived exertion, greater muscular damage, higher cortisol concentration and longer recovery times compared to non-failure training (González-Badillo et al., 2016;Refalo et al., 2023). For longterm adaptations, research suggests that, on average, muscle hypertrophy increases as sets are performed closer to failure (Hickmott et al., 2022;Pareja-Blanco et al., 2017;Robinson et al., 2024). However, differences in hypertrophy between close proximities to failure (e.g., 1-2 repetitions in reserve (RIR) versus failure) appear to be negligible (Pareja-Blanco, Alcazar, et al., 2020;Refalo et al., 2022Refalo et al., , 2024. ...
... Velocity-based approaches have become popular among practitioners for objectively monitoring proximity to failure (Hickmott et al., 2024). Numerous studies have highlighted a strong relationship between the percentage of velocity loss within a set and the percentage of repetitions completed, relative to the maximum possible repetitions (%Rep) Pareja-Blanco et al., 2017). This allows for an accurate prescription of the level of effort experienced during a set based on the percentage of velocity loss (e.g., reaching a 20% velocity loss would correspond to completing 50%Rep in squat training sets) . ...
... Current knowledge suggests that women generally tolerate higher training volumes and can achieve more repetitions at a given velocity loss threshold during exercises like the back squat and bench press compared to men (Jukic et al., 2023;Pérez-Castilla et al., 2024;Rissanen et al., 2022). In contrast, men tend to achieve similar or greater strength improvements with lower volume and level of efforts (Pareja-Blanco et al., 2017;Rissanen et al., 2022). Thus, as the accuracy of estimating RIR through RIR-MV relationships may vary between men and women in free-weight back squat , sex-specific research is warranted. ...
This study explored the accuracy of using the relationship between repetitions in reserve (RIR) and mean velocity (MV) to predict proximity to failure in bench press exercises across two modes (Smith machine and free-weight) and sexes (men and women). Twenty-eight recreationally trained individuals completed two sessions of each exercise mode, with sets performed to failure at 65% and 75% of one-repetition maximum. Individualized RIR-MV relationships showed a higher goodness-of-fit for the Smith machine compared to the free-weight bench press (R² = 0.79-0.87 vs. 0.41-0.78), without significant sex differences (P = 0.880). MV values were mostly similar between exercise modes across different RIRs (P > 0.077), but men demonstrated higher MV values than women for RIR 5-1 (P ≤ 0.013). Individualized RIR-MV relationships were more accurate at estimating RIR 5 at 65%1RM in subsequent sessions than generalized RIR-MV relationships (absolute errors = 0.64-1.36 vs. 1.25-2.00 repetitions; P < 0.001), regardless of sex. However, prediction accuracy was similar for both relationships at RIRs 2 and 0 (absolute errors ≤ 1 repetition; P ≥ 0.164). These results suggest that RIR-MV relationships can effectively estimate proximity to failure across exercise modes and sexes, with individualized relationships offering greater accuracy.
... However, the effects on training intensity variables, such as movement velocity, are still relatively unexplored, especially in sets performed not to failure. Previous studies have revealed greater improvements in athletic performance when RT sets are not performed to failure [8,9]. In these cases, limits of unintentional decreases in maximum movement velocity are typically used to control the mechanical fatigue induced in training, known as velocity loss threshold (VLT) [10][11][12], which allows for individualizing set duration through the percentage relativization of mechanical fatigue [13]. ...
... In these cases, limits of unintentional decreases in maximum movement velocity are typically used to control the mechanical fatigue induced in training, known as velocity loss threshold (VLT) [10][11][12], which allows for individualizing set duration through the percentage relativization of mechanical fatigue [13]. This is an important aspect because maintaining fast velocities during RT has been associated with larger improvements in sport actions such as sprinting and jumping [8,14,15]. Specific adaptations in neuromuscular capabilities (e.g., muscle power) have been observed when using VLT ≤ 20% [16]. ...
... As depicted in Table 1, across all sets and the three recovery intervals utilized, there was a notable decline (at least 20%) in MPV during the final repetitions compared to the initial ones. Previous studies have indicated greater enhancements in athletic performance when resistance training sets are not executed to failure [8,16]. We employed a VLT of 20%, a threshold at which specific adaptations in neuromuscular capabilities, such as muscle strength or power, have been observed [16], likely due to the appropriate intensity imposed and the minimal fatigue generated. ...
Purpose
The percentage loss of speed is used in individualized control of set volume to mitigate unwanted fatigue. However, the effect of this monitoring on mechanical fatigue in the face of different inter-set recovery intervals is not known. Therefore, this study aimed to compare the mean propulsive velocity (MPV) during a bench press exercise session performed at maximal intentional velocity across different inter-set rest intervals (1, 2 and 3 minutes).
Methods
Fifteen individuals performing three sets of bench press with rest intervals of 1, 2, and 3 min between sets. Bench press was performed at 75% of 1 RM (repetition maximum), estimated from a load-velocity profile. MPV was measured using a linear position transducer (Encoder®).
Results
Main results showed that MPV decreased among all three sets for 1 min interval and from set 1 to set 3 for 2 min interval. Only the 3 min rest interval allowed complete recovery of MPV between sets (i.e., no differences of MPV among sets).
Conclusions
Therefore, professionals should consider at least a 3 min rest interval when performing 3 sets or 2 min when performing 2 sets to maintain movement velocity and effectively mitigate fatigue.
... Velocity-based resistance training (VBRT) is a fundamental approach to improve strength performance and assess the athlete's fatigue state (Pareja-Blanco et al., 2017). As far as fatigue is concerned, this may be caused through various mechanisms; still, their particular contribution and the extent of their influence remain uncertain, which the nature of the effort exerted (Allen et al., 2008). ...
... In this sense, velocity loss could be regarded a good index of volume training (García-Ramos, Torrejón, et al., 2018;Guez-Rosell et al., 2020) since participants showed the same time of effort and stress across intensities when only one velocity loss criterion was applied. Therefore, velocity loss could be used for individualised training Pareja-Blanco et al., 2017), because it allows to establish the same level of fatigue during the resistance training regardless of the exercise's intensity. ...
... Subsequently, the presence of higher cortisol concentrations promotes a higher muscle protein degradation (Wing & Goldberg, 1993). Therefore, it could be suggested that velocity-based training regardless of intensity is an ideal training method to improve the strength-conserving muscle protein as Pareja-Blanco et al. (2017) has shown when lowvelocity loss criteria are applied. ...
Velocity loss has been recognized as an effective fatigue index in resistance training. However, the physiological consequences of this fatigue should be described. Traditionally, researchers have debated the hormonal response to non-failure resistance training. Cortisol on salivary concentration was one of the hormones under study, which is linked to the inflammatory process from exercise. This study aimed to compare the acute salivary cortisol (Sal-C) response at different percentages of 1RM with fatigue standardized by a 10% velocity loss. An experimental, randomized, and counterbalanced activity was designed. Fifteen men took part in the study (they fasted for 12 hours before carrying out the test), performing 6 sets of bench press throw with different 1RM percentages (30% - 90% 1RM). Salivary Cortisol was collected before and after each test. Velocity loss was measured by a linear encoder. ANOVA and Effect Size were performed. Sal-C showed a significant decrease in all percentages and effect size was greater with low loads (1.61 high) than with high loads (0.95-1 moderate). Peak power was significantly higher between 40-70% of 1RM compared to other percentages (30-80% 1RM). The results of this research support the idea that velocity-based training sustains the dynamic equilibrium of organisms independently of intensity training. Moreover, untrained subjects could perform efficiently up to six sets at all percentages but with fewer repetitions at higher intensities, as this study shows that untrained subjects achieved 10% velocity loss under four repetitions.
... Recent studies have found that velocity-based training can lead to similar gains in muscle strength and power compared with "traditional" resistance training approaches [6,7], but the velocity-based training approach allows those improvements with a reduced training volume [8,9]. However, these studies analyzed muscle strength gains using one repetition maximum (1RM) or maximum voluntary contraction (MVC) tests, which do not consider the production of muscle strength per unit of time (i.e., rate of force development [RFD]), also known as explosive force [10]. ...
... A decline in barbell velocity has been associated with neuromuscular fatigue [13], whereas greater velocity attained against a given absolute load has been related to enhanced neuromuscular readiness [4,13]. The velocity-based training approach allows greater movement velocities and power outputs during resistance exercise sessions compared to using a percentage of 1RM [8,13]. For this reason, velocity-based training can potentially promote velocity-specific adaptations, such as better early-phase neural drive [14]. ...
... We employed a mixed experimental design, with the group as between-participants factor and time as within-participants factor. Participants attended 45 sessions over 15 weeks, consisting of three familiarizations (first week), three baseline evaluations (second week), 36 resistance exercise sessions (weeks [3][4][5][6][7][8][9][10][11][12][13][14], and three postexperiment evaluation sessions (week 15). ...
This study aimed to analyze the chronic effect of high cognitive effort immediately before resistance exercise sessions on neuromuscular performance in untrained male adults. We used a mixed experimental design, with the group as between‐participants factor and time as within‐participants factor. Thirty‐four participants were randomly assigned to two parallel groups: high cognitive effort (n = 17) and control (n = 17). Subjects in the control group were seated for 30 min before the resistance exercise sessions, while the high cognitive effort group completed incongruent trials of the Stroop task until subjective mental fatigue was present immediately before resistance exercise sessions. Participants attended 45 sessions over 15 weeks, consisting of three familiarizations, three baseline evaluations, 36 velocity‐based training sessions, and three postexperiment evaluation sessions. Rate of force development (RFD) during the isometric mid‐thigh pull, half back‐squat 1‐RM, and countermovement jump (CMJ) were measured before and after the 12‐week intervention. A significant group × time interaction effect was found for the average RFD at 0–250 ms (p < 0.05), with greater improvements for the control group than for the high cognitive effort group. There was no group × time interaction for half back‐squat 1‐RM (p > 0.05). Also, there was no group × time interaction for CMJ (p > 0.05). In conclusion, repeated high cognitive effort immediately prior to resistance exercise sessions is a phenomenon that can induce greater early velocity loss and, consequently, impairs the improvements in RFD. However, this did not inhibit the increased performance for explosive strength and CMJ in male untrained adults. High cognitive effort before resistance exercise sessions should be avoided.
... Because the amount of volume required for adaptation can be highly variable (30,89), it can be speculated that by monitoring and individualized RT volumes, we could improve the stimulus-to-fatigue ratio, favoring less fatigue and enhancing readiness for subsequent training sessions (74). The velocity of movement and session density are also considerable "volume"related variables, which provide some trade-offs (75). The use of VL thresholds is an emerging strategy used in resistance exercise, which involves terminating the set once the bar speed reaches a predetermined reduction in velocity (87), which serves the purpose of keeping a set sufficiently stimulating without reaching momentary failure. ...
... The use of VL thresholds is an emerging strategy used in resistance exercise, which involves terminating the set once the bar speed reaches a predetermined reduction in velocity (87), which serves the purpose of keeping a set sufficiently stimulating without reaching momentary failure. Higher VL can impair rapid force production and induce greater fatigue in the short term, which may interfere with subsequent "endurance" or sports-specific sessions (75,86). With this in mind, velocity-based training may have practical significance in helping to limit training volume to the amount necessary to stimulate improvements. ...
Concurrent training (CT), which combines resistance exercise and energy systems conditioning, is the default approach to preparation in high-intensity intermittent (“stop and go”) team sports. This review provides an overview of CT, emphasizing its complexities and challenges in managing fatigue and optimizing performance. These complexities are specifically compounded by the variability in game demands across the season, where the presence of intensified and nonintensified competition periods necessitates a flexible and adaptive training approach. In this context, there are essential training variables to consider, including intensity, volume, session order, and recovery intervals between sessions. In addition, nontraining variables such as travel, sleep, and nutrition play a role in the fatigue experienced while training and competing. These variables interact to influence acute performance and training adaptations and can be strategically adjusted by strength and conditioning practitioners. The aim of this review is to provide a comprehensive understanding of fatigue management for practitioners in team sports, emphasizing the complexities and challenges of CT and offering simplified practical recommendations for adjusting training variables within any given microcycle.
... Igualmente apoya la hipótesis que indica que el estímulo generado por el grupo VBT, caracterizado por un bajo grado de fatiga y alta velocidad en las repeticiones dentro de la serie, puede ser suficiente para inducir adaptaciones de fuerza y potencia en población no atlética. Adicionalmente, el grupo VBT realizó el mismo volumen de entrenamiento (número de series en cada sesión de entrenamiento) que el grupo PBT, pero con una menor carga de entrenamiento en cada sesión, presento mayores ganancias en CMJ, RV30, PP y DMO que el grupo PBT, resultados van en la misma línea que los reportados en investigaciones previas (González-Hernández et al., 2017;Jiménez-Reyes et al., 2021;Pareja-Blanco et al., 2017); y destacan la utilidad de VBT en RT. Otro aporte fundamental del presente estudio es el ajuste en cada serie de la carga objetivo. ...
... En cuanto a los efectos de estos dos tipos de entrenamiento sobre las variables cinéticas y cinemáticas, estudios previos (Banyard et al., 2019;Dorrell et al., 2020;Ikezoe et al., 2020;Pareja-Blanco et al., 2017;Blazevich & Jenkins, 2002;Dorrell et al., 2020;Fernandez et al., 2020;Seitz et al.,2014), indican una tendencia que observa efectos más acentuados en el RT basado en la velocidad de ejecución, versus el realizado con alto %1RM, sobre la velocidad de carrera 30m, la altura del salto y la potencia de pedaleo. El RT realizado a máxima velocidad voluntaria es de suma importancia para maximizar las ganancias de fuerza y el rendimiento deportivo (capacidad de salto, velocidad de carrera, potencia de pedaleo) (Banyard et al., 2019). ...
El propósito de este estudio, fue investigar los efectos de dos tipos de entrenamiento de fuerza (RT), uno basado en la velocidad de desplazamiento de la carga (VBT), versus otro realizado al 70-80% de 1RM (PBT), sobre la masa muscular (MM), densidad mineral ósea (DMO), componente mineral óseo (CMO), activación neuromuscular (EMG), fuerza máxima en sentadilla (FSQ), salto vertical (VJ), potencia de pedaleo (PP) y velocidad de desplazamiento sobre 30 m (RV30). 31 mujeres se distribuyeron aleatoriamente en los dos grupos: VBT (n=16) o PBT (n=15), que entrenaron 3 veces por semana, durante 12 semanas. Antes y después del entrenamiento se determinaron los valores de FSQ, VJ, PP, RV30, BMD, BMC, MM y EMG. El grupo VBT entrenó a una velocidad propulsiva (VMP) de 0,68 ±0,08 m s − 1 y PBT entrenó a 70-80% de 1RM. El RT produjo aumentos significativos (p < 0,05) en los dos grupos en FSQ (VBT 33,79%, PBT 27,94%), VJ (VBT 19,11%, 8,77% PBT), RV30 (VBT 6,27%, PBT 1,66%), PP (VBT 32,2%, PBT 16,11%), MM sin grasa (VBT 3,7%, PBT 2,64%) CMO (VBT 0,39%, PBT 0,25%) y en DMO (VBT 0,76%, PBT 0,80%). No se observaron variaciones significativas en la actividad EMG en ninguno de los grupos. Se identificaron diferencias significativas entre los dos grupos de entrenamiento para DMO, PP, CMJ y RV30. En conclusión, el grupo VBT mostró mejores resultados que PBT con una menor carga de entrenamiento, lo cual es importante para un mejor seguimiento de la fatiga durante el entrenamiento de fuerza.
... Numerous studies conducted over the past few decades have examined various percentages of velocity loss (%VL). Some research [14][15][16] indicates that a low %VL (5-15%) leads to comparable or greater improvements in strength, sprint time, and jumping ability than a higher %VL (greater than 20%), while not all studies have reached the same conclusion [17,18]. Interestingly, two recently published reviews comparing the effectiveness of velocity-based training (VBT) and traditional strength training presented conflicting results. ...
... A growing body of studies have recently emerged evaluating the impacts of different %VLs on the set on performance outcomes in athletic populations, with the presented data generally in line with this study's findings. In an 8-week study involving 16 training sessions conducted by Pareja-Blanco et al. [15], it was found that velocity-based training (VBT) with a 20% velocity loss produced squat strength gains similar to those achieved with a 40% velocity loss (18% and 13.4%, respectively). Additionally, the 20% velocity loss group demonstrated significantly greater improvements in counter-movement jump (CMJ) performance, showing an increase of 9.5% compared to just 3.5% in the 40% velocity loss group (p < 0.05) among resistance-trained young athletes. ...
The objectives of this study were to compare the effects of two in-season velocity loss training methods (VBT) on performance outcomes and to evaluate the effects of velocity-based training compared to traditional resistance training (TRT) on performance outcomes in young elite soccer players. VBT utilized the same relative load but varied in the extent of velocity loss during the set: 15% (VL15%) and 30% (VL30%). Thirty-four players were recruited and randomly distributed into three groups: the VL15% group (n = 12; age = 18.50 ± 0.67 years; stature = 183.41 ± 4.25 cm; body mass = 75.08 ± 5.57 kg), the VL30% group (n = 11; age = 17.91 ± 0.60 years; stature = 181.21 ± 6.56 cm, body mass = 73.58 ± 6.22 kg), and the traditional strength training group TRT (n = 11; age = 18.14 ± 0.74 years; stature = 182.17 ± 5.52 cm; body mass = 74.86 ± 6.68 kg). Alongside regular soccer sessions and matches, the groups underwent a four-week (2 sesions per week) resistance training intervention with back squats involved. Changes in leg strength (SQ1RM), 20 m sprint time (SPR 20 m), countermovement jump height (CMJ), reactive strength index (RSI), and change of direction (COD) from before and after were evaluated using a 3 × 2 ANOVA. While no significant interaction was found for SQ1RM and SPR20, all of the groups showed significant pre to post improvements. Significant interactions were observed for CMJ (F = 38.24, p = 0.000), RSI (F = 8.33; p = 0.001), and change of direction agility test (COD) (F = 3.64; p = 0.038), with a post hoc analysis showing differences between the VL15 (6.0%) and TRT (1.7%) groups (p = 0.034); VL15 (12.2%) and VL30 (3.2%) groups (p = 0.004); VL15 and TRT (0.4%) (p = 0.018); VL15 (2.4%) and VL30 (1.5%) (p = 0.049); and between the VL15 and TRT (0.4%) groups (p = 0.015). Four weeks of VL15% training during the season induced similar strength increases to VL30% and TRT, superior improvements in RSI and COD compared to VL30%, and superior improvements in CMJ, RSI, and COD tests compared to TRT. Thus, incorporating the VL15% training method may be recommended to improve power-related performance metrics in elite young soccer players.
... When short inter-set rest periods are used, it is also possible that the fastest mean velocity of the set (MVfastest) is progressively reduced over the RT session, which can potentially impact the computations of two variables commonly used in practice: mean velocity decline (MVD) and mean velocity maintenance (MVM) Tufano et al., 2016). MVD, computed using the fastest MV of each specific set, has been employed to prescribe the volume of repetitions in RT sessions comprising multiple sets (Pareja-Blanco et al., 2017, whereas MVM is used for testing the ability to maintain high velocity output during a set of multiple repetitions (Tufano et al., 2016). ...
... Future studies should also examine whether neural, metabolic, or neuroendocrine mechanisms can explain these findings. Numerous studies have used relative MVTs (i.e., MVD) as a means to prescribe the number of repetitions during sets not performed to failure Pareja-Blanco et al., 2017Weakley et al., 2020aWeakley et al., , 2020b. It is important to note that all these studies computed MVD using the MVfastest of each specific set as the reference repetition. ...
This study aimed to determine the optimal inter-set rest periods that would maximize the number of repetitions completed before surpassing various cut-off velocities (COVs) during the prone bench pull exercise. Twenty-three physically active individuals, 15 men and 8 women, participated in six random testing sessions. Each session included four sets of the prone bench pull exercise performed with maximum intent on a Smith machine at 75% of the one-repetition maximum (1RM). The length of the inter-set rest interval (1 [R1], 3 [R3], and 5 [R5] min) and COV used (0.65 m•s⁻¹ [COV0.65] and 0.55 m•s⁻¹ [COV0.55]) varied between sessions. Longer inter-set rest periods led to a higher volume of repetitions (R5 > R3 > R1), whereas the differences between the rest protocols were larger for COV0.55 (R1: 28.4 ± 6.0 repetitions; R3: 36.4 ± 9.4 repetitions; R5: 41.1 ± 11.4 repetitions) compared to COV0.65 (R1: 24.2 ± 7.3 repetitions; R3: 25.4 ± 10.1 repetitions; R5: 28.3 ± 9.7 repetitions). Increasing the number of sets negatively impacted the number of completed repetitions for R1 using both COV0.65 and COV0.55, as well as for R3 using COV0.55. The fastest velocity of the set (MVfastest) did not differ between the inter-set rest protocols for COV0.65, while for COV0.55, R3 and R5 provided a greater MVfastest than R1 for sets 2–4. These findings suggest that the duration of inter-set rest periods is an important factor to consider when aiming to maximize mechanical performance across multiple sets of the prone bench pull exercise.
... However, R 50-85 appears to induce greater improvements in SQ strength from the middle to the end of the training program. In line with these results, again, it seems that the specificity of the loads used (>70% 1RM) from the middle to the last training program (Table 2) accomplished by R 50-85 induces higher strength adaptations in SQ compared to other groups [26,27]. ...
(1) Background: The range of loads is defined as the difference between the highest and the lowest relative load (i.e., %1RM) used throughout a resistance training program. However, the optimal range of loads has not been studied yet. Thus, the aim of this study was to compare the effects of different ranges of load (from 50 to 85% 1RM (R50–85), from 55 to 75% 1RM (R55–75), and from 60 to 70% 1RM (R60–70) on physical performance using velocity-based resistance training (VBT). (2) Methods: Thirty-eight men (mean ± standard deviation; age: 23.3 ± 3.6 years, body mass: 76.5 ± 8.3 kg, and height: 1.77 ± 0.04 m) were randomly assigned to R50–85, R55–75 and R60–70 groups and followed an 8-week VBT intervention using the full squat (SQ) exercise. All groups trained with similar mean relative intensity (65% 1RM) and total volume (240 repetitions). Pre- and post-training measurements included the following: in the SQ exercise, 1RM load, the average velocity attained for all absolute loads common to pre-tests and post-tests (AV), and the average velocity for those loads that were moved faster (AV > 1) and slower (AV < 1) than 1 m·s⁻¹ at Pre-training tests. Moreover, countermovement jump (CMJ) height and 10 m (T10), 20 m (T20), and 10–20 m (T10–20) running sprint times were measured. (3) Results: Significant group x time interactions were observed in AV (p ≤ 0.01), where R50–85 obtained significantly greater gains than R60–70 (p ≤ 0.05). All groups attained significant increases in 1RM, AV, AV > 1, AV < 1, and CMJ (p ≤ 0.001–0.005). Significant improvements were observed in running sprint for R60–70 in T10–20 and R60–70 in T20 and T10–20 (p ≤ 0.05), but not for R50–85. (4) Conclusions: Different ranges of loads induce distinct strength adaptions. Greater ranges of loads resulted in greater strength gains in the entire load-velocity spectrum. However, in high-velocity actions, such as sprinting, significant enhancements were observed only for smaller ranges of loads. Coaches and strength and conditioning professionals could use a range of loads according to the time-related criterion (i.e., proximity or number of future competitions), enabling better adaptation and increasing physical performance at a specific time.
... This indicates that the postural muscles may become more efficient as they strengthen, which could be relevant in preventing posture-related injuries. 20,21 In the present study, electromyographic activity was observed in all PNF patterns and linear movement (p < 0.05), indicating that both diagonal and rectilinear Table 3. ...
Introduction: Proprioceptive neuromuscular facilitation (PNF) is a concept that promotes functional movement through facilitation, inhibition, strengthening, and relaxation of muscle groups. Among its principles, irradiation is defined as the propagation of the response to the stimulus, which can be evidenced as increased contraction or relaxation in synergistic muscles and movement patterns. Objective: To evaluate PNF patterns in muscle irradiation to the contralateral lower limb through surface electromyography in physical therapy students. Methods: This is a cross-sectional study with a quantitative and analytical approach. Thirty healthy volunteers participated in the study and were evaluated with surface electromyography as they performed PNF and rectilinear movement patterns. Results: It was found that PNF patterns radiate to the contralateral limb, with the flexion-abduction-internal rotation pattern with knee flexion being statistically significant (p < 0.05). It was observed that the upper patterns do not significantly irradiate to the contralateral limb when compared with lower limb movements (LL). In the correlation between strength and electromyographic activation, the medial gastrocnemius obtained the greatest strength and the lowest muscle activation in movements involving hip or shoulder flexion. Conclusion: PNF diagonals irradiate to the LL contralateral to that tested in the electromyography. New studies with a larger sample size are needed to investigate contralateral muscle irradiation in healthy individuals through surface electromyography in order to obtain a more robust correlation.
... Por su parte, la configuración clúster comparte el control sistemática de la resistencia (%1RM), pero se diferencia por la inclusión de pausas dentro de cada serie (intraserie) (Lawton et al., 2006); es decir, recuperación entre cada repetición (Haff et al., 2008) permitiendo tiempos de recuperación entre 10 a 30 segundos por cada repetición o bloques de repeticiones; estas pausas se ajustan según las pérdidas de velocidad observadas durante la ejecución (Haff et al., 2008;Haff et al., 2003). El principal objetivo del clúster es minimizar los niveles de fatiga muscular acumulados a lo largo de la serie, preservando la mayor velocidad de ejecución posible según lo programado; facilitando el mantenimiento de altos niveles de aplicación de fuerza, traduciéndose en mejoras en el rendimiento neuromuscular (Haff et al., 2003;Pareja-Blanco et al., 2017;Poliquin, 1997). En contraste, la configuración tradicional incorpora el descanso entre series completas (Haff et al., 2003;Latella et al., 2019;Tufano et al., 2016), lo que también ha demostrado ser eficaz para mejorar la fuerza (Janićijević et al., 2023;Rahimi, 2005;Santana et al., 2024;Schoenfeld et al., 2016). ...
Introduction: The set configuration in strength training is key to optimising chronic adaptations. Objective: The study aimed to compare the effects of cluster and traditional set configurations on maximal dynamic strength in young weightlifting. Methodology: A quasi-experimental design with repeated measures was employed. Nine Tier 3 athletes participated in the study (age: 15.4 ± 0.9 years, body mass: 61.4 ± 10.9 kg, height: 163.9 ± 10.4 cm, peak height velocity:-0.41 ± 0.44 years). Participants were assigned to either the experimental group or the control group and underwent a four-week intervention. The experimental group performed the cluster configuration (intraset rest [30 seconds]), while the control group followed the traditional configuration (intraset rest [0 seconds]). Maximal dynamic strength was assessed using the one-repetition maximum in the snatch, back squat, and bench press exercises. Results: A significant interaction was found between time (pretest and posttest) and group (ex-perimental vs. control) in the back squat and bench press (p < 0.05), but not in the snatch (p = 0.227). In the temporal analysis, the cluster group showed significant improvements in both exercises (p < 0.05). The increases in maximum dynamic strength ranged from 7% to 8%; however , these variations did not exceed the minimal detectable change. The effect size associated with the differences was considered large (ES ≥ 0.14). Conclusions: The cluster configuration was more effective than the traditional method in the squat and bench press movements, inducing improvements in maximum dynamic strength in the short term.
... En este sentido, la evaluación de la fuerza se posiciona como uno de los criterios más válidos en el rendimiento deportivo , siendo el objetivo principal del entrenamiento de fuerza en futbolistas, el mejorar su capacidad de desplazamiento horizontal (aceleraciones y cambios de dirección), y vertical mediante el salto (Styles et al., 2016). Entre las acciones 4 analizadas para evaluar la potencia mecánica en miembros inferiores, existen múltiples investigaciones que han usado la sentadilla como ejercicio base (Balsalobre-Fernández et al., 2012;Pareja-Blanco et al., 2017;Rodríguez-Rosell et al., 2021), ya que se trabaja la fuerza y la potencia en los músculos extensores de cadera, rodilla y tobillo, lo que contribuye a una mayor capacidad de generación de fuerza en acciones como el esprint y los saltos (Keiner et al., 2013;Silva et al., 2015) Cabe destacar que el DBL no es necesariamente un indicador negativo o positivo por sí mismo, ya que puede haber variaciones individuales y contextuales en relación con cada deporte y sus demandas específicas (Ascenzi et al., 2020). En este sentido, en el fútbol existe un requerimiento multifacético en términos de fuerza, potencia, velocidad, coordinación y agilidad (Rampinini et al., 2011). ...
En el deporte, más concretamente en el fútbol, el déficit bilateral (DBL) tiene efecto sobre el rendimiento físico y la prevención de lesiones. El déficit bilateral puede cambiar los patrones de movimiento, lo que lleva a una mala técnica y a la pérdida de potencia, velocidad y precisión en los jugadores de fútbol. El presente estudio tiene como objetivo evaluar los efectos del DBL en el salto contra movimiento (CMJ) y el rendimiento de la sentadilla trasera con el máximo peso en una repetición máxima (1RM). En total, 40 jugadores de fútbol participaron en este estudio y realizaron CMJ bilaterales y unilaterales y sentadillas traseras 1RM. Se clasificaron en tres grupos en función de su nivel de DBL, que se calculó a partir de la diferencia entre la altura bilateral de CMJ y la suma de las dos alturas unilaterales de CMJ. Los resultados mostraron diferencias significativas entre los grupos en las variables tiempo de vuelo (p=.001), altura de salto (p=.001), y potencia (p=.003), así como las diferencias entre piernas según el nivel de déficit en la altura del CMJ de una sola pierna (tanto derecha como izquierda) y doble pierna. También se encontraron diferencias significativas entre el DBL y la potencia mecánica en la sentadilla trasera (F=7.373, p= .04, η²=0.285). En conclusión, un DBL alto se asocia con un menor rendimiento en variables del salto como tiempo de vuelo, altura y potencia, así como una menor potencia generada en la sentadilla trasera.
... While individualized relationships provide greater accuracy in estimating proximity to failure, they require individuals to perform sets to failure for their assessment, which presents practical challenges. Note that training to failure intensifies immediate mechanical, metabolic, and perceptual fatigue and prolong recovery periods following RT sessions [21][22][23], whereas it fails to maximize neuromuscular adaptations and strength gains [6,24,25]. ...
Background
This study compared the accuracy of three generalized approaches for estimating proximity to failure during the Smith machine bench press: (i) the relationship between relative load (%1RM) and maximum repetitions performed to failure (%1RM-RTF), (ii) the relationship between maximum repetitions to failure and fastest set velocity (RTF-velocity), and (iii) the relationship between repetitions left in reserve (RIR) and lifting velocity (RIR-velocity).
Methods
Nineteen physically active men (22.9 ± 2.7 years old) with at least two years of resistance training experience participated. Their 1-repetition maximum (1RM = 86.8 ± 16.7 kg) was determined during the first session. In the second session, participants performed single sets to failure at 60% and 80% 1RM, with proximity to failure (2RIR and 4RIR) estimated using each approach.
Results
The RIR-velocity relationship was the only approach that did not significantly deviate from the intended RIR (errors = -0.4 to 0.6 repetitions). In contrast, both the %1RM-RTF and RTF-velocity relationships overestimated the intended RIR at 60%1RM for both 2RIR (2.9 and 5.8 repetitions, respectively) and 4RIR (2.8 and 5.7 repetitions, respectively), while no significant differences were observed at 80%1RM (errors = -0.6 to 0.9 repetitions). The RIR-velocity relationship generally demonstrated the lowest absolute errors compared to the actual RIR (1.3 ± 0.7 repetitions), with greater differences compared to the other two approaches at lighter loads and closer proximities to failure.
Conclusions
In the absence of individual relationships, the general RIR-velocity relationship should be used by coaches to control the proximity to failure of their athletes during the bench press exercise.
... In fact, some studies have suggested the role of VBT in enhancing athletic performance, including power, countermovement jumping (CMJ) and sprinting ability (Banyard et al., 2020;Pareja et al., 2017a;Ramírez et al., 2015). However, some researchers have reported results related to VBT, including non-significant changes in CMJ, sprint and power test sense (Pareja et al., 2017b;Rodríguez et al., 2021;Orange et al., 2019). Research has emphasised the effectiveness of VBT compared to traditional 1RMbased resistance training in improving lower limb explosive strength (Held et al., 2022). ...
The aim of the study was to investigate the effects of velocity-based (VBT) and traditional strength training (TST) methods on vertical jump, dynamic balance, agility, 10 m acceleration and 20 m sprint performances. Twelve volunteer men randomly divided into two groups participated in the study. After 1 Repetition Maximum (1RM) was determined, the TST group performed 3 sets of 10 repetitions with 40-60% of their maximum weight, while the VBT group performed 3 sets of strength training at a velocity range of 0.75-1.0 m/s for 6 weeks, 2 days a week. In the VBT group, a significant difference was found between 55.16±6.17 cm in the pre-test and 59.16±4.99 cm in the post-test of vertical jump and 4.05±0.27 in the pre-test and 1.72±0.27 in the post-test of balance (p<0.05). There was a significant difference between 48.33±3.98 cm in the pre-test and 53.66±4.03 cm in the post-test; between 4.29±0.29 in the pre-test and 3.65±0.48 in the post-test. Optimising the speed while lifting load in VBT enables athletes to react faster to sudden position changes by improving dynamic balance. Although 6 weeks of VBT training increased vertical jump, the difference was not statistically significant, which may be due to sample size, training duration or individual differences. As a result, the increase in vertical jump and balance in both strength training exercises can be explained by the fact that squat exercise activates the quadriceps muscles by activating the knee joint and increases leg strength, endurance and knee stabilisation.
... Birds were required to individually run up the ramp a minimum of 10 times before the end-ofexercise criteria was considered to be achieved based on Pareja-Blanco et al. [31]. Briefly, the WAIR exercise training regimen was considered complete for the day once a 40% decrease in velocity from the fastest run was recorded twice consecutively, two unsuccessful runs were recorded, or a combination of both. ...
Domestic chickens kept for egg laying navigate inclines such as ramps in some commercial housing systems to aid in transitions between housing tiers. Laying hens use their wings and hindlimbs in a locomotion called wing-assisted incline running (WAIR) to ascend steep inclines. There is a potential relationship between the strength of the main flight muscles and the health of the keel bone from which they originate. We sought to test the effects of a controlled, WAIR-based exercise regimen during rearing on keel bone health and muscle properties of white- and brown-feathered laying hens. The WAIR exercise regimen, which consisted of exercise twice weekly for 16 weeks did not promote increases in muscle mass or physiological cross-sectional area at 21 weeks of age (WOA) and did not provide long-term benefits on keel fracture prevalence at 40 WOA. However, the brown-feathered birds were found to have lower amounts of keel fractures at 40 WOA in comparison with the white-feathered birds. Future studies should test for training that begins before chicks become fully feathered, exercises that emphasize full excursion of the wing during downstroke and different levels of intensity, frequency and duration to optimize flight muscle architecture and promote keel bone health.
... If the MCV is found to differ from the target MCV in each training set, the difference is ±0.06 mV. With a difference of ±0.06 m/s, the barbell load of ±5% 1RM was adjusted for later training [21]. All the training loads are shown in Table 1. ...
Purpose: Footwork speed is closely linked to explosive strength, and both percentage- (PBRT) and velocity-based resistance training (VBRT) are popular methods for developing muscle strength. This study aimed to compare the effects of PBRT and VBRT on lower limb explosive power and footwork movement speed in elite university badminton players over a 6-week training period. Methods: A total of 20 elite badminton players (12 males, 8 females) from Tongji University were randomly divided into VBRT (n = 10) and PBRT groups (n = 10). The VBRT group trained with loads determined by target speed and velocity loss, while the PBRT participants used fixed loads based on a percentage of their one-repetition maximum (1RM). Both the groups performed free-weight back squats with relative loads ranging from 65% to 95% of 1RM over 6 weeks. The pre- and post-training measurements included back squat 1RM; countermovement (CMJ), squat (SJ), and standing long jumps (SLJs); self-weighted squat jump speed (SJS); left and right touch line (LRF), full-field four-point (FF), and front and back touch net footwork (FBF). Results: (1) The baseline measurements showed no significant differences between the groups (p > 0.05). (2) Post-training, both VBRT and PBRT improved the participants’ lower limb explosive power and footwork movement (p < 0.05). (3) The VBRT group demonstrated significantly greater improvements than the PBRT group in all the measures (p < 0.05). Conclusions: VBRT was superior to PBRT in boosting lower limb explosive power and footwork speed in badminton players over 6 weeks, leading to more significant strength–related and neural adaptations.
... Dentro de la dinámica de la aplicación del método de entrenamiento, diversos artículos han documentado mejoras significativas en la fuerza al considerar la velocidad y el tiempo como parámetros relevantes. Estos cambios se han observado en una variedad de ejercicios, lo que subraya la versatilidad y eficacia del enfoque (Conceição et al., 2016;Pareja et al., 2017;Cormie et al., 2011;Pareja et al., 2020;García et al., 2021;Cosic et al., 2021;Alcázar et al., 2021;González et al., 2011;Nuzzo et al., 2023;Bastos et al., 2024;Bird et al., 2005). En relación con la secuencia temporal donde establece la mejor relación entre fuerza y velocidad ) y Shimano et al. (2006, sugieren que los intervalos de tiempo ideales para esta interacción oscilarían entre los (50 y 300) ms. ...
El análisis de la relación fuerza-velocidad es crucial para optimizar el rendimiento deportivo en basquetbolistas, ya que permite ajustar las cargas de entrenamiento de manera precisa para mejorar la fuerza aplicada en situaciones de juego real. Objetivos: El objetivo principal de este artículo es determinar la mejor relación entre fuerza y velocidad para estimar tanto los porcentajes de carga relativos como absolutos que optimizan la mejora de la fuerza en los jugadores de baloncesto. Métodos: A través de un muestreo probabilístico aleatorio simple, se seleccionarán 65 participantes, todos basquetbolistas de edad media 19.42±0.5. estatura 1.74±11.4. peso 72.91±4.05. Vo2max 53.32±7.27. Fcmax 196.5±5.90. % grasa 25.38±3.77. % masa muscular 39.75±3.58. Los participantes realizarán dos pruebas de fuerza máxima: sentadilla media y press de banca, utilizando un encoder lineal para medir la fuerza y velocidad de los movimientos. Resultados: La mejor relación entre fuerza y velocidad en sentadilla media se encuentra con una carga media 53.38 kg, velocidad de 1.05 m/s. En el press banca 37.58 kg, velocidad 0.99 m/s. y los rangos relativos para desarrollar la potencia, varían entre 46.3% y el 73.6% en sentadilla media, y el 34.8% y el 55.8% press banca. Conclusiones: EL estudio identifica los rangos ideales de peso y velocidad para la ejecución en sentadilla y press banca, determinando los porcentajes de carga relativa más efectivos para maximizar la potencia muscular. Además, enfatiza la importancia de adaptar tanto la carga como la velocidad según los objetivos específicos del entrenamiento, destacando que la evaluación de la fuerza máxima (1RM) es un elemento esencial para personalizar el entrenamiento y optimizar los resultados.
... Thus, subjects had to put a weight on the bar with which they could lift for a maximum of 15 repetitions (70% MDF, i.e., 1RM), but they only had to complete 7. Completing half of the total repetitions possible against 70% 1RM would result in a velocity loss of ~20% [18]. This level of intraset fatigue has been shown to be an effective and efficient stimulus to promote lowerlimb neuromuscular adaptations [19,20]. All sets were supervised by two experienced researchers who verified adequate compliance with the aforementioned training parameters and gave feedback to the participants when appropriate. ...
This randomized controlled trial compared the effectiveness of high-intensity off- and on-bike resistance training (RT) in well-trained cyclists. Thirty-seven cyclists incorporated into their cycling routine a 10-week RT only differing in the exercise used: full squat (off-bike RT, n = 12) or high-intensity all-out pedaling efforts (on-bike RT, n = 12). RT variables like intensity (% maximal dynamic force, MDF), volume, sets, and rest were identical between groups. A third group of cyclists who continued their cycling routine but did not include additional RT stimuli was used as a control (n = 13). The cycling volume at each intensity zone was also matched between the three groups. No significant differences were found between off- and on-bike RT in any parameter. RT groups improved the maximal aerobic power (ES ≥ 0.37) and that attained at the respiratory compensation point (RCP, ES ≥ 0.20). The on-bike RT also significantly enhanced power attained at the ventilatory threshold (ES = 0.24). Off-bike MDF was meaningfully enhanced by both RT groups (ES ≥ 0.16), whereas the on-bike group also significantly increased pedaling MDF (ES = 0.67). Quadriceps size was significantly increased by the off-bike group (ES = 0.22), whereas the on-bike RT also tended to augment this parameter (ES = 0.15) and patellar tendon size (ES = 0.35). Improvements in both RT regimes for time-to-exhaustion capacity (ES ≥ 0.30) were considerable but not significant. The off-bike group tended to increase injury-related symptoms (ES ≥ 0.33). The control group significantly decreased off-and on-bike MDF (ES ≤ -0.40) and quadriceps size (ES = -0.26). These findings suggest that high-intensity on-bike RT is an effective alternative to off-bike RT to safely increase strength, muscle-tendon structure, and cycling performance.
... On the third visit, participants performed the incremental loading protocol for the squat exercise. Participants were instructed to perform the eccentric phase at a controlled velocity (i.e., 0.45-0.65 m.s-1 ) and to move as fast as possible during the concentric phase (Pareja-Blanco et al., 2017). ...
Post-activation performance enhancement (PAPE) refers to the temporary improvement in physical abilities resulting from a previous conditioning activity (CA), and velocity-based resistance training has been proposed to optimise PAPE. The present study aimed to evaluate the optimal rest interval to induce PAPE in the countermovement jump using heavy parallel squats monitored by the velocity loss (VL) threshold. The study had a randomised repeated measures design, with three sessions that included a control session and two different squat conditions (80% of 1 repetition maximum (RM) with 10% and 30% VL of mean propulsive velocity). Ten men (age 21.91.16 years, height 1.80.04m, body weight 78.59.9kg, relative strength: 1.40.29kgkg-1) and ten women (age 20.71.16 years, height 1.60.06m, body weight 56.94.67kg, relative strength: 1.10.19kgkg-1) participated in the study. They had at least 1 year of experience with the back squat but no experience in power training. Measurements were taken at baseline and at six time points after the conditioning activity or rest period. The study found no significant effects between intervention and moment and no optimal rest time to induce PAPE, but women had significantly lower countermovement jump (CMJ) values than men(Mmen = 30.01, SE = 1.35; 95% CI 27.17-32.84, Mwomen = 24.33, SE = 1.35, 95% CI = 21.50-27.16), but when values were normalised to body weight, there were no significant differences. In conclusion, a single set of 80% 1RM in the squat to a VL of 10% or 30% is not sufficient to induce PAPE in CMJ; therefore, there is no optimal rest time.
... Lifters interested in this area of study should reference a more objective source on the topic (13). The emphasis is that improved transition from the first to second pull is achieved by exercises completed from the floor and blocks (3,12). The use of blocks supports error correction at different phases of the transition, and in Figure 1, a box height that includes the end of the first pull (knee height) and leads into the second pull is used because it results in the desired velocity profile where the transition point shows an increase in velocity for this lifter. ...
This article examines how to use linear position transducers to support training for weightlifters performing the snatch. These commercially available devices provide valuable velocity data from the first pull, transition, and through the second pull, which all occur before the athlete rotating under the bar for the catch. Athletes benefit from this discussion given the need to maximize training repetitions before fatigue. Velocity data are useful in applying autoregulation principles before workouts and during training sessions. An individualized approach helps weightlifting coaches identify errors and avoid loss of velocity during key points in the lift. This includes determining each lifter's threshold velocities for successful lifts. Deviations from a successful lift/velocity profile (following a missed lift) help identify where errors occur or if fatigue is a factor. This is important to support technique in lifters who are not represented in the published studies. Examining velocity data in conjunction with video analysis provides information needed to prescribe auxiliary exercises or loads for pulling exercises to ensure that velocity loss is minimized. Velocity feedback helps lifters select loads for successful repetitions that produce a desired force profile and result in improved snatches contributing to higher totals during competition.
... This trend is consistent with muscle architecture changes from traditional intervention studies using the leg extension machine (22,33,62,86). Conversely, squats tend to show greater growth of the vasti muscles with minimal effects on the rectus femoris (46,47,67). Therefore, the reverse Nordic may be programmed as an alternative to the machine leg extension and complement the squat. ...
The reverse Nordic is a single joint (knee), controlled open kinetic chain exercise with a predominantly eccentric focus. This review summarizes the reverse Nordic, including exercise benefits, muscles involved, exercise technique, progressions, regressions, and programming strategies. Furthermore, this review outlines how strength and conditioning coaches can use the reverse Nordic within a training program to improve athletic performance and mitigate injury risk.
... This is because regular soccer training increases the accumulation of metabolic byproducts, which can impair the muscle's ability to contract rapidly at high intensity (Rampinini et al. 2011). Similarly, muscle fatigue can also limit the enhancement of muscle strength and speed (Pareja-Blanco et al. 2017). ...
Objective
This study investigates the impact of plyometric training on age-related lower limb explosive strength in male adolescents and its effectiveness in female adolescents.
Methods
A thorough search was conducted across five databases from their inception until September 20, 2024. Study quality was assessed using the Cochrane Risk Assessment Tool, and data analysis was performed with Stata 15 software.
Results
Plyometric training positively affected countermovement jump (CMJ) (MD = 2.90 cm, 95% CI (2.35, 3.45)), squat jump (SJ) (MD = 2.57 cm, 95% CI (1.69, 3.44)), and 20-m sprint performance (MD = − 0.09 s, 95% CI (− 0.14, − 0.05)). Subgroup analysis revealed varying improvements across age stages. In CMJ, the early adolescence (EA) group (MD = 2.57 cm, 95% CI (1.74, 3.40)), mid-adolescence (MA) group (MD = 3.04 cm, 95% CI (2.30, 3.79)), and post-adolescence (PA) group (MD = 3.89 cm, 95% CI (1.96, 5.81)) showed progressive enhancement. The MA group exhibited superior improvements in SJ (MD = 3.78 cm, 95% CI (2.19, 5.36)) and 20-m sprint (MD = − 0.11 s, 95% CI (− 0.18, − 0.05)) compared to the EA group (SJ: MD = 2.10 cm, 95% CI (1.43, 2.77); sprint: MD = − 0.06 s, 95% CI (− 0.11, − 0.01)). The PA group showed no significant improvements (SJ: MD = 1.31 cm, 95% CI (− 1.05, 3.67); sprint: MD = − 0.27 s, 95% CI (− 0.61, 0.07)). For female adolescents, plyometric training effectively improved CMJ (MD = 2.55 cm, 95% CI (1.43, 3.66)), SJ (MD = 2.33 cm, 95% CI (1.36, 3.31)), and 20-m sprint performance (MD = − 0.22 s, 95% CI (− 0.33, − 0.12)).
Conclusion
Plyometric training significantly enhances lower limb explosive strength in both male and female adolescents, with age-dependent effects for male adolescents. The greatest improvement in CMJ was observed in the PA stage, followed by the MA stage, while the EA stage showed the least. The MA stage exhibited the best improvements in SJ and sprint performance.
Trail Registry
The study has been registered in the International Prospective Register of Systematic Reviews (PROSPERO: CRD42023406914).
... Simultaneously, the number of repetitions in the set is determined by the accumulated velocity loss during the set (i.e., decreases in concentric velocity correlate with fatigue and proximity to muscle failure) (44). Thus, it is recommended that the set be stopped when the subject performs 2 consecutive repetitions outside the predetermined speed range for any given goal (45). In this example, the set would be stopped if the subject performed 2 consecutive repetitions with a mean propulsive velocity lower than 0.32 m/s. ...
This review briefly outlines the benefits and limitations of traditional methods for prescribing resistance training (RT) exercise intensity (i.e., the percentage of one-repetition maximum, velocity-based training, and rating of perceived exertion) for special populations based on mechanical and psychological indicators. Given these limitations, the RIR method, which quantifies the discrepancy between potential and actual repetitions, has been proposed as a safer, more effective, and adaptable alternative to optimize RT in special populations. This study provides an overview of the main RIR scales used in scientific literature and synthesizes RIR validation studies. Although the validity and reliability of the RIR method have not been extensively tested across different special populations, and a scarcity of studies applying it in clinical contexts has been detected, this review proposes a practical application that integrates existing scales for prescribing RT in rehabilitation settings and for individuals with chronic health conditions. In conclusion, the RIR method shows promise for broader application in clinical settings, and further research is needed to validate its effectiveness in diverse population groups.
... Hartz Charlini S has proved through experiments that when the strength level is low, low resistance or heavy load should be selected for exercise [6]. Pareja-Blanco Fernando can realize motion control and training effect prediction by using EMG (electromyogram) signal and biofeedback technology [7]. Suchomel Timothy J found that there was a significant positive correlation between the range and speed of joint flexion and extension when the athletes squatted and bent their upper body backward, and between the angle and range of knee joint when they bent their upper body forward [8]. ...
Muscle training is an important part of athletes’ physical training. Its goal is to keep athletes in high intensity and improve sports performance in physical training. With the continuous improvement of the level of competitive sports, there are still many problems in the training of competitive athletes. The research on the control strategies of some technical movements in the process of athletes’ muscle development would help to improve the efficiency and effect of athletes’ training. By analyzing and quant description of muscle movement control process based on blockchain and visual image processing technology, the muscle movement control rule is discussed and then a complete movement database is constructed. At the same time, combined with the sports experiment method and cognitive behavioral theory, this paper analyzed the exercise load, exercise time allocation, muscle training time allocation methods and the corresponding muscle training strategy selection methods under different muscle states, providing theoretical basis for athletes to conduct muscle strength training scientifically and efficiently. This paper first analyzed the importance of athletes’ muscle training action control. After that, the research was mainly carried out from the following two aspects. The first is to analyze the motion control strategy of athlete muscle training based on blockchain and visual image, and summarize its characteristics. The second is to use electronic imaging technology to analyze the data related to posture control in athletes’ muscle training, and explore the characteristics and changes of muscle posture. At last, this paper put forward relevant algorithms about visual images and conducted experimental research on athletes’ physical indicators and performance under different muscle training according to the research in this paper. It was concluded that the score ratio of athletes’ performance after muscle training action control was 7.39% higher than that of general muscle training. Therefore, it is very important to strengthen the research of movement technology in muscle training and analyze the influence of some training control strategies on the development of athletes’ muscles in training.
... Nesse sentido, a série de repetições comumente utilizada em programas de TF resulta em um declínio na força, na velocidade de movimento e também na proficiência da técnica da primeira à última repetição (ou seja, afeta a duração da série) (GOROSTIAGA et al., 2010(GOROSTIAGA et al., , 2012HARDEE et al., 2012), provavelmente devido a um aumento na demanda metabólica e à fadiga neuromuscular (CARNEIRO et al., 2018;GOROSTIAGA et al., 2010GOROSTIAGA et al., , 2012. Além disso, a literatura aponta que programas de TF que promovem fadiga intrassérie podem afetar negativamente os ganhos de potência muscular (uma relação entre força e velocidade) (ANDERSEN; AAGAARD, 2000;ANDERSEN et al., 2010;PAREJA-BLANCO et al., 2017). Em contrapartida, a introdução de períodos curtos de recuperação intrassérie (definido como sistema de treinamento cluster) é capaz de reduzir a fadiga durante as séries (TUFANO; BROWN; HAFF, 2017). ...
... 3 Recent research has investigated the effects of different velocity loss (VL) thresholds as cutoffs for terminating the working set. 7,9 Intensity-matched RT programs differing in VL have been shown to provide distinct adaptations, as RT with higher VL (>20%) resulted in greater muscle hypertrophy, while lower VL (10%-20%) induced greater strength gains. 7,8,10 The greater hypertrophy observed for higher VL thresholds may be due to the combination of high fatigue and volume observed in these protocols, which induces high exerciseinduced metabolic, and mechanical stress, 11 great secretion of growth-promoting hormones, and muscle damage. ...
Purpose: To investigate the effects of 3 training volumes in the bench-press exercise performed with interrepetition rest periods, matched for fatigue, on strength gains and neuromuscular adaptations. Methods: Forty-three resistance-trained men were randomized into 3 groups: low (LOW), moderate (MOD), and high (HIG) volume. The intensities increased from 70% to 85% of 1-repetition maximum (1RM) over the 8-week training period. Each session consisted of only 1 set with short interrepetition rest periods. LOW performed only 3 repetitions per session (8-wk total: 48 repetitions); MOD completed 15, 12, 10, and 8 repetitions per session with 70%, 75%, 80%, and 85% 1RM, respectively (8-wk total: 180); and HIG performed 24, 21, 18, and 15 repetitions per session with 70%, 75%, 80%, and 85% 1RM, respectively (8-wk total: 312). Progressive loading and fatigue tests were conducted in the bench-press exercise before and after the training period. Electromyography (EMG) signals from the triceps brachii were registered during these tests. Results: HIG and MOD showed higher velocity loss than LOW (16% vs 12%). No significant group × time interaction was observed for any variable. All groups improved significantly in all strength-related variables, except for maximal unloaded velocity, where only MOD obtained significant gains. Only LOW and MOD induced significant improvements in EMG. MOD obtained the greatest effect sizes in almost all strength variables. Conclusions: No significant differences were found in the performance gains obtained by each group despite the wide differences in the total volume accumulated by each group.
... The recruitment of more fast musCIe fibres was facilitated by 20% VL, as the preliminary activation training increased neural excitability and accelerated the conduction rate of action potentials in the nerves. This enabled the body to recruit more fast motor units (Pareja-Blanco et al., 2017a), which ultimately manifested itself in the enhancement of the subject's punching force. This hypothesis has been corroborated by previous studies, inCIuding those conducted by Galiano et al. who conCIuded that 20% VL was efficacious in augmenting maximal strength and lower limb explosive power (Galiano et al., 2022), and Folland and Santanielo et al. who demonstrated that 20% VL was beneficial in promoting changes in the pinnation angle of the musCIe fibres, thereby increasing the force of the musCIe contraction (Folland and Williams, 2007;Santanielo et al., 2020). ...
This study was conducted in accordance with the principles of velocity-based training theory, with the objective of investigating the effects of post-activation potentiation (PAP) induced by different velocity loss (VL) thresholds (10% vs. 20%) on the punching ability of boxers. In addition, the aim was to determine the velocity loss thresholds and time nodes that produced the optimal activation effect. Twenty-four male elite boxers were randomly assigned to three groups: CON, 10 VL, and 20 VL. All subjects in the three groups underwent an activation intervention involving an 85% of the one-repetition maximum (1RM) squat, with 6-8 repetitions performed in the CON. The number of repetitions in the 20%VL and 10 VL was determined based on the velocity loss monitored by the GymAware PowerTool system. Four time points were selected for observation: the 4th, 8th, 12th and 16th minutes. These were chosen to test the subjects’ punching ability. The results demonstrated that activation training at different VL induced a post-activation potentiation in boxers, improving punching ability bilaterally and to a greater extent than in the CON. The dominant side demonstrated the greatest efficacy at the 12th minute under the 20% velocity loss threshold, while the non-dominant side exhibited the greatest efficacy at the 8th minute under the 10% velocity loss threshold.
... 1,2 Furthermore, engaging in submaximal levels of effort during RT effectively contributes to positive neuromuscular and athletic performance, while maximal levels of effort tend to favor morphological adaptations. [3][4][5][6][7] Monitoring repetition velocity (under the so-called velocitybased training: VBT) has turned out to be an objective, reliable, and practical methodology for training load prescription. 1,[8][9][10][11][12] VBT allows coaches to control the level of effort incurred during RT using the magnitude of velocity loss (VL, ie, the relative difference between the fastest and the last repetition) attained in each exercise set. ...
Purpose : This study analyzed the influence of 2 velocity-based training-load prescription strategies (general vs individual load–velocity equations) on the relationship between the magnitude of velocity loss (VL) and the percentage of repetitions completed in the bench-press exercise. Methods : Thirty-five subjects completed 6 sessions consisting of performing the maximum number of repetitions to failure against their 40%, 60%, and 80% of 1-repetition maximum (1RM) in the Smith machine bench-press exercise using generalized and individualized equations to adjust the training load. Results : A close relationship and acceptable error were observed between percentage of repetitions completed and the percentage of VL reached for the 3 loading magnitudes and the 2 load-prescription strategies studied ( R 2 from .83 to .94; standard error of the estimate from 7% to 10%). A simple main effect was observed for load and VL thresholds but not for load-prescription strategies. No significant interaction effects were revealed. The 40% and 60% 1RM showed equivalence on data sets and the most regular variation, whereas the 80% 1-repetition maximum load showed no equivalence and more irregular variation. Conclusion : These results suggest that VL is a useful variable to predict percentage of repetitions completed in the bench-press exercise, regardless of the strategy selected to adjust the relative load. However, caution should be taken when using heavy loads.
... On the other hand, increasing the time in the concentric phase does not seem to have clear benefits on muscle hypertrophy [102]. Therefore, it is not advisable to deliberately slow down this phase but to allow it to slow down when the character of the effort at the end of the series requires it [103]. ...
The present chapter delves into the topic of muscle hypertrophy in detail, focusing on defining what muscle hypertrophy is, the types of hypertrophy, the mechanisms, and the relationship with resistance training, as well as the variables affecting hypertrophy such as nutrition, rest, exercise selection, training volume, and training frequency, among others. The importance of mechanical tension, metabolic stress, and muscle damage as triggers for muscle hypertrophy is emphasized. Various types of muscle hypertrophy are explored, including connective tissue hypertrophy and sarcoplasmic and myofibrillar hypertrophy. The text also delves into how hypertrophy mechanisms relate to resistance training, highlighting the significance of mechanical tension and metabolic stress as stimuli for muscle hypertrophy. In a practical point of view, the text also discusses factors like nutrition and recovery, highlighting the importance of maintaining a positive energy balance and adequate protein intake to promote muscle growth optimally. Training variables such as exercise selection, exercise order, intensity, volume, frequency, and tempo of execution are discussed in detail, outlining their impact on muscle hypertrophy. The text provides a comprehensive overview of muscle hypertrophy, analyzing various factors that influence the ability to increase muscle mass. It offers detailed information on the biological mechanisms, types of hypertrophy, training strategies, and nutritional and recovery considerations necessary to achieve optimal results in terms of muscle hypertrophy.
... This is because an appropriate load effectively prevents fatigue from occurring prematurely, and during training, subjects can maintain high neural excitability, which accelerates the conduction rate of action potentials in the nerves. This, in turn, provides the organism with the possibility of recruiting more fast motor units (Pareja-Blanco et al., 2017b), which is ultimately manifested in the enhancement of the subject's punching force. Previous studies have also corroborated this hypothesis. ...
Optimal load training is a method of training that aims to maximize power output. This is achieved by arranging optimal loads (optimal ratios of load intensity and load volume) during strength training. The fixed load intensity and number of repetitions employed in traditional strength training. The present study will investigate the applicability of these two load arrangements to female elite boxers. Twenty-four elite female boxers were divided into three groups [optimal load (OL = 8), traditional load (TL = 8) and control group (CG = 8)]. The six-week intervention consisted of strength training with different loading arrangements. The punching ability and strength were tested before and after the intervention. We found that optimal load training enhances a boxer’s punching ability and economy, which aligns with the demands of boxing and is suitable for high-level athletes, whose strength training loads require a more individualised and targeted approach.
... Optimal VBT programming, load prescription and management, and potentially the athlete's adaptive response to training hinges on the validity and reliability of the measurement device utilized. Pareja-Blanco et al. (30) found that small changes in velocity over the course of a set can signify practically significant fatigue-induced changes in neuromuscular and functional performance. Other research describing the load-velocity relationship for various resistance training exercises observed that changes ranging from 0.05 to 0.10 m/s in the bench press and full squat on a Smith machine could represent a 5% 1RM improvement (23,31). ...
The aim of this study was to determine the validity, reliability, and sensitivity of a new linear position transducer (LPT) device (RepOne) to a previously validated LPT (Tendo) during the barbell back squat and bench press exercises. Fourteen recreationally resistancetrained individuals (7 males and 7 females) performed three repetitions for the back squat and bench press at loads ranging from 30–90% 1RM. Both devices recorded average (ACV) and peak (PCV) concentric velocities concurrently for every repetition at each load. Significant correlations were observed between RepOne and Tendo during the back squat (PCV: r = 0.90–0.99, p < 0.01; ACV: r = 0.84–0.99, p < 0.01), bench press (PCV: r = 0.74–0.99, p < 0.01; ACV r = 0.81–0.99, p < 0.01). ICCs reveal good to excellent reliability between devices for back squat (PCV, 0.85–0.99; ACV, 0.83–0.99) and bench press (PCV, 0.79–0.99; ACV, 0.83–0.99). Bland-Altman plots revealed greater bias during PCV for both exercises across intensities (back squat, 0.072 to 0.110 m/s; bench press, 0.039 to 0.107 m/s), although ACV bias was lower for both exercises (back squat, −0.002 to −0.029 m/s; bench press, −0.022 to 0.015 m/s). The RepOne device generally exhibited higher smallest detectable change (SDC) values compared to the Tendo, except for specific loads in certain conditions. Additionally, the RepOne device demonstrated higher smallest worthwhile change (SWC) values than the Tendo unit for most loads in back squat ACV. Collectively, the RepOne exhibits strong validity and reliability comparable to the Tendo across both barbell back squat and bench press exercises, despite some variations in sensitivity metrics like SDC and SWC, indicating its efficacy for resistance training application.
... This study is based on the analysis of resting and post-exercise skeletal muscle biopsies obtained in research projects from our laboratory to determine mechanisms of fatigue after a strength-training intervention [14,43] and high-intensity exercise [3,4,44]. In the main experiments 1 and 2, resting muscle biopsies were obtained from the vastus lateralis (VL) muscle of a healthy, physically active human. ...
... 8,9 Longitudinal RT studies have already been conducted to examine the effect of RT with different VL thresholds. [10][11][12][13][14][15][16][17][18] Previous research focusing on the upper limb indicates that due to the higher metabolic and mechanical stress, higher VL thresholds (25%-50%) maximize muscle hypertrophy. 12 Conversely, as a consequence of increased motor unit frequency, increased discharge doublets, and changes in fiber types, lower VL thresholds (<25%) result in positive neuromuscular-related adaptations. ...
Purpose: This study explored the effects of 4 bench-press (BP) training programs with different velocity-loss (VL) thresholds (0%, 15%, 25%, and 50%) on strength gains and neuromuscular adaptations. Methods: Forty-six resistance-trained men (22.8 [4.4] y) were randomly assigned into 4 groups that differed in the VL allowed within the set: 0% (VL0), 15% (VL15), 25% (VL25), and 50% (VL50). Training loads (40%–55% 1-repetition maximum), frequency (2 sessions/wk), number of sets (3), and interset recovery (4 min) were identical for all groups. Participants completed the following tests before and after an 8-week (16-session) BP training program: (1) maximal isometric test, (2) progressive loading test, and (3) fatigue test in the BP exercise. During all tests, triceps brachii muscle electromyography was assessed. Results: After completing the resistance-training program, no significant group × time interactions were noticed for isometric and dynamic BP strength variables. The dose–response relationship exhibited an inverted U-shaped relationship pattern, with VL25 showing the greatest effect sizes for almost all strength variables analyzed. The total number of repetitions performed during the training program increased as the VL magnitude increased. Conclusions: The group that trained with high VL threshold (50%), which performed a total of 876 repetitions, did not experience additional strength gains compared with those experienced by the 0%, 15%, and 25% of VL groups, which performed significantly fewer repetitions (48, 357, and 547, respectively). These findings suggest that when light loads (40%–55% 1-repetition maximum) are used, low and moderate VL thresholds (0%–25%) provide a higher training efficiency.
... This would be due to concurrent training, which improves the energy cost of locomotion [46]. Moreover, low to moderate strength training efforts with repetitions together with muscle failure avoidance may improve performance while also preventing the negative effects of muscle hypertrophy or fatigue [47]. In addition, isometric strength work is a good complement to the aforesaid type of training, as it increases strength without generating any major muscle fatigue [35]. ...
1) Background: Studies on injury prevention programs are lacking for triathletes. The aim of the present study was to describe the results of a holistic (injury) training prevention program (HITP), based on training load control and strength training, in elite triathletes. (2) Methods: The study was conducted over 2021-2023 and involved 18 males and 10 females from the same training group. The HITP itself included various methods of fatigue monitoring, strength training focused on the prevention of overuse injuries (OIs), cycling skills training, and recovery strategies. The total number and type of injuries that were sustained, subsequent training/competition absence time, and injury incidence were determined. (3) Results: Twenty-four injuries were recorded over all three seasons, i.e., 0.65 injuries per 1000 h of training and competition exposure. Fourteen injuries were traumatic injuries (TIs) and ten were OIs. Of the OIs, four were of minimal severity, two were mild, three were moderate, and one was severe (accounting for 1-3, 4-7, 8-28, and >28 days of training absenteeism, respectively). A total of 46.4% of the participants did not present any type of injury and 71,4% did not incur any OIs. Average absenteeism was 17.3 days per injury. (4) Conclusions: The HITP design and implementation resulted in low OI and severe injury incidence. Due to their unpredictable nature, the number of TIs was not reduced. The TIs were suffered more frequently by men. Women are more likely to suffer from OIs, so it is particularly important to prevent OIs in women.
... For athletes, having strong and explosive muscles is essential for high vertical jumping ability and overall athletic performance (Secomb et al., 2015). Longterm physical training can lead to changes in muscle ACSA, MT, FL, and PA, thereby improving muscle strength and explosiveness levels (Narici et al., 1996;Blazevich, 2006;Pareja-Blanco et al., 2017). This training method has a significant impact on performance in activities such as jumping, sprinting, and change of direction, and it also plays an important role in specialized sports skills and performance (Suchomel et al., 2018;Suchomel et al., 2016). ...
Objective
The objective of this investigation is to examine the contribution of key muscle groups in the lower limbs to vertical jumping performance in elite male volleyball players. Specifically, the study focuses on the rectus femoris (RF), vastus lateralis (VL), and lateral gastrocnemius (LG), as well as exploring differences between attack jump and other vertical jump types.
Methods
To achieve this, we employed B-mode ultrasound to evaluate the anatomical cross-sectional area (ACSA), muscle thickness (MT), pennation angle (PA), and fascicle length (FL) of the RF, VL, and LG in the participants. Fifteen elite male volleyball players were recruited as participants for this study. Jump heights were measured for four types of vertical jumps: attack jump (AJ), countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ). We conducted regression analyses to assess whether the previously mentioned muscle structures could predict jump performance.
Results
Our findings reveal that the muscle structure of the RF does not exhibit any significant correlation with the height of any jump. However, VL-ACSA displays a significant and the most potent predictive effect on jump height for all four jump types (AJ: R 2 = 0.32, p = 0.001; CMJ: R 2 = 0.37, p = 0.005; SJ: R 2 = 0.52, p = 0.001; DJ: R 2 = 0.25, p = 0.021). Conversely, LG-FL only demonstrates a significant and stronger predictive effect on AJ jump height (R 2 = 0.18, p = 0.009). Combining VL-ACSA, LG-FL, and training age through multiple linear regression analysis resulted in a highly significant model for predicting AJ jump height (F = 13.86, R 2 = 0.73). Moreover, the model incorporating VL-ACSA and training age is also important for predicting CMJ, SJ, and DJ jump heights (F = 8.41, R 2 = 0.51; F = 13.14, R 2 = 0.63; F = 5.95, R 2 = 0.41; respectively).
Conclusion
The muscle structure indicators in the lower limbs significantly predict jump performance among elite male volleyball players. However, different jump types are influenced by distinct indicators, particularly in the case of AJ, which is associated with LG-FL. This suggests that enhancing LG-FL may positively impact AJ ability, thereby emphasizing the importance of specificity in training. To optimize specialized jump performance in volleyball players, practitioners are advised to assess VL-ACSA and LG-FL and incorporate step-up and eccentric strength training targeting the calf muscles to yield considerable benefits.
Bu çalışma, 6 haftalık hız temelli güç antrenmanı (HTGA) programının futbolcuların dikey sıçrama performansı üzerindeki etkilerini incelemiştir. Toplam 24 erkek futbolcu, rastgele iki gruba ayrılmıştır: performans grubu (n = 12) ve kontrol grubu (n = 12). Performans grubu, haftada iki kez HTGA programına katılırken, kontrol grubu standart antrenmanlarına devam etmiştir. Dikey sıçrama performansı, Vald Performance ForceDecks sistemi ile ön test ve son test olarak değerlendirilmiştir. Veriler, SPSS yazılımı (sürüm 25.0) kullanılarak analiz edilmiştir. Tüm değişkenler için tanımlayıcı istatistikler (ortalama ± standart sapma) hesaplanmıştır. Verilerin normalliği Shapiro-Wilk testi ile değerlendirilmiş, gruplar arasındaki ön test ve son test sonuçları için iki yönlü tekrarlayan ölçümler ANOVA analizi yapılmıştır. Sonuçlar, performans grubunun kontrol grubuna göre dikey sıçrama yüksekliğinde anlamlı bir artış gösterdiğini (p<0,05) ortaya koymuştur. Bu bulgular, HTGA'nın alt vücut gücünü artırmada etkili olduğunu göstermektedir. Gelecek araştırmalar, HTGA'nın diğer performans metrikleri ve sakatlanma önleme potansiyelini incelemelidir. Abstract This study examined the effects of a 6-week velocity-based power training (VBPT) program on the vertical jump performance of football players. A total of 24 male football players were randomly divided into two groups: the performance group (n = 12) and the control group (n = 12). The performance group participated in the VBST program twice a week, while the control group continued with standard training sessions. Vertical jump performance was assessed using the Vald Performance ForceDecks system through pre-tests and post-tests. Data were analyzed using SPSS software (version 25.0). Descriptive statistics (mean ± standard deviation) were calculated for all variables. The normality of the data was evaluated using the Shapiro-Wilk test, and a two-way repeated measures ANOVA was performed to compare pre-test and post-test results between groups. The results revealed a significant increase in vertical jump height for the performance group compared to the control group (p<0.05). These findings indicate that VBST is an effective method for enhancing lower body strength. Future research should investigate the long-term effects of VBST on other performance metrics and its potential for injury prevention.
Resistance training (RT) load and volume are considered crucial variables to appropriately prescribe and manage for eliciting the targeted acute responses (i.e., minimizing neuromuscular fatigue) and chronic adaptations (i.e., maximizing neuromuscular adaptations). In traditional RT contexts, load and volume are generally pre-prescribed; thereby, potentially yielding sub-optimal outcomes. A RT concept that individualizes programming is autoregulation: a systematic two-step feedback process involving, (1) monitoring performance and its constituents (fitness, fatigue, and readiness) across multiple time frames (short-, moderate-, and long-term); and (2) adjusting programming (i.e., load and volume) to elicit the targeted goals (i.e., responses and adaptations). A growing body of load and volume autoregulation research has accelerated recently, with several meta-analyses suggesting that autoregulation may provide a small advantage over traditional RT. Nonetheless, the existing literature has typically conceptualized these current autoregulation methods as standalone practices, which has limited their extensive utility in research and applied settings. The primary purpose of this review was three-fold. Initially, we synthesized the current methods of load and volume autoregulation, while disseminating each method’s main advantages and limitations. Second, we conceptualized a theoretical Integrated Velocity Model (IVM) that integrates the current methods for a more holistic perspective of autoregulation that may potentially augment its benefits. Lastly, we illustrated how the IVM may be compared to the current methods for future directions and how it may be implemented for practical applications. We hope that this review assists to contextualize a novel autoregulation framework to help inform future investigations for researchers and practices for RT professionals.
High-load resistance exercise (>60% of 1-repetition maximum) is a well-known stimulus to enhance skeletal muscle hypertrophy with chronic training. However, studies have intriguingly shown that low-load resistance exercise training (RET) (≤60% of 1-repetition maximum) can lead to similar increases in skeletal muscle hypertrophy as compared to high-load RET. This has raised questions about the underlying mechanisms for eliciting the hypertrophic response with low-load RET. A key characteristic of low-load RET is performing resistance exercise to, or close to, task failure, thereby inducing muscle fatigue. The primary aim of this evidence-based narrative review is to explore whether muscle fatigue may act as an indirect or direct mechanism contributing to skeletal muscle hypertrophy during low-load RET. It has been proposed that muscle fatigue could indirectly stimulate muscle hypertrophy through increased muscle fibre recruitment, mechanical tension, ultrastructural muscle damage, the secretion of anabolic hormones, and/or alterations in the expression of specific proteins involved in muscle mass regulation (e.g., myostatin). Alternatively, it has been proposed that fatigue could directly stimulate muscle hypertrophy through the accumulation of metabolic by-products (e.g., lactate), and/or inflammation and oxidative stress. This review summarizes the existing literature eluding to the role of muscle fatigue as a stimulus for low-load RET-induced muscle hypertrophy and provides suggested avenues for future research to elucidate how muscle fatigue could mediate skeletal muscle hypertrophy.
This study examined the relationship between velocity-loss and different squat exercise intensities. Twenty-two male college students who were actively exercising performed repetitive lifting in squatting exercises at five different velocity-zones. The result showed that the slope of the velocity decrease was large in the medium-intensity-high-intensity range. At low intensities, the velocity decrease was moderate. It was also clear that the degree of fatigue varied greatly depending on the number of repetitions and the duration of exercise at the same rate of velocity-loss. In addition, higher exerted power was observed at low and medium intensities. The minimum power relative to the maximum peak power was approximately 70% of the peak power. This suggests that the acceptable range of the rate of velocity reduction relative to intensity may differ in order to control excessive fatigue in velocity-based training and to obtain the desired training effect.
We determined the acute biomechanical, physiological, and perceptual effects of using individualised velocity targets (IVT) or a percentage of one repetition maximum (%1RM) to regulate resistance training load. Thirty-nine resistance-trained adults (age: 21.8±3.2 years) completed two strength training sessions (five sets of five free-weight back squats) in a randomised, counterbalanced order. The %1RM session involved using a fixed load at 80% 1RM, whereas the IVT session used a modifiable load corresponding to the mean velocity at 80% 1RM. Kinetic and kinematic data and rating of perceived exertion (RPE) were recorded during training sessions. Countermovement jump (CMJ) height and blood lactate concentration were measured pre- and post-session, and perceived muscle soreness and fatigue were measured 24-hours post-exercise using 10-point Likert scales. We used null-hypothesis significance testing to test for differences between conditions and two one-sided tests (TOST) to assess equivalence. IVT significantly increased sessional mean velocity (mean difference=0.05 m·s-1), peak velocity (0.08 m·s-1), mean power (54.4 W), and peak power (141 W), while significantly reducing barbell load (-2.7 kg), RPE (-0.49), time under tension (-0.13 s), and velocity loss (0.02 m·s-1), compared to %1RM. IVT and %1RM had equivalent effects on post-exercise perceived fatigue (0.11, 10-point-scale) and pre-post changes in blood lactate (-0.50 mmol/L) and CMJ height (-0.75 cm). In conclusion, using individualised velocity targets to regulate resistance training load increases movement velocity in repeated sets of free-weight back squats but does not meaningfully influence markers of post-exercise fatigue compared to %1RM.
This study aimed to analyze the evolution of repetition velocity throughout a set until failure in the bench-press exercise and to analyze the relationships between the percentage of performed repetitions (%Rep) regarding the maximum number of repetitions that can be completed (MNR) and the percentage of velocity loss (VL) in women. Sixteen women performed one set until failure with four different intensities (50%, 60%, 70%, and 80% of one-repetition maximum, 1RM). Two-testing sessions were performed with 50% and 80% 1RM to evaluate data stability. The level of significance was set at p ≤ 0.05. A close relationship was observed between the magnitude of VL and the %Rep (R² = 0.85–0.92) and a low standard error of the estimation (6.85–9.81%). Regarding reliability, the MNR showed a coefficient of variation (CV) of 16.1% and 20.8% for 50% and 80% 1RM, respectively. Regarding the %Rep for a given VL (from 15% VL), CVs were: 6.3–19.6%, being higher when VL reached in the set was lower. This study shows the usefulness of monitoring VL to estimate, with considerable precision, the %Rep in women. However, the %Rep when a given VL was reached revealed only satisfactory absolute reliability from a certain VL threshold (>15% VL).
Background
The squat exercise has been shown to improve athletic performance. However, the use of the deep squat has been questioned due to claims that it may cause knee joint injuries. Therefore, the purpose of this scoping review was to synthesize existing literature concerning the impact of deep squats on knee osteoarticular health in resistance-trained individuals.
Methods
This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-ScR) guidelines. The original protocol was prospectively registered in Figshare (https://doi.org/10.6084/m9.figshare.24945033.v1). A systematic and exhaustive search was conducted in different databases: PubMed, Scopus, Web of Science, and SPORTDiscus. Additional searches were performed in Google Scholar and PEDro. The main inclusion criteria were the following: (1) Articles of experimental, observational, or theoretical nature, including randomized controlled trials, longitudinal studies, case reports, integrative reviews, systematic reviews, and meta-analyses(Primary studies were required to have a minimum follow-up duration of 6 weeks, whereas secondary studies were expected to adhere to PRISMA or COCHRANE guidelines or be registered with PROSPERO; (2) Peer-reviewed articles published between 2000 and 2024; (3) Publications written in English, Spanish and Portuguese; (4) Studies reporting the effects of deep half, parallel or quarter squats on the knee or evaluating squats as a predictor of injury.
Results
The keyword search resulted in 2,274 studies, out of which 15 met all inclusion criteria. These 15 studies comprised 5 cohort studies, 3 randomized controlled trials, 4 literature or narrative reviews, 1 case study, and 2 systematic reviews, one including a meta-analysis. Overall, the risk of bias (ROB) across these studies was generally low. It is worth noting that only one study, a case study, associated deep squats with an increased risk of injury, the remaining 14 studies showed no negative impact of deep squats on knee joint health.
Conclusion
The deep squat appears to be a safe exercise for knee joint health and could be included in resistance training programs without risk, provided that proper technique is maintained.
Spor Bilimleri Alanında Farklı Paradigmalar- I başlıklı bu kitap, spor bilimleri alanındaki akademik çalışmaların kapsamlı ve disiplinler arası bir koleksiyonunu temsil etmektedir. Bu kitap, spor bilimlerinin çeşitli konularını ele almaktadır. Kitap bölümlerimiz multidisipliner alanda çeşitli konulara ilişkin iç görüler sunan, alandaki uzmanlar tarafından titizlikle hazırlanmıştır. Dahil edilen çalışmalar literatüre değerli katkılar sunmayı ve spor bilimleri anlayışımızı ilerletmeyi amaçlamaktadır. Bu kitap aracılığıyla, alana özgü konulara değinmekle kalmayıp aynı zamanda spor bilimleri alanındaki ortaya çıkan zorlukları da ele alan zengin bir bilgi dokusu sunmayı amaçlıyoruz. Bu koleksiyon, spor bilimlerinin dinamik ve sürekli kendini yenileyen iklimini geliştirmeye hevesli akademisyenler, araştırmacılar, uygulayıcılar ve öğrenciler için tasarlanmıştır.
Resistance training (RT) triggers diverse morphological and physiological adaptations that are broadly considered beneficial for performance enhancement as well as injury risk reduction. Some athletes and coaches therefore engage in, or prescribe, substantial amounts of RT under the assumption that continued increments in maximal strength capacity and/or muscle mass will lead to improved sports performance. In contrast, others employ minimal or no RT under the assumption that RT may impair endurance or sprint performances. However, the morphological and physiological adaptations by which RT might impair physical performance, the likelihood of these being evoked, and the training program specifications that might promote such impairments, remain largely undefined. Here, we discuss how selected adaptations to RT may enhance or impair speed and endurance performances while also addressing the RT program variables under which these adaptations are likely to occur. Specifically, we argue that while some myofibrillar (muscle) hypertrophy can be beneficial for increasing maximum strength, substantial hypertrophy can lead to macro- and microscopic adaptations such as increases in body (or limb) mass and internal moment arms that might, under some conditions, impair both sprint and endurance performances. Further, we discuss how changes in muscle architecture, fiber typology, microscopic muscle structure, and intra- and intermuscular coordination with RT may maximize speed at the expense of endurance, or maximize strength at the expense of speed. The beneficial effect of RT for sprint and endurance sports can be further improved by considering the adaptive trade-offs and practical implications discussed in this review.
Graphical abstract
Calaway, C, Walls, K, Levitt, H, Caplan, J, Mann, B, Martinez, K, Gastaldo, R, Haq, I, and Signorile, JF. Frequency of velocity-based-training frequency impacts changes in muscle morphology, neuromuscular performance and functional capability in persons with Parkinson's disease. J Strength Cond Res XX(X): 000–000, 2024—Velocity-based training (VBT) positively impacts muscle morphology and performance in persons with Parkinson's disease (PD); however, optimal training frequencies for VBT in patients with PD remain undetermined. Changes in ultrasound-determined muscle thickness (MT) and echo intensity (EI)–derived muscle quality of the rectus femoris (RF) and vastus lateralis (VL), neuromuscular performance, and functional capacity were examined following 2 VBT frequencies (2–3 d·wk ⁻¹ ) using 30% velocity loss thresholds for 12 weeks. Neuromuscular performance was assessed using computerized pneumatic resistance machines. For each variable, 2 (time) × 2 (group) repeated-measures analyses of variance (ANOVA) were used to determine significant main effects and interactions. Significant time effects were seen for MT and EI of all muscles ( p < 0.05). Muscle thickness improvements included right VL (RVL) (0.171 ± 0.065 cm; p = 0.019), left VL (LVL) (0.214 ± 0.101 cm; p = 0.049), right RF (RRF) (0.194 ± 0.077 cm; p = 0.023), and left RF (LRF) (0.318 ± 0.109 cm; p = 0.010). For EI, improvements occurred in RVL (−18.688 ± 3.600; p = <0.001), LVL (−10.959 ± 4.894; p = 0.040), RRF (−9.516 ± 3.537; p = 0.016), and LRF (−9.018 ± 3.444; p = 0.019). Time effects were seen for leg-press 1-repetition maximum and peak power ( p < 0.01) and habitual walking speed ( p = 0.022), with a group by time interaction for maximal gait speed favoring the 3 d·wk ⁻¹ condition (∆0.15 m·s ⁻¹ , p = 0.002). The results indicate that VBT at 2 or 3 d·wk ⁻¹ can significantly improve muscle morphology, neuromuscular performance, and functional capability in patients with PD; however, improvements in maximal gait speed require 3 d·wk ⁻¹ . These findings provide flexibility when developing exercise prescriptions for patients with PD.
This investigation sought to determine the effect of resistance training to failure on functional, structural and neural elbow flexor muscle adaptation. Twenty-eight males completed a 4-week familiarization period and were then counterbalanced on the basis of responsiveness across; non-failure rapid shortening (RS; rapid concentric, 2 s eccentric), non-failure stretch-shortening (SSC; rapid concentric, rapid eccentric), and failure control (C, 2 s concentric, 2 s eccentric), for a 12-week unilateral elbow flexor resistance training regimen, 3 × week using 85% of one repetition maximum (1RM). 1RM, maximal voluntary contraction (MVC), muscle cross-sectional area (CSA), and muscle activation (EMGRMS ) of the agonist, antagonist, and stabilizer muscles were assessed before and after the 12-week training period. The average number of repetitions per set was significantly lower in RS 4.2 [confidence interval (CI): 4.2, 4.3] and SSC 4.2 (CI: 4.2, 4.3) compared with C 6.1 (CI: 5.8, 6.4). A significant increase in 1RM (30.5%), MVC (13.3%), CSA (11.4%), and agonist EMGRMS (22.1%) was observed; however, no between-group differences were detected. In contrast, antagonist EMGRMS increased significantly in SSC (40.5%) and C (23.3%), but decreased in RS (13.5%). Similar adaptations across the three resistance training regimen suggest repetition failure is not critical to elicit significant neural and structural changes to skeletal muscle.
© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
To propose a manual segmentation method for individual quadriceps femoris (QF) muscles and to test its reliability for muscle volume estimation.
Images were acquired every 5 mm along the thigh using a 3T MRI scanner on 10 young (mean age: 25 years) and 10 older (mean age: 75 years) adults using a three-point 3D Dixon sequence. In each slice, anatomical cross-sectional areas of the individual quadriceps muscles of the dominant leg were outlined by two operators working independently. Differences between operators were assessed by means of Bland-Altman plots and intraclass correlation coefficients (ICC). This study was approved by the local Ethics Committee.
Precise delimitation of individual muscles along the femur often remains challenging, particularly near their insertion areas where some muscles may be partially or totally fused. There was, however, an excellent interoperator segmentation reliability despite a systematic significant difference between operators (ICC > 0.99), mainly due to delineation divergences. Considering all subjects and muscles, differences between operators were all lower than 4.4%.
This work has demonstrated the excellent reliability of manual segmentation to assess cross-sectional areas and therefore the volume of individual QF muscles using MRI. It may serve as a basis for a future segmentation consensus of the QF muscles.J. Magn. Reson. Imaging 2013;. © 2013 Wiley Periodicals, Inc.
This investigation examined the influence of the number of repetitions per set on power output and muscle metabolism during leg press exercise. Six trained men (age 34 ± 6 yr) randomly performed either 5 sets of 10 repetitions (10REP), or 10 sets of 5 repetitions (5REP) of bilateral leg press exercise, with the same initial load and rest intervals between sets. Muscle biopsies (vastus lateralis) were taken before the first set, and after the first and the final sets. Compared with 5REP, 10REP resulted in a markedly greater decrease (P<0.05) of the power output, muscle PCr and ATP content, and markedly higher (P<0.05) levels of muscle lactate and IMP. Significant correlations (P<0.01) were observed between changes in muscle PCr and muscle lactate (R(2) = 0.46), between changes in muscle PCr and IMP (R(2) = 0.44) as well as between changes in power output and changes in muscle ATP (R(2) = 0.59) and lactate (R(2) = 0.64) levels. Reducing the number of repetitions per set by 50% causes a lower disruption to the energy balance in the muscle. The correlations suggest that the changes in PCr and muscle lactate mainly occur simultaneously during exercise, whereas IMP only accumulates when PCr levels are low. The decrease in ATP stores may contribute to fatigue.
Thirty-five healthy men were matched and randomly assigned to one of four training groups that performed high-intensity strength and endurance training (C; n = 9), upper body only high-intensity strength and endurance training (UC; n = 9), high-intensity endurance training (E; n = 8), or high-intensity strength training (ST; n = 9). The C and ST groups significantly increased one-repetition maximum strength for all exercises (P < 0.05). Only the C, UC, and E groups demonstrated significant increases in treadmill maximal oxygen consumption. The ST group showed significant increases in power output. Hormonal responses to treadmill exercise demonstrated a differential response to the different training programs, indicating that the underlying physiological milieu differed with the training program. Significant changes in muscle fiber areas were as follows: types I, IIa, and IIc increased in the ST group; types I and IIc decreased in the E group; type IIa increased in the C group; and there were no changes in the UC group. Significant shifts in percentage from type IIb to type IIa were observed in all training groups, with the greatest shift in the groups in which resistance trained the thigh musculature. This investigation indicates that the combination of strength and endurance training results in an attenuation of the performance improvements and physiological adaptations typical of single-mode training.
To asses if tennis at prepubertal age elicits the hypertrophy of dominant arm muscles.
The volume of the muscles of both arms was determined using magnetic resonance imaging (MRI) in 7 male prepubertal tennis players (TP) and 7 non-active control subjects (CG) (mean age 11.0 ± 0.8 years, Tanner 1-2).
TP had 13% greater total muscle volume in the dominant than in the contralateral arm. The magnitude of inter-arm asymmetry was greater in TP than in CG (13 vs 3%, P<0.001). The dominant arm of TP was 16% greater than the dominant arm of CG (P<0.01), whilst non-dominant arms had similar total muscle volumes in both groups (P = 0.25), after accounting for height as covariate. In TP, dominant deltoid (11%), forearm supinator (55%) and forearm flexors (21%) and extensors (25%) were hypertrophied compared to the contralateral arm (P<0.05). In CG, the dominant supinator muscle was bigger than its contralateral homonimous (63%, P<0.05).
Tennis at prepubertal age is associated with marked hypertrophy of the dominant arm, leading to a marked level of asymmetry (+13%), much greater than observed in non-active controls (+3%). Therefore, tennis particpation at prepubertal age is associated with increased muscle volumes in dominant compared to the non-dominant arm, likely due to selectively hypertrophy of the loaded muscles.
To determine the volume and degree of asymmetry of iliopsoas (IL) and gluteal muscles (GL) in tennis and soccer players.
IL and GL volumes were determined using magnetic resonance imaging (MRI) in male professional tennis (TP) and soccer players (SP), and in non-active control subjects (CG) (n = 8, 15 and 6, respectively).
The dominant and non-dominant IL were hypertrophied in TP (24 and 36%, respectively, P<0.05) and SP (32 and 35%, respectively, P<0.05). In TP the asymmetric hypertrophy of IL (13% greater volume in the non-dominant than in the dominant IL, P<0.01) reversed the side-to-side relationship observed in CG (4% greater volume in the dominant than in the contralateral IL, P<0.01), whilst soccer players had similar volumes in both sides (P = 0.87). The degree of side-to-side asymmetry decreased linearly from the first lumbar disc to the pubic symphysis in TP (r = -0.97, P<0.001), SP (r = -0.85, P<0.01) and CG (r = -0.76, P<0.05). The slope of the relationship was lower in SP due to a greater hypertrophy of the proximal segments of the dominant IL. Soccer and CG had similar GL volumes in both sides (P = 0.11 and P = 0.19, for the dominant and contralateral GL, respectively). GL was asymmetrically hypertrophied in TP. The non-dominant GL volume was 20% greater in TP than in CG (P<0.05), whilst TP and CG had similar dominant GL volumes (P = 0.14).
Tennis elicits an asymmetric hypertrophy of IL and reverses the normal dominant-to-non-dominant balance observed in non-active controls, while soccer is associated to a symmetric hypertrophy of IL. Gluteal muscles are asymmetrically hypertrophied in TP, while SP display a similar size to that observed in controls. It remains to be determined whether the different patterns of IL and GL hypertrophy may influence the risk of injury.
The quest to increase lean body mass is widely pursued by those who lift weights. Research is lacking, however, as to the best approach for maximizing exercise-induced muscle growth. Bodybuilders generally train with moderate loads and fairly short rest intervals that induce high amounts of metabolic stress. Powerlifters, on the other hand, routinely train with high-intensity loads and lengthy rest periods between sets. Although both groups are known to display impressive muscularity, it is not clear which method is superior for hypertrophic gains. It has been shown that many factors mediate the hypertrophic process and that mechanical tension, muscle damage, and metabolic stress all can play a role in exercise-induced muscle growth. Therefore, the purpose of this paper is twofold: (a) to extensively review the literature as to the mechanisms of muscle hypertrophy and their application to exercise training and (b) to draw conclusions from the research as to the optimal protocol for maximizing muscle growth.
The purpose of this study was to examine the efficacy of 8 wk of resistance training to failure versus not to failure training regimens at both moderate and low volumes for increasing upper-body strength and power as well as cardiovascular parameters into a combined resistance and endurance periodized training scheme.
Forty-three trained male rowers were matched and then randomly assigned to four groups that performed the same endurance training but differed on their resistance training regimen: four exercises leading to repetition failure (4RF; n = 14), four exercises not leading to failure (4NRF; n = 15), two exercises not to failure (2NRF; n = 6), and control group (C; n = 8). One-repetition maximum strength and maximal muscle power output during prone bench pull (BP), average power during a 20-min all-out row test (W 20 min), average row power output eliciting a blood lactate concentration of 4 mmol x L(-1) (W 4 mmol x L(-1)), and power output in 10 maximal strokes (W 10 strokes) were assessed before and after 8 wk of periodized training.
4NRF group experienced larger gains in one- repetition maximum strength and muscle power output (4.6% and 6.4%, respectively) in BP compared with both 4RF (2.1% and j1.2%) and 2NRF (0.6% and -0.6%). 4NRF and 2NRF groups experienced larger gains in W 10 strokes (3.6% and 5%) and in W 20 min (7.6% and 9%) compared with those found after 4RF (-0.1% and 4.6%), whereas no significant differences between groups were observed in the magnitude of changes in W 4 mmol x L(-1) (4NRF = 6.2%, 4RF = 5.3%, 2NRF = 6.8%, and C = 4.5%).
An 8-wk linear periodized concurrent strength and endurance training program using a moderate number of repetitions not to failure (4NRF group) provides a favorable environment for achieving greater enhancements in strength, muscle power, and rowing performance when compared with higher training volumes of repetitions to failure in experienced highly trained rowers.
Six women who had participated in a previous 20-wk strength training study for the lower limb detrained for 30-32 wk and subsequently retrained for 6 wk. Seven untrained women also participated in the 6-wk "retraining" phase. In addition, four women from each group volunteered to continue training an additional 7 wk. The initial 20-wk training program caused an increase in maximal dynamic strength, hypertrophy of all three major fiber types, and a decrease in the percentage of type IIb fibers. Detraining had relatively little effect on fiber cross-sectional area but resulted in an increased percentage of type IIb fibers with a concomitant decrease in IIa fibers. Maximal dynamic strength decreased but not to pretraining levels. Retraining for 6 wk resulted in significant increases in the cross-sectional areas of both fast fiber types (IIa and IIab + IIb) compared with detraining values and a decrease in the percentage of type IIb fibers. The 7-wk extension accentuated these trends such that cross-sectional areas continued to increase (nonsignificant) and no IIb fibers could be found. Similar results were found for the nonpreviously trained women. These data suggest that rapid muscular adaptations occur as a result of strength training in previously trained as well as non-previously trained women. Some adaptations (fiber area and maximal dynamic strength) may be retained for long periods during detraining and may contribute to a rapid return to "competitive" form.
The role of intramuscular metabolite changes in the adaptations following isometric strength training was examined by comparing the effect of short, intermittent contractions (IC) and longer, continuous (CC) contractions. In a parallel study, the changes in phosphate metabolites and pH were examined during the two protocols using whole-body nuclear magnetic resonance spectroscopy (NMRS). Seven subjects trained three time per week for 14 weeks. The right leg was trained using four sets of ten contractions, each lasting 3 s with a 2-s rest period between each contraction and 2 min between each set. The left leg was trained using four 30-s contractions with a 1-min rest period between each. Both protocols involved isometric contractions at 70% of a maximum voluntary isometric contraction (MVC). The MVC, length:tension and force:velocity relationships and cross-sectional area (CSA) of each leg were measured before and after training. The increase in isometric strength was significantly greater (P = 0.041) for the CC leg (median 54.7%; P = 0.022) than for IC (31.5%; P = 0.022). There were no significant differences between the two protocols for changes in the length:tension or force:velocity relationships. There were significant increases in muscle CSA for the CC leg only. NMRS demonstrated that the changes in phosphate metabolites and pH were greater for the CC protocol. These findings suggest that factors related to the greater metabolite changes during CC training results in greater increases in isometric strength and muscle CSA.
Skeletal muscle (SM) is a large body compartment of biological importance, but it remains difficult to quantify SM with affordable and practical methods that can be applied in clinical and field settings.
The objective of this study was to develop and cross-validate anthropometric SM mass prediction models in healthy adults.
SM mass, measured by using whole-body multislice magnetic resonance imaging, was set as the dependent variable in prediction models. Independent variables were organized into 2 separate formulas. One formula included mainly limb circumferences and skinfold thicknesses [model 1: height (in m) and skinfold-corrected upperarm, thigh, and calf girths (CAG, CTG, and CCG, respectively; in cm)]. The other formula included mainly body weight (in kg) and height (model 2). The models were developed and cross-validated in nonobese adults [body mass index (in kg/m(2)) < 30].
Two SM (in kg) models for nonobese subjects (n = 244) were developed as follows: SM = Ht x (0.00744 x CAG(2) + 0.00088 x CTG(2) + 0.00441 x CCG(2)) + 2.4 x sex - 0.048 x age + race + 7.8, where R:(2) = 0.91, P: < 0.0001, and SEE = 2.2 kg; sex = 0 for female and 1 for male, race = -2.0 for Asian, 1.1 for African American, and 0 for white and Hispanic, and SM = 0.244 x BW + 7.80 x Ht + 6.6 x sex - 0.098 x age + race - 3.3, where R:(2) = 0.86, P: < 0.0001, and SEE = 2.8 kg; sex = 0 for female and 1 for male, race = -1.2 for Asian, 1.4 for African American, and 0 for white and Hispanic.
These 2 anthropometric prediction models, the first developed in vivo by using state-of-the-art body-composition methods, are likely to prove useful in clinical evaluations and field studies of SM mass in nonobese adults.
High resistance training enhances muscular strength, and recent work has suggested an important role for metabolite accumulation in this process.
To investigate the role of fatigue and metabolite accumulation in strength gains by comparing highly fatiguing and non-fatiguing isotonic training protocols.
Twenty three healthy adults (18-29 years of age; eight women) were assigned to either a high fatigue protocol (HF: four sets of 10 repetitions with 30 seconds rest between sets) to maximise metabolic stress or a low fatigue protocol (LF: 40 repetitions with 30 seconds between each repetition) to minimise changes. Subjects lifted on average 73% of their 1 repetition maximum through the full range of knee extension with both legs, three times a week. Quadriceps isometric strength of each leg was measured at a knee joint angle of 1.57 rad (90 degrees ), and a Cybex 340 isokinetic dynamometer was used to measure the angle-torque and torque-velocity relations of the non-dominant leg.
At the mid-point of the training, the HF group had 50% greater gains in isometric strength, although this was not significant (4.5 weeks: HF, 13.3 (4.4)%; LF, 8.9 (3.6)%). This rate of increase was not sustained by the HF group, and after nine weeks of training all the strength measurements showed similar improvements for both groups (isometric strength: HF, 18.2 (3.9)%; LF, 14.5 (4.0)%). The strength gains were limited to the longer muscle lengths despite training over the full range of movement.
Fatigue and metabolite accumulation do not appear to be critical stimuli for strength gain, and resistance training can be effective without the severe discomfort and acute physical effort associated with fatiguing contractions.
Previous studies show that cessation of resistance training, commonly known as "detraining," is associated with strength loss, decreased neural drive, and muscular atrophy. Detraining may also increase the expression of fast muscle myosin heavy chain (MHC) isoforms. The present study examined the effect of detraining subsequent to resistance training on contractile performance during slow-to-medium velocity isokinetic muscle contraction vs. performance of maximal velocity "unloaded" limb movement (i.e., no external loading of the limb). Maximal knee extensor strength was measured in an isokinetic dynamometer at 30 and 240 degrees/s, and performance of maximal velocity limb movement was measured with a goniometer during maximal unloaded knee extension. Muscle cross-sectional area was determined with MRI. Electromyographic signals were measured in the quadriceps and hamstring muscles. Twitch contractions were evoked in the passive vastus lateralis muscle. MHC isoform composition was determined with SDS-PAGE. Isokinetic muscle strength increased 18% (P < 0.01) and 10% (P < 0.05) at slow and medium velocities, respectively, along with gains in muscle cross-sectional area and increased electromyogram in response to 3 mo of resistance training. After 3 mo of detraining these gains were lost, whereas in contrast maximal unloaded knee extension velocity and power increased 14% (P < 0.05) and 44% (P < 0.05), respectively. Additionally, faster muscle twitch contractile properties along with an increased and decreased amount of MHC type II and MHC type I isoforms, respectively, were observed. In conclusion, detraining subsequent to resistance training increases maximal unloaded movement speed and power in previously untrained subjects. A phenotypic shift toward faster muscle MHC isoforms (I --> IIA --> IIX) and faster electrically evoked muscle contractile properties in response to detraining may explain the present results.
Thirty-two untrained men [mean (SD) age 22.5 (5.8) years, height 178.3 (7.2) cm, body mass 77.8 (11.9) kg] participated in an 8-week progressive resistance-training program to investigate the "strength-endurance continuum". Subjects were divided into four groups: a low repetition group (Low Rep, n = 9) performing 3-5 repetitions maximum (RM) for four sets of each exercise with 3 min rest between sets and exercises, an intermediate repetition group (Int Rep, n = 11) performing 9-11 RM for three sets with 2 min rest, a high repetition group (High Rep, n = 7) performing 20-28 RM for two sets with 1 min rest, and a non-exercising control group (Con, n = 5). Three exercises (leg press, squat, and knee extension) were performed 2 days/week for the first 4 weeks and 3 days/week for the final 4 weeks. Maximal strength [one repetition maximum, 1RM), local muscular endurance (maximal number of repetitions performed with 60% of 1RM), and various cardiorespiratory parameters (e.g., maximum oxygen consumption, pulmonary ventilation, maximal aerobic power, time to exhaustion) were assessed at the beginning and end of the study. In addition, pre- and post-training muscle biopsy samples were analyzed for fiber-type composition, cross-sectional area, myosin heavy chain (MHC) content, and capillarization. Maximal strength improved significantly more for the Low Rep group compared to the other training groups, and the maximal number of repetitions at 60% 1RM improved the most for the High Rep group. In addition, maximal aerobic power and time to exhaustion significantly increased at the end of the study for only the High Rep group. All three major fiber types (types I, IIA, and IIB) hypertrophied for the Low Rep and Int Rep groups, whereas no significant increases were demonstrated for either the High Rep or Con groups. However, the percentage of type IIB fibers decreased, with a concomitant increase in IIAB fibers for all three resistance-trained groups. These fiber-type conversions were supported by a significant decrease in MHCIIb accompanied by a significant increase in MHCIIa. No significant changes in fiber-type composition were found in the control samples. Although all three training regimens resulted in similar fiber-type transformations (IIB to IIA), the low to intermediate repetition resistance-training programs induced a greater hypertrophic effect compared to the high repetition regimen. The High Rep group, however, appeared better adapted for submaximal, prolonged contractions, with significant increases after training in aerobic power and time to exhaustion. Thus, low and intermediate RM training appears to induce similar muscular adaptations, at least after short-term training in previously untrained subjects. Overall, however, these data demonstrate that both physical performance and the associated physiological adaptations are linked to the intensity and number of repetitions performed, and thus lend support to the "strength-endurance continuum".
High-resistance strength training (HRST) is one of the most widely practiced forms of physical activity, which is used to enhance athletic performance, augment musculo-skeletal health and alter body aesthetics. Chronic exposure to this type of activity produces marked increases in muscular strength, which are attributed to a range of neurological and morphological adaptations. This review assesses the evidence for these adaptations, their interplay and contribution to enhanced strength and the methodologies employed. The primary morphological adaptations involve an increase in the cross-sectional area of the whole muscle and individual muscle fibres, which is due to an increase in myofibrillar size and number. Satellite cells are activated in the very early stages of training; their proliferation and later fusion with existing fibres appears to be intimately involved in the hypertrophy response. Other possible morphological adaptations include hyperplasia, changes in fibre type, muscle architecture, myofilament density and the structure of connective tissue and tendons. Indirect evidence for neurological adaptations, which encompasses learning and coordination, comes from the specificity of the training adaptation, transfer of unilateral training to the contralateral limb and imagined contractions. The apparent rise in whole-muscle specific tension has been primarily used as evidence for neurological adaptations; however, morphological factors (e.g. preferential hypertrophy of type 2 fibres, increased angle of fibre pennation, increase in radiological density) are also likely to contribute to this phenomenon. Changes in inter-muscular coordination appear critical. Adaptations in agonist muscle activation, as assessed by electromyography, tetanic stimulation and the twitch interpolation technique, suggest small, but significant increases. Enhanced firing frequency and spinal reflexes most likely explain this improvement, although there is contrary evidence suggesting no change in cortical or corticospinal excitability. The gains in strength with HRST are undoubtedly due to a wide combination of neurological and morphological factors. Whilst the neurological factors may make their greatest contribution during the early stages of a training programme, hypertrophic processes also commence at the onset of training.
Acute hormonal and neuromuscular responses and recovery three days after the exercises were examined during the maximum repetitions (MR) and forced repetitions (FR) resistance exercise protocols in 16 male athletes. MR included 4 sets of leg presses, 2 sets of squats and 2 sets of knee extensions (with 12 RM) with a 2-min recovery between the sets and 4 min between the exercises. In FR the initial load was chosen to be higher than in MR so that the subject could not lift 12 repetitions per set by himself. After each set to failure the subject was assisted to perform the remaining repetitions to complete the 12 repetitions per set. Thus the exercise intensity was greater in FR than in MR. Both loading protocols led to the great acute increases (p < 0.05 - 0.001) in serum testosterone, free testosterone, cortisol and GH concentrations. However, the responses in cortisol (p < 0.05) and GH (p < 0.01) were larger in FR than in MR. The decrease of 56.5 % (p < 0.001) in maximal isometric force in FR was greater (p < 0.001) than that of 38.3 % in MR (p < 0.001) and force remained lower (p < 0.01) during the recovery in FR compared to MR. The larger decrease in isometric strength in FR than in MR was also associated with the decreased maximal voluntary EMG of the loaded muscles. The data indicate that the forced repetition exercise system induced greater acute hormonal and neuromuscular responses than a traditional maximum repetition exercise system and therefore it may be used to manipulate acute resistance exercise variables in athletes.
The effects of a training program consisting of weight lifting combined with plyometric exercises on kicking performance, myosin heavy-chain composition (vastus lateralis), physical fitness, and body composition (using dual-energy X-ray absorptiometry (DXA)) was examined in 37 male physical education students divided randomly into a training group (TG: 16 subjects) and a control group (CG: 21 subjects). The TG followed 6 weeks of combined weight lifting and plyometric exercises. In all subjects, tests were performed to measure their maximal angular speed of the knee during instep kicks on a stationary ball. Additional tests for muscle power (vertical jump), running speed (30 m running test), anaerobic capacity (Wingate and 300 m running tests), and aerobic power (20 m shuttle run tests) were also performed. Training resulted in muscle hypertrophy (+4.3%), increased peak angular velocity of the knee during kicking (+13.6%), increased percentage of myosin heavy-chain (MHC) type IIa (+8.4%), increased 1 repetition maximum (1 RM) of inclined leg press (ILP) (+61.4%), leg extension (LE) (+20.2%), leg curl (+15.9%), and half squat (HQ) (+45.1%), and enhanced performance in vertical jump (all p 0.05). In contrast, MHC type I was reduced (5.2%, p 0.05) after training. In the control group, these variables remained unchanged. In conclusion, 6 weeks of strength training combining weight lifting and plyometric exercises results in significant improvement of kicking performance, as well as other physical capacities related to success in football (soccer).
Drinkwater, E.J., T.W. Lawton, R.P. Lindsell, D.B. Pyne, P.H. Hunt, and M.J. McKenna. Training leading to repetition failure contributes to bench press strength gains in elite junior athletes. J. Strength Cond. Res. 19(2):382-388. 2005. The purpose of this study was to investigate the importance of training leading to repetition failure in the performance of 2 different tests: 6 repetition maximum (6RM) bench press strength and 40-kg bench throw power in elite junior athletes. Subjects were 26 elite junior male basketball players (n 12; age = 18.6 +/- 0.3 years; height = 202.0 +/- 11.6 cm; mass = 97.0 +/- 12.9 kg; mean SD) and soccer players (n = 14; age = 17.4 +/- 0.5 years; height = 179.0 +/- 7.0 cm; mass = 75.0 +/- 7.1 kg) with a history of greater than 6 months' strength training. Subjects were initially tested twice for 6RM bench press mass and 40-kg Smith machine bench throw power output (in watts) to establish retest reliability. Subjects then undertook bench press training with 3 sessions per week for 6 weeks, using equal volume programs (24 repetitions X 80-105% 6RM in 13 minutes 20 seconds). Subjects were assigned to one of two experimental groups designed either to elicit repetition failure with 4 sets of 6 repetitions every 260 seconds (RF4x6) or allow all repetitions to be completed with 8 sets of 3 repetitions every 113 seconds (NF8x3). The RF4X6 treatment elicited substantial increases in strength (7.3 +/- 2.4 kg, + 9.5%, p < 0.001) and power (40.8 +/- 24.1 W, + 10.6%, p < 0.001), while the NF8X3 group elicited 3.6 +/- 3.0 kg (+ 5.0%, p < 0.005) and 25 +/- 19.0 W increases (+ 6.8%, p < 0.001). The improvements in the RF4x6 group were greater than those in the repetition rest group for both strength (p < 0.005) and power (p < 0.05). Bench press training that leads to repetition failure induces greater strength gains than nonfailure training in the bench press exercise for elite junior team sport athletes.
Bicinchoninic acid, sodium salt, is a stable, water-soluble compound capable of forming an intense purple complex with cuprous ion (Cu1+) in an alkaline environment. This reagent forms the basis of an analytical method capable of monitoring cuprous ion produced in the reaction of protein with alkaline Cu2+ (biuret reaction). The color produced from this reaction is stable and increases in a proportional fashion over a broad range of increasing protein concentrations. When compared to the method of Lowry et al., the results reported here demonstrate a greater tolerance of the bicinchoninate reagent toward such commonly encountered interferences as nonionic detergents and simple buffer salts. The stability of the reagent and resulting chromophore also allows for a simplified, one-step analysis and an enhanced flexibility in protocol selection. This new method maintains the high sensitivity and low protein-to-protein variation associated with the Lowry technique.
Recent advances in molecular biology have elucidated some of the mechanisms that regulate skeletal muscle growth. Logically, muscle physiologists have applied these innovations to the study of resistance exercise (RE), as RE represents the most potent natural stimulus for growth in adult skeletal muscle. However, as this molecular-based line of research progresses to investigations in humans, scientists must appreciate the fundamental principles of RE to effectively design such experiments. Therefore, we present herein an updated paradigm of RE biology that integrates fundamental RE principles with the current knowledge of muscle cellular and molecular signalling. RE invokes a sequential cascade consisting of: (i) muscle activation; (ii) signalling events arising from mechanical deformation of muscle fibres, hormones, and immune/inflammatory responses; (iii) protein synthesis due to increased transcription and translation; and (iv) muscle fibre hypertrophy. In this paradigm, RE is considered an ‘upstream’ signal that determines specific downstream events. Therefore, manipulation of the acute RE programme variables (i.e. exercise choice, load, volume, rest period lengths, and exercise order) alters the unique ‘fingerprint’ of the RE stimulus and subsequently modifies the downstream cellular and molecular responses.
This study aimed to compare the effect on neuromuscular performance of 2 isoinertial resistance training programs that differed only in actual repetition velocity: maximal intended (MaxV) vs. half-maximal (HalfV) concentric velocity. 21 resistance-trained young men were randomly assigned to a MaxV (n=10) or HalfV (n=11) group and trained for 6 weeks using the full squat exercise. A complementary study (n=8) described the acute metabolic and mechanical response to the protocols used. MaxV training resulted in a likely more beneficial effect than HalfV on squat performance: maximum strength (ES: 0.94 vs. 0.54), velocity developed against all (ES: 1.76 vs. 0.88), light (ES: 1.76 vs. 0.75) and heavy (ES: 2.03 vs. 1.64) loads common to pre- and post-tests, and CMJ height (ES: 0.63 vs. 0.15). The effect on 20-m sprint was unclear, however. Both groups attained the greatest improvements in squat performance at their training velocities. Movement velocity seemed to be of greater importance than time under tension for inducing strength adaptations. Slightly higher metabolic stress (blood lactate and ammonia) and CMJ height loss were found for MaxV vs. HalfV, while metabolite levels were low to moderate for both conditions. MaxV may provide a superior stimulus for inducing adaptations directed towards improving athletic performance.
Abstract The purpose of this study was to compare the effect on strength gains of two isoinertial resistance training (RT) programmes that only differed in actual concentric velocity: maximal (MaxV) vs. half-maximal (HalfV) velocity. Twenty participants were assigned to a MaxV (n = 9) or HalfV (n = 11) group and trained 3 times per week during 6 weeks using the bench press (BP). Repetition velocity was controlled using a linear velocity transducer. A complementary study (n = 10) aimed to analyse whether the acute metabolic (blood lactate and ammonia) and mechanical response (velocity loss) was different between the MaxV and HalfV protocols used. Both groups improved strength performance from pre- to post-training, but MaxV resulted in significantly greater gains than HalfV in all variables analysed: one-repetition maximum (1RM) strength (18.2 vs. 9.7%), velocity developed against all (20.8 vs. 10.0%), light (11.5 vs. 4.5%) and heavy (36.2 vs. 17.3%) loads common to pre- and post-tests. Light and heavy loads were identified with those moved faster or slower than 0.80 m·s(-1) (∼60% 1RM in BP). Lactate tended to be significantly higher for MaxV vs. HalfV, with no differences observed for ammonia which was within resting values. Both groups obtained the greatest improvements at the training velocities (≤0.80 m·s(-1)). Movement velocity can be considered a fundamental component of RT intensity, since, for a given %1RM, the velocity at which loads are lifted largely determines the resulting training effect. BP strength gains can be maximised when repetitions are performed at maximal intended velocity.
High-resistance strength training (HRST) is one of the most widely practiced forms of physical activity, which is used to enhance athletic performance, augment musculo-skeletal health and alter body aesthetics. Chronic exposure to this type of activity produces marked increases in muscular strength, which are attributed to a range of neurological and morphological adaptations. This review assesses the evidence for these adaptations, their interplay and contribution to enhanced strength and the methodologies employed.
The primary morphological adaptations involve an increase in the cross-sectional area of the whole muscle and individual muscle fibres, which is due to an increase in myofibrillar size and number. Satellite cells are activated in the very early stages of training; their proliferation and later fusion with existing fibres appears to be intimately involved in the hypertrophy response. Other possible morphological adaptations include hyperplasia, changes in fibre type, muscle architecture, myofilament density and the structure of connective tissue and tendons.
Indirect evidence for neurological adaptations, which encompasses learning and coordination, comes from the specificity of the training adaptation, transfer of unilateral training to the contralateral limb and imagined contractions. The apparent rise in whole-muscle specific tension has been primarily used as evidence for neurological adaptations; however, morphological factors (e.g. preferential hypertrophy of type 2 fibres, increased angle of fibre pennation, increase in radiological density) are also likely to contribute to this phenomenon. Changes in inter-muscular coordination appear critical. Adaptations in agonist muscle activation, as assessed by electromyography, tetanic stimulation and the twitch interpolation technique, suggest small, but significant increases. Enhanced firing frequency and spinal reflexes most likely explain this improvement, although there is contrary evidence suggesting no change in cortical or corticospinal excitability.
The gains in strength with HRST are undoubtedly due to a wide combination of neurological and morphological factors. Whilst the neurological factors may make their greatest contribution during the early stages of a training programme, hypertrophic processes also commence at the onset of training.
This study compared the velocity- and power-load relationships of the antagonistic upper-body exercises of prone bench pull (PBP) and bench press (BP). 75 resistance-trained athletes performed a progressive loading test in each exercise up to the one-repetition maximum (1RM) in random order. Velocity and power output across the 30-100% 1RM were significantly higher for PBP, whereas 1RM strength was greater for BP. A very close relationship was observed between relative load and mean propulsive velocity for both BP (R2=0.97) and PBP (R2=0.94) which enables us to estimate %1RM from velocity using the obtained prediction equations. Important differences in the load that maximizes power output (Pmax) and the power profiles of both exercises were found according to the outcome variable used: mean (MP), peak (PP) or mean propulsive power (MPP). When MP was considered, the Pmax load was higher (56% BP, 70% PBP) than when PP (37% BP, 41% PBP) or MPP (37% BP, 46% PBP) were used. For each variable there was a broad range of loads at which power output was not significantly different. The differing velocity- and power-load relationships between PBP and BP seem attributable to the distinct muscle architecture and moment arm levers involved in these exercises.
This study aimed to analyze the acute mechanical and metabolic response to resistance exercise protocols (REP) differing in the number of repetitions (R) performed in each set (S) with respect to the maximum predicted number (P).
Over 21 exercise sessions separated by 48-72 h, 18 strength-trained males (10 in bench press (BP) and 8 in squat (SQ)) performed 1) a progressive test for one-repetition maximum (1RM) and load-velocity profile determination, 2) tests of maximal number of repetitions to failure (12RM, 10RM, 8RM, 6RM, and 4RM), and 3) 15 REP (S × R[P]: 3 × 6[12], 3 × 8[12], 3 × 10[12], 3 × 12[12], 3 × 6[10], 3 × 8[10], 3 × 10[10], 3 × 4[8], 3 × 6[8], 3 × 8[8], 3 × 3[6], 3 × 4[6], 3 × 6[6], 3 × 2[4], 3 × 4[4]), with 5-min interset rests. Kinematic data were registered by a linear velocity transducer. Blood lactate and ammonia were measured before and after exercise.
Mean repetition velocity loss after three sets, loss of velocity pre-post exercise against the 1-m·s load, and countermovement jump height loss (SQ group) were significant for all REP and were highly correlated to each other (r = 0.91-0.97). Velocity loss was significantly greater for BP compared with SQ and strongly correlated to peak postexercise lactate (r = 0.93-0.97) for both SQ and BP. Unlike lactate, ammonia showed a curvilinear response to loss of velocity, only increasing above resting levels when R was at least two repetitions higher than 50% of P.
Velocity loss and metabolic stress clearly differs when manipulating the number of repetitions actually performed in each training set. The high correlations found between mechanical (velocity and countermovement jump height losses) and metabolic (lactate, ammonia) measures of fatigue support the validity of using velocity loss to objectively quantify neuromuscular fatigue during resistance training.
This study analyzed the contribution of the propulsive and braking phases among different percentages of the one-repetition maximum (1RM) in the concentric bench press exercise. One hundred strength-trained men performed a test with increasing loads up to the 1RM for the individual determination of the load-power relationship. The relative load that maximized the mechanical power output (P(max)) was determined using three different parameters: mean concentric power (MP), mean power of the propulsive phase (MPP) and peak power (PP). The load at which the braking phase no longer existed was 76.1+/-7.4% 1RM. P(max) was dependent on the parameter used: MP (54.2%), MPP (36.5%) or PP (37.4%). No significant differences were found for loads between 40-65% 1RM (MP) or 20-55% 1RM (MPP and PP), nor between P(max) (% 1RM) when using MPP or PP. P(max) was independent of relative strength, although certain tendency towards slightly lower loads was detected for the strongest subjects. These results highlight the importance of considering the contribution of the propulsive and braking phases in isoinertial strength and power assessments. Referring the mean mechanical values to the propulsive phase avoids underestimating an individual's true neuromuscular potential when lifting light and medium loads.
This study examined the possibility of using movement velocity as an indicator of relative load in the bench press (BP) exercise. One hundred and twenty strength-trained males performed a test (T1) with increasing loads for the individual determination of the one-repetition maximum (1RM) and full load-velocity profile. Fifty-six subjects performed the test on a second occasion (T2) following 6 weeks of training. A very close relationship between mean propulsive velocity (MPV) and load (%1RM) was observed (R (2)=0.98). Mean velocity attained with 1RM was 0.16+/-0.04 m x s(-1) and was found to influence the MPV attained with each %1RM. Despite a mean increase of 9.3% in 1RM from T1 to T2, MPV for each %1RM remained stable. Stability in the load-velocity relationship was also confirmed regardless of individual relative strength. These results confirm an inextricable relationship between relative load and MPV in the BP that makes it possible to: 1) evaluate maximal strength without the need to perform a 1RM test, or test of maximum number of repetitions to failure (XRM); 2) determine the %1RM that is being used as soon as the first repetition with any given load is performed; 3) prescribe and monitor training load according to velocity, instead of percentages of 1RM or XRM.
The objective of this study is to investigate the potentially opposing influence of qualitative and quantitative muscular adaptations in response to high-intensity resistance training on contractile rate of force development (RFD) in the early (<100 ms) and later phases (>200 ms) of rising muscle force. Fifteen healthy young males participated in a 14-week resistance training intervention for the lower body and 10 matched subjects participated as controls. Maximal muscle strength (MVC) and RFD were measured during maximal voluntary isometric contraction of the quadriceps femoris muscle. Muscle biopsies were obtained from the vastus lateralis. The main findings were that RFD in the late phase of rising muscle force increased in response to resistance training whereas early RFD remained unchanged and early relative RFD (i.e., RFD/MVC) decreased. Quantitatively, muscle fiber cross-sectional area and MVC increased whereas, qualitatively, the relative proportion of type IIX muscle fibers decreased. Multiple regression analysis showed that while increased MVC positively influenced both early and late RFD, decreased-type IIX negatively influenced early RFD only. In conclusion, early and late RFD responded differently to high-intensity resistance training due to differential influences of qualitative and quantitative muscular adaptations on early and later phases of rising muscle force.
The effects of professional tennis participation on dominant and non-dominant upper extremity muscle volumes, and on fiber types of triceps brachii (lateral head) and vastus lateralis muscles were assessed in 15 professional tennis players. Magnetic resonance imaging (MRI, n=8) examination and dual-energy x-ray absorptiometry (DXA, n=7) were used to assess muscle volumes and lean body mass. Muscle fiber-type distribution assessed by biopsy sampling was similar in both triceps brachii (2/3 were type 2 and 1/3 type 1 fibers). The VL was composed of 1/3 of type 2 and 2/3 of type 1 fibers. The dominant had 12-15% higher lean mass (DXA/MRI) than the non-dominant (P<0.05). Type 1, 2a and 2x muscle fibers of the dominant were hypertrophied compared with the non-dominant by 20%, 22% and 34% (all P<0.01), respectively. The deltoid, triceps brachii, arm flexors and forearm superficial flexor muscles of the dominant were hypertrophied (MRI) compared with the non-dominant by 11-15%. These muscles represented a similar fraction of the whole muscle volume in both upper extremities. Dominant muscle volume was correlated with 1RM on the one-arm cable triceps pushdown exercise (r=0.84, P<0.05). Peak power during vertical jump correlated with VL muscle fibers's cross-sectional area (r=0.82-0.95, P<0.05).
Electrophoretic analysis in the presence of 33% glycerol of purified myosin from normal human muscle shows three distinct protein bands which are identified as type 1, 2B, and 2A myosin heavy chain (MHC) isoforms by affinity-purified polyclonal antibodies. Analysis of MHC of single human muscle fibres shows that human muscles contain a large population of fibres showing the coexistence of type 2A and 2B MHC.
Bicinchoninic acid, sodium salt, is a stable, water-soluble compound capable of forming an intense purple complex with cuprous ion (Cu1+) in an alkaline environment. This reagent forms the basis of an analytical method capable of monitoring cuprous ion produced in the reaction of protein with alkaline Cu2+ (biuret reaction). The color produced from this reaction is stable and increases in a proportional fashion over a broad range of increasing protein concentrations. When compared to the method of Lowry et al., the results reported here demonstrate a greater tolerance of the bicinchoninate reagent toward such commonly encountered interferences as nonionic detergents and simple buffer salts. The stability of the reagent and resulting chromophore also allows for a simplified, one-step analysis and an enhanced flexibility in protocol selection. This new method maintains the high sensitivity and low protein-to-protein variation associated with the Lowry technique.
STUDIES on normal and pathological striated muscle are increasingly clouded by inconsistencies in the definition of fiber types and lack of correlation between different systems of nomenclature. The purpose of the present communication is to point out some of the problems involved in the classification of fibers and to add new information of value in the analysis of human biopsy material. The histochemical reaction for myosin adenosine triphosphatase (ATPase) and the pH lability of this reaction is used to characterize the various types of fibers.
Material and Methods
Muscle was obtained by biopsy in man, rat, and rabbit. Gastrocnemius and soleus were investigated in the animals. The human biopsies were taken from the biceps. The methods used for histochemical analysis have been given elsewhere.1 In summary, unfixed frozen material was sectioned at 10μ thickness in the cryostat and the following histochemical reactions were carried out: (1) reduced diphosphopyridine
The fibre type composition (type I, IIA and IIB) was determined in repeated needle biopsies from the vastus lateralis muscle of 34 healthy male subjects. Repeated biopsies were taken from one leg (n = 20), and from both legs (n = 14). The variation between duplicate biopsies was 6.2% and 12.3%, with regard to % type I-fibres, respectively. Corresponding variation in % type IIA-fibres was 4.4% and 7.3%, respectively, and in % type IIB-fibres 5.0% and 7.4%, respectively. The variation in fibre type distribution within a single biopsy was 2.2-3.0% when 200 fibres were classified and counted. Increasing the number of fibres did not reduce the calculated variation to any great extent. A major reduction of the methodological error is obtained when two biopsies are taken from the same site of the muscle. The error in the technique in classifying the type I-fibres was slight; the classification between the subgroups of type II-fibres was, however, to some extent subjected to personal estimate. There was no consistent difference in fibre type composition between the right and the left leg.
Muscle performance declines during prolonged and intense activity; important components are a reduction in force production and shortening velocity and a prolongation of relaxation. In this review we consider how the changes in metabolites (particularly H+, inorganic phosphate (Pi), ATP and ADP) and changes in sarcoplasmic reticulum Ca2+ release lead to the observed changes in force, shortening velocity and relaxation. The reduced force is caused by a combination of reduced maximum force-generating capacity, reduced myofibrillar Ca2+ sensitivity and reduced Ca2+ release. The reduced maximum force and Ca2+ sensitivity are largely explained by the effects of H+ and Pi that have been observed in skinned fibres. At least three different forms of reduced Ca2+ release can be recognized but the mechanisms involved are incompletely understood. The reduced shortening velocity can be partly explained by the effects of H+ that have been observed in skinned fibres. In addition it is proposed that ADP, which depresses shortening velocity, increases during contractions to a level that is considerably higher than existing measurements suggest. Changes in Ca2+ release are probably unimportant for the reduced shortening velocity. The prolongation of relaxation can arise both from slowing of the rate of decline of myoplasmic calcium concentration and from slowing of cross-bridge detachment rates. A method of analysis which separates these components is described. The increase in H+ and the other metabolite changes during fatigue can independently affect both components. Finally we show that reduced force, shortening velocity and slowed relaxation all contribute to the decline in muscle performance during a working cycle in which the muscle first shortens actively and then is stretched passively by an antagonist muscle.
To investigate the role of fatigue in strength training, strength increases produced by a training protocol in which subjects rested between contractions were compared with those produced when subjects did not rest. Forty-two healthy subjects were randomly allocated to either a no-rest group, a rest group, or a control group. Subjects in the two training groups trained their elbow flexor muscles by lifting a 6RM weight 6-10 times on 3 d each week for 6 wk. Subjects in the no-rest group performed repeated lifts without resting, whereas subjects in the rest group rested for 30 s between lifts. Both training groups performed the same number of lifts at the same relative intensity. The control group did not train. Subjects who trained without rests experienced significantly greater mean increases in dynamic strength (56.3% +/- 6.8% (SD)) than subjects who trained with rests (41.2% +/- 6.6%), and both training groups experienced significantly greater mean increases in dynamic strength than the control group (19.7% +/- 6.6%). It was concluded that greater short-term strength increases are achieved when subjects are required to lift training weights without resting. These findings suggest that processes associated with fatigue contribute to the strength training stimulus.
Sprint training represents the condition in which increases in muscle shortening speed, as well as in strength, might play a significant role in improving power generation. This study therefore aimed to determine the effects of sprint training on 1) the coupling between myosin heavy chain (MHC) isoform expression and function in single fibers, 2) the distribution of MHC isoforms across a whole muscle, and 3) in vivo muscle function. Seven young male subjects completed 6 wk of training (3-s sprints) on a cycle ergometer. Training was without effect on maximum shortening velocity in single fibers or in the relative distribution of MHC isoforms in either the soleus or the vastus lateralis muscles. Electrically evoked and voluntary isometric torque generation increased (P < 0.05) after training in both the plantar flexors (+8% at 50 Hz and +16% maximal voluntary contraction) and knee extensors (+8% at 50 Hz and +7% maximal voluntary contraction). With the shortening potential of the muscles apparently unchanged, the increased strength of the major lower limb muscles is likely to have contributed to the 7% increase (P < 0.05) in peak pedal frequency during cycling.
The purpose of this study was to investigate the relationship between myosin heavy chain (MHC) composition and maximal contraction strength of the human quadriceps femoris muscle.
Muscle biopsies were obtained from m. vastus lateralis in your highly physical active males (N = 7). The MHC composition of muscle homogenates was determined by electrophoresis techniques (SDS-PAGE). Isokinetic peak torque and constant-angle torque (50 degrees knee flexion) were obtained during slow (30 degrees.s-1), medium (120 degrees.s-1), and fast (240 degrees.s-1) maximal concentric and eccentric quadriceps contractions and expressed relative to muscle volume.
The percentage of MHC II in the quadriceps muscle was positively correlated (rs = 0.61-0.93; P < 0.05-0.01) to maximal concentric quadriceps strength obtained at medium to high knee angular velocity. In contrast, no consistent pattern of correlation was observed for maximal eccentric quadriceps strength.
The relationship observed between muscular MHC composition and maximal contractile strength is suggested to appear as a consequence of MHC -related differences in contractile force-velocity characteristics and/or contractile Rate of Force Development (RFD).
The distribution of myosin heavy chain (MHC) isoforms, fiber type composition, and fiber size of the vastus lateralis muscle were analyzed by sodium dodecylsulfate polymerase gel electrophoresis (SDS-PAGE), ATPase histochemistry, and immunocytochemistry in a group of adult sedentary men before and after 3 months of heavy-load resistance training and, subsequently, after 3 months of detraining. Following the period of resistance training, MHC IIX content decreased from 9.3 +/- 2.1% to 2.0 +/- 0.8% (P < 0.01), with a corresponding increase in MHC IIA (42.4 +/- 3.9% vs. 49.6 +/- 4.0% [P < 0.05]). Following detraining the amount of MHC IIX reached values that were higher than before and after resistance training (17.2 +/- 3.2% [P < 0.01]). Changes in fiber type composition resembled the changes observed in MHC isoform content. Significant hypertrophy was observed for the type II fibers after resistance training. Maximal isometric quadriceps strength increased after resistance training, but returned to pretraining levels after detraining. The present results suggest that heavy-load resistance training decreases the amount of MHC IIX while reciprocally increasing MHC IIA content. Furthermore, detraining following heavy-load resistance training seems to evoke an overshoot in the amount of MHC IIX to values markedly higher than those observed prior to resistance training.
In human pennate muscle, changes in anatomical cross‐sectional area (CSA) or volume caused by training or inactivity may not necessarily reflect the change in physiological CSA, and thereby in maximal contractile force, since a simultaneous change in muscle fibre pennation angle could also occur.
Eleven male subjects undertook 14 weeks of heavy‐resistance strength training of the lower limb muscles. Before and after training anatomical CSA and volume of the human quadriceps femoris muscle were assessed by use of magnetic resonance imaging (MRI), muscle fibre pennation angle (θ p ) was measured in the vastus lateralis (VL) by use of ultrasonography, and muscle fibre CSA (CSA fibre ) was obtained by needle biopsy sampling in VL.
Anatomical muscle CSA and volume increased with training from 77.5 ± 3.0 to 85.0 ± 2.7 cm ² and 1676 ± 63 to 1841 ± 57 cm ³ , respectively (± s.e.m .). Furthermore, VL pennation angle increased from 8.0 ± 0.4 to 10.7 ± 0.6 deg and CSA fibre increased from 3754 ± 271 to 4238 ± 202 μm ² . Isometric quadriceps strength increased from 282.6 ± 11.7 to 327.0 ± 12.4 N m.
A positive relationship was observed between θ p and quadriceps volume prior to training ( r = 0.622). Multifactor regression analysis revealed a stronger relationship when θ p and CSA fibre were combined ( R = 0.728). Post‐training increases in CSA fibre were related to the increase in quadriceps volume ( r = 0.749).
Myosin heavy chain (MHC) isoform distribution (type I and II) remained unaltered with training.
VL muscle fibre pennation angle was observed to increase in response to resistance training. This allowed single muscle fibre CSA and maximal contractile strength to increase more (+16 %) than anatomical muscle CSA and volume (+10 %).
Collectively, the present data suggest that the morphology, architecture and contractile capacity of human pennate muscle are interrelated, in vivo . This interaction seems to include the specific adaptation responses evoked by intensive resistance training.
The present study had two aims: (1) to investigate potential differences in proportion of myosin heavy chain isoforms in the trapezius muscle between female cleaners with and without trapezius myalgia and healthy teachers, and (2) to elucidate if myosin heavy chain composition and surface electromyogram (EMG) during an isokinetic endurance test of shoulder flexors are significantly related. The subjects were divided into three groups: (1) 25 female cleaners with diagnosed work-related trapezius myalgia; (2) 25 female cleaners without work-related trapezius myalgia; (3) a control group of 21 healthy female teachers who were not exposed to repetitive or static muscle work. All subjects performed a test involving150 forward flexions using an isokinetic dynamometer. During the test surface EMG was recorded from the trapezius muscle. Muscle samples were obtained from the descending part of the trapezius muscle. The fibre type area percentage based on ATPase staining and the proportions of different MHC isoforms as determined by gel electrophoresis. The trapezius was dominated by MHC I (71%), followed by MHC IIA (22-24%), and MHC IIX (5-7%); no significant differences between the three groups of subjects were found. The proportion of MHC I correlated negatively with MHC IIA ( r=-0.78; P<0.001) and MHC IIX ( r=-0.53; P<0.001). Significant correlations existed between the proportion of the MHC isoforms and the corresponding proportion of the fibre type area; 27-45% of the variance was explained. The multivariate analysis of the three groups of subjects revealed that MHC variables showed intercorrelations with EMG (both amplitude and frequency variables). However, the directions of the relationships differed among the three groups; the cleaners with myalgia and the teachers showed the greatest similarities in patterns. Intrinsic muscle properties appear to influence the frequency content of the EMG, which is in contrast to some of the theoretical models of the EMG. Our data could suggest that monotonous work such as professional cleaning can change the relationships between muscle structure and the frequency content of the EMG.
The purpose of this study was to investigate the importance of training leading to repetition failure in the performance of 2 different tests: 6 repetition maximum (6RM) bench press strength and 40-kg bench throw power in elite junior athletes. Subjects were 26 elite junior male basketball players (n = 12; age = 18.6 +/- 0.3 years; height = 202.0 +/- 11.6 cm; mass = 97.0 +/- 12.9 kg; mean +/- SD) and soccer players (n = 14; age = 17.4 +/- 0.5 years; height = 179.0 +/- 7.0 cm; mass = 75.0 +/- 7.1 kg) with a history of greater than 6 months' strength training. Subjects were initially tested twice for 6RM bench press mass and 40-kg Smith machine bench throw power output (in watts) to establish retest reliability. Subjects then undertook bench press training with 3 sessions per week for 6 weeks, using equal volume programs (24 repetitions x 80-105% 6RM in 13 minutes 20 seconds). Subjects were assigned to one of two experimental groups designed either to elicit repetition failure with 4 sets of 6 repetitions every 260 seconds (RF(4 x 6)) or allow all repetitions to be completed with 8 sets of 3 repetitions every 113 seconds (NF(8 x 3)). The RF(4 x 6) treatment elicited substantial increases in strength (7.3 +/- 2.4 kg, +9.5%, p < 0.001) and power (40.8 +/- 24.1 W, +10.6%, p < 0.001), while the NF(8 x 3) group elicited 3.6 +/- 3.0 kg (+5.0%, p < 0.005) and 25 +/- 19.0 W increases (+6.8%, p < 0.001). The improvements in the RF(4 x 6) group were greater than those in the repetition rest group for both strength (p < 0.005) and power (p < 0.05). Bench press training that leads to repetition failure induces greater strength gains than nonfailure training in the bench press exercise for elite junior team sport athletes.
The purpose of this study was to examine the efficacy of 11 wk of resistance training to failure vs. nonfailure, followed by an identical 5-wk peaking period of maximal strength and power training for both groups as well as to examine the underlying physiological changes in basal circulating anabolic and catabolic hormones. Forty-two physically active men were matched and then randomly assigned to either a training to failure (RF; n = 14), nonfailure (NRF; n = 15), or control groups (C; n = 13). Muscular and power testing and blood draws to determine basal hormonal concentrations were conducted before the initiation of training (T0), after 6 wk of training (T1), after 11 wk of training (T2), and after 16 wk of training (T3). Both RF and NRF resulted in similar gains in 1-repetition maximum bench press (23 and 23%) and parallel squat (22 and 23%), muscle power output of the arm (27 and 28%) and leg extensor muscles (26 and 29%), and maximal number of repetitions performed during parallel squat (66 and 69%). RF group experienced larger gains in the maximal number of repetitions performed during the bench press. The peaking phase (T2 to T3) after NRF resulted in larger gains in muscle power output of the lower extremities, whereas after RF it resulted in larger gains in the maximal number of repetitions performed during the bench press. Strength training leading to RF resulted in reductions in resting concentrations of IGF-1 and elevations in IGFBP-3, whereas NRF resulted in reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration. This investigation demonstrated a potential beneficial stimulus of NRF for improving strength and power, especially during the subsequent peaking training period, whereas performing sets to failure resulted in greater gains in local muscular endurance. Elevation in IGFBP-3 after resistance training may have been compensatory to accommodate the reduction in IGF-1 to preserve IGF availability.
The purpose of this study was to investigate the hypothesis that cycling efficiency in vivo is related to mitochondrial efficiency measured in vitro and to investigate the effect of training status on these parameters. Nine endurance trained and nine untrained male subjects (V(O2peak) = 60.4 +/- 1.4 and 37.0 +/- 2.0 ml kg(-1) min(-1), respectively) completed an incremental submaximal efficiency test for determination of cycling efficiency (gross efficiency, work efficiency (WE) and delta efficiency). Muscle biopsies were taken from m. vastus lateralis and analysed for mitochondrial respiration, mitochondrial efficiency (MEff; i.e. P/O ratio), UCP3 protein content and fibre type composition (% MHC I). MEff was determined in isolated mitochondria during maximal (state 3) and submaximal (constant rate of ADP infusion) rates of respiration with pyruvate. The rates of mitochondrial respiration and oxidative phosphorylation per muscle mass were about 40% higher in trained subjects but were not different when expressed per unit citrate synthase (CS) activity (a marker of mitochondrial density). Training status had no influence on WE (trained 28.0 +/- 0.5, untrained 27.7 +/- 0.8%, N.S.). Muscle UCP3 was 52% higher in untrained subjects, when expressed per muscle mass (P < 0.05 versus trained). WE was inversely correlated to UCP3 (r = -0.57, P < 0.05) and positively correlated to percentage MHC I (r = 0.58, P < 0.05). MEff was lower (P < 0.05) at submaximal respiration rates (2.39 +/- 0.01 at 50% V(O2max)) than at state 3 (2.48 +/- 0.01) but was neither influenced by training status nor correlated to cycling efficiency. In conclusion cycling efficiency was not influenced by training status and not correlated to MEff, but was related to type I fibres and inversely related to UCP3. The inverse correlation between WE and UCP3 indicates that extrinsic factors may influence UCP3 activity and thus MEff in vivo.
Few studies and reports in the body of literature have directly addressed the issue of whether resistance exercise sets should be performed to failure. Research has clearly demonstrated the superiority of performing multiple sets vs. single sets for increases in maximal strength. However, there is little direct evidence to decide conclusively whether or not multiple sets should be performed to failure. Therefore, the purpose of this research note was to discuss what is currently known concerning the application of training to failure and to stimulate further research on this topic. Although not essential for increases in muscular characteristics such as strength and hypertrophy, training to failure might allow advanced lifters to break through training plateaus when incorporated periodically into short-term microcycles. Because muscular hypertrophy is a key contributor to long-term increases in maximal strength, advanced lifters should consider training to failure occasionally. The potential mechanisms by which training to failure might provide an advantage are through greater activation of motor units and secretion of growth-promoting hormones. However, training to failure is not an effective stimulus without lifting at a sufficient intensity (percentage of 1 repetition maximum). Furthermore, training to failure should not be performed repeatedly over long periods, due to the high potential for overtraining and overuse injuries. Therefore, the training status and the goals of the lifter should guide the decision-making process on this issue.
Human skeletal muscle is a highly heterogeneous tissue, able to adapt to the different challenges that may be placed upon it. When overloaded, a muscle adapts by increasing its size and strength through satellite-cell-mediated mechanisms, whereby protein synthesis is increased and new nuclei are added to maintain the myonuclear domain. This process is regulated by an array of mechanical, hormonal and nutritional signals. Growth factors, such as insulin-like growth factor I (IGF-I) and testosterone, are potent anabolic agents, whilst myostatin acts as a negative regulator of muscle mass. Insulin-like growth factor I is unique in being able to stimulate both the proliferation and the differentiation of satellite cells and works as part of an important local repair and adaptive mechanism. Speed of movement, as characterized by maximal velocity of shortening (V(max)), is regulated primarily by the isoform of myosin heavy chain (MHC) contained within a muscle fibre. Human fibres can express three MHCs: MHC-I, -IIa and -IIx, in order of increasing V(max) and maximal power output. Training studies suggest that there is a subtle interplay between the MHC-IIa and -IIx isoforms, with the latter being downregulated by activity and upregulated by inactivity. However, switching between the two main isoforms appears to require significant challenges to a muscle. Upregulation of fast gene programs is caused by prolonged disuse, whilst upregulation of slow gene programs appears to require significant and prolonged activity. The potential mechanisms by which alterations in muscle composition are mediated are discussed. The implications in terms of contractile function of altering muscle phenotype are discussed from the single fibre to the whole muscle level.
Recent advances in molecular biology have elucidated some of the mechanisms that regulate skeletal muscle growth. Logically, muscle physiologists have applied these innovations to the study of resistance exercise (RE), as RE represents the most potent natural stimulus for growth in adult skeletal muscle. However, as this molecular-based line of research progresses to investigations in humans, scientists must appreciate the fundamental principles of RE to effectively design such experiments. Therefore, we present herein an updated paradigm of RE biology that integrates fundamental RE principles with the current knowledge of muscle cellular and molecular signalling. RE invokes a sequential cascade consisting of: (i) muscle activation; (ii) signalling events arising from mechanical deformation of muscle fibres, hormones, and immune/inflammatory responses; (iii) protein synthesis due to increased transcription and translation; and (iv) muscle fibre hypertrophy. In this paradigm, RE is considered an 'upstream' signal that determines specific downstream events. Therefore, manipulation of the acute RE programme variables (i.e. exercise choice, load, volume, rest period lengths, and exercise order) alters the unique 'fingerprint' of the RE stimulus and subsequently modifies the downstream cellular and molecular responses.
Velocityand power-load relationships of the bench pull vs
- S Anchez-Medina
- L Badillo
- Ce Pallar Es
S anchez-Medina L, Gonz alez-Badillo
JJ, P erez CE, Pallar es JG. Velocityand power-load relationships of the
bench pull vs. bench press exercises.
Restoration of muscle power by heavy-resistance exercises
- T Delorme
Delorme T. Restoration of muscle
power by heavy-resistance exercises.
J Bone Joint Surg Am 1945: 27: 645-667.