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Velocity Loss as an Indicator of Neuromuscular Fatigue during Resistance Training
Abstract
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.
... Velocity-based training has been proposed as a suitable method for the real-time monitoring and prescription of resistance training (RT) outcomes, such as intensity and volume. [1][2][3] Regarding volume, the number of repetitions that individuals can perform with a specific percentage of 1-repetition maximum (%1RM) shows a great variability (coefficient of variation ∼ 20%). 4,5 This fact may lead to different levels of effort among athletes performing the same number of repetitions per set when using a similar %1RM because the repetitions left in reserve may differ considerably between them. ...
... 7 In this context, when the VL reaches 40% in SQ, it indicates that the set is close to failure (ie, when the subject cannot complete another repetition due to fatigue), whereas a 20% VL suggests that practitioners are completing approximately half of their maximal repetitions. 2,7 This approach serves to standardize the effort levels among practitioners regardless of the number of repetitions performed within the RT set. In addition, VL has shown a strong relationship with metabolic and mechanical fatigue markers after 15 different RT conditions (R 2 = .85-.97). 2 Accordingly, these findings support the use of VL monitoring as a valuable tool for managing fatigue levels. ...
... In addition, VL has shown a strong relationship with metabolic and mechanical fatigue markers after 15 different RT conditions (R 2 = .85-.97). 2 Accordingly, these findings support the use of VL monitoring as a valuable tool for managing fatigue levels. ...
Purpose : To compare the acute effects on mechanical, metabolic, neuromuscular, and muscle contractile responses to different velocity-loss (VL) thresholds (20% and 40%) under distinct blood-flow conditions (free [FF] vs restricted [BFR]) in full squat (SQ). Methods : Twenty strength-trained men performed 4 SQ protocols with 60% 1-repetition maximum that differed in the VL within the set and in the blood-flow condition (FF20: FF with 20% VL; FF40: FF with 40% VL; BFR20: BFR with 20% VL; and BFR40: BFR with 40% VL). The level of BFR was 50% of the arterial occlusion pressure. Before and after the SQ protocols, the following tests were performed: (1) tensiomyography, (2) blood lactate, (3) countermovement jump, (4) maximal voluntary isometric SQ contraction, and (5) performance with the load that elicited a 1 m·s ⁻¹ at baseline measurements in SQ. Results : No “BFR × VL” interactions were observed. BFR protocols resulted in fewer repetitions and lower increases in lactate concentration than FF protocols. The 40% VL protocols completed more repetitions but resulted in lower mechanical performance and electromyography median frequency during the exercise than the 20% VL protocols. At postexercise, the 40% VL protocols also experienced greater blood lactate concentrations, higher alterations in tensiomyography-derived variables, and accentuated impairments in SQ and countermovement-jump performances. The 20% VL protocols showed an increased electromyography median frequency at postexercise maximal voluntary isometric contraction. Conclusions : Despite BFR-accelerated fatigue development during exercise, a given VL magnitude induced similar impairments in the distinct performance indicators assessed, regardless of the blood-flow condition.
... When performing resistance exercises, muscle fatigue is generally considered unavoidable [1]. When muscle fatigue occurs, the muscle's ability to generate force is compromised, which negatively impacts explosive athletic performance, including peak velocity and power output [2,3]. These impairments in force-generating capacity have also been linked to an increased risk of injuries. ...
... However, fatigue-induced shifts in the power spectrum typically occur over a longer timescale, making it less effective for real-time monitoring. When the training goal is to enhance explosive athletic performance, athletes must lift weights as explosively as possible while minimizing any significant velocity decreases caused by muscle fatigue [3]. In such scenarios, sEMG-based muscle fatigue assessment has limited effectiveness, as it cannot provide the real-time feedback necessary for explosive resistance training programs. ...
... To address the limitations in muscle fatigue assessment, several indirect muscle fatigue markers have been proposed [3,17,18]. For example, blood lactate, ammonia, and cortisol concentrations have been suggested as valid indirect indicators of muscle fatigue [19]. ...
Background: Muscle fatigue is inevitable during resistance exercises, making its monitoring essential for maintaining athletic performance and reducing the risk of injury. Ratings of perceived exertion (RPE) and velocity loss have been reported as reliable indicators of muscle fatigue during explosive resistance exercises. However, their validity has been assessed only indirectly. This study aimed to directly examine the validity of RPE and velocity loss as markers of muscle fatigue during explosive back squat (BS) exercises. Methods: Seventeen trained men performed three BS tasks with varying volumes (low, medium, high) at 65% of their one-repetition maximum. RPE, spectral fatigue index (SFI), and velocity loss were measured throughout the tasks. Results: Significant effects were observed across conditions for overall RPE (p < 0.001) and velocity loss (p < 0.001), while no significant effect was found for SFI. RPE and SFI increased significantly as the tasks progressed (p < 0.001), while velocity did not significantly decrease. Significant but weak correlations were found between RPE and SFI (r = 0.325, p < 0.001) and between velocity loss and SFI (r = 0.224, p < 0.001). Conclusions: These findings suggest that RPE and muscle fatigue levels increase correspondingly, indicating that RPE could serve as a practical, indirect fatigue marker for explosive BS exercises. However, velocity loss may not fully reflect muscle fatigue during lower-body explosive training and should not be used as the sole indicator. Additionally, caution is warranted when applying velocity-related parameters as indirect physiological markers for resistance exercises. The significant but weak correlations between RPE, velocity loss, and SFI suggest that assessing muscle fatigue in lower-body exercises remains challenging.
... The term "level of effort" refers to the number of repetitions performed in each set relative to the maximum number that can be completed. 1 In this regard, it has been observed that acute mechanical and metabolic stress varies significantly based on the level of effort the athletes exert. 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. ...
... 1 In this regard, it has been observed that acute mechanical and metabolic stress varies significantly based on the level of effort the athletes exert. 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. ...
... [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. This capability is supported by 2 key factors: (1) the manipulation of the level of effort significantly alters the magnitude of VL over the set 1 and (2) the observed high relationship (R 2 = .93-.97) between the magnitude of VL within the set and the relative difference between the number of repetitions performed and the maximum number that can be completed (%Rep) in both benchpress (BP) and full-squat exercises performed on a Smith machine across a range of intensities (from 50% to 85% of 1-repetition maximum [1RM]). ...
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.
... Fatigue management becomes crucial as the stimulus to the fatigue ratio is a key factor in achieving the desired adaptations. Contrary to the common belief that high loads are always more fatiguing, evidence has shown that low loads can, in fact, induce greater fatigue, particularly when sets are performed close to failure [8][9][10]. Fatigue should be understood holistically as a symptom [11,12] involving physiological, psychological, cognitive, subjective, and biomechanical fatigability factors. ...
... It is recommended to combine subjective and objective measures of fatigue [15,16], and the need for holistic models is still present, given that the majority of previous research has focused on physiological or perceptual mechanisms of fatigue in isolation [9,10,13,14]. ...
... Integral approximations for Bayes factors were based on 10,000 steps, while Posteriors and errors were calculated with 10,000 Markov Chain Monte Carlo samples. For Bayesian RMANOVA, informed prior probabilities were established for VL, EI, La, VL1, VL0.5, and RPE, based on results from relevant references with similar designs to ours [9,10,[21][22][23][24] and two metaanalyses [4,25]. For the remaining variables and post hoc comparisons, non-informed priors were used. ...
Background/Objective: This study investigated the differences in acute fatigue following resistance training performed with low versus high loads in the bench press (BP). Methods: Trained males (n = 5, 21.2 ± 2.77 years; 81.86 ± 6.67 kg; 177 ± 7.52 cm) undertook three protocols with 50%RM and three with 85%RM with volume equalized between protocols: muscular failure protocols (TF, RTP1 and 2), half-maximum repetition protocols (RTP3 and 4), and cluster set protocols (RTP5 and 6). Mechanical performance, lactate, and perceptual responses were analyzed during protocols and at post 0, 24, and 48 h using frequentist (p < 0.05) and Bayesian approaches. Results: Moderate to large (ES ≥ 0.3) and trivial to moderate (ES < 0.3) effects were observed at 0 and 24 h post-session, respectively, across all protocols. TF protocols, particularly RTP1, showed the greatest impairments when compared to the other RTP (ES ≥ 0.3). The Bayesian analysis supported the frequentist results, showing strong-decisive evidence for our data under the model that included protocols as predictors for mechanical, metabolic, and perceptual variables during protocols. Inter-individual variability in responses was observed in the neuromuscular tests, potentially related to the strength level and perceptual responses. Conclusions: In summary, TF generates greater fatigue, while reducing set volume to half of maximum repetitions or including intra-set rest that helps to mitigate fatigue symptoms.
... 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]. ...
... 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]. ...
... 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]. ...
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.
... Before beginning the 1-RM test (32,38,41,42), subjects performed the following standardized warmup: 5 min of rowing on a rowing ergometer followed by cat-cow flow, thoracic rotations, dynamic down dogs, and pushups (8-10 repetitions each). After the standardized warm-up, subjects were permitted 3-5 min to perform any exercise that they would typically do before a bench press training session. ...
... For each repetition, subjects were instructed to grip the barbell as they would during their usual training sessions and to maintain 5 points of body contact throughout: head, upper back, and buttocks on the bench with both feet planted firmly on the floor (43). Lifters controlled the eccentric phase of motion, paused for ~1 s with the barbell on their chest, and performed the concentric phase of motion as fast as possible following a "go" command from a researcher (41,42). Velocity was monitored with the linear velocity transducer (Power Analyzer V-620, TENDO Sports Machines, London, UK) that was fixed to the right side of the barbell via a velcro strap. ...
... Following the above-mentioned warm up, subjects performed a bench-press-specific warm up: 10 repetitions with the barbell followed by 3 repetitions with 35, 45, and 55% 1-RM. Subjects were encouraged to perform these warm-up sets with maximal intent, especially because the 45% 1-RM set was used to help quantify mechanical fatigue (38,41). One extra warm-up set of 1-2 repetitions was performed with 65% 1-RM before the CL session and two extra warm-up sets of 1-2 repetitions were performed with 65% and 75% 1-RM before the DP session. ...
This study analyzed the effect of ascending pyramid (AP), constant load (CL), and descending pyramid (DP) training on repetition performance, training volume, barbell velocity, mechanical fatigue, and perceptual measurements during bench press exercise. Eighteen well-trained young males (18-40 years) performed AP, CL, and DP in a randomized order. Subjects were ranked according to relative strength ratio (Bench press 1-RM ÷ body mass) and the total sample of 18 males was divided into two groups: group 1 (G1), n = 9, RSR = 1.20-1.56; group 2 (G2), n = 9, RSR = 0.75-1.16. Volume (5 sets), relative intensity (65-85% 1-RM), set end point (25% velocity loss (VL)), and rest intervals (5 min) were matched between conditions. Relative intensity did not change during CL (75% 1-RM), while sets were performed from light-to-heavy during AP (65-70-75-80-85% 1-RM), and heavy-to-light during DP (85-80-75-70-65% 1-RM). Repetition performance, total volume load (TVL), mean and peak velocity, VL, and ratings of perceived exertion (set-RPE) were measured during each session while affect, discomfort, enjoyment, and session-RPE were measured after each session. Mean and peak velocity with 45% 1-RM were assessed before, 5-min after, and 10-min after each session. Data indicated that peak velocity and set-RPE were significantly lower during DP (p ≤ 0.05) while no differences were detected between AP and CL. Session x set interactions (p ≤ 0.05) were observed for repetition performance, mean velocity, peak velocity, VL, and set-RPE, but differences were likely influenced by fluctuating relative intensities during AP and DP. Data also revealed that lifters from G2 executed their repetitions with greater mean and peak velocities than G1 (p ≤ 0.05), suggesting that relative strength influences barbell velocity. In conclusion, AP, CL, and DP are viable options for training sessions, but the latter may negatively affect peak velocity.
... Por otro lado, se ha demostrado que entrenar hasta el fallo muscular resulta innecesario, y es menos beneficioso que entrenar lejos del fallo muscular para el rendimiento deportivo [22][23][24][25] , siendo especialmente negativo para el RFD 12 . Se ha observado un patrón de pérdida de velocidad respecto a la máxima posible durante una serie al fallo, donde la última repetición coincide con la velocidad del RM 26 ; y por otro lado, se ha descrito una relación lineal entre la pérdida de velocidad y las concentraciones de lactato; y una relación no lineal con las concentraciones de amonio, independiente del número de repeticiones realizadas 27 . Recientemente se ha podido comprobar cómo al comparar los efectos de protocolos de entrenamientos que diferían en el total de trabajo realizado en función del % de pérdida de velocidad durante la serie; se obtienen 1) mejoras superiores en el 1RM y la velocidad de ejecución en sujetos entrenados al comparar pérdidas de velocidad del 20% frente a un entrenamiento al fallo muscular 28 ; y 2) mejoras superiores en CMJ y menores descensos en el porcentaje de cabezas pesadas de miosina (MHC-IIX), con mejoras similares en la fuerza máxima al comparar pérdidas de velocidad del 20% frente al 40% 29 . ...
... Los resultados obtenidos se pueden relacionar con estudios previos en los que se ha demostrado la validez del RPE basado en el RIR de los sujetos 43 ; y por otro lado, la relación entre la perdida velocidad y el número de repeticiones realizado respecto al máximo posible (fallo muscular) 26,27 . Teniendo en cuenta que el concepto de RIR hace referencia al número de repeticiones que los sujetos perciben que podrían realizar hasta llegar al fallo, estas investigaciones muestran la relación del RIR tanto con el RPE como con la pérdida de velocidad; por tanto parece lógico pensar que también exista una relación RPE-pérdida de velocidad, como demuestran los resultados de este estudio. ...
... Sin embargo nuestros resultados no concuerdan con estudios previos que han encontrado valores superiores de RPE al realizar menos repeticiones con intensidades altas que al realizar más repeticiones con intensidades bajas 35 ; y por otro lado, al comparar un entrenamiento de fuerza en circuito con cargas altas con un entrenamiento de fuerza en circuito orientado a la potencia con cargas ligeras y moderadas, se ha comprobado como la RPE resulta superior para el entrenamiento de fuerza con cargas altas 47 . No obstante, en estos dos estudios no se equipararon ni el volumen total de carga, ni el número de repeticiones respecto al fallo muscular entre los protocolos analizados; lo que puede explicar las diferencias con nuestros resultados, donde la carga total ha sido controlada mediante la pérdida de velocidad, que está relacionada con marcadores metabólicos y mecánicos de fatiga 27 . ...
Resumen: Controlar las variables de entrenamiento es vital para garantizar las adaptaciones deseadas en el entrenamiento de fuerza, siendo la intensidad especialmente importante para mejorar la fuerza máxima y el RFD. La velocidad de ejecución ha resultado ser la mejor variable para monitorizar la intensidad del entrenamiento de fuerza, en particular las pérdidas de velocidad relacionadas con la fatiga. Sin embargo, existen impedimentos materiales para poder utilizar esta variable. Por tanto, el objetivo de este trabajo es analizar la relación entre el RPE y las pérdidas de velocidad como alternativa para controlar el entrenamiento. Se midió a 5 sujetos (4 hombres y 1 mujer) pertenecientes a la selección española de lucha libre olímpica un total de 15 series de press de banca (3 series/sujeto), de las cuales solo 14 se incluyeron en el análisis estadístico por incumplir una de ellas el protocolo, con 3 cargas relativas distintas (5 series/carga) y una pérdida de velocidad entre 20%-32%. Las variables dependientes fueron: RPE, la pérdida de velocidad, el número de repeticiones realizadas en cada serie y velocidad de la mejor repetición de cada serie. Se analizaron las correlaciones entre las variables RPE-pérdida de velocidad; RPE-número de repeticiones; RPE-velocidad mejor repetición, obteniéndose solamente correlación significativa (r Pearson 0,843; P <0,001) entre el RPE y la pérdida de velocidad; la correlaciones entre el RPE-número de repeticiones y RPE-velocidad mejor repetición no mostraron significación estadística. Estos resultados podrían indicar la posibilidad de gestionar la fatiga y la intensidad del entrenamiento utilizando la relación RPE-pérdida de velocidad, aunque es necesario llevar a cabo estudios similares con tamaños muestrales mayores que refuercen los resultados obtenidos en este estudio.
Summary: Controlling the training variables is vital to ensure the desired adaptations in resistance training; intensity is the most important variable to improve maximum strength and rate of force development (RFD). The movement velocity has shown to be the best variable to monitor the intensity of resistance training, in particular the velocity loss related to fatigue. However, there are material impediments to use this variable. Therefore, the aim of this paper is to analyze the relationship between RPE and velocity losses as an alternative to control training. Sample included 5 subjects (4 men and 1 woman) from the Spanish Olympic Wrestling team who performed a total of 15 sets of bench press (3 set/subject), of which only 14 were included in the statistical analysis for breaching one of them the protocol, with 3 different relative loads (5 set/load) and a velocity loss between 20%-32%. The dependent variables were: RPE, the velocity loss, the number of repetitions performed in each set and the velocity of the best repetition of each set. The correlations between the RPE-velocity loss; RPE-number of repetitions; and RPE-velocity best repetition variables were analyzed, obtaining only significant correlation (r Pearson 0.843, P <0.001) between the RPE and the velocity loss; correlations between RPE-number of repetitions; and RPE-velocity best repetition did not show statistical significance. The results of the present work could indicate the possibility of managing fatigue and controlling training intensity using the RPE-velocity loss relationship, although it is necessary to carry out similar studies with larger sample sizes that reinforce the results of this study.
... In fact, athletes exhibiting lower initial 1RM values demonstrate greater potential for improvement, and the training status itself significantly affects the results achieved with the training program. 23 This can be the main reason why 27,28 Inoltre, avremo un numero inferiore di ripetizioni, 2, 25 e di tempo di tensione muscolare, 6,9 oltre ad un maggiore reclutamento delle fibre muscolari di tipo II. 24 1 There is a restricted number of studies in which researchers used 10% of velocity loss and interestingly, they all showed similar improvement, around 18% in squat RM, 10,24,25 like in the present study. ...
... This enables athletes to optimize their training outcomes, potentially leading to reduced levels of fatigue. 27,28 As a result, a lower number of repetitions occurs, 2, 25 and time under tension 6, 9 but also bigger recruitment of muscle fiber type II. 24 A higher percentage of velocity loss is related to greater muscle hypertrophy, most likely due to the higher number of repetitions. ...
... 26 This indicates that the volume of the training (which can be quantified by the level of velocity loss) has a high impact on neuromuscular adaptation, fatigue, and hormonal and metabolic stress. 2,27 Therefore, it can be concluded that the VBT training method is safer in terms of muscle damage. Most importantly, monitoring CK levels can be a useful tool for coaches and athletes to gauge the extent of muscle damage and recovery following training sessions. ...
BACKGROUND: Available literature referring to the differences in the efficiency between velocity-based training (VBT) and percentage-based strength training (PBT) relating to the neuromuscular performances and markers of muscle damage in young males is quite scarce. Therefore, the goal of the current study was to investigate the differences between VBT and PBT programs in terms of their effects on absolute strength, explosive power, speed, and agility, as well as their influence on muscle damage as indicated by changes in biochemical markers following a 6-week resistance training programs.
METHODS: The study included 42 young men, divided into two experimental groups, VBT (N.=17) and PBT (N.=15), and the control group (N.=10). Before and after the experimental treatments, the respondents performed the following tests: one-repetition maximum (1RM) in squat and bench press exercises for absolute strength, squat jump (SJ) and countermovement jump (CMJ) for explosiveness, 5m and 20m running for speed, and 505 test around both legs for agility. In addition, creatine kinase (CK) and creatine kinase isoenzyme (CK-MB) were evaluated as markers of muscle damage.
RESULTS: The obtained results suggested statistically significant differences between analyzed groups in terms of absolute strength and explosiveness in favor of the VBT program. It is also indispensable to highlight that VBT group demonstrated greater enhancement than PBT group in the following tests: 1RM squat (Δ% 17.9 and Δ% 11.9, respectively), 1RM bench press (Δ% 13.5 and Δ% 6.96, respectively), SJ (Δ% 13.89 and Δ% 5.15, respectively), CMJ (Δ% 16.96 and Δ% 5.37, respectively). The levels of CK marker were substantially lower at the third measurement in the VBT group compared to the PBT intervention.
CONCLUSIONS: VBT was more effective regarding the development of absolute and explosive strengths and elicited lower muscle damage compared to the PBT program.
... observed between the achieved VL within the set and the percentage of completed repetitions relative to the maximum possible [21,22]. Specifically for the full-squat (SQ) exercise, when 50% of possible repetitions are completed, it has been suggested that VL is approximately 20%, while when repetitions are performed close to failure, VL is around 40-50% [20,21]. This fact is relevant for load control, as individuals may not perform the same number of repetitions at a certain %1RM, yet they would exert a comparable level of effort (i.e., proximity to failure) with a given VL. ...
... This practice leads to exceptionally high levels of fatigue, potentially causing counterproductive effects on specific neuromuscular adaptations. Moreover, VL within the set has been suggested as an indicator of fatigue development during RE [20][21][22]. However, no previous study has explored the use of VL for quantifying fatigue in the context of BFR-RE. ...
... While the eccentric phase was performed in a controlled manner, participants were instructed to execute the concentric phase at maximal velocity for each repetition. All repetitions were recorded with a linear velocity transducer (T-Force System Ergotech, Murcia, Spain), which is highly reliable [20]. The warm-up comprised 5 min of jogging at a self-selected easy pace, succeeded by 2 sets of 10 squats performed without external load, followed by 6 repetitions using a 20 kg load on the Smith machine. ...
(1) Background: The aim of this paper is to analyze the acute effects of different velocity loss (VL) thresholds during a full squat (SQ) with blood-flow restriction (BFR) on strength performance, neuromuscular activity, metabolic response, and muscle contractile properties. (2) Methods: Twenty strength-trained men performed four protocols that differed in the VL achieved within the set (BFR0: 0% VL; BFR10: 10% VL; BFR20: 20% VL; and BFR40: 40% VL). The relative intensity (60% 1RM), recovery between sets (2 min), number of sets (3), and level of BFR (50% of arterial occlusion pressure) were matched between protocols. Tensiomyography (TMG), blood lactate, countermovement jump (CMJ), maximal voluntary isometric SQ contraction (MVIC), and performance with the absolute load required to achieve 1 m·s−1 at baseline measurements in SQ were assessed before and after the protocols. (3) Results: BFR40 resulted in higher EMG alterations during and after exercise than the other protocols (p < 0.05). BFR40 also induced greater impairments in TMG-derived variables and BFR10 decreased contraction time. Higher blood lactate concentrations were found as the VL within the set increased. BFR0 and BFR10 showed significantly increased median frequencies in post-exercise MVIC. (4) Conclusions: High VL thresholds (BFR40) accentuated metabolic and neuromuscular stress, and produced increased alterations in muscles’ mechanical properties. Low VL could potentiate post-exercise neuromuscular activity and muscle contractile properties.
... We chose to evaluate L-V profiles with peak velocity because the breaking phase of the bench press at lighter loads causes mean velocity to depreciate the evaluation of the lift (34). Subjects completed 3 consecutive repetitions for loads of 40-80% 1RM and 2 repetitions for 90% 1RM with [27,33] 37 [33,41] 3 minutes of rest between load conditions (23). Subjects were instructed to lift the load as fast as possible with verbal encouragement from researchers. ...
... We chose to evaluate L-V profiles with peak velocity because the breaking phase of the bench press at lighter loads causes mean velocity to depreciate the evaluation of the lift (34). Subjects completed 3 consecutive repetitions for loads of 40-80% 1RM and 2 repetitions for 90% 1RM with [27,33] 37 [33,41] 3 minutes of rest between load conditions (23). Subjects were instructed to lift the load as fast as possible with verbal encouragement from researchers. ...
... Fourteen subjects are an adequate sample size to detect a 5% difference in peak velocity with the reported standard error of the measurement ranging 0.02-0.06 m·s 21 , 0.8 effect size with strong test-retest correlation of 0.90 when a 5 0.05 and b 5 0.80 (14,23,33). Sixteen subjects were recruited for anticipated attrition, but all 16 finished both trials. ...
Sweet, DK, Qiao, J, Rosbrook, P, and Pryor, JL. Load-velocity profiles before and after heated resistance exercise. J Strength Cond Res 38(6): 1019–1024, 2024—This study examined neuromuscular performance using load-velocity (L-V) profiles in men and women before and after resistance exercise (RE) in hot (HOT; 40° C) and temperate (TEMP; 21° C) environments. Sixteen ( f = 8, m = 8) resistance-trained individuals completed a single 70-minute whole-body high-volume load (6 exercises, 4 sets of 10 repetitions) RE bout in HOT and TEMP. Before and after RE, rectal temperature (T RE ), muscle temperature of the vastus lateralis (T VL ) and triceps brachii (T TB ), and an L-V profile for the deadlift and bench press were recorded. Thermoregulatory and L-V data were analyzed using separate 2-way repeated measures analysis of variances (ANOVAs; condition [hot, temperate] and time [pre, post]) with significance level set at p ≤ 0.05. Deadlift peak velocity was reduced at 60% 1 repetition maximum (1RM) after RE in HOT but not TEMP. Peak velocity of 40% 1RM bench press was lower in TEMP vs. HOT pre-RE ( p < 0.01). Peak velocity was decreased at all loads in the deadlift L-V profile after RE, regardless of condition. Despite elevated T RE (TEMP; 37.58 ± 0.35, HOT; 38.20 ± 0.39° C), T VL (TEMP; 35.24 ± 0.62, HOT; 37.92 ± 0.55° C), and T TB (TEMP; 35.05 ± 0.78, HOT; 38.00 ± 0.16° C) after RE in HOT vs. TEMP ( p < 0.01), RE in HOT did not broadly affect L-V profiles. This indicates heated resistance exercise can be performed with high-volume load and high ambient temperature with minimal performance impairment.
... Neuromuscular fatigue is defined as a transient reduction in the ability to produce force or power induced by exercise, which results in a temporary decrease in performance [2]. The accumulated fatigue in the RT session increases metabolic stress and the recovery time of neuromuscular function [3,4]. There are training periods in which it is desirable to attenuate the level of mechanical, metabolic, and psychobiological stress, as well as to avoid an exacerbated reduction in neuromuscular performance [5]. ...
... Monitoring bar velocity in resistance exercise through linear encoders and accelerometers has emerged as a methodological alternative to control neuromuscular fatigue in RT [15]. Sánchez-Medina and González-Badillo [4] investigated whether the loss of bar velocity can be used as an optimal indicator of fatigue. The results showed significant reductions in bar velocity against a moderate load (~1 m/s -1 ) and countermovement jump (CMJ) height pre-post exercise. ...
... Previous studies have also proposed that bar velocity monitoring can be applied in various ways to assess and control neuromuscular fatigue in RT [4,16]. The magnitude of fatigue can be controlled in real-time using intra-set velocity loss thresholds to regulate the volume [17]. ...
We analyzed the effects of load magnitude and bar velocity variables on sensitivity to fatigue. Seventeen resistance-trained men (age=25.7±4.9 years; height=177.0±7.2 cm; body mass=77.7±12.3 kg; back-squat 1RM=145.0±33.9 kg; 1RM/body mass=1.86) participated in the study. Pre- and post-exercise changes in the mean propulsive velocity (MPV) and peak velocity (PV) in the back-squat at different intensities were compared with variations in the countermovement jump (CMJ). CMJ height decreased significantly from pre- to post-exercise (∆%=-7.5 to -10.4; p<0.01; ES=0.37 to 0.60). Bar velocity (MPV and PV) decreased across all loads (∆%=-4.0 to -12.5; p<0.01; ES=0.32 to 0.66). The decrease in performance was similar between the CMJ, MPV (40% and 80% 1RM; p=1.00), and PV (80% 1RM; p=1.00). The magnitude of reduction in CMJ performance was greater than MPV (60% 1RM; p=0.05) and PV (40% and 60% 1RM; p<0.01) at the post-exercise moment. Low systematic bias and acceptable levels of agreement were only found between CMJ and MPV at 40% and 80% 1RM (bias=0.35 to 1.59; ICC=0.51 to 0.71; CV=5.1% to 8.5%). These findings suggest that the back-squat at 40% or 80% 1RM using MPV provides optimal sensitivity to monitor fatigue through changes in bar velocity.
... 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. 12 These extenuating environment does not seem to be optimal to maximize strength gains. ...
... 7,8,10 However, using VL as a criterion to determine when the set should be terminated affects not only the induced fatigue level, but also the RT volume that has been performed. 11 Accordingly, the resulting RT adaptations are the products of both different RT volumes and levels of fatigue. ...
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.
... 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]. 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]. ...
... In the current study, sets were not taken to failure; instead, unintentional decreases in movement velocity were used as limits to control set volume, a concept known as velocity loss threshold (VLT) [10,11]. 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. ...
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.
... 4 In recent years, the practicability of the velocity-based resistance training (RT) approach for monitoring and real-time prescription of RT intensity and volume has been demonstrated. [5][6][7] In this context, velocity loss (VL) provides practitioners with a useful and practical tool to monitor training volume and level of effort. 8,9 Therefore, VL can be used to determine when each set should be stopped. ...
... 24 Indeed, in the present study, the VL25 group performed the slowest repetitions, on average, around 0.70 m · s −1 , still far from the velocity at which muscle failure is attained in BP (∼0.17 m · s −1 ). 6,25 A plausible explanation is that in the present study, participants performed each repetition at maximal intended velocity, and it has been shown that strength gains in the BP exercise can be maximized when repetitions are performed at maximal intended concentric velocity. 26 Another interesting result is that the VL0 group, the group that trained with the minimum dose of VL (only one repetition per set), obtained significant gains in 1RM. ...
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.
... It is widely recognized that, when repetitions are carried out with maximum concentric effort, there is a gradual reduction in barbell velocity as fatigue sets in [11,12]. Earlier research has shown that (i) the reduction in velocity during RT (i.e., the percentage of velocity decline between the fastest and last repetition of the set; %VL) correlates strongly with both mechanical (e.g., decrease in jump height) and metabolic (e.g., increase in blood lactate levels) indicators of fatigue [13,14]; and (ii) there is a robust association between %VL and the percentage of performed repetitions relative to the maximum number that can be achieved until failure (%Rep) across different loads [5,6]. Drawing on this evidence, numerous researchers have suggested that %VL could provide a more objective measure of exertion in a set compared to traditional methods of RT prescription [5,13]. ...
... Earlier research has shown that (i) the reduction in velocity during RT (i.e., the percentage of velocity decline between the fastest and last repetition of the set; %VL) correlates strongly with both mechanical (e.g., decrease in jump height) and metabolic (e.g., increase in blood lactate levels) indicators of fatigue [13,14]; and (ii) there is a robust association between %VL and the percentage of performed repetitions relative to the maximum number that can be achieved until failure (%Rep) across different loads [5,6]. Drawing on this evidence, numerous researchers have suggested that %VL could provide a more objective measure of exertion in a set compared to traditional methods of RT prescription [5,13]. In particular, employing %VL might promote a more uniform exertion level among individuals due to the minimal variability in %Rep at different levels of %VL [5,6]. ...
This study explored the goodness-of-fit and the effect of fatigue on the precision of both generalized and individualized relationships between the velocity loss (%VL) magnitude and the percentage of completed repetitions with respect to the maximal that can be performed to failure (%Rep) in the Smith machine parallel back-squat exercise. Twenty-nine resistance-trained males completed four sets to failure, with a rest period of 2 min, against 75% of the one-repetition maximum. Generalized and individualized %Rep-%VL equations determined in the first set were used to estimate %Rep when a 20%VL was achieved during the three successive sets. Individualized %Rep-%VL relationships (R 2 = 0.84-0.99) showed a greater goodness-of-fit than the generalized %Rep-%VL relationship (R 2 = 0.82). However, the accuracy in the %Rep estimation was always low (absolute errors > 10%) and comparable for both regression models (p = 0.795). %Rep was progressively overestimated when increasing the number of sets using the MV fastest of the first set (from 15% to 45%), but no meaningful overestimations were observed using the MV fastest of each set (~2%). In conclusion, neither the generalized nor the individual %Rep-%VL equations provide accurate estimations of %Rep during the parallel back-squat exercise executed under fatigue.
... Subjects were required to execute the concentric phase at maximal intended velocity and the eccentric phase at a controlled mean velocity (;0.50-0.65 m·s 21 ). All data were recorded at 1,000 Hz using a linear velocity transducer (T-Force System, Ergotech, Murcia, Spain), whose reliability has been previously reported (31). Warm-up consisted of 5 minutes of jogging at a self-selected easy pace, and then subjects performed 2 sets of 10 squats without external load, and after 2 minutes of rest, performed 6 repetitions with a 20-kg load on the Smith machine. ...
... V1-Load Test. This test consisted of performing 3 repetitions with 60% 1RM (MPV ;1 m·s 21 at the pre-test) (31). EMG data (i.e., RMS and MDF) were recorded as described below. ...
Cornejo-Daza, PJ, Sánchez-Valdepeñas, J, Páez-Maldonado, J, Rodiles-Guerrero, L, Boullosa, D, León-Prados, JA, Wernbom, M, and Pareja-Blanco, F. Acute responses to traditional and cluster-set squat training with and without blood flow restriction. J Strength Cond Res XX(X): 000–000, 2024—To compare the acute responses to different set configurations (cluster [CLU] vs. traditional [TRA]) under distinct blood flow conditions (free vs. restricted) in full-squat (SQ). Twenty resistance-trained males performed 4 protocols that differed in the set configuration (TRA: continuous repetitions; vs. CLU: 30 seconds of rest every 2 repetitions) and in the blood flow condition (FF: free-flow; vs. blood flow restriction [BFR]: 50% of arterial occlusion pressure). The relative intensity (60% 1RM), volume (3 sets of 8 repetitions), and resting time (2 minutes) were equated. Mean propulsive force (MPF), velocity (MPV) and power (MPP), and electromyography (EMG) parameters were recorded during each repetition. Tensiomyography (TMG), blood lactate, countermovement jump (CMJ) height, maximal voluntary isometric contraction, in SQ, and movement velocity against the load that elicited a 1 m·s ⁻¹ velocity at baseline (V1-load) in SQ were assessed at pre- and post-exercise. The CLU protocols allowed a better maintenance of MPF, MPV, MPP, and EMG median frequency during the exercise compared to TRA (clu-time interaction, p < 0.05). The TRA protocols experienced greater impairments post-exercise in TMG- and EMG-derived variables (clu-time interaction, p < 0.05) and SQ and CMJ performance (clu-time interaction, p = 0.08 and p < 0.05, respectively), as well as higher blood lactate concentrations (clu-time interaction, p < 0.001) than CLU. Moreover, BFR displayed decreases in TMG variables (bfr-time interaction, p < 0.01), but BFR-CLU resulted in the greatest reduction in twitch contraction time ( p < 0.001). Cluster sets reduced fatigue during and after the training session and BFR exacerbated impairments in muscle mechanical properties; however, the combination of both could improve contraction speed after exercise.
... (p = 0.033; ω2 = 0.004) in the comparison of three series S1 vs S2 vs S3. The post hoc analysis using Holm's correction revealed that V signi cantly increased for 50% 1RM protocol between S1 and S2 (S1: 76. 39 ...
The main purpose of this study was to assess the changes in energy expenditure (EE), oxygen volume (VO 2 ), heart rate (HR), and velocity (V) measurements obtained during three sets of each of two squat training protocols in a group of healthy young adults. Twenty-nine students of Sports Sciences volunteered to participate in this study. They attended the laboratory on four different days and performed four sessions: two of 3 sets of 12 repetitions at 75% 1 repetition maximum (RM) and two of 3 sets of 30 repetitions at 50% 1RM while EE, VO 2 , HR and V was evaluated. The major outcomes of this study indicated that EE, VO2, HR, and V tended to decrease in both protocols as the sets were performed. Despite this, the creation of fresh insights regarding the assessment of different strengths and metabolic variables can help illuminate the underlying causes of these distinctions. Furthermore, these findings have important implications for the design of effective and personalized strength training programs.
... Therefore, sessions' V loss was calculated from the mean loss of the sets performed and calculated as previously suggested: V loss = 100× [(maximal velocity x -minimal velocity)/maximal velocity]. 15,20 rpe of the session (s-rpe) was obtained using the category ratio scale (ranging from 0, "nothing at all" to 10, "very very difficult") by asking participants "how was your workout?". 21 The scale was explained to participants when they gave their written informed consent to participate, and investigators asked them to use the scale during their own training sessions. ...
Background:
Effects comparison of resistance exercises may require equalizing the exercise-induced dose, this is currently done by using methods based on total weight lifted or on sets performed until failure. Dose equalization of resistance training sessions by these methods was analyzed in the present study.
Methods:
Twelve trained participants performed five bench-press sessions with a similar relative endpoint determined by the inability to complete a set of 50% of the maximum repetitions number (MNR). Sessions were performed at 50 or 85% of one-repetition maximum (1-RM) with sets until failure or sets prescribing 50% of MNR. The last session was performed with a reduced recovery pause to match the exercise density (total weight lifted/pause duration) of a previous session.
Results:
Sessions resulted in different total weight lifted (3158±1592 kg at 85% of 1-RM vs. 5330±1967 at 50%, P<0.001) and number of sets until failure (5.1±1.9 at 85% of 1-RM vs. 2.9±1.1 at 50%, P<0.001). Matching of sessions' density suppressed the differences in the number of sets performed (P=0.50).
Conclusions:
Protocols' equalization based on the total weight lifted is likely to result in exercise volumes close to maximums when performed with heavy loads, whereas equalization based on sets to failure could induce a sets number close to the maximum when performed with light loads. Current methods for protocols equalization rely on gross values of exercise volume without considering maximums, that can result in markedly unbalanced efforts and biased results. Prescribing each exercise volume according to its maximum might optimize the training protocols' equalization.
... The countermovement squat jump (CMJ) height loss is used for monitoring the levels of fatigue during a training session (Jimenez-Reyes et al., 2016;Sanchez-Medina & González-Badillo, 2011) due to the strong correlations (0.92-0.97) observed between jump height loss and blood lactate and ammonia. In addition, heart rate (HR) recovery is suggested to be a marker of physical fitness (Shetler et al., 2001). ...
This study aimed to assess the acute effects of the sequence of concurrent training (CT) on physiological, neuromuscular, and perceptive parameters in recreational athletes. Eighteen active men (mean ± SD: 22.00 ± 2.00 years; 79.40 ± 9.87 kg and 175.62 ± 6.35 cm) performed two CT sessions consisting of repeated sprint endurance exercise followed by resistance exercise (E-R) or the reverse sequence (R-E) in a randomized order. The E exercise consisted of 6x30s of cycling “all-out” interspersed by 15s of passive recovery, while the R exercise consisted of 3x15 repetitions near failure (1 repetition in reserve) of back squat exercise with rest intervals of 45s. Height in CMJ, heart rate (HR), rating of perceived exertion (RPE) after each exercise, and at the final of the session (sRPE) were recorded. The R-E sequence showed a higher HR at 10s, 1min and 6min (p < .05) post E exercise compared to R exercise. Significant protocol x time interactions were observed for sRPE (p < .001) being higher after the R-E sequence compared to E-R sequence. RPE was significantly higher (p < .01) after E exercise compared to R exercise in both sequences, without differences between the E exercises. However, there were significant differences between the R exercises (p < .01) being higher in the R-E sequence. Our results suggest that the order of exercises during CT affects the second exercise when performed in a R-E sequence, with more cardiovascular stress and higher perceived exertions.
... The validity and reliability of the T-Force system have been reported elsewhere. 21 The repetition with the highest MV (ie, average velocity from the start of the concentric phase until the bar reached the maximum height) of each loading condition was used to determine the individualized L-V relationships through a least-square linear regression model (L[V] = L 0 − sV), where L 0 represents the load at zero velocity and s is the slope of the L-V relationship. The maximal velocity capacity (v 0 ) and A line were calculated as follows: v 0 = L 0 /s and A line = L 0 ·v 0 /2. ...
Purpose: This study's purpose is to investigate the midterm effects of alternative set configurations (cluster [CL] and rest redistribution [RR]) on lower-and upper-body neuromuscular capacities in female athletes. Method: Twenty team sport female athletes were randomly assigned to a CL (n = 10) or RR (RRG; n = 10) training group. The study protocol comprised 2 pretests, 12 training sessions, and a posttest. Both groups engaged in identical exercises (squat and bench press), load intensity (75% of 1-repetition maximum), and volume (18 repetitions per exercise). The distinction between the groups lay in the total session rest time: CL group had 23 minutes (3 sets of 6 repetitions with 30 s of intraset rest every 2 repetitions and 3 min of interset rest), whereas RRG had 17 minutes (9 sets of 2 repetitions with 45 s of interset rest). Countermovement jump height and load-velocity relationship variables (load-intercept [L 0 ], velocity-intercept [v 0 ], and area under the load-velocity relationship line) were assessed during the squat and bench press exercises. Results: All dependent variables revealed greater values at post-compared with pretest (P ≤ .040; averaged Hedges g = 0.35 for CL group and 0.60 for RRG), but "time" × "group" interactions never reached statistical significance (P ≥ .144). Likewise, the comparison of the magnitude of changes between the 2 groups revealed only trivial differences, except for a small greater change in bench press area under the load-velocity relationship line for RRG (Hedges g = 0.40). Conclusions: RR is a more efficient strategy than CL for inducing strength gains in female athletes.
... Specifically, although slightly fewer repetitions were performed per set in the BFR-RI condition, the shared endpoint of set termination (muscle failure) effectively neutralized the impact of variations in exercise volume on fatigue levels. Sanchez-Medina et al. [33] established a link between velocity loss and metabolites like ammonia and lactate. Given the absence of a significant divergence in lactate levels between the BFR-RI and control groups in our investigation, it stands to reason that the MCV outcomes exhibited no disparity between the conditions. ...
... Velocity zones with real-time feedback can be used to enhance athletic performance [18]. According to Sánchez-Medina et al. [19], when quantifying this intervention, we know that greater velocity loss corresponds to higher metabolic demand and, consequently, greater fatigue (particularly related to lactate and ammonia). Therefore, the velocity loss method, measured with a linear transducer, is valid for objectively quantifying neuromuscular fatigue during strength training. ...
Background: Although the comparison between self-managed rest and fixed rest periods in subjects experienced in lower-limb strength training has been investigated, the results remain unclear due to controversies among some studies. Therefore, the present study aimed to analyze the role of self-managed rest versus fixed rest in athletic performance, mean propulsive velocity, velocity loss, muscle oxygen saturation, and rest time in trained subjects; Methods: Thirteen subjects with a minimum of one year of training experience (age (years): 26.31 ± 3.84; height (cm): 175.46 ± 5.61; weight (kg): 79.24 ± 6.83) were randomly assigned to two groups (self-selected rest group [SR] = 7 and fixed rest group [FR] = 6). The subjects underwent a session for evaluation (one maximum repetition (1RM) estimation, familiarization, and data collection) and another day for a traditional strength training session for the back squat, consisting of five sets of four repetitions at 80% of 1RM. One group took a fixed 2 min break, while the other group managed their breaks autonomously (resuming when they felt ready to perform the next set at maximum velocity). Mean propulsive velocity (MPV) was monitored using a linear position transducer, and muscle oxygen saturation (SmO2) was measured with a near-infrared spectroscopy device; Results: Significant differences between the groups were found for the rest time between the first and second sets (SR 97.29 ± 23.70 seg vs. FR 120 ± 0.00 seg). However, no differences were found for MPV, velocity loss, or SmO2; Conclusions: Given the similarities in performance and physiological outcomes between fixed and self-selected rest conditions, both can be used equally depending on the preferences and training goals of coaches and athletes.
... The same happens with the implementation of an easily replicable, standardised exercise, and transferring it to sports abilities such as bench press throw, which has been used by other authors (Baker et al., 2001;Sánchez-Medina et al., 2014;Stokes et al., 2013). Furthermore, as fatigue progresses continuously until muscle failure occurs (Sánchez-Medina & González-Badillo, 2011), homogenizing effort levels is of the essence so as to gain clearer insights into the relation between fatigue and its hormonal effects. Consequently, individualized training is relevant, since an individual may reach similar fatigue levels through OL and OR, instead of resorting to traditional performance criteria such as executing only half of the repetitions at a given onerepetition/maximum percentage (1RM) (Legaz-Arrese et al., 2007). ...
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.
... In addition, the percentage of velocity loss (percentage decrease in movement velocity between the fastest and the last repetition in the set) is directly related to the percentage of repetitions performed with respect to the maximum number of repetitions that can be completed during a set against a given relative [2,8,9] and its magnitude determine the acute metabolic stress, hormonal response, and mechanical fatigue [10][11][12][13]. Thus, by monitoring the velocity of the first repetition and the velocity loss in each training set, it would be possible to know with considerable precision the degree of actual effort exerted by individuals in each RT session [2,8]. ...
This study aimed to analyze the intra-device agreement of a new linear position transducer (Vitruve, VT) and the inter-device agreement with a previously validated linear velocity transducer (T-Force System, TF) in different range of velocities. A group of 50 healthy, physically active men performed a progressive loading test during a bench press (BP) and full-squat (SQ) exercise with a simultaneous recording of two VT and one TF devices. The mean propulsive velocity (MPV) and peak of velocity (PV) were recorded for subsequent analysis. A set of statistics was used to determine the degree of agreement (Intraclass correlation coefficient [ICC], Lin’s concordance correlation coefficient [CCC], mean square deviation [MSD], and variance of the difference between measurements [VMD]) and the error magnitude (standard error of measurement [SEM], smallest detectable change [SDC], and maximum errors [ME]) between devices. The established velocity ranges were as follows: >1.20 m·s−1; 1.20–0.95 m·s−1; 0.95–0.70 m·s−1; 0.70–0.45 m·s−1; ≤0.45 m·s−1 for BP; and >1.50 m·s−1; 1.50–1.25 m·s−1; 1.25–1.00 m·s−1; 1.00–0.75 m·s−1; and ≤0.75 m·s−1 for SQ. For the MPV, the VT system showed high intra- and inter-device agreement and moderate error magnitude with pooled data in both exercises. However, the level of agreement decreased (ICC: 0.790–0.996; CCC: 0.663–0.992) and the error increased (ME: 2.8–13.4% 1RM; SEM: 0.035–0.01 m·s−1) as the velocity range increased. For the PV, the magnitude of error was very high in both exercises. In conclusion, our results suggest that the VT system should only be used at MPVs below 0.45 m·s−1 for BP and 0.75 m·s−1 for SQ in order to obtain an accurate and reliable measurement, preferably using the MPV variable instead of the PV. Therefore, it appears that the VT system may not be appropriate for objectively monitoring resistance training and assessing strength performance along the entire spectrum of load-velocity curve.
... The two factors that most affect lactate production and the consequent metabolic stress are as follows: the relative load or number of repetitions per set, together with the character of the effort or proximity to muscle failure of these sets [23]. Therefore, the greater the range of repetitions and character of effort, the greater the metabolic stress. ...
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.
... The use of movement velocity allows accurate quantification, monitoring, and prescription of %1RM during resistance training, eliminating the requirement for maximal lifts (1RM) and reducing the potential impact on blood pressure, and muscle and bone stress [7]. This method also avoids the necessity of performing repetitions to failure (XRM), which may induce significant fatigue due to excessive mechanical and metabolic strain [8]. Recent studies have already used the load-velocity relationship to estimate the %1RM among clinical populations, including multiple sclerosis [9], older adults [10][11][12], and breast cancer survivors [13,14]. ...
Purpose
Resistance training mitigates side effects during and after cancer treatment. To provide a new approach for precisely and safely assessing and prescribing the intensity of resistance training in supportive cancer care, the purpose of this study was to evaluate the load-velocity relationship during the row exercise in women survivors of breast cancer.
Methods
Twenty women survivors of breast cancer who had undergone surgery and had completed core breast cancer treatment within the previous 10 years completed an incremental loading test until the one repetition maximum (1RM) in the row exercise. The velocity was measured during the concentric phase of each repetition with a linear velocity transducer, and their relationship with the relative load was analyzed by linear and polynomial regression models.
Results
A strong relationship was observed between movement velocity and relative load for all measured velocity variables using linear and polynomial regression models (R² > 0.90; SEE < 6.00%1RM). The mean velocity and mean propulsive velocity of 1RM was 0.40 ± 0.03 m·s⁻¹, whereas the peak velocity at 1RM was 0.64 ± 0.07 m·s¹.
Conclusion
In women survivors of breast cancer, monitoring movement velocity during the row exercise can facilitate precise assessment and prescription of resistance training intensity in supportive cancer care.
... In the second session, we implemented the progressive loading test in the bench press and squat following the procedures described elsewhere [7,19]. Moreover, the reliability and validity of assessments have been already reported [8,20,21]. Both exercises were performed using a Smith machine (Multipower Fitness Line, Perola, Murcia, Spain) with a linear velocity transducer (T-Force Dynamic Measurement System, Ergotech, Murcia, Spain) attached to the barbell. ...
We analyzed the influence of exercise order using the bench press and squat as the first or second exercise of the session on velocity performance. Ten male trained individuals (20.9 ± 0.7 years) randomly performed two protocols of three sets of six repetitions at 80% of their one-repetition maximum with different exercise sequences: the bench press followed by the squat (BP + S) and the squat followed by the bench press (S + BP). A linear velocity transducer attached to the Smith machine barbell measured the mean propulsive velocity (MPV), peak velocity (PV), and time to peak velocity. Additionally, blood lactate and heart rate were measured. Regarding the bench press, differences were found in the MPV in the first (BP + S: 0.50 ± 0.07 m·s−1 vs. S + BP: 0.42 ± 0.08 m·s−1; p = 0.03, g = 0.72) and second sets (0.50 ± 0.06 m·s−1 vs. 0.42 ± 0.07 m·s−1; p = 0.03, g = 0.73), and in the PV in the second set (0.74 ± 0.09 m·s−1 vs. 0.63 ± 0.09 m·s−1; p = 0.02, g = 0.86). Regarding the squat, although the S + BP sequence tended to show higher velocities, no significant differences were found between protocols. These results showed that squatting first decreased subsequent bench press velocity performance. On the other hand, squat velocity performance was not impaired when preceded by the bench press.
... However, when normalized as a percentage of 1-RM, the 3-, 6-, and 10-RM were not significantly different between the sexes ( Table 1). The average barbell velocity development showed a consistent decrease across all repetition ranges (Fig 2), as subjects approached voluntary failure, which was due to accumulated fatigue decreasing their ability to sustain force output, which was expected based upon earlier research [35]. However, this reduction in velocity was not sex-specific, as no significant differences were observed between men and women for any of the repetitions. ...
Barbell squats are commonly utilized in resistance training for rehabilitation, daily living enhancement, and improving sports performance. The current study investigated the kinematic and electromyographic (EMG) parameters in the squat between sexes across different repetition ranges (1-, 3-, 6-, and 10-RM) among recreationally strength-trained subjects. A total of 26 subjects (13 men: age 25 ± 3.5 years, height 178.2 ± 5.8 cm, weight 82.3 ± 9.1 kg; 13 women: age 24 ± 4.1 years, height 165.4 ± 6.3 cm, weight 68.2 ± 8.7 kg) participated in the study. The level of significance was set at p<0.05. The findings revealed no sex-specific differences in average barbell velocity across repetition ranges. However, the 1-RM showed a significantly lower average velocity compared to the final repetition of other repetition ranges (p<0.001), with the last repetition at 10-RM revealing a significantly higher velocity (p<0.001). Women had greater maximal angular hip extension velocity in the final repetitions of the 6- and 10-RM (p≤0.035, ηp²≤0.20), while both sexes displayed lower maximal angular knee extension velocity in the final repetition of the 10-RM (p = 0.028, ηp² = 0.15). Moreover, men had lower EMG amplitude in the rectus femoris (3- and 10-RM), soleus, and lateral vastus (10-RM) compared to women (p≥0.011, ηp²≥0.26). It was concluded that 10-RM differed greatly in kinematics and EMG, suggesting different fatigue mechanisms compared to other repetition ranges with heavier loads. Furthermore, sex differences in EMG and angular hip extension velocity might imply sex-specific fatiguing mechanisms during high-repetition squats. These considerations could be important when prescribing training programs.
... level of fatigue, and R5 produced a consistent MNR across all four sets. These results are not surprising considering the extensive body of evidence demonstrating that higher levels of fatigue (i.e., resulting in greater velocity losses), regardless of whether sets are performed to failure or not, consistently result in increased metabolic markers such as lactate or ammonia Sánchez-Medina and González-Badillo, 2011;. Therefore, the minimal duration of inter-set rest periods to maintain consistent mechanical performance across multiple sets appears to be contingent upon the level of fatigue, with greater proximity to failure necessitating longer inter-set rest periods. ...
This study aimed to determine the optimal inter-set rest periods that maximize the number of repetitions completed before surpassing various minimum velocity thresholds (MVT) 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 in a Smith machine at 75% of the one-repetition maximum. The length of the inter-set rest time (1 [R1], 3 [R3], and 5 [R5] minutes) and MVT used (0.65 ms-1 [MVT0.65] and 0.55 ms-1 [MVT0.55]) 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 MVT0.55 (R1: 28.4 ± 6.0 repetitions; R3: 36.4 ± 9.4 repetitions; R5: 41.1 ± 11.4 repetitions) compared to MVT0.65 (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 MVT0.65 and MVT0.55, as well as for R3 using MVT0.55. The fastest velocity of the set (MVfastest) did not differ between the inter-set rest protocols for MVT0.65, while for MVT0.55, 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.
... m/s) for their training sessions and adjust the load accordingly between sets to meet these goals. Furthermore, when each repetition is performed with maximal effort then neuromuscular fatigue will be accompanied by an involuntary decrease in movement velocity Sanchez-Medina & González-Badillo, 2011). This allows individuals to objectively monitor their fatigue by measuring the relative magnitude of velocity loss between each exercise set. ...
Background
Velocity-based training (VBT) is commonly used for programming and autoregulation of resistance training. Velocity may also be measured during resistance training to estimate one repetition maximum and monitor fatigue. This study quantifies the validity of Metric VBT, a mobile application that uses camera-vision for measuring barbell range of motion (RoM) and mean velocity during resistance exercises.
Methods
Twenty-four participants completed back squat and bench press repetitions across various loads. Five mobile devices were placed at varying angles (0, ±10, and ±20°) perpendicular to the participant. The validity of Metric VBT was assessed in comparison to Vicon motion analysis using precision and recall, Lin’s concordance correlation coefficient, and Bland-Altman plots. Proportional bias was assessed using linear regression.
Results
Metric VBT accurately detected over 95% of repetitions. It showed moderate to substantial agreement with the Vicon system for measuring RoM in both exercises. The average Limits of Agreement (LoA) for RoM across all camera positions were −5.45 to 4.94 cm for squats and −5.80 to 3.55 cm for bench presses. Metric VBT exhibited poor to moderate agreement with the Vicon system for measuring mean velocity. The average LoA for mean velocity were 0.03 to 0.25 m/s for squats and −5.80 to 3.55 m/s for bench presses. A proportional bias was observed, with bias increasing as repetition velocity increased.
Conclusions
Metric VBT’s wide LoA for measuring RoM and mean velocity highlights significant accuracy concerns, exceeding acceptable levels for practical use. However, for users prioritizing repetition counts over precise RoM or mean velocity data, the application can still provide useful information for monitoring workout volume.
... The vertical velocity of the center of mass (COM) is calculated using the impulse method, which involves integrating the ground reaction force (GRF) before the jump. The maximum take-off velocity is reached at the end of the jump's concentric phase, and jump height is derived from this velocity and the force of gravity [56]. Power is determined from the force-time curve using the impulse-momentum principle, and relative power is the product of mean velocity and the vertical GRF component [57,58]. ...
Background: β-alanine, a non-essential amino acid found in the diet and produced through nucleotide catabolism, is significant for muscle performance due to its role in carnosine synthesis. This study aims to assess the impact of a 4-week β-alanine supplementation on neuromuscular fatigue in individuals engaging in High-Intensity Functional Training (HIFT) and its subsequent effect on sports performance, distinguishing between central fatigue from the CNS and peripheral fatigue from the muscular system. Materials and methods: This study (a randomized controlled trial) comprised a total of 27 subjects, who were divided into two groups. Group A (the control group) was administered sucrose powder, while Group B (the experimental group) was given β-alanine powder. The subjects were randomly assigned to either the experimental or control groups. This study lasted four weeks, during which both groups participated in high-intensity interval training (HIFT) on the first day to induce fatigue and work close to their VO2 max. Results: Statistically significant changes were in the sports performance variables, specifically vertical jump and jumping power (p = 0.027). These changes were observed only in the group that had been supplemented with β-alanine. Nevertheless, no alterations were observed in any other variables, including fatigue, metabolic intensity of exercise, or perceived intensity (p > 0.05). Conclusions: A four-week β-alanine intake program demonstrated an improvement in the capacity of subjects, as evidenced by enhanced vertical jump and power performance. Nevertheless, it does result in discernible alterations in performance.
... e. load), volume, frequency, degree of effort (i. e. relationship between repetitions actually performed and repetitions in reserve) or exercise selection [1,3]. There are several resistance training modalities such as traditional resistance training based on the addition of external loads (i. ...
Resistance training is the most effective strategy to modify muscle architecture, enhancing sport performance and reducing injury risk. The aim of this study was to compare the effects of high loads (HL) versus lower loads (LL), maximal versus submaximal efforts, and high frequency (HF) versus low frequency (LF) on quadriceps architectural adaptations in team sports players. Five databases were searched. Vastus lateralis thickness, fascicle length and pennation angle, and rectus femoris thickness were analyzed as main outcomes. Overall, resistance training significantly improved muscle thickness and pennation angle, but not fascicle length. LL led to greater fascicle length adaptations in the vastus lateralis compared to HL (p = 0.01), while no substantial differences were found for other load comparisons. Degree of effort and training frequency did not show meaningful differences (p > 0.05). In conclusion, LL lengthen the fascicle in a greater extent than HL, training with LL and twice a week could maximize architectural adaptations, whereas the degree of effort does not appear to be a determinant variable on quadriceps architectural adaptations.
... An alternative to indirectly measure force production is through the recording of lifting velocity during multi-joint resisted movements like a barbell squat or a bench press [19][20][21] . Lifting velocity can be precisely and reliably measured during multi-joint resisted movements using commercial linear position transducers or even smartphone apps 22,23 , allowing for the description of mechanical capabilities of the neuromuscular system, which has been extensively used in the context of resistance training prescription and monitoring 24 . ...
Objectives
The synergy between arm and shoulder muscles, along with isometric finger flexor strength, are crucial for climbing proficiency. However, tests often assess these factors separately rather than in a unified action. This study aimed to determine the intra- and inter-session reliability of the mean propulsive velocity (MPV) during pull-ups on a large hold and on small climbing edges.
Methods
Ten male climbers (self-reported maximal grade 6b-8b on French scale) participated in two identical sessions. During each session, participants performed two blocks of two pull-ups on a large hold and on four small climbing edges (25, 20, 15, and 10mm) in randomized order. The MPV was recorded using a linear position transducer.
Results
The MPV during climbing pull-ups at 20mm (0.75±0.16 m/s), 15mm (0.73±0.16 m/s), and 10mm (0.52±0.15 m/s) was reduced compared to a pull-up on a large hold (0.84±0.16m/s). Intraclass correlation coefficients (ICCs) were good-to-excellent across hold sizes for intra-session (ICC 0.84-0.99) and inter-session (ICC 0.73-0.96) measurements.
Conclusion
The results suggest that the MPV assessed during climbing-specific pull-ups on small holds provides valuable insights into finger, elbow and shoulder muscle force capacities in a unified action. This test could be considered a sport-specific test for monitoring performance in climbers.
... Changes in the lifting velocity can provide direct feedback on an athlete's performance and fatigue levels. 15 In this case, the barbell average velocity (external load of ∼40% of 1-repetition maximum) was 1.44 m/s (6 d prior) and 1.52 m/s (3 d prior), representing improvements of 6% and 12%, respectively, compared with the average of the 3 previous sessions (1.36 m/s) assessed over 3 weeks prior. As a result, these positive outcomes should further reinforce the previous regular monitoring data, indicating the athlete's improvement in explosive performance and readiness to compete. ...
Background: In high performance sport, the support provided by sports scientists and other staff can be a valuable resource for coaches and athletes. Purpose: We propose and detail here the approach of "minimal, adequate, and accurate" sports science support to ensure that programs of work and solutions are both economical and effective. Methods: Our support provision advocates for utilization of “minimal” resources (employing the least amount of time, tools, and funding) necessary to achieve the desired outcomes. We strive for “adequate” information that fulfil specific ojectives without excess, and the requirement that methods and data used are “accurate” (valid and reliable). To illustrate the principles of this approach we outline a real-world example of supporting 100-m track (athletics) sprinters preparing and competing in an international competition. The provision of performance support emphasizes an integrated approach, combining knowledge and insights from multiple sports science disciplines. The key facets managed under this approach are: (i) neuromuscular readiness, (ii) wellness monitoring, (iii) movement observation, (iv) motivation, (v) biomechanics and performance analysis, and (vi) qualitative feedback. These facets are based on the specific performance determinants and influencing factors of an event (100-m dash). Conclusions: Application of this quantitative and qualitative approach can enhance the ability to make informed decisions. Nevertheless, the approach must be planned, evaluated and refined on a regular basis to enable effective decision-making in sport science support. The three element approach of “minimal, adequate, and accurate” should be co-designed and supported by the athletes, coaches, and staff to ensure successful implementation.
... The first familiarization session and, a week later, two evaluation sessions, with a 48-hour washout period between sessions to ensure consistency. 20 The trial was conducted under stable temperature (22 ± 1.0 °C) and humidity conditions (52.7 ± 4.0 %), in the same training facility and at the same time of the day (from 8 to 11 am). Participants were instructed to maintain their daily habits and avoid performing any kind of physical activity during the 24 h before the first intervention or the 48-hour washout period until the next session. ...
... Eight to ten percent jump height losses correspond to 70-80 µmol·l-1 and 8-10 mmol·l-1 of ammonia and lactate in the blood, representing the onset of metabolic instability in male athletes (15). These data can help practitioners to monitor and manage induced neuromuscular fatigue during a male training session (35). ...
The present study aimed to determine whether neuromuscular fatigue monitored through countermovement jump height was a reliable and helpful marker for monitoring acute (session) and chronic (between sessions/periods of the season) fatigue throughout an entire basketball season. A longitudinal observational study analyzed the neuromuscular performance (i.e., through countermovement jump) during a basketball season. Fourteen semiprofessional male basketball players participated in the study between September 2021 and May 2022 (34 weeks, 102 practices, and 1574 jumps analyzed). Upon waking up, they completed an online wellness questionnaire. Before practices began, players performed three countermovement jumps on a contact platform after a structured warm-up, repeating the protocol at the end of each practice. Ten minutes after finishing such practice, they also reported perceived exertion's muscular and cardiovascular ratings. The preseason was the period of the season with the lowest absolute countermovement jump height levels (2.06 to 2.50 cm; d = 1.92 to 2.74, very large, p < 0.02). Average pre-session jumps were very largely higher on Wednesdays (0.62 cm, 95% CI = 0.29-0.95, p = 0.0095, d = 2.09) and Fridays (0.62 cm, 95% CI = 0.06-0.88, p = 0.06, d = 1.43) compared to Mondays. The countermovement jump is a valuable marker for assessing fatigue in semiprofessional basketball players. Games played on weekends mainly and consistently affected Monday's jumping performance, showing the lowest average values. Finally, preseason values were lower than those observed for the rest of the season.
... Birincisi, ortalama hız ile göreceli yük (bir tekrar maksimumunun yüzdesi) arasındaki doğrusal ilişkiye dayanarak, direnç egzersizi yoğunluğu günlük olarak belirlenmektedir (Conceição, Fernandes, Lewis, Gonzaléz-Badillo, ve Jimenéz-Reyes, 2016;García-Ramos, Pestaña-Melero, Pérez-Castilla, Rojas, ve Haff;Jidovtseff, Harris, Crielaard, ve Cronin, 2011). İkincisi, hız kaybının büyüklüğü ile nöromüsküler yorgunluk derecesi arasındaki güçlü ilişkiye dayanarak antrenman hacmi belirlenmektedir (Pareja-Blanco ve ark., 2020; Sanchez-Medina ve González-Badillo, 2011). Üçüncüsü, bir lineer transdüser (LT) tarafından sağlanan gerçek zamanlı hız verisinin geri bildirimiyle sporcular her tekrarda maksimum çaba göstermeye teşvik edilmekte ve böylece antrenman kalitesi artmaktadır (Randell, Cronin, Keogh, Gill, ve Pedersen, 2011). ...
Öz: Hız temelli kuvvet antrenmanları, son yıllarda büyük ilgi gören bir yaklaşım olarak öne çıkmaktadır. Bu
yöntemin uygulanmasında en sık tercih edilen cihazlar lineer transdüserlerdir. Bu araştırmada, donanımı ve
yazılımı yazar tarafından geliştirilen bir lineer transdüserin güvenirlik ve geçerliğinin değerlendirilmesi
amaçlanmıştır. Optik kodlayıcı, bluetooth ve Wi-Fi modülü ile donatılmış bir mikrodenetleyiciden oluşan bu
lineer transdüser, kriter cihaz Tendo Power Analyzer ile karşılaştırılmıştır. Araştırmaya 13 halterci gönüllü
olarak katılmıştır. Silkme çekişi esnasında, farklı yüklerle (%40, %60, %90 ve %110 1TM) gerçekleştirilen eş
zamanlı maksimum hız ölçümleri alınarak geçerlik değerlendirilmiş; bir hafta arayla, aynı saatte ve aynı test
prosedürleri uygulanarak test-tekrar test güvenirliği incelenmiştir. Güvenirlik analizi için sınıf içi korelasyon
katsayısı (ICC), varyasyon katsayısı (CV), ölçümlerin standart hatası (SEM) ve minimum tespit edilebilir
değişim (MDC) hesaplanmıştır. Geçerlik, eşli örneklemler t-testi, regresyon analizi ve Bland-Altman analizi
kullanılarak değerlendirilmiştir. ICC değerleri 0.85 ile 0.96 arasında değişmiş, CV değerleri %1.62 ile %4.12
arasında bulunmuştur. SEM değerleri 0.045 m·s⁻¹ ile 0.084 m·s⁻¹ arasında hesaplanmış, MDC değerleri ise 0.137
m·s⁻¹ ile 0.236 m·s⁻¹ arasında değişmiştir. Bland-Altman grafiklerine göre, ölçüm sonuçları genel olarak yüksek
uyum göstermiştir. Regresyon analizleri sonucunda da sabit veya oransal sapma tespit edilmemiştir. Analiz
sonuçları, geliştirilen cihazın silkme çekişi esnasında farklı yüklerle gerçekleştirilen maksimal hız ölçümlerinde
güvenilir ve geçerli olduğunu ortaya koymaktadır.
Anahtar Kelimeler: Halter, kuvvet antrenmanı, nöromüsküler performans, kuvvet ve kondisyon
VALIDITY AND RELIABILITY OF A LINEAR TRANSDUCER DEVELOPED FOR
USE IN VELOCITY-BASED TRAINING
Abstract: Velocity-based strength training (VBT) has gained significant attention in recent years. The most
preferred devices for implementing this method are linear position transducers (LPT). This study aimed to
evaluate the reliability and validity of an LPT developed by the author, which includes both hardware and
software components. The LPT, consisting of an optical encoder, Bluetooth and Wi-Fi modules integrated into a
microcontroller, was compared against the criterion device, the Tendo Power Analyzer. Thirteen weightlifters
volunteered to participate in the study. Validity was assessed through simultaneous measurements of peak
velocity during the clean pull dat various loads (40%, 60%, 90%, and 110% of 1RM), while test-retest reliability
was evaluated by repeating the same test protocols at the same time of day, one week apart. Reliability analysis
included calculating the intraclass correlation coefficient (ICC), coefficient of variation (CV), standard error of
measurement (SEM), and minimum detectable change (MDC). Validity was assessed using paired samples t-test,
regression analysis, and Bland-Altman analysis. The ICC values ranged from 0.85 to 0.96, and the CV values
ranged from 1.62% to 4.12%. The SEM values were calculated to be between 0.045 m·s⁻¹ and 0.084 m·s⁻¹, while
the MDC values ranged from 0.137 m·s⁻¹ to 0.236 m·s⁻¹. The Bland-Altman plots indicate that the measurement
results exhibited a strong overall agreement. Similarly, regression analyses revealed no fixed or proportional
bias. The results of the analyses demonstrate that the developed LPT is reliable and valid for measuring peak
velocity during clean pull across different loads.
Key Words: Weightlifting, strength training, neuromuscular performance, strength and conditioning
... Therefore, in addressing the issue of objectively quantifying and monitoring athletes' actual training loads, it is suggested to monitor the load based on the magnitude of VL achieved in each set of strength training, rather than being limited to fixed repetitions prescribed by relative loads (%1RM). Additionally, monitoring VL load can not only ensure accurate matching of target intensity with actual training intensity but also control the level of fatigue during each set, avoiding excessive fatigue and achieving consistency in stimulus levels among individuals [12,13]. ...
Proper Post-Activation Performance Enhancement helps to improve athletic performance. This study aimed to investigate the effects of two different velocity loss (VL), 10%VL and 20%VL, on post-activation performance enhancement (PAPE) in 20m sprint performance among sprint athletes. Twenty-four male sprint athletes (100m sprint time: 10.96±0.15 s) were recruited. A randomized crossover experimental design was used for traditional group (TG), 10%VL, and 20%VL interventions. Sprint tests were conducted at the 4th, 8th, 12th, and 16th minutes after the intervention. Two-way repeated measures ANOVA revealed an interaction effect between group and time on 20m sprint performance (F=2.817, p=0.037, partial η²=0.585). Simple effect analyses showed significant differences compared to baseline at the 4th minute for the 20%VL group (P<0.05). Cohen's d values indicated improvement in 10m sprint times at the 8th minute of the rest interval for all three intervention groups (TG: ES=-0.270, 10%VL: ES=-0.038, 20%VL: ES=-0.279). Improvement in 20m sprint times was observed at the 4th minute for the 20%VL group (ES=-0.296) and at the 16th minute for the 10%VL group (ES=-0.276). Compared to traditional PAPE schemes based on 1RM, PAPE schemes based on velocity loss (20%VL) can better induce PAPE effects in sprint athletes.
... Therefore, in addressing the issue of objectively quantifying and monitoring athletes' actual training loads, it is suggested to monitor the load based on the magnitude of VL achieved in each set of strength training, rather than being limited to fixed repetitions prescribed by relative loads (%1RM). Additionally, monitoring the VL load can not only ensure the accurate matching of target intensity with actual training intensity but also control the level of fatigue during each set, avoiding excessive fatigue and achieving consistency in stimulus levels among individuals [14,15]. ...
Post-activation performance enhancement (PAPE) can significantly improve athletic performance. This study investigated the effects of two different velocity loss (10% VL and 20% VL) protocols on PAPE in 20 m sprint performance among sprint athletes. Twenty-four male sprint athletes (100 m sprint time: 10.96 ± 0.15 s) participated in the study. A randomized crossover experimental design was used to compare the traditional group (TG) and 10% VL and 20% VL interventions. Sprint tests were conducted at 4, 8, 12, and 16 min post-intervention. A two-way repeated measures ANOVA revealed a significant interaction effect between group and time on 20 m sprint performance (F = 2.817, p = 0.037, partial η2 = 0.585). Simple main effects analysis revealed significant improvements at 4 min for the 20% VL group (p < 0.05). Cohen’s d values indicated improvements in 10 m sprint times at 8 min for all groups (TG: effect size (ES) = −0.270, 10% VL: ES = −0.038, 20% VL: ES = −0.279). Improvements in 20 m sprint times were observed at 4 min for the 20% VL group (ES = −0.296) and at 16 min for the 10% VL group (ES = −0.276). In conclusion, the velocity loss-based PAPE protocol (20% VL) demonstrated a superior induction of PAPE effects in sprint athletes at 4 min compared to traditional 1RM-based PAPE protocols. However, no significant differences were observed between the two protocols at 8, 12, and 16 min.
This study aimed to elucidate whether the performance of high-velocity soccer-related tasks is compromised immediately after completing squat-based resistance training sessions differing in the level of effort. Eleven young male soccer goalkeepers (age: 17.1±1.7 years) completed four testing sessions. The parallel back-squat one-repetition maximum (1RM) was determined in the first session. The remaining sessions were applied in a counterbalanced order and they consisted of the assessment of four high-velocity soccer-related tasks (countermovement jump [CMJ], horizontal jump, soccer kicking, and soccer throwing) at rest (control protocol) and immediately after completing four sets of the squat exercise against the 60%1RM until reaching a velocity loss of 15% (low-effort protocol) and 30% (moderate-effort protocol). The mean velocity of the fastest repetition did not differ between the protocols (≈ 0.80 m·s-1 ; p=.447), whereas the number of repetitions was greater for the moderate-effort (18.2±5.3 repetitions) compared to the low-effort (10.1±4.5 repetitions) protocol (p<.001). The protocols were ranked according to the magnitude of the dependent variables as follows: CMJ height (control > low-effort = moderate-effort), horizontal jump distance (control > low-effort > moderate-effort), kicking ball distance (low-effort = control = moderate-effort), and throwing ball distance (control = low-effort = moderate-effort). These results indicate that squat-based RT sessions compromise the performance of some high-velocity tasks (vertical and horizontal jumps) but not others (kicking and throwing), whereas a greater level of effort (i.e., velocity loss) only induced larger reductions in the performance of the horizontal jump distance.
This research examines the reliability, validity, and usefulness of the Jump Power application by comparing it with the reliable and validated Optojump photoelectric cell system in measuring squat jump (SJ) and countermovement jump (CMJ) in professional athletes. Twenty-two soccer players volunteered to participate in the research. The participants were the players of the U21 team in the 1st League. All athletes were subjected to SJ and CMJ tests. Jump Power app and Optojump data were acquired simultaneously during SJ and CMJ. Trial procedure was performed on three separate occasions (Session 1, Session 2, and Session 3), with 48 h intervals to examine the reliability of the data from session to session. For reliability analysis, coefficients of variation percent (%CV). Jump power app reliability values CV% is below 5%. In the validity analysis, significant differences were observed between the Optojump photoelectric cell system and the Jump Power App for SJ and CMJ. In conclusion, this study revealed that the Jump Power app is a reliable but not valid tool to measure vertical jumps in soccer players.
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.
Purpose: The present study aimed to compare final partial range of motion (final pROM) vs. full range of motion (fROM) in muscle hypertrophy and maximal strength development in physically active young men. Methods: Ten physically active young men (age=22.90±2.47 years; body mass=83.85±11.67 kg; height=176.30±6.22 cm) participated in a randomized, intra-subject experimental design in which RT was performed using the upper- and lower-limbs with final pROM or fROM three times per week for six weeks. For all subjects, an arm or thigh was randomly selected and assigned for the final pROM condition, and the contralateral limb for the fROM condition. The subjects performed three sets of 12 repetitions at 60% of one-repetition maximum (1-RM), with two-minute rest interval between the sets and between limbs. The muscle hypertrophy of the elbow flexors and the knee extensors and the 1-RM test in the specific ROM that has been trained was measured before and after the intervention. An analysis of covariance was used to compare the different conditions on muscle hypertrophy and the maximal strength development. Results: The results showed that there was no statistically significant difference between the conditions for elbow flexors muscle hypertrophy (p=0.920; Cohen’s d=0.046) and knee extensors muscle hypertrophy (p=0.291; Cohen’s d=0.152). Similarly, there was no statistically significant difference between the conditions for 1-RM of the arm (p=0.161; Cohen’s d=0.898) and 1-RM of the thigh (p=0.276; Cohen’s d=0.533). Conclusions: Therefore, these findings suggest that there was no statistically significant difference between the different ROM, however, the moderate-large effect size (leg=0.533 and arm=0.898) in favor of final pROM in the maximal strength development, may indicate a potential direction for future research in physically active young men.
This systematic review synthesizes evidence on biomarker responses to physiological loads in professional male team sport athletes, providing insights into induced fatigue states. Structured searches across major databases yielded 28 studies examining various biomarkers in elite team sport players. Studies evaluated muscle damage markers, anabolic/catabolic hormones reflecting metabolic strain, inflammatory markers indicating immune activity and tissue damage, immunological markers tied to infection risk, and oxidative stress markers showing redox imbalances from excessive physiological load. Responses were examined in official matches and training across competitive seasons. The evidence shows that professional team sports induce significant alterations in all studied
biomarkers, reflecting measurable physiological strain, muscle damage, oxidative stress, inflammation, and immunosuppression during intensive exercise. These effects tend to be larger and more prolonged after official matches compared to training. Reported recovery time courses range from 24-h to several days post-exercise. Monitoring biomarkers enables quantifying cumulative fatigue and physiological adaptations to training/competition loads, helping to optimize performance while mitigating injury and overtraining. Key biomarkers include creatine kinase, testosterone, cortisol, testosterone/cortisol ratio, salivary immunoglobulin-A, and markers of inflammation and oxidative stress. Further research should extend biomarker monitoring to cover psychological stress and affective states alongside physiological metrics for deeper insight into athlete wellness and readiness.
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.
The objective of the present study was to verify the agreement and correlation between effort intensity determined from the rate of perceived exertion (RPE) and loss velocity in sets performed to exhaustion in the bench press exercise at a self-selected velocity. Thirty-five men and women practitioners of resistance training (33.61±8.16 years; 172.75±11.04 cm of stature; 76.79±15.57 kg of body mass) were evaluated. Participants were familiarized and then performed two sets of bench press performed until exhaustion at a self-selected velocity at 70% and 85% of one-repetition maximum (1RM). Loss velocity was measured by a linear position transducer (Ergonauta® encoder) applied to velocity-based training. A 3-point RPE scale was used to evaluate the perceived exertion of the individuals. The analysis of agreement (Kappa test) and correlation (Spearman test) were applied (p<0.05). The results of the study indicated the existence of a moderate degree of agreement (κ = 0.499; κ = 0.509 for 70% and 85% of 1RM, respectively), but a strong correlation (ρ = 0.720; ρ = 0.753 for 70% and 85% of 1RM, respectively) between the effort intensity determined by the Ergonauta and the RPE, at both intensities analyzed (70% and 85% of 1RM). Despite the lack of perfect agreement between methods, loss velocity and RPE seem to demonstrate strong consistency, allowing both to be used for controlling intensity in resistance training. The results of this study should be interpreted in light of individual characteristics, type of exercise, and training objectives.
Background: Endurance, defined as the ability to sustain exercise, involves multiple organs and physiological processes. Aim : This study aimed to evaluate of INDUS1710, a composition of 4-hydroxyisoleucine, trigonelline, and select glycosides-based standardised fenugreek seed extracts, during treadmill running exercise (EXE) for endurance enhancement in laboratory rats. Methods: Male Wistar rats were randomly divided into six groups of 12 rats each and orally administered vehicle (distilled water, VC), INDUS1710 (20, 30, or 60 mg/kg), L-arginine (308 mg/kg), or vehicle for 28 days. All groups, except VC, underwent EXE without incline at a speed of 14 m/min for 6 days, followed by a speed of 20 m/min on the 7th day for 28 days until exhaustion. The physiological, functional, and metabolic parameters; relative organ weights; glycogen content of gastrocnemius muscle; and histological parameters of the heart were recorded. Results: Subacute supplementation with EXE of INDUS1710 resulted in a dose-dependent increase in time to exhaustion and prevented EXE-induced changes in organ function (heart, lungs, kidney, and liver), metabolic processes (carbohydrates, proteins, and lipids), and skeletal muscle glycogen content without causing pathological changes in skeletal or cardiac muscles. Conclusion: INDUS1710 supplementation with EXE showed comprehensive endurance enhancement efficacy and safety in laboratory rats.
Introduction
Muscle fatigue, characterized by diminished force production and contraction sustainability, can impair muscle coordination and increase joint instability. Differing force profiles used in fatiguing tasks, such as prolonged eccentric trunk protocols, might provide insights into individualized strategies and resulting spinal stability. Thus, this study assessed individual differences in fatigue characteristics during an eccentric trunk flexion-extension protocol in a population of asymptomatic individuals.
Methods
Twelve participants (2 f/10 m, 29 ± 4 years, 78.4 ± 16.9 kg, 1.76 ± 0.10 m) performed an eccentric trunk flexion and extension protocol on an isokinetic dynamometer (45° flexion to 10° extension; 60°/s), with final analysis on 8 participants for trunk flexion and 11 for trunk extension due to data exclusions. Participants engaged in a maximal all-out (AO) task for 2 min. Each participant's torque output (Nm) was assessed on a repetition-by-repetition basis, and smoothened by a moving average of 5 repetitions. Individual time profiles for reaching fatigue thresholds (10%, 15%, 20% and 30% reduction of initial torque output), and inter subject variability (by coefficient of variation, CV in %) were assessed throughout the AO task. Further, percentage torque reduction and variability were assessed at mid (1-minute) and end (2-minute) of task.
Results
On average, for flexor and extensor muscles combined, participants reached a force reduction of 10% within 23.2 ± 19.1 s, of 15% within 44.9 ± 19.6 s, of 20% in 62.4 ± 26.3 s, and of 30% within 79.2 ± 21.8 s. The variability between individuals for the timepoint of reaching the defined torque thresholds was assessed by CV ranged between 23.4% and 103.8% for trunk flexor muscles, and between 28.4% and 56.5% for trunk extensor muscles.
Discussion
A reduction of up to 20% was seen on average for all participants within 1-minute of eccentric trunk flexion and extension. Different inter-individual force output profiles were seen throughout the AO protocol, potentially related to physiological, skill-based, technical, adaptational, and/or motivational factors. The increase in fatigue resulted in a reduction in variability among individuals. A 2-minute protocol effectively induced pronounced fatigue, offering insights into individual force profiles and strategies.
The use of weightlifting exercises is prevalent in competitive and recreational environments, as well as sport-specific training. Traditionally, weightlifting coaches prescribe specific training loads based on an individual's maximal ability. Velocity-based training offers an alternative method that promises to quantify strength based on velocity and provides information that increases competitiveness through real-time feedback. Various velocity measurement devices are available on the market. Their precision is critical for the adequate implementation of velocity-based training. The aim of the present study was to compare the concentric peak velocity measurements of five of these devices during two weightlifting movements, the snatch and clean, to data collected with a 12-camera motion capture system, which was considered as gold standard. It was hypothesized that the velocity measurement devices used in this study would vary in accuracy based on their retail prices. Velocity readings associated with light and moderate (40% and 70% of one-repetition max) loads were measured for both the snatch and clean performed by 12 competitive weightlifters. A least products regression was used to assess validity by comparing five devices against a criterion measure. A general linear model showed statistical differences in the velocities measured with these five devices ( p < 0.001). Specifically, the GymAware RS linear position transducer was the most accurate device, demonstrating no fixed or proportional bias when used to quantify velocity during the snatch and clean. The remaining four devices significantly underestimated peak velocity, which would directly impact the daily planning of lifters’ training. Practitioners must consider the error and bias of each device before implementing velocity-based training.
The aim of the study was to assess differences in strength performance, neuromuscular fatigue and perceived exertion across phases of the menstrual cycle (MC, early follicular [eFP], late follicular [lFP] and mid-luteal phase [mLP]) and oral contraceptives (OC, active pill phase [aPP] and non-active pill phase [nPP]). Secondly, in naturally menstruating women, the influence of fluctuating serum 17β-estradiol nd progesterone concentrations on these parameters were analysed. Thirty-four women (21 with a natural MC and 13 using OCs) completed three or two experimental sessions, respectively. Mean mean propulsive velocity (MPV mean ) and total number of repetitions (REP total ) were assessed during a power (3x8 at 60%1RM) and hypertrophy squat loading (3 sets to failure at 70%1RM), respectively. Change in bench press and squat MPV at 60%1RM in response to the loadings were used as surrogates for non-local and local fatigue, respectively. Total blood lactate accumulation (BLA A ) and markers of perceived exertion were assessed in each session. No significant differences between any of the MC or OC phases were observed for MPV mean , REP total , non-local and local fatigue and markers of perceived exertion (all p>0.050). A higher intraindividual 17β-estradiol concentration was significantly associated with a lower MPV mean (p=0.019). BLA A was significantly higher in lFP compared to mLP (p=0.019) and negatively associated with the intraindividual progesterone concentration (p=0.005). While 17β-estradiol may negatively influence the MPV, it appears that fluctuations of both sex hormones across the MC and OC phases are not prominent enough to induce significant nor practically relevant changes in the assessed parameters.
Background
High resistance training enhances muscular strength, and recent work has suggested an important role for metabolite accumulation in this process.
Objective
To investigate the role of fatigue and metabolite accumulation in strength gains by comparing highly fatiguing and non-fatiguing isotonic training protocols.
Methods
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°), and a Cybex 340 isokinetic dynamometer was used to measure the angle-torque and torque-velocity relations of the non-dominant leg.
Results
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.
Conclusions
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.
This study was conducted (a) to determine the effects of varying levels of muscular fatigue on vertical jump performance and (b) to see if the initial level of leg strength influenced this response. Twelve college men were tested for leg-press strength (1-RM) and for vertical jump. Subjects were separated into a high- or low-strength group (n = 6 per group) based on 1-RM leg press. Vertical jump was measured before and after fatigue was induced (by lifting loads of 50, 70, or 90% 1-RM until exhaustion). The effect was to produce strength decrements of 50, 30, and 10%, respectively. All fatigue values differed significantly (p < 0.01) from resting values. When comparing work and distance jumped, there were significant differences between 50% and 10% fatigue levels, as well as between 30% and 10% only on the work produced. No differences (p > 0.05) were found between groups under all conditions. Thus, increasing fatigue by reducing the strength capacity of the leg muscles leads to gradual decrements in vertical jump, but not in proportion to strength decrement. The decrease in vertical jump performance is independent of the initial strength level.
(C) 1998 National Strength and Conditioning Association
The time course of venous blood ammonia and lactate formation has been investigated on 5 separate occasions in each of two subjects. Blood was sampled from a free flowing catheter for every 30 s during a ramp bicycle test to exhaustion. In each subject blood ammonia was rapidly elevated even at work rates as low as 40–50% of
[(V)\dot]O2\dot VO_2
max. On cessation of exercise blood concentrations fell rapidly. Lactate concentration in blood on the other hand was more slowly elevated during the test and continued to rise in the usual fashion after the completion of the work. It is suggested that ammonia may be a primary toxin during exhaustive exercise inducing changes, which ultimately become incapacitating, in essential metabolic functions.Thus fast ammonia accumulation in tissue reflected by increased blood ammonia levels may induce glycolysis and an early excessive tissue pyruvate accumulation and lactate formation.Ammonia also passes the blood brain barrier and might possibly result in the observable central nervous system symptoms of dysfunction which accompany exhaustion such as ataxia, mental confusion and syncope. These findings have important implications for the integrity of the classically accepted lactate theory of exercise fatigue.
Prolonged dynamic exercise and sustained isometric contractions induce muscle fatigue, as manifested by decreased performance and a reduction in the maximum voluntary contraction force. Studies with non-invasive measurements in exercising humans show that mechanisms located beyond the sarcolemma are important in the fatigue process. In this review, we describe probable cellular mechanisms underlying fatigue-induced changes in excitation-contraction (E-C) coupling occurring in human muscle fibres during strenuous exercise. We use fatigue-induced changes observed in intact single muscle fibres, where force and cellular Ca(2+) handling can be directly measured, to explain changes in E-C coupling observed in human muscle during exercise.
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.
This study examined the effects of heavy resistance training on dynamic exercise-induced fatigue task (5 x 10RM leg-press) after two loading protocols with the same relative intensity (%) (5 x 10RM(Rel)) and the same absolute load (kg) (5 x 10RM(Abs)) as in pretraining in men (n=12). Maximal strength and muscle power, surface EMG changes [amplitude and spectral indices of muscle fatigue], and metabolic responses (i.e.blood lactate and ammonia concentrations) were measured before and after exercise. After training, when the relative intensity of the fatiguing dynamic protocol was kept the same, the magnitude of exercise-induced loss in maximal strength was greater than that observed before training. The peak power lost after 5 x 10RM(Rel) (58-62%, pre-post training) was greater than the corresponding exercise-induced decline observed in isometric strength (12-17%). Similar neural adjustments, but higher accumulated fatigue and metabolic demand were observed after 5 x 10RM(Rel). This study therefore supports the notion that similar changes are observable in the EMG signal pre- and post-training at fatigue when exercising with the same relative load. However, after training the muscle is relatively able to work more and accumulate more metabolites before task failure. This result may indicate that rate of fatigue development (i.e. power and MVC) was faster and more profound after training despite using the same relative intensity.
This study compared failure versus nonfailure training with equated intensity and volume on lower body muscular endurance in trained men.
Each subject performed one lower body workout per week for 6 weeks; the Failure group performed 3 sets of the squat, leg curl, and leg extension exercises to the point of voluntary exhaustion, while the Nonfailure group performed 4 sets for each of these exercises, but with a submaximal number of repetitions that did not allow failure to occur on any set. All subjects performed a pre- and postintervention muscular endurance test that involved 3 sets each for the squat, leg curl, and leg extension exercises. Blood lactate concentration (BL) was assessed before, and at 5 and 10 minutes following the test. Heart rate (HR) was assessed before the test, following the last set of each exercise, and for 10 minutes following the test.
Both groups demonstrated significant increases in total work (P < .0001) for the postintervention test, with no significant differences between the groups (P = .882). When comparing the pre- and postintervention tests, BL and HR were not significantly different at any time point (P > .05).
These results indicate that when intensity and volume are equated, failure or nonfailure training results in similar gains in lower body muscular endurance. Therefore, when assessed over relatively short training cycles, the total volume of training might be more important versus whether sets are performed to failure for muscular endurance-related adaptations.
Muscle fatigue encompasses a class of acute effects that impair motor performance. The mechanisms that can produce fatigue involve all elements of the motor system, from a failure of the formulation of the descending drive provided by suprasegmental centers to a reduction in the activity of the contractile proteins. We propose four themes that provide a basis for the systematic evaluation of the neural and neuromuscular fatigue mechanisms: 1) task dependency to identify the conditions that activate the various mechanisms; 2) force-fatigability relationship to explore the interaction between the mechanisms that results in a hyperbolic relationship between force and endurance time; 3) muscle wisdom to examine the association among a concurrent decline in force, relaxation rate, and motor neuron discharge that results in an optimization of force; and 4) sense of effort to determine the role of effort in the impairment of performance. On the basis of this perspective with an emphasis on neural mechanisms, we suggest a number of experiments to advance our understanding of the neurobiology of muscle fatigue.
To examine endogenous anabolic hormone and growth factor responses to various heavy resistance exercise protocols (HREPs), nine male subjects performed each of six randomly assigned HREPs, which consisted of identically ordered exercises carefully designed to control for load [5 vs. 10 repetitions maximum (RM)], rest period length (1 vs. 3 min), and total work effects. Serum human growth hormone (hGH), testosterone (T), somatomedin-C (SM-C), glucose, and whole blood lactate (HLa) concentrations were determined preexercise, midexercise (i.e., after 4 of 8 exercises), and at 0, 5, 15, 30, 60, 90, and 120 min postexercise. All HREPs produced significant (P less than 0.05) temporal increases in serum T concentrations, although the magnitude and time point of occurrence above resting values varied across HREPs. No differences were observed for T when integrated areas under the curve (AUCs) were compared. Although not all HREPs produced increases in serum hGH, the highest responses were observed consequent to the H10/1 exercise protocol (high total work, 1 min rest, 10-RM load) for both temporal and time integrated (AUC) responses. The pattern of SM-C increases varied among HREPs and did not consistently follow hGH changes. Whereas temporal changes were observed, no integrated time (AUC) differences between exercise protocols occurred. These data indicate that the release patterns (temporal or time integrated) observed are complex functions of the type of HREPs utilized and the physiological mechanisms involved with determining peripheral circulatory concentrations (e.g., clearance rates, transport, receptor binding). All HREPs may not affect muscle and connective tissue growth in the same manner because of possible differences in hormonal and growth factor release.
The effect of high-intensity intermittent training on the adenine nucleotide content of skeletal muscle was studied. Eleven male subjects (group A) performed high-intensity intermittent training on a cycle ergometer three times per week for 6 wk, followed by 1 wk of the same kind of training with two sessions per day. Nine males (group B) exclusively performed 1 wk of training with two sessions per day. In group A, skeletal muscle total adenine nucleotide (TAN) levels decreased from 25.1 +/- 0.7 (SE) to 22.0 +/- 0.6 mmol/kg dry wt over the 6-wk period (P < 0.01). The subsequent intensive week did not further alter TAN levels. In group B, the intensive week of training reduced TAN levels from 25.1 +/- 0.5 to 19.4 +/- 0.6 mmol/kg dry wt (P < 0.001). The decrease was sustained 72 h after training (P < 0.001). During the intensive week, there was no change in plasma creatine kinase activity in either group A or group B. The plasma activity was, however, higher in group B than in group A on days 4 and 7 of the intensive week (P < 0.05). The results from this study indicate that high-intensity intermittent exercise causes a decrease in resting levels of skeletal muscle adenine nucleotide without a concomitant indication of muscle damage. A training-induced adaptation appears to occur with training by which a further loss of adenine nucleotides is prevented despite an increased training dose.
The influence of the number of sprint bouts on purine loss was examined in nine men (age 24.8 +/- 1.6 yr, weight 76 +/- 3.9 kg, peak O(2) consumption 3.87 +/- 0.16 l/min) who performed either one (B1), four (B4), or eight (B8) 10-s sprints on a cycle ergometer, 1 wk apart, in a randomized order. Forearm venous plasma inosine, hypoxanthine (Hx), and uric acid concentrations were measured at rest and during 120 min of recovery. Urinary inosine, Hx, and uric acid excretion were also measured before and 24 h after exercise. During the first 120 min of recovery, plasma inosine and Hx concentrations, and urinary Hx excretion rate, were progressively higher (P < 0.05) with an increasing number of sprint bouts. Plasma uric acid concentration was higher (P < 0.05) in B8 compared with B1 and B4 after 45, 60, and 120 min of recovery. Total urinary excretion of purines (inosine + Hx + uric acid) was higher (P < 0. 05) at 2 h of recovery after B8 (537 +/- 59 micromol) compared with the other trials (B1: 270 +/- 76; B4: 327 +/- 59 micromol). These results indicate that the loss of purine from the body was enhanced by increasing the number of intermittent 10-s sprint bouts.
The aim of this study was to investigate the segmental coordination of vertical jumps under fatigue of the knee extensor and flexor muscles.
Eleven healthy and active subjects performed maximal vertical jumps with and without fatigue, which was imposed by requesting the subjects to extend/flex their knees continuously in a weight machine, until they could not lift a load corresponding to approximately 50% of their body weight. Knee extensor and flexor isokinetic peak torques were also measured before and after fatigue. Video, ground reaction forces, and electromyographic data were collected simultaneously and used to provide several variables of the jumps.
Fatiguing the knee flexor muscles did not reduce the height of the jumps or induce changes in the kinematic, kinetic, and electromyographic profiles. Knee extensor fatigue caused the subjects to adjust several variables of the movement, in which the peak joint angular velocity, peak joint net moment, and power around the knee were reduced and occurred earlier in comparison with the nonfatigued jumps. The electromyographic data analyses indicated that the countermovement jumps were performed similarly, i.e., a single strategy was used, irrespective of which muscle group (extensor or flexors) or the changes imposed on the muscle force-generating characteristics (fatigue or nonfatigue). The subjects executed the movements as if they scaled a robust template motor program, which guided the movement execution in all jump conditions. It was speculated that training programs designed to improve jump height performance should avoid severe fatigue levels, which may cause the subjects to learn and adopt a nonoptimal and nonspecific coordination solution.
It was suggested that the neural input used in the fatigued condition did not constitute an optimal solution and may have played a role in decreasing maximal jump height achievement.
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.
This study examined the effects of the number of sets on testosterone, cortisol, and growth hormone (hGH) responses after maximum strength (MS), muscular hypertrophy (MH), and strength endurance (SE) protocols.
Eleven young men performed multi-joint dynamic exercises using MS (5 reps at 88% of one-repetition maximum (1-RM), 3-min rest) and MH (10 reps at 75% of 1-RM, 2-min rest) protocols with 2, 4, and 6 sets at each exercise; and an SE (15 reps at 60% of 1-RM, 1-min rest) with 2 and 4 sets. Hormonal concentrations were measured before exercise, immediately after, and at 15 and 30 min of recovery.
The number of sets did not affect the hormonal responses after the MS protocol. Cortisol and hGH were higher (P < 0.05) after the four-set compared with the two-set sessions in the MH and SE protocols. No differences were observed between the six-set and the four-set sessions in the MH protocol. Cortisol and hGH were higher (P < 0.05) than the MS after the SE and MH protocols, and only when four and six sets were performed in the latter. hGH was higher than the MH after the SE protocol, whether two or four sets were executed, whereas cortisol (P < 0.05) was higher after the SE protocol only when two sets were performed. Testosterone did not change with any workout.
The number of sets functions up to a point as a stimulus for increased hormonal concentrations in order to optimize adaptations with MH and SE protocols, and has no effect on a MS protocol. Furthermore, the number of sets may differentiate long-term adaptations with MS, MH, and SE protocols causing distinct hormonal responses.
Guidelines for resistance training include the number of exercises, sets, repetitions, and frequency of training, but only vaguely mention movement velocity. Nevertheless, different velocities imply different performances, i.e. a different number of repetitions or different loads. Studies investigating the effect of different movement velocities on resistance training have not reached a consensus. Some studies indicate specificity in strength gains while others indicate generality. Some indicate slow training to be better, others indicate fast training, and still others indicate no differences. Most of these studies were conducted on isokinetic or hydraulic equipment. Very few used isotonic equipment for training, and their results seem to tend towards generality and no differences in gains of strength between velocities. Defining the training velocity is mostly important for athletic performances where a wide range of velocities is needed and transfer of gains would greatly optimise training. At the other end of the spectrum, there are the most frail and elderly, to whom power loss may impair even daily functions, but training with fast velocities might increase injury risk and, therefore, transfer of gains from slow training would be greatly beneficial. Movement velocity for resistance training with isotonic equipment needs to be further investigated so that recommendations may be made.
A great deal of literature has investigated the effects of various resistance training programmes on strength and power changes. Surprisingly, however, our understanding of the stimuli that affect adaptation still remains relatively unexplained. It is thought that strength and power adaptation is mediated by mechanical stimuli, that is the kinematics and kinetics associated with resistance exercise (e.g. forces, contraction duration, power and work), and their interaction with other hormonal and metabolic factors. However, the effect of different combinations of kinematic and kinetic variables and their contribution to adaptation is unclear. The mechanical response to single repetitions has been investigated by a number of researchers; however, it seems problematic to extrapolate the findings of this type of research to the responses associated with a typical resistance training session. That is, resistance training is typified by multiple repetitions, sets and exercises, rest periods of varying durations and different movement techniques (e.g. controlled and explosive). Understanding the mechanical stimuli afforded by such loading schemes would intuitively lead to a better appreciation of how various mechanical stimuli affect adaptation. It will be evident throughout this article that very little research has adopted such an approach; hence our understanding in this area remains rudimentary at best. One should therefore remain cognizant of the limitations that exist in the interpretation of research in this field. We contend that strength and power research needs to adopt a set kinematic and kinetic analysis to improve our understanding of how to optimise strength and power.
The metabolic response to resistance exercise, in particular lactic acid or lactate, has a marked influence upon the muscular environment, which may enhance the training stimulus (e.g. motor unit activation, hormones or muscle damage) and thereby contribute to strength and power adaptation. Hypertrophy schemes have resulted in greater lactate responses (%) than neuronal and dynamic power schemes, suggesting possible metabolic-mediated changes in muscle growth. Factors such as age, sex, training experience and nutrition may also influence the lactate responses to resistance exercise and thereafter, muscular adaptation. Although the importance of the mechanical and hormonal stimulus to strength and power adaptation is well recognised, the contribution of the metabolic stimulus is largely unknown. Relatively few studies for example, have examined metabolic change across neuronal and dynamic power schemes, and not withstanding the fact that those mechanisms underpinning muscular adaptation, in relation to the metabolic stimulus, remain highly speculative. Inconsistent findings and methodological limitations within research (e.g. programme design, sampling period, number of samples) make interpretation further difficult. We contend that strength and power research needs to investigate those metabolic mechanisms likely to contribute to weight-training adaptation. Further research is also needed to examine the metabolic responses to different loading schemes, as well as interactions across age, sex and training status, so our understanding of how to optimise strength and power development is improved.
The purpose of this study was to determine the change in weight training repetition power output as a consequence of interrepetition rest intervals. Twenty-six elite junior male basketball and soccer players performed bench presses using a 6 repetition maximum (6RM) load. The power output for each repetition was recorded using a linear encoder sampling each 10 ms (100 Hz). Subjects were assigned to 1 of 3 intervention groups, differentiated by the arrangement of rest intervals within the 6 repetitions: 6 x 1 repetition with 20-second rest periods between each repetition (Singles); 3 x 2 repetitions with 50 seconds between each pair of repetitions (Doubles); or 2 x 3 repetitions with 100 seconds of rest between each 3 repetitions (Triples). A timer was used to ensure that the rest interval and duration to complete all interrepetition interventions was equated across groups (118 seconds). Significantly (p < 0.05) greater repetition power outputs (25-49%) were observed in the later repetitions (4-6) of the Singles, Doubles, and Triples loading schemes. Significantly greater total power output (21.6-25.1%) was observed for all interrepetition rest interventions when compared to traditional continuous 6RM total power output. No significant between-group differences were found (p = 0.96). We conclude that utilizing interrepetition rest intervals enables greater repetition and total power output in comparison to traditional loading parameters.
The endocrine system plays an important role in strength and power development by mediating the remodelling of muscle protein. Resistance training scheme design regulates muscle protein turnover by modifying the anabolic (testosterone, growth hormone) and catabolic (cortisol) responses to a workout. Although resistance exercise increases the concentrations of insulin-like growth factor 1 in blood following exercise, the effect of scheme design is less clear, most likely due to the different release mechanisms of this growth factor (liver vs muscle). Insulin is non-responsive to the exercise stimulus, but in the presence of appropriate nutritional intake, elevated blood insulin levels combined with resistance exercise promotes protein anabolism. Factors such as sex, age, training status and nutrition also impact upon the acute hormonal environment and, hence, the adaptive response to resistance training. However, gaps within research, as well as inconsistent findings, limit our understanding of the endocrine contribution to adaptation. Research interpretation is also difficult due to problems with experimental design (e.g. sampling errors) and various other issues (e.g. hormone rhythms, biological fluid examined). In addition to the hormonal responses to resistance exercise, the contribution of other acute training factors, particularly those relating to the mechanical stimulus (e.g. forces, work, time under tension) must also be appreciated. Enhancing our understanding in these areas would also improve the prescription of resistance training for stimulating strength and power adaptation.