No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
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.
... Based on this, a specific number of repetitions are often prescribed for a group of individuals using the same relative load for all exercises. However, this method of prescribing RT volume might not provide the planned training stimulus for all individuals since the number of repetitions that can be completed against a given %1RM is both individual-and exercise-specific [4,5]. For instance, if all individuals perform the same number of repetitions per set against the same relative load, it is possible that they will experience different degrees of fatigue upon completing a set, as the number of repetitions left in reserve could be considerably different between individuals. ...
... For instance, if all individuals perform the same number of repetitions per set against the same relative load, it is possible that they will experience different degrees of fatigue upon completing a set, as the number of repetitions left in reserve could be considerably different between individuals. To combat these issues, instead of performing a fixed, predetermined number of repetitions, researchers have suggested terminating each training set as soon as a predetermined percentage of velocity loss (VL) is reached [5,6]. ...
... In this regard, it has been suggested that monitoring VL across sets could serve as a precise method of quantifying the so-called level of effort (i.e. repetitions performed with respect to the maximum number that can be completed) [5]. Indeed, recent studies have reported strong relationships between the VL experienced in a set and the percentage of performed repetitions with respect to the maximum number that can be completed in bench press and back-squat exercises with different loads [6,9]. ...
Purpose
This study aimed to quantify the potential variability in the volume of work completed after reaching different velocity loss (VL) thresholds and determine the effects of sex, training status and history, as well as psychological traits on the reliability and magnitude of the amount of work completed after reaching different VL thresholds using different loads in the back-squat exercise.
Methods
Forty-six resistance-trained people (15 females and 31 males; 18 to 40 years of age) with a wide range of strength levels, training experience, and different training practices were recruited and performed a one-repetition maximum (1RM) test, and two repetitions to failure (RTF) tests 72 h apart. RTF tests were performed with 70, 80, and 90% of 1RM with 10 min of rest between sets. The Bland–Altman analysis for multiple observations per participant and equivalence tests were used to quantify the variability in the volume of work completed after reaching different VL thresholds, whereas linear and generalised mixed-effects models were used to examine the effects of different moderators on the stability and magnitude of the amount of work completed after reaching different VL thresholds.
Results
The findings of the present study question the utility of using VL thresholds to prescribe resistance training (RT) volume as the agreement in the amount of work completed across two consecutive testing sessions was not acceptable. Regardless of the load used, females completed more repetitions than males across VL thresholds, while males performed repetitions at higher velocities. In addition, individuals with higher levels of emotional stability also tended to perform more repetitions across VL thresholds. Finally, sex, choice of load, strength levels and training practices, as well as emotional stability affected the linearity of the repetition–velocity relationship and when sets terminated.
Conclusion
Using the same VL thresholds for all individuals, while assuming generalisability of the stimuli applied, would likely lead to variable acute physiological responses to RT and divergent neuromuscular adaptations over long term. Therefore, VL monitoring practices could be improved by considering sex, training status, history, and psychological traits of individuals due to their effects on the variability in responses to different VL thresholds.
... The dynamic force parameters (MPV, Vmax, and Power) were recorded using a Vitruve encoder (Vitruve, Madrid, Spain) [33]. The analysis of these parameters was performed before and after a training session using a load of 45% of 1 RM, where the velocity would be close to 1.0 m.s −1 [34,35]. These dynamic parameters were also compared between the first and last series of the five sets of five repetitions (5 × 5). ...
... Izquierdo et al. (2006) showed that mean velocity during bench press was reduced between intensities of 65% and 80% of 1 RM, indicating that time under muscular tension is directly related to intensity, and higher loads compromise adaptations and joint functions, impacting movement symmetry [4,38,50]. Previous studies have indicated that a reduction in velocity is directly related to the intensity and action of a movement, being an important indicator of fatigue [34,35]. ...
... The force-velocity relationship has increasingly been used for training purposes [57,58]. This relationship would also be a good tool for assessing the consequences of fatigue [35,59], allowing for better control of loads and effort during training [60,61], particularly important for Paralympic powerlift thletes. ...
Background:
Paralympic powerlifting (PP) is performed on a bench press, aiming to lift as much weight as possible in a single repetition.
Purpose:
To evaluate thermal asymmetry and dynamic force parameters with 45 and 80% 1 Repetition Maximum (1 RM) in PP athletes.
Methods:
Twelve elite PP male athletes were evaluated before and after a training session regarding skin temperature (thermography) and dynamic force indicators (Average Propulsive Velocity-MPV, Maximum Velocity-VMax, and Power). The training consisted of five series of five repetitions (5 × 5) with 80% 1 RM. The force indicators and dynamics before and after (45% 1 RM) were evaluated in series "1" and "5" with 80% 1 RM.
Results:
The temperature did not present asymmetry, and there were differences between the moment before and after. In MPV, Vmax, and Power, with 45% 1 RM, there were differences both in asymmetry and in moments (p < 0.005). With 80% 1 RM, asymmetry was observed, but no differences between moments (p < 0.005).
Conclusion:
No thermal asymmetry was observed. There were reductions in MVP and VMax at 45 and 80% 1 RM but without significant differences between time points (before and after). However, there was asymmetry in the moments before and after within a safety standard, where Paralympic powerlifting was safe in terms of asymmetries.
... 1.2 mg in gummy format) did not reach significant differences in summed torque or fatigue index of an isokinetic knee extension exercise in a randomized, double-blinded, controlled trial [18]. Within this context, although velocity-based training has been proposed as an objective approach to monitoring resistance training load by reflecting the state of the neuromuscular system to produce force against a load [19,20], only one study has examined the effects of capsaicin on velocity variables in resistance training [17]. Furthermore, research approaching capsaicinoids effects on velocity-derived outcomes has only been reported for upper-limb exercises but not for any lower-limb activity (e.g. ...
... This load was chosen because this 1RM percentage may involve a submaximal non-extenuating (i.e. without reaching muscle failure) high effort for the selected repetitions [20]. Finally, as MPV and, consequently, the percentage of velocity loss (VL) are indicators of neuromuscular fatigue [20], two repetitions with 60% 1RM load were performed 3 min and 24 h after the last set of the 3 × 8 protocol. ...
... without reaching muscle failure) high effort for the selected repetitions [20]. Finally, as MPV and, consequently, the percentage of velocity loss (VL) are indicators of neuromuscular fatigue [20], two repetitions with 60% 1RM load were performed 3 min and 24 h after the last set of the 3 × 8 protocol. Velocity values were treated as the fastest, mean, and slowest obtained for the three sets. ...
Background: The aim of this study was to explore the effects
of a low dose (LD) of 0.625 mg and a high dose (HD) of 2.5 mg
of phenylcapsaicin (PC) on full squat (SQ) performance, active
muscle (RPE-AM) and overall body (RPE-OB) ratings of perceived
exertion, muscle damage, protein breakdown, metabolic
response, and 24-h recovery in comparison to placebo
(PLA).
Method: Twenty-five resistance-trained males (age = 21.00 ± 2.15
years, SQ 1-repetition maximum [1RM] normalized = 1.66 ± 0.22 kg)
were enrolled in this randomized, triple-blinded, placebocontrolled,
crossover trial. Participants completed 2 weekly sessions
per condition (LD, HD, and PLA). The first session consisted of preblood
testing of lactate, urea, and aspartate aminotransferases
(AST) and 2 SQ repetitions with 60% 1RM followed by the resistance
exercise protocol, which consisted of SQ sets of 3 × 8 × 70% 1RM
monitoring lifting velocity. RPE-OB and RPE-AM were assessed after
each set. After the first session, 2 SQ repetitions with 60% 1RM were
performed, and blood lactate and urea posttests were collected.
After 24 h, AST posttest and 1 × 2 × 60% 1RM were determined as
biochemical and mechanical fatigue outcomes.
Results: HD reported significant differences for RPE-AM, AST, and
SQ performance compared to LD and PLA. Post-hoc analyses
revealed that HD attained faster velocities in SQ than LD (p =
0.008). HD induced a lower RPE-AM when compared with LD (p =
0.02) and PLA (p = 0.004). PLA resulted in higher AST concentrationsat 24-h post than HD (p = 0.02). No significant differences were
observed for the rest of the comparisons.
Conclusions: This study suggests that PC may favorably influence
SQ performance, RPE-AM, and muscle damage compared to PLA.
However, HD exhibited most of the biochemical and mechanical
anti-fatigue effects instead of LD.
... A 3-min rest interval was established between subsequent sets. To assess the time course of muscle fatigue, changes in peak barbell velocity [16] during the bench press throw (BPT) were analyzed, as several previous studies have shown movement velocity to be a reliable indicator of neuromuscular fatigue [17,18]. To define the differences in the time course of muscle damage between STD and CMB the activity of serum creatine kinase was analyzed [19,20,21]. ...
... Taking into account no significant differences in mean barbell velocity between the barbells, given that a movement velocity is a reliable indicator of neuromuscular fatigue [17,18], it can be assumed that the use of a cambered barbell does not require longer rest intervals between sets across a training session. In conclusion, the bench press exercise performed the use of CMB, which allows for a greater ROM might not require specific training approach and even higher training frequency might be applied. ...
Introduction: Range of motion (ROM) of resistance exercise affects the muscle damage magnitude and the recovery-time course. Thus, the main aim of this study was to compare conventional and extended ROM in the bench press exercise on neuromuscular fatigue assessed by velocity changes during bench press throw, as well on the exercise-induced muscle damage evaluated by creatine kinase (CK) activity in the blood. Material and Methods: A total of fourteen healthy, well-trained males performed 5 sets of the bench press exercise at 70% of one repetition maximum with either standard (STD) and cambered (CMB) barbell until reaching volitional failure. CK and barbell velocity changes were assessed at the baseline and 1h, 24h, 48h post exercise protocol. Results: The results showed that higher peak barbell velocity was reached during the bench press throw after the CMB when compared to the STD condition. Moreover, CK activity showed an overall significant growing trend from baseline to time points following exercise during the STD, whereas the CMB post-48h CK was higher in comparison to pre and post, but not than post-24h. Conclusion: the bench press exercise performed with the use of CMB barbell might not require a specific training approach, and even higher training frequency might be applied.
... It has been shown in many studies that there are changes in the kinematics and kinetics of the movement due to the fatigue. Some of these; more forward leaning [6], forward shifting of the ground reaction force [11], reduction of range of motions [3] and decelerate the linear velocity of the joints [12]. In resistance exercises, a phenomenon occurs in the fatigue condition. ...
... In the studies of squat exercise related to velocity, it is generally performed by following the bar velocity [12,14,[40][41][42]. The excessive forward lean of the trunk could be observed in the free weight back squat exercise [43], as a result of this, it might have a negative effect on the condition. ...
This study was aimed to analyze in detail how the fatigue effects to kinematic parameters of body weight squat exercise (BSQ) by dividing a squat cycle into four different regions. Twenty-one male athletes participated in this study. Participants were divided into two groups according to their lower limb muscle ratio (LLMR). The BSQ was performed until participants were unable to continue the exercise due to the fatigue. Linear and angular kine-matics were obtained by motion analysis software which has high validity and reliability. There was no significant but had large effect size interaction between fatigue conditions and LLMR groups in terms of knee ROM in the extension phase and hip angular velocity in braking phase of the flexion (0.08 > p >0.05, 0.18 > Z 2 r > 0.16). Fatigue condition did not have a significant effect on the duration in the acceleration and braking phases of BSQ (p > 0.05). There were many significant main effects on kinematics in the different regions due to the fatigue (0.01 < p <0.05, 0.44 > Z 2 r > 0.14). In the fatigue condition, there was a polynomial relationship between velocity of shoulder and hip joints (R² flex = 0.82, R² ext = 0.72) rather than linear (R² flex = 0.64, R²ext = 0.53) and coefficient correlations also decreased (r flex = 0.88 to 0.80, r ext = 0.92 to 0.73). The sticking region was observed in the non-fatigue condition and disappeared when fatigue occurred. These results suggest that LLMR may be taken into consideration in the squat exercises, joint tracking may vary for velocity-based squat training and pre-test for sticking region observation may be apply with the BSQ.
... Two principal autoregulatory programs involve the systematic manipulation of load and volume through subjective or objective strategies (18). In the past decade, velocity loss (VL)-based autoregulation has emerged as the primary objective approach for RT volume owing to its ability to monitor daily fluctuations and accurately quantify acute neuromuscular fatigue (33). According to the concept of kinematics, changes in repetition power output during RT directly reflect strength performance, exertion, and the degree of neuromuscular fatigue, similar to the VL principle (33). ...
... In the past decade, velocity loss (VL)-based autoregulation has emerged as the primary objective approach for RT volume owing to its ability to monitor daily fluctuations and accurately quantify acute neuromuscular fatigue (33). According to the concept of kinematics, changes in repetition power output during RT directly reflect strength performance, exertion, and the degree of neuromuscular fatigue, similar to the VL principle (33). Despite the importance of monitoring and autoregulating training, a significant proportion of previous research analyzing the response to different RT programs has overlooked monitoring repetition power loss (PL). ...
Application of a new monitoring variable: Effects of power loss during squat training on strength gains and sports performance. J Strength Cond Res XX(X): 000-000, 2023-This study aimed to compare the effects of power loss (PL) autoregulated volume (PL10 and PL20) with standardized fixed-load (FL) prescription on strength, sports performance, and lean body mass (LBM). Thirty-five female basketball players from a sports college were randomly assigned to 3 experimental groups (PL10, n 5 12; PL20, n 5 12; and FL, n 5 11, respectively) that performed a resistance training (RT) program with wave-like periodization for 10 weeks using the back squat exercise. Assessments performed before (Pre) and after (Post) intervention included assessed 1 repetition maximum (1RM), body composition, 20-m sprint (T20M), change of direction (COD), and jump performance, including countermovement jump with arm swing, maximum vertical jump, and reactive strength index. Three groups showed significant improvements in strength (effect size [ES]: PL10 5 2.98, PL20 5 3.14, and FL 5 1.90; p , 0.001) and jump performance (ES: PL10 5 0.74, PL20 5 1.50, and FL 5 0.50; p ,0.05-0.001). However, PL10 and PL20 demonstrated different advantages in sports performance compared with FL (group 3 time interaction, p ,0.05). Specifically, PL10 significantly improved COD performance (ES 5 20.79 ; 20.53, p ,0.01), whereas PL20 showed greater improvements in sprint (ES 5 20.57, p ,0.05) and jump performance (ES 5 0.67-1.64, p ,0.01-0.001). Moreover, PL10 resulted in similar gains to PL20 and beneficial improvements compared with FL in LBM, despite performing the least repetitions. Overall, the study indicates that power loss-based autoregulation induces greater gains in LBM and sports performance, as well as eliciting a higher efficiency dose response than standardized FL prescriptions, particularly for PL10. Therefore, incorporating PL monitoring in training programs is recommended, and further studies on power-based RT would be worthwhile.
... Two principal autoregulatory programs involve the systematic manipulation of load and volume through subjective or objective strategies (18). In the past decade, velocity loss (VL)-based autoregulation has emerged as the primary objective approach for RT volume owing to its ability to monitor daily fluctuations and accurately quantify acute neuromuscular fatigue (33). According to the concept of kinematics, changes in repetition power output during RT directly reflect strength performance, exertion, and the degree of neuromuscular fatigue, similar to the VL principle (33). ...
... In the past decade, velocity loss (VL)-based autoregulation has emerged as the primary objective approach for RT volume owing to its ability to monitor daily fluctuations and accurately quantify acute neuromuscular fatigue (33). According to the concept of kinematics, changes in repetition power output during RT directly reflect strength performance, exertion, and the degree of neuromuscular fatigue, similar to the VL principle (33). Despite the importance of monitoring and autoregulating training, a significant proportion of previous research analyzing the response to different RT programs has overlooked monitoring repetition power loss (PL). ...
... Direnç antrenmanı sırasında hızın izlenmesi, egzersiz sırasında metabolik stres ve nöromusküler yorgunluğu tahmin etmek için kullanılabilir. 29 Direnç barına hareket hızını ölçen bir cihaz takılarak, sporcunun ağırlığı kaldırırken hızı rahatlıkla ölçülebilmekte ve antrenman şiddeti planlanabilmektedir. 30 Sporcunun belirli bir hareket için minimum hızı biliniyorsa, yorgunluğun derecesi değerlendirilebilir ve sporcunun antrenmana hazır olup olmadığı tahmin edilebilir. 4,29 Örneğin antrenman seansına başlarken, sporcuya hafif yükleri maksimal hızda kaldıracağı özel bir ısınma seti uygulanabilir. ...
... 29 Direnç barına hareket hızını ölçen bir cihaz takılarak, sporcunun ağırlığı kaldırırken hızı rahatlıkla ölçülebilmekte ve antrenman şiddeti planlanabilmektedir. 30 Sporcunun belirli bir hareket için minimum hızı biliniyorsa, yorgunluğun derecesi değerlendirilebilir ve sporcunun antrenmana hazır olup olmadığı tahmin edilebilir. 4,29 Örneğin antrenman seansına başlarken, sporcuya hafif yükleri maksimal hızda kaldıracağı özel bir ısınma seti uygulanabilir. Sporcunun ısınma setindeki performansına göre antrenman seansının şiddeti yeniden planlanabilir. 4 DİRENÇ ANTRENMANLARININ İŞ YüKüNü BELİRLEME YÖNTEMLERİ Direnç antrenmanlarının planlanmasında antrenman yükünün veya toplam işin belirlenmesi önemlidir. ...
Turkiye Klinikleri J Sports Sci. 2023;15(3):464-74 464 Kondisyonerlerin ve spor bilimcilerin direnç an-trenmanlarının periyodizasyonunu tasarlarken, genel antrenman planının çeşitli aşamalarında yer alan iş yüklerindeki ve yükleme modellerindeki varyasyon-ları anlaması ve tanımlaması önemlidir. Antrenman-ların sporcuda yarattığı stresi ölçebilme yeteneği, yapılan antrenmanların dönemsel planlamaya uygun olup olmadığının belirlenmesine imkân tanır. Antrenman yükü, egzersizin kapsamı (hacmi) ve şiddetinin ürünü olarak kabul edilebilir. Kuvvet ÖZET Sporcunun direnç antrenmanlarına adaptasyonu ve ilerlemesi, büyük ölçüde verimli ve etkili bir antrenman sürecini oluşturma ve sür-dürme becerisiyle ilişkilidir. Bu derlemenin amacı, kuvvet-güç sporla-rında direnç antrenmanları için programlama yöntemleri ve periyodizasyon kavramlarıyla ilgili bilimsel literatürü incelemektir. Di-renç antrenmanlarında iş (kapsam) yükünün planlanması, ölçülmesi ve takip edilmesi, performans gelişimi için antrenman streslerinin ve yor-gunluğun daha iyi yönetilmesine imkân tanır. Belirli bir direnç egzer-sizi veya antrenman seansı sırasında toplam iş, tamamlanan toplam tekrarlar ile kaldırılan ağırlığın hesaba katıldığı kapsam yükü hesapla-maları ile tahmin edilebilir. Direnç antrenmanlarının bölgeleri (zon-ları), maksimal kuvvet, hipertrofi, maksimal güç ve lokal kas dayanıklılığı gibi geliştirilmek istenilen fizyolojik adaptasyonlar doğ-rultusunda belirli bir yük ve tekrar ilişkisine göre belirlenir. Yıllık plan-lama yapılırken geliştirilmek istenilen kassal uygunluk bileşenlerine göre antrenman bölgelerinin farklı kombinasyonları sıralı bir ilerleme ile uygulanmaktadır. Direnç antrenmanlarının lineer, nonlineer veya blok gibi farklı periyodizasyonları yapılabilmektedir. Kuvvet-güç spor-larında yıllık planın makro döngüleri, sırasıyla hipertrofi, maksimal kuvvet ve maksimal güç olmak üzere genel olarak belirli bir kuvvet bi-leşenini vurgulamak için tasarlanır. Maksimum tekrar yöntemi, kuvvet gelişimini takip etmek, günlük kuvvet düzeyine göre yük artışlarını planlamak ve ilerlemeyi sağlamak için kullanışlı olabilir. Antrenman planlamasında, kapsam ve şiddetin rölatif değerlerine göre haftalık ağır ve hafif antrenman günlerine yer verilerek dalgalı bir yaklaşım izlene-bilir. Bu sayede antrenmanların yarattığı yorgunluğun etkisi ile günlük maksimal kuvvet seviyelerindeki dalgalanmalar dengelenebilir. Anah tar Ke li me ler: Kuvvet antrenmanı; maksimal kuvvet; hipertrofi; kapsam yükü; blok periyodizasyon ABS TRACT The athlete's adaptation and progression to resistance training is largely related to the athlete's ability to create and maintain an efficient and effective training process. This review examines the scientific literature on programming methods and periodization concepts for resistance training in strength-power-sports. Planning, measuring and monitoring the volume load in resistance training allows better management of training stresses and fatigue for performance improvement. Total work during a given resistance exercise or training session can be estimated by volume load calculations that take into account total reps completed and weight lifted. The zones of resistance training are determined according to a certain load and repetition relationship in line with the desired physiological adaptations such as maximal power, hypertrophy, maximal strength and local-muscle endurance. While making annual planning, different combinations of training zones are implemented in a sequential progression according to the muscular fitness components desired to be developed. Different periodizations of resistance training such as linear, non-linear, block are implemented. In strength-power-sports, the macro cycles of the annual plan are generally designed to emphasize a particular strength component, namely hypertrophy, maximal strength, power, respectively. The repetition maximum method can be useful for monitoring strength development, planning load increments based on daily strength level, and progressing. In training planning, an undulating approach can be used, allowing weekly heavy and light training days according to the relative values of volume and intensity. In this way, fluctuations in daily maximal strength levels due to the effect of fatigue created by training can be balanced.
... 52 Therefore, monitoring MV and VL during RE allows a precise knowledge of %1RM without the need to perform any 1RM or nRM test 43 and to quantify neuromuscular fatigue objectively. 53 However, measuring MV and VL requires specialised instruments (ie, transducers or validated mobile applications); therefore, we again propose using the RPE scale, as it validly measures exercise intensity and physiological exertion during RE. 54 55 For example, the RPE (0-10 scale) in experienced and novice subjects has been reported to be a valid indicator for estimating %1RM and RIR at moderate-loads to highloads, where an RPE of 1-2, 5-6 or 10, represented little to no effort, more repetitions can be performed or no more repetitions (max effort), respectively. ...
... 54 55 For example, the RPE (0-10 scale) in experienced and novice subjects has been reported to be a valid indicator for estimating %1RM and RIR at moderate-loads to highloads, where an RPE of 1-2, 5-6 or 10, represented little to no effort, more repetitions can be performed or no more repetitions (max effort), respectively. 56 Besides the RPE, the LoE approach, which is the relationship between the number of repetitions that are done in a set and those that could be done 53 can also be used for prescribing RE. Interestingly, the LoE approach can be applied with traditional multi-joint exercises, relative intensities and in subjects with different strength levels. ...
Physical inactivity is a major health concern, associated with the development of several non-communicable diseases and with an increased mortality rate. Therefore, promoting active lifestyles has become a crucial public health necessity for enhancing overall health and quality of life. The WHO guidelines for physical activity (PA) present valuable contributions in this respect; however, we believe that greater specificity should be added or complemented towards physical exercise (PE) testing, prescription and programming in future recommendations. In this review article, we suggest simple and practical tools accessible to the entire population to improve the specificity of this approach, highlighting aspects of PE programming used by trained subjects. By adopting these suggestions, exercise professionals, clinicians and physical trainers can optimise the current general PA recommendations towards PE prescription to improve fitness status and encourage PE adherence in the general population.
... The increase in asymmetries would be related to the increased risk of injuries [10,11]. Thus, training load control has been important in reducing the risk of injuries and improving performance [1,12]. On the other hand, fatigue would be related to loss of speed and metabolic stress [12,13]. ...
... Thus, training load control has been important in reducing the risk of injuries and improving performance [1,12]. On the other hand, fatigue would be related to loss of speed and metabolic stress [12,13]. Allied with this, the decrease in asymmetries would be related to improvements in function, strength, and power. ...
Background:
Strength training is a complex task, as it requires a combination of many variables. In paralympic powerlifting (PP) asymmetries for the evaluation of activation, and static force indicators have been increasingly studied.
Objective:
To investigate the asymmetries in the strength and muscle activation indicators, before and after a training session of PP athletes.
Methodology:
Twelve elite athletes from the PP participated in the study, and asymmetry was evaluated through surface electromyography (sEMG) and static strength indicators. Evaluations were made before and after a protocol of five series of five repetitions (5 × 5), with 80% of 1-Maximum Repetition (1RM).
Results:
In the pectoral muscles, there were differences in the non-dominant limbs between the before and after in the sEMG. There were differences in the pectoralis muscle in the non-dominant limb between moments before (110.75 ± 59.52%) and after (130.53 ± 98.48%, p < 0.001), and there was no difference in triceps activation. In the Maximum Isometric Strength (MIF), there was a difference in the non-dominant limb between before (710.36 ± 129.36) and after (620.27 ± 69.73; p < 0.030). There was a difference before in the dominant (626.89 ± 120.16; 95% CI 550.55-703.24) and non-dominant (710.36 ± 129.36; p = 0.011) limbs. There was no difference in time to MIF.
Conclusion:
PP athletes showed small levels of asymmetry before and after training, and adaptation to training tends to promote fewer asymmetries.
... Furthermore, when the exercise is performed with maximal concentric effort and fatigue ensues, velocity will decline 10 . In this regard, research has shown that monitoring velocity loss (VL) incurred in a set is an objective, practical and non-invasive indicator of the acute metabolic stress, hormonal response and mechanical fatigue induced by RT 12 . Although this velocity-based approach to RT monitoring and prescription is now widely used among different populations, several factors such as the cost of the equipment and its accuracy must be considered. ...
... Regardless of the population in question, it is evident that the efficacy of the velocity-based approach to RT monitoring and prescription depends upon the reliability of devices used to record barbell velocity. This requirement also represents one of the main drawbacks of the velocity-based approach to RT monitoring and prescription since very small changes in velocity can represent decisive changes in neuromuscular status and functional performance 12,13 . In this regard, 3-dimensional motion capture systems are considered gold-standard for movement velocity monitoring. ...
This study examined the reproducibility of GymAware, PUSH2 and Vmaxpro velocity monitoring devices during resistance training (RT). The sensitivity of these devices to detect the smallest changes in velocity that correspond to true changes in RT performance was also investigated. Fifty-one resistance-trained men and women performed an incremental loading (1RM) test, and two repetitions to failure tests with different loads, 72 h apart. During all repetitions, mean velocity (MV) and peak velocity (PV) were simultaneously recorded by two devices of each brand. Overall, GymAware was the most reliable and sensitive device for detecting the smallest changes in RT performance, regardless of the velocity metric used. Vmaxpro can be considered as an equivalent, cheaper alternative to GymAware for RT monitoring and prescription, but only if the MV metric is used. Caution should be exercised when using PUSH2 in practice due to their comparatively higher, unacceptable measurement error and generally low sensitivity to detect changes in RT performance. Collectively, these findings support the use of MV and PV from GymAware and MV from Vmaxpro devices for RT monitoring and prescription due to their low magnitudes of error; thus, allowing for the detection of meaningful changes in neuromuscular status and functional performance during RT.
... In addition, none of those studies were designed to compare the effects of bench presses on immediate and delayed fatigue, despite the fact that the ROM may have an impact on its magnitude. However, in the study by Krzysztofik et al. (2021), changes in barbell velocity, which is considered an indicator of neuromuscular fatigue (de-Oliveira et al., 2022;Sánchez-Medina and González-Badillo, 2011), were assessed. Those authors compared the velocities obtained during successive sets of standard and cambered barbell presses until failure and found a similar decrease in peak velocity from set to set. ...
... The current study's findings revealed a similar trend of decreasing velocity from set to set with no difference between barbells. Considering that previous research on resistance training has shown that velocity loss may objectively quantify neuromuscular fatigue (de-Oliveira et al., 2022;Sánchez-Medina and González-Badillo, 2011), it indicates that bench pressing with either a cambered or a standard barbell contributes to a similar increase in fatigue with each successive set. This confirms that using a cambered barbell may not require longer rest intervals between sets. ...
The objective of this study was to compare the impact of cambered and standard barbells used during the bench press exercise on the number of performed repetitions and mean velocity during a bench press training session that included 5 sets performed to volitional failure at 70% of one-repetition maximum (1RM) (for each barbell type). An additional objective was to determine whether there would be any difference in neuromuscular fatigue assessed by peak velocity changes during bench press throws performed 1 and 24 hours after the cessation of each session. The research participants included 12 healthy resistance-trained men. Participants performed 5 sets of the bench press exercise to volitional failure against 70% of 1RM with the cambered or standard barbell. The Friedman’s test showed an overall trend of a significant decrease in the mean velocity (p < 0.001) and a number of performed repetitions (p < 0.001) from the first to the fifth set (p < 0.006 and p < 0.02, respectively for all) under both conditions, yet neither bar showed significant differences between the corresponding sets. Two-way ANOVA indicated a significant main effect of time (p < 0.001) for peak velocity during the bench press throw. The post-hoc comparisons showed significantly lower peak velocity during the bench press throw one hour after the bench press compared to pre (p = 0.003) and 24-hour post intervention (p = 0.007). Both barbells caused a similar decrease in peak barbell velocity during the bench press throw performed one hour after the bench press training session, with values returning to baseline 24 hours later. This indicates that bench press workouts with either a standard or a cambered barbell present the same training demands.
... The use of relative VLTs during resistance training have received increased attention because of their ability to alter the external and internal responses during exercise (19,25). For example, previous research has shown that kinetic and kinematic outputs can be reliably and consistently applied to athletes as they train (20,35). ...
Weakley, J, Johnston, RD, Cowley, N, Wood, T, Ramirez-Lopez, C, McMahon, E, and García-Ramos, A. The effects and re-producibility of 10, 20, and 30% velocity loss thresholds on acute and short-term fatigue and recovery responses. J Strength Cond Res XX(X): 000-000, 2023-This study aimed to establish the effects and reproducibility of implementing 10, 20, and 30% velocity loss thresholds (VLTs) during the free-weight barbell back squat on acute and short-term perceived soreness, neuromuscular fatigue, and physical performance. Using a repeated, counterbalanced, crossover design, 12 team-sport athletes completed on separate sessions 5 sets of the free-weight barbell back-squat until reaching VLTs of either 10, 20, or 30%. Outcomes were measured immediately postexercise and 24 hourS after each session. To assess reproducibility, the same sessions were repeated after 4 weeks. Immediately postexercise, small differences in countermovement jump (CMJ) and 10-m sprint performance were observed between VLT conditions, whereas small to moderate differences in differential ratings of perceived exertion were reported (10% , 20% , 30%). At 24 hours, trivial differences in CMJ outcomes were found but small differences in 10-m sprint performance were detected between conditions (10% , 20% , 30%). In addition, at 24 hours, a single small difference in radial deformation using tensiomyography was found between 10 and 30% conditions, whereas large to very large differences in perceived soreness were reported between conditions (10% , 20% , 30%). Finally, the standard error of measurement of all outcome measures at 24 hours were of a similar magnitude to those reported in tightly controlled, short-term studies. Collectively, these findings demonstrate that VLTs help control the fatigue outcomes that occur as a response to resistance training and that they are reproducible. Therefore, for practitioners who wish to prescribe resistance training and be confident in the subsequent fatigue response, it is strongly advised that VLTs are implemented.
... As linear position transducers are often used as a tool to monitor changes in velocity on an inter-set basis (22), as is observed in VBT, we sought to evaluate the inter-set reliability of HUMAC. As a result, the HUMAC does not appear to provide criterion referenced validity for measures of velocity in the barbell back squat when compared to TEN-DO, as repetition-to-repetition comparisons demonstrated significant differences in all variables across all intensities. ...
The purpose of this investigation was to determine the validity and reliability of the Humac360 linear position transducer (LPT) as compared to Tendo Weightlifting Analyzer. Seventeen recreationally active men and women completed three visits. Visit one included maximal strength assessments via one-repetition maximum (1RM) for the barbell back squat. On visits two and three, participants completed two sets of three repetitions at 30-, 50-, 60-, and 70% 1RM. Mean Concentric Velocity (MCV), Peak Velocity (PV), Displacement (D), and Duration (T) were collected. Repetition data agreement was assessed with Intraclass Correlation Coefficients (ICCs) and were categorized as poor (<0.50), moderate (0.50-0.75), good (0.75-0.90), and excellent (>0.90). Significance was accepted at an alpha (p) value < 0.05. Repetition-to-repetition comparisons between devices demonstrate varying degrees of agreement, with significant differences between devices across all intensities and all measurements (p < 0.001). Inter-set reliability was excellent for MCV, PV, D, and T with the exceptions of MCV and PV at 70% 1RM (ICC 2,k = 0.548 and 0.816). Inter-session reliability data demonstrated reduced agreeableness in an intensity-dependent manner, with ICCs decreasing and SEMs increasing with increases in intensity. The Humac360 LPT does not appear to be valid when compared to the criterion method, though we contend it maintains construct validity. Coaches may use the Humac360 LPT as a tool to monitor fatigue, and the associated changes in trainee movement velocity on an inter-set and inter-session basis.
... For untrained individuals, the literature tends to indicate that one set of 8-15 repetitions will improve muscle strength and power without the need for lifting to momentary repetition failure or adding forced repetitions to increase the stress associated with more numerous repetitions. The number of repetitions to perform before reaching momentary failure may be detected by monitoring the movement velocity as the decrease in velocity is a strong indicator of the degree of fatigue before reaching momentary failure [100][101][102]. Kubo et al. [103] compared four, eight, and 12 repetition maximums with twice-weekly training over 10 weeks, and found that increases in muscle hypertrophy were similar among the three training protocols when the training volume was equated. ...
Background Findings from original research, systematic reviews, and meta-analyses have demonstrated the effectiveness of resistance training (RT) on markers of performance and health. However, the literature is inconsistent with regards to the dosage effects (frequency, intensity, time, type) of RT to maximize training-induced improvements. This is most likely due to moderating factors such as age, sex, and training status. Moreover, individuals with limited time to exercise or who lack motivation to perform RT are interested in the least amount of RT to improve physical fitness. Objectives The objective of this review was to investigate and identify lower than typically recommended RT dosages (i.e., shorter durations, lower volumes, and intensity activities) that can improve fitness components such as muscle strength and endurance for sedentary individuals or beginners not meeting the minimal recommendation of exercise. Methods Due to the broad research question involving different RT types, cohorts, and outcome measures (i.e., high het-erogeneity), a narrative review was selected instead of a systematic meta-analysis approach. Results It seems that one weekly RT session is sufficient to induce strength gains in RT beginners with < 3 sets and loads below 50% of one-repetition maximum (1RM). With regards to the number of repetitions, the literature is controversial and some authors report that repetition to failure is key to achieve optimal adaptations, while other authors report similar adaptations with fewer repetitions. Additionally, higher intensity or heavier loads tend to provide superior results. With regards to the RT type, multi-joint exercises induce similar or even larger effects than single-joint exercises. Conclusion The least amount of RT that can be performed to improve physical fitness for beginners for at least the first 12 weeks is one weekly session at intensities below 50% 1RM, with < 3 sets per multi-joint exercise.
... For untrained individuals, the literature tends to indicate that one set of 8-15 repetitions will improve muscle strength and power without the need for lifting to momentary repetition failure or adding forced repetitions to increase the stress associated with more numerous repetitions. The number of repetitions to perform before reaching momentary failure may be detected by monitoring the movement velocity as the decrease in velocity is a strong indicator of the degree of fatigue before reaching momentary failure [100][101][102]. Kubo et al. [103] compared four, eight, and 12 repetition maximums with twice-weekly training over 10 weeks, and found that increases in muscle hypertrophy were similar among the three training protocols when the training volume was equated. ...
Background
Findings from original research, systematic reviews, and meta-analyses have demonstrated the effectiveness of resistance training (RT) on markers of performance and health. However, the literature is inconsistent with regards to the dosage effects (frequency, intensity, time, type) of RT to maximize training-induced improvements. This is most likely due to moderating factors such as age, sex, and training status. Moreover, individuals with limited time to exercise or who lack motivation to perform RT are interested in the least amount of RT to improve physical fitness.
Objectives
The objective of this review was to investigate and identify lower than typically recommended RT dosages (i.e., shorter durations, lower volumes, and intensity activities) that can improve fitness components such as muscle strength and endurance for sedentary individuals or beginners not meeting the minimal recommendation of exercise.
Methods
Due to the broad research question involving different RT types, cohorts, and outcome measures (i.e., high heterogeneity), a narrative review was selected instead of a systematic meta-analysis approach.
Results
It seems that one weekly RT session is sufficient to induce strength gains in RT beginners with < 3 sets and loads below 50% of one-repetition maximum (1RM). With regards to the number of repetitions, the literature is controversial and some authors report that repetition to failure is key to achieve optimal adaptations, while other authors report similar adaptations with fewer repetitions. Additionally, higher intensity or heavier loads tend to provide superior results. With regards to the RT type, multi-joint exercises induce similar or even larger effects than single-joint exercises.
Conclusion
The least amount of RT that can be performed to improve physical fitness for beginners for at least the first 12 weeks is one weekly session at intensities below 50% 1RM, with < 3 sets per multi-joint exercise.
... The upward displacement of the barbell was also used to explore potential differences in the range of motion between the BP variants. A validated linear velocity transducer (T-Force System; Ergotech, Murcia, Spain) was used to obtain MV and displacement variables (24). Of note is that during all tests, 2 trained spotters were present on each side of the barbell to ensure safety and motivate subjects to lift the barbell as fast as possible (explosive strength test), to lift as many kilograms as possible (maximal strength test), and to complete as many repetitions as possible (endurance strength test). ...
The objective of this study was to explore the effect of retracting the scapulae during the free-weight bench press (BP) exercise on various strength manifestations and perceptual variables. Twenty-eight recreationally trained male lifters (BP 1-repetition maximum [1RM] 5 96.1 6 20.8 kg) randomly performed in 2 different sessions: the flat BP (scapulae free to move during the movement) and retracted BP (shoulders retracted during the movement). Three strength manifestations were evaluated: (a) explosive strength—mean velocity (MV) achieved against 3 submaximal loads (40, 60, and 80%1RM); (b) maximal strength—1RM; and (c) endurance strength—number of repetitions completed to failure against the 70%1RM. Discomfort and ratings of perceived exertion (RPE) values were also recorded immediately after completing each test. The upward displacement of the barbell was lower for the retracted BP compared with the flat BP at the 3 submaximal loads (p 0 0.024), but no significant differences between the BP variants were observed for the MV at submaximal loads (p 0 0.473), 1RM (p = 0.147), number ofrepetitions completed to failure (p = 0.447), RPE at submaximal loads (p = 0.363), or discomfort during any test (p = 0.611). Subjects always demonstrated a greater strength performance with the BP variant most used in their training programs, but the differences between the flat and retracted BP were not affected by subjects’ maximal strength values (p $ 0.162). These results suggest that retracting the scapulae during the BP exercise presents minor effects on different strength manifestations and perceptual measures of effort and discomfort.
... The protocol used VPM, MaxV, and Power indicators to assess velocity loss using load equivalent to 45% of 1RM [37]. Athletes' performance was evaluated through three repetitions, both before and immediately after training, as well as 24 and 48 hours later. ...
Background: Several reports have highlighted the beneficial impacts of caffeine on performance in various disciplines of Para-lympic Powerlifting (PP), a sport renowned for its emphasis on maximal strength. Moreover, caffeine consumption within the context of PP has been found to be safe. Objective: To examine the effects of caffeine intake before, during, and after PP training sessions at national level in Brazil. Methods: Thirteen male PP athletes competing at national level (31.31 ± 10.13 years, 80.77 ± 22.66 kg) participated in the study. They were provided with either 9.0 mg/kg of Caffeine Anhydrous (CA) or Placebo (PL) and were evaluated using 45% of their one-repetition maximum (1RM) before and after training sessions, as well as 24 and 48 hours after sessions. Additionally, they performed five sets of five repetitions maximum (5x5), with assessments carried out during the first and fifth sets for all five repetitions. Evaluations focused on Mean Propulsive Velocity (MPV), Maximum Velocity (MaxV), and Power. Results: No significant differences were observed with 45% 1RM. However, at 80% 1RM, CA demonstrated significant improvement compared to PL during Set 1 and Set 5 (p < 0.05). Conclusions: CA exhibits promising ergogenic properties, enabling athletes to sustain training intensity throughout the session, even when working with heavier PP loads.
... A decrease of ≥ 20% in velocity/power has been reported as an indicator of neuromuscular fatigue during resistance training www. (González-Badillo & Sánchez-Medina, 2010;Pareja-Blanco et al., 2017;Sánchez-Medina & González-Badillo, 2011). All analyses were performed in Microsoft Excel. ...
The aim of this study was to investigate the desired number of repetitions required to maintain a consistent maximum power output of concentric, eccentric, and eccentric overload in a flywheel Romanian deadlift (FW RDL). Fourteen male recreational athletes (27.9 ± 6.4 years old, 90 ± 10.7 kg, 180.7 ± 5.5 cm tall) participated in the study. They had a minimum of two years resistance training experience, but none of them had any experience in flywheel inertia training (FIT). The participants performed FW RDL on an FW device (kBox 3, Exxentric, ABTM, Bromma, Sweden). Each participant attended a single test session. The testing session consisted of four sets of 14 repetitions of the RDL. Both the first and second repetitions of each set were used to ‘increase momentum’ and were excluded from data analysis. Each set incorporated different inertial loads. The order of inertial load settings was randomised for each participant. A five-minute inter-set rest period was given to allow the cessation of any fatigue effects and to enable adequate recovery. During the repetition analysis, a ≥ 20% drop in value from the preceding repetition was used as a cut-off point and recorded. The optimal number of repetitions required to maintain peak concentric and eccentric power was between 10 and 11, whereas 6 to 8 repetitions is advised to maintain eccentric overload.
... Moreover, in these previous studies, submaximal (i.e., not performed until failure) intensities were not assessed (Jiménez-Martínez et al., 2022), which reduces the real applicability of capsaicin on physical conditioning because the induction of excessive fatigue can disturb training adaptations (Pareja-Blanco et al., 2020a). Furthermore, most of the current research studies have not used objective measures of performance (e.g., infrared detection of jump height or linear velocity), which may hinder the estimate of the real impact of this substance on mechanical performance and fatigue (e.g., linear velocity loss) (Sánchez-Medina and González-Badillo, 2011). ...
Objective: This study aimed to examine the effects of phenylcapsaicin (PC) supplementation on strength performance and neuromuscular activity in young trained male subjects.
Materials and methods: A total of 25 trained subjects [full-squat (SQ) one repetition maximum (1RM) = 125.6 ± 21.0 kg] were enrolled in this randomized, triple-blinded, crossover, placebo-controlled trial. The subjects performed a first session and a post-24 h session for each condition. In the first session, the subjects ingested a high dose of PC (HD, 2.5 mg), a low dose (LD, 0.625 mg), or a placebo (PLA). Their performance in SQ was assessed under a 3% × 8 × 70% 1RM protocol in the first session. Their performances in countermovement jump (CMJ), SQ with 60% 1RM, and isometric squat were measured before and after the SQ protocol in both sessions. The neural activity of the vastus lateralis (VL) and vastus medialis (VM) was recorded via surface electromyography (EMG) and averaged in both sessions.
Results: Significant differences between the conditions were reported for lifting velocity, velocity loss, and the 60% load in dynamic SQ ( p range = 0.02–0.04). Electrical changes were not identified for any outcome, although neural activity changed across time ( p range ≤0.001–0.006). A significant condition × time effect was observed in CMJ compared to PLA ( p ≤0.001) and LD ( p ≤0.001). Intra-set analyses revealed higher velocities in HD compared to those in LD ( p = 0.01) and PLA ( p range = 0.004–0.008).
Conclusion: Therefore, PC may improve the strength performance and attenuate the mechanical fatigue induced by resistance training in SQ and CMJ exercises.
... However, it is also known that corticospinal excitability increases after BFRT, showing higher activation levels in comparison with traditional training [2]. These findings suggests that BFRT may lead to a better neural performance [15], which is usually monitored during training through velocity movement control [16] since it allows load quantification [17], 1-RM estimation [18], and neuromuscular fatigue monitorization [19,20]. ...
Unlabelled:
The aim of this study was to verify the effects of blood flow restriction on movement velocity and muscle activity during the back squat exercise.
Methods:
Twenty-four university students participated in this study. In two randomized sessions 72 h apart, participants performed a 4-set protocol consisting of 30-15-15-15 repetitions performed at 30% of their one-repetition maximum in the back squat exercise. In both sessions, neuromuscular function was monitored by surface electromyography (EMG) and movement velocity (mean propulsive velocity (MPV), peak concentric velocity (Vmax), and the effort index (EI)). Blood flow restriction (BFR) was applied during exercise in one of the experimental sessions with 80% of full arterial occlusion pressure over lower limbs.
Results:
The BFR condition showed higher (p < 0.05) EI, peak, and rooted mean square normalized EMG in Set 1 compared to Set 2. Similar MPV and Vmax were observed in each set for both the BFR and control conditions. No significant differences were observed between conditions in any set.
Conclusions:
BFR did not imply changes in neuromuscular performance during low-intensity resistance training, but it might induce greater intra-series velocity loss and less excitation of the muscles involved.
... Measuring training load accurately has been a challenge in the field of exercise training (Gonzalez-Badillo et al., 2017;Sanchez-Medina & Gonzalez-Badillo, 2011;Sanchez-Moreno et al., 2020). In recent years, measuring the velocity of the first repetition has emerged as a precise method to determine the training intensity since the percentage of 1-RM can vary from day to day (Baena-Marin et al., 2022). ...
The Pull-up (PU) is a multi-joint upper body exercise that is included in the physical fitness assessments for tactical occupations such as police, firefighters, and military personnel. This study aimed to evaluate the post-activation performance enhancement (PAPE) in the PU exercise using elastic resistance training (ERT) and traditional resistance training (RT). A total of 18 resistance-trained male firefighters (28.3 [5.6] years; 178.1 [6.8] cm; 78.1 [8.2] kilograms; 24.6 [2.4] kg·m-2) participated in the study and performed four PAPE protocols in a cross-over fashion. Two protocols consisted of three sets of 3 repetitions at 75 and 85% of the maximum repetition (RM) in the lat pull down (LPD-M and LPD-H, respectively). The other two protocols consisted of three sets of 3 repetitions using elastic bands for vertical traction (VTEB) at “moderate” (VTEB- M) and “hard” intensity (VTEB-H), based on the Thera Band perceived exertion scale. Repetitions until failure in the PU exercise were measured before and after the application of the four protocols, with an 8-minute pause before and after the PAPE. Results showed a significant increase on repetitions until exhaustion after all PAPE protocols: LPD-M (P=0.007, d=0.19), LPD-H (P=0.023, d=0.17), VTEB-M (P=0.01, d=0.13) and VTEB-H (P=0.001, d=0.28). The use of ERT and traditional RT at moderate and high intensities represent a proper stimulus for the generation of PAPE in the PU. Keywords: Physical performance, conditioning activity, warm-up exercise, muscle power
... Cluster training is a global term for a number of different set structures that include basic cluster sets, equal work-to-rest ratio and the rest pause method, and is defined as a set structure that includes the normal inter-set rest periods but involves pre-planned rest intervals within the set (39). When performing traditional sets, movement velocity and therefore power output, tend to decline as more repetitions are performed (96). Cluster training facilitates superior maintenance of repetition velocity and power output, while also allowing for the potential to perform a greater number of repetitions, increased loads, or a combination of the two through minimising the effect of accumulated fatigue per 'bout' (43,111). ...
Microdosing, in the context of resistance training, has increased in popularity within sporting environments where it is frequently used among strength and conditioning professionals. Although there is a clear definition for the concept within the literature, it is still commonly incorrectly used, and the extent to which microdosing has been explicitly investigated in empirical research is limited. However, there are many related research areas or themes (including programming for acute and chronic responses, programming around competition schedules, motor learning, and individualization) that indicate the potential benefits of microdosing as an overarching concept. There are also misinterpretations about the term and what microdosing entails; for example, the term microdosing is often used interchangeably with the concept of the minimum effective dose. Therefore, the aim of this review is to outline and discuss where some of these theories and concepts may or may not be appropriate for use within team sports, while also highlighting areas in which the application of microdosing requires further investigation. Although microdosing may be a relatively new term, which is considered “trendy” among practitioners, the underlying principles associated with microdosing have been expressed and investigated for a long time.
... These findings suggests that BFRT may lead to a better neural performance (14), which is usually monitorized during training through velocity movement control (15). Since it allows to load quantification (16), 1-RM estimation (17) and neuromuscular fatigue monitorization (18,19). ...
The aim of this study was to verify the effects of blood flow restriction on movement velocity and muscle activity during the back-squat exercise. Methods: Twenty-four university students participated in this study. In two randomized 72-hours apart sessions, participants performed a 4-set protocol consisting of 30-15-15-15 repetitions performed at 30% of their one-repetition maximum in the back-squat exercise. In both sessions, neuromuscular function was monitored by surface electromyography (EMG) and movement velocity (mean propulsive velocity [MPV], peak concentric velocity [Vmax] and the effort index [EI]). Blood flow restriction (BFR) was applied during exercise in one of the experimental sessions with 80% of full arterial occlusion pressure over lower limbs. Results: BFR condition showed higher (p<0.05) EI, peak and rooted mean square normalized EMG in set 1 compared to set 2. Similar MPV and Vmax were observed at each set for both BFR and control conditions. No significant differences were observed between conditions at any set. Conclusions: BFR did not imply changes in neuromuscular performance during low-intensity resistance training, but it might induce greater intra-series velocity loss and less activation of the muscles involved.
... However, especially when it comes to improving the athletic performance, the creation of a load/velocity profile and determination of intensity based on velocity measurement during the concentric phase of major strength exercises has started to be used as an alternative method (Guerriero et al., 2018). Although a pronounced emphasis should be placed upon velocity during any exercise; many studies have failed to attach necessary importance to this parameter (Pereire & Gomez, 2003;Harris et al., 2007;Sanchez-Medina et al., 2011). According to Behm and Sale (1993), optimal improvement in strength and power ability through specific resistance training can be achieved by performing the training at an exact or close to optimal training velocity. ...
The aim of this study is to investigate the effects of traditional strength and power interval training methods on the development of velocity parameters in the concentric phase of loaded-squat jump exercise and to determine which training method improves velocity parameters more. To achieve this goal, 30 male students who were studying at the School of Physical Education and Sports and did not regularly exercise participated voluntarily in this study. Participants were divided into three different groups using randomization: traditional strength training group, power interval training group, and control group. The participants performed a weighted squat jump exercise using external loads equivalent to 40% of their body weight in both pre-test and post-test measurements, and their mean velocity, mean propulsive velocity, and peak velocity values were obtained through an isoinertial velocity transducer. According to the analysis results, it was found that peak velocity significantly increased after traditional strength training. In addition, the power interval training method made a significant difference on the 1 RM pre-post test. The effect size of traditional strength training on peak velocity was determined as "small". In conclusion, it is thought that traditional strength training is a more prominent training method in improving movement velocity compared to power interval training.
... During resistance training, changes in strength and power can regularly be assessed through monitoring the kinetic and kinematic outputs produced with submaximal loads at the end of a warm-up or throughout a training session. Because of the linear and relatively stable load-velocity relationship and the knowledge that velocity at 1RM shows minimal variation within-athletes and between-athletes (2,19,33,66), changes in the velocities with submaximal loads can infer improvements in maximal strength/ power qualities. Examples include monitoring the changes in barbell velocity with a set load (e.g., 100 kg) at the end of a warm-up, measuring changes in set loads based on a previously constructed load-velocity profile, or using multiple loads and velocities from a warm-up to estimate changes in maximal strength (e.g., implementation of the "2-point method") (3,21,88,98). ...
Understanding the physical qualities of athletes can lead to improved training prescription, monitoring, and ranking. Consequently, testing and profiling athletes is an important aspect of strength and conditioning. However, results can often be difficult to interpret because of the wide range of available tests and outcome variables, the diverse forms of technology used, and the varying levels of standardization implemented. Furthermore, physical qualities can easily be misrepresented without careful consideration if fundamental scientific principles are not followed. This review discusses how to develop impactful testing batteries so that practitioners can maximize their understanding of athletic development while helping to monitor changes in performance to better individualize and support training. It also provides recommendations on the selection of tests and their outcome measures; considerations for the proper interpretation, setup, and standardization of testing protocols; methods to maximize testing information; and techniques to enhance visualization and interpretation.
... A 26 practically perfect relationship (r ≥ 0.94) has been established between MCV and % 1-RM 27 in the bench press, back squat, and deadlift among other exercises, enabling practitioners to 28 accurately estimate 1-RM and its percentages by measuring lifting velocity (5,7,9,20,21). By 29 doing so, practitioners can utilize velocity to inform training prescriptions, test athletes, 30 provide feedback, autoregulate, and control volume (6,11,17,22). In addition, subjective (i.e., 31 the rate of perceived exertion or the number of repetitions in reserve) parameters have been 32 ...
The purpose of the present study was to explore the validity and within-session reliability of the newly developed My Jump Lab application (app), which uses artificial intelligence techniques to monitor barbell velocity in real time. Twenty-seven sport science students performed 5 repetitions at 50% and 75% of their self-reported bench press one repetition maximum (1-RM) during a single testing session, while barbell velocity was concurrently measured using the app (installed on an iPhone 12 Pro) and the GymAware linear position transducer (LPT). A very high correlation was observed between devices at each loading condition (50%1-RM: r = 0.90 [0.82, 0.97]; 75%1-RM: r = 0.92 [0.86, 0.98]). Results showed trivial differences between the app and LPT at both 50%1-RM (g = -0.06) and 75%1-RM (g = -0.12). Bland-Altman analysis showed a bias estimate of -0.010 m.s-1 and -0.026 m.s-1 for the 50% and 75%1-RM, respectively. Finally, similar levels of reliability, as revealed by the coefficient of variation (CV) were observed for both devices (50%1-RM: LPT = 6.52%, app = 8.17%; 75%1-RM: LPT = 12.10%, app = 13.55%). Collectively, the findings of this study support the use of My Jump Lab for the measurement of real time barbell velocity in the bench press exercise.
... 13 The applied BFR stimulus may have contributed to augmenting the compression of the musculature underneath the cuff application in the hip region, acting in a similar capacity to compressive therapy applied to the knees. Unfortunately, as muscle activation and concentric contraction velocity 14 were not measured in this study, 1 it leaves many questions unanswered as to the acute performance responses of the HL BFR group. As BFR continues to gain more popularity, it is important to understand device features and that may impact the BFR stimulus. ...
A letter to the editor regarding a critical oversight in methodological design in Wang (2022). We discuss the challenges of extrapolating research algorithms from a single-chambered bladder system to a multi-chamber bladder system. We also highlight the implications of said methodological concern.
... Besides, RPE, neuromuscular performance measured by movement velocity of repetitions, and the capacity of estimating the proximity to failure measured as repetitions in reserve (RIR) were compared between conditions for each set. Note that movement velocity indicates the state of the neuromuscular system to produce force (Sánchez-Medina & González-Badillo, 2011), and RIR estimation is an important resistance training tool to modulate the level of the effort by the proximity to failure and could be affected by the effects of MF on perceptions related to physical exercise (Martin et al., 2018). We hypothesize that both MF conditions will impair strength endurance performance (i.e., expressed as the number of performed repetitions at a given load) and generate higher-than-normal levels of RPE compared to CON condition. ...
This study aimed to explore the effects of mental fatigue (MF) induced by an incongruent Stroop task (ST) and by using social media (SM) compared to watching a documentary (control) on dynamic resistance training. Twenty-one resistance-trained males attended three identical experimental sessions with the only difference of the randomized cognitive task (ST, SM, or control). Each session consisted of (a) baseline MF and motivation visual analogue scale responses, (b) cognitive task, (c) postvisual analogue scale responses, (d) warm-up, and (e) resistance training based on three sets of bench press at 65% of one-repetition maximum till concentric failure. Number of repetitions, ratings of perceived exertion, mean velocity of repetitions, and three repetitions in reserve estimated by subjects were recorded for each set. Both ST (p < .001) and SM (p = .010) effectively induced MF, but only ST impaired the number of repetitions performed in Set 2 (p = .036) and generated higher-than-normal levels of ratings of perceived exertion even reaching significant differences compared to SM in Set 1 (p = .005). However, SM also affected neuromuscular performance by impairing movement velocity in Set 1 (p = .003). The ability of estimating three repetitions in reserve or motivation was not affected by any condition (p range = .362-.979). MF induced by ST impaired the number of repetitions performed, what seems to be mediated by higher-than-normal levels of ratings of perceived exertion. Besides, SM also impaired the ability to apply force against 65% of one-repetition maximum measured by movement velocity.
... The emergence of the velocity-based method represented a turning point among resistance training methodologies. This approach has proven to be a practical and accurate strategy to program the target intensity (%1RM) (7), monitor intraset fatigue (12,33), and evaluate performance changes after training or detraining periods (19,25). ...
Hernández-Belmonte, A, Buendía-Romero, Á, Pallares, JG, and Martínez-Cava, A. Velocity-based method in free-weight and machine-based training modalities: the degree of freedom matters. J Strength Cond Res XX(X): 000-000, 2023-This study aimed to analyze and compare the load-velocity relationships of free-weight and machine-based modalities of 4 resistance exercises. Moreover, we examined the influence of the subject's strength level on these load-velocity relationships. Fifty men completed a loading test in the free-weight and machine-based modalities of the bench press, full squat, shoulder press, and prone bench pull exercises. General and individual relationships between relative intensity (%1RM) and velocity variables were studied through the coefficient of determination (R2) and standard error of the estimate (SEE). Moreover, the velocity attained to each %1RM was compared between both modalities. Subjects were divided into stronger and weaker to study whether the subject's strength level influences the mean test (mean propulsive velocity [MPVTest]) and 1RM (MPV1RM) velocities. For both modalities, very close relationships (R2 ≥ 0.95) and reduced estimation errors were found when velocity was analyzed as a dependent (SEE ≤ 0.086 m·s-1) and independent (SEE ≤ 5.7% 1RM) variable concerning the %1RM. Fits were found to be higher (R2 ≥ 0.995) for individual load-velocity relationships. Concerning the between-modality comparison, the velocity attained at each intensity (from 30 to 100% 1RM) was significantly faster for the free-weight variant. Finally, nonsignificant differences were found when comparing MPVTest (differences ≤ 0.02 m·s-1) and MPV1RM (differences ≤ 0.01 m·s-1) between stronger and weaker subjects. These findings prove the accuracy and stability of the velocity-based method in the free-weight and machine-based variants but highlight the need to use the load-velocity relationship (preferably the individual one) specific to each training modality.
... That is, either motor cortex or local muscle fiber/metabolite change can hardly reflect the fatigue of walking-like exercise that relates to multi-muscle coordination. Some studies leveraged the decline of motor performance [9], [35] to assess fatigue. For the multi-muscle exercises, non-specific fatigue measuring protocol (e.g. ...
Assessing the progression of muscle fatigue for daily exercises provides vital indicators for precise rehabilitation, personalized training dose, especially under the context of Metaverse. Assessing fatigue of multi-muscle coordination-involved daily exercises requires the neuromuscular features that represent the fatigue-induced characteristics of spatiotemporal adaptions of multiple muscles and the estimator that captures the time-evolving progression of fatigue. In this paper, we propose to depict fatigue by the features of muscle compensation and spinal module activation changes and estimate continuous fatigue by a physiological rationale model. First, we extract muscle synergy fractionation and the variance of spinal module spikings as features inspired by the prior of fatigue-induced neuromuscular adaptations. Second, we treat the features as observations and develop a Bayesian Gaussian process to capture the time-evolving progression. Third, we solve the issue of lacking supervision information by mathematically formulating the time-evolving characteristics of fatigue as the loss function. Finally, we adapt the metrics that follow the physiological principles of fatigue to quantitatively evaluate the performance. Our extensive experiments present a 0.99 similarity between days, a over 0.7 similarity with other views of fatigue and a nearly 1 weak monotonicity, which outperform other methods. This study would aim the objective assessment of muscle fatigue.
... However, subjects 121 were asked to alternate both the right and left leg during the 180° COD. Three CMJs were also executed 122 immediately after the RSA and CMJ height measures were collected [39,40]. After that, subjects performed 123 3 trials of maximal isometric contractions with each leg, as previously described, but in a fatigued state. ...
Hamstring strain injuries (HSI) represents a significant burden in soccer. High speed running is one of the most common HSI mechanism, in particular during match congested periods. Peak force and rate of force development (RFD) of the hamstring muscles tested at long muscle length have shown reductions following fatiguing tasks. However, no study has used a meticulous fatiguing protocol nor reliability scores have been provided. Hamstring peak force, RFD50-100 and RFD100-150 were assessed at long muscle length in 19 soccer players (26.0 ± 4.1 years) before and after the repeated sprint ability (RSA) test. We aimed to calculate reliability scores for both limbs before and after the fatiguing task, and to compare peak force, RFD50-100 and RFD100-150 following the RSA test to baseline values. Peak force displayed "excellent" reliability scores before and after the RSA test, whereas RFD ICC showed "good" values in both time points, but CV scores were not acceptable (i.e., > 10%). Significant moderate to large decreases were found in peak force (g =-1.11 to-0.90), RFD50-100 (g =-1.37 to-1.11) and RFD100-150 (g =-0.84 to-0.69) in both dominant and non-dominant limbs. Maximal isometric peak force, RFD50-100 and RFD100-150 of the hamstrings tested at long muscle length reduced following the RSA test. However, only peak force displayed "excellent" reliability scores, whereas RFD measures could not be considered acceptable owing to their lower reliability scores. Thus, practitioners can be confident about peak force changes, whilst caution should be used when examining such changes in RFD.
... The Smith machine was instrumented with a linear encoder, which was attached to one end of the bar to determine bar velocity (in meters per second) at 1000 Hz (T-Force System®; Ergotech, Murcia, Spain). The reliability of this device has been reported elsewhere (Sánchez-Medina & González-Badillo, 2011). Two sets of eight and four repetitions with 20 and 40 kg, respectively, were performed before testing as a warm-up protocol. ...
Padel is an intermittent racket sport played in pairs (2 vs. 2) on a small-sized grass court (20 x 10 m), involving high physical fitness demands for the players. Therefore, this study aims to compare the effect of two 8-week in-season training programs on the athletic performance of male padel players. Participants (age,
22.1±0.8; body height, 182.0±1.0; body mass, 74.7±0.7) were randomly assigned to the integrated training group (IG, n=12) and non-integrated training group (NIG, n=12). The IG trained inside the padel court, integrating neuromuscular exercises with sport-specific (i.e., use of the racket) technical actions. The NIG trained outside the padel court, performing the same neuromuscular exercises and sport-specific technical actions as the IG, although not simultaneously. Before and after the intervention, athletes were assessed for their hand-grip strength, two legged and one-legged Abalakov jump, bench press performance, padel stroke velocity, cardiorespiratory endurance (30-15IFT), 5-m and 10-m linear sprint time and change of direction ability at 90º and 180º using left and right leg. Both groups improved their scores on Abalakov jump tests, bench press performance, stroke velocity, cardiorespiratory endurance (30-15IFT), and change of direction ability at 90º and 180º (all changes p<.05; effect size = 0.22-2.58). The IG improved stroke velocity compared to NIG (p<.05), and only the IG showed pre-post improvements (p<.05; effect size = 0.30-0.76) in change of direction ability at 90º and 180º involving the non-dominant leg (i.e., turn to the right). An 8-week in-season integrated training approach and a non-integrated training approach may induce similar improvements
in athletic performance among highly trained male padel players. However, the neuromuscular training program involving an integration of padel-specific and non-specific training exercises may induce greater improvements in padel-specific performance (i.e., stroke velocity) and change of direction speed ability, particularly in movements involving the non-dominant leg .
Cornejo-Daza, PJ, Villalba-Fernández, A, González-Badillo, JJ, and Pareja-Blanco, F. Time course of recovery from different velocity loss thresholds and set configurations during full-squat training. J Strength Cond Res XX(X): 000–000, 2023—The aims of the research were to examine the effects of (a) velocity loss (VL) thresholds and (b) set configuration, traditional or cluster, on time-course recovery. A randomized cross-over research design was conducted, in which 15 resistance-trained men performed 4 protocols consisting of 3 sets of 70% 1RM in full squat (SQ), differing in the VL incurred during the set assessed with a linear velocity transducer: (a) 20% (70-20), (b) 30% (70-30), (c) 40% (70-40), and in the set configuration (d) 20% of VL using a cluster methodology (70-CLU). Movement velocity against the load that elicited a 1 m·s ⁻¹ velocity at baseline measurements (V1-load) in SQ, countermovement jump (CMJ) height, and sprint time in 20 m (T20) were assessed at baseline (Pre) and postintervention (Post, 6 hour-Post, 24 hour-Post, and 48 hour-Post). The 70-20 protocol resulted in fewer total repetitions than the other protocols ( p = 0.001), whereas 70-CLU, 70-30, and 70-40 completed similar total repetitions. The 70-30 protocol significantly worsened T20 at 6 hours-Post, CMJ at 48 hours-Post, and V1-load at 6 hours-Post ( p < 0.05). The 70-40 protocol significantly impaired T20 at 6 hours-Post, and CMJ and V1-load at 24 hours-Post ( p < 0.05). No significant performance reductions were observed for 70-20 and 70-CLU at 6 hours-Post, 24 hours-Post, and 48 hours-Post. Protocols with higher VL resulted in more pronounced fatigue and a slower rate of recovery. Cluster sets (70-CLU) resulted in higher volume than protocols with a similar level of fatigue (70-20) and a quicker recovery than protocols with a similar volume (70-30 and 70-40).
This study aimed to assess the validity of three commercial devices in recording mean velocity (MV) and peak velocity (PV) during a unilateral resistance exercise. 18 strength-trained and healthy males performed repetitions of Bulgarian split squats at loads ranging from 40% to 90% of their one-repetition maximum. The MV and PV were simultaneously recorded by GymAware, PUSH, My Lift and compared to Vicon for all repetitions. Concurrent validity was assessed through a linear mixed model, as well as mean difference (MD), mean absolute error (MAE) and Hedge's g effect sizes. GymAware was found to be valid in MV (MD = -0.02 to -0.01 m/s, MAE = 0.02 to 0.03 m/s, g = -0.08 to -0.19) and PV (MD = 0.01 to 0.05 m/s, MAE = 0.05 to 0.07 m/s, g = -0.06 to -0.22) recordings. Significant differences were identified between GymAware, PUSH, My Lift and Vicon for both MV (p < 0.01) and PV (p < 0.01) assessments. Moreover, when comparing the MV and PV recorded by PUSH and My Lift to Vicon, larger MD and MAE, and trivial to moderate effects were also evident. Therefore, our findings suggest that GymAware could be an alternative for recording MV and PV during unilateral resistance exercises.
Personalized learning is one of the main characteristics of an Intelligent Tutoring System (ITS). In the case of strength development, individualization consists in defining exercise characteristics starting from a program template and adjusting the function of several data such as trainee characteristics, calibration test results, fatigue level estimation, or estimation of the number of repetitions in reserve. A recent ITS built for supporting the development of strength skills is Selfit, currently in the second release. Most data collected within Selfit is subjective and relies on trainees’ self-evaluation abilities. To complete them with objective ones, a study evaluating the relevance of Velocity-Based Training (VBT) demonstrates that an ITS's GUI module can collect the speed of realization of a movement performed by a trainee through computer vision technologies. A batch of 25 athletes, from which 14 experienced rugby players and 11 elite swimmers, performed 2 sets at 80% of their 1-repetition maximum back-squat in their usual practice environment. A smartphone was used to record sagittal plane video and track the shape of the weight plate from which the barbell center was derived. The added value of the approach is that the system can support the definition of an objective measure of the difference between prescribed and realized exercise. Lessons from the study support the definition of requirements to enhance the Selfit v2.0 learning individualization functionalities.
Velocity-based training (VBT) is an increasingly popular programming strategy used by strength and conditioning professionals to develop their athlete's ability to express force rapidly. To implement the varying forms of VBT effectively within their training regimes, strength and conditioning professionals need to understand the strengths and weaknesses of strategies, such as predicting 1 repetition maximum using the load-velocity profile, modulating training loads using the load-velocity profile, and controlling training volume using the magnitude of velocity-loss. The aim of this review was to highlight these strengths and weaknesses and then provide practical examples of when each programming strategy may be most effectively implemented.
Wer wünscht sich nicht ein einfaches System zur Ermittlung der optimalen Trainingsbelastung? Herkömmliche Verfahren sind oft aufwendig, wenig objektiv und werden den Trainierenden wegen der unvermeidbaren Leistungsschwankungen oft nicht gerecht. Geschwindigkeitsbasiertes Krafttraining verspricht hier Abhilfe. Es ermöglicht eine relativ einfache Ermittlung der optimalen Trainingsparameter, verspricht gute Ergebnisse bei geringerer Ermüdung und lässt sich im Trainingsalltag leicht umsetzen.
Geschwindigkeitsbasiertes Krafttraining verbessert die Sprung-, Spring- und Kraftleistung. Die Autoren haben verschiedene Studien miteinander verglichen, um herauszufinden, ob die Trainingseffekte hierbei besser sind als bei traditionellem Krafttraining.
BACKGROUND: Muscle fatigue is nearly unavoidable during resistance exercise, yet evaluating it in such circumstances can be challenging. OBJECTIVE: This study aimed to evaluate the validity of using the rating of perceived exertion (RPE) as a measure of muscle fatigue during non-explosive bench press (BP) exercise. METHODS: Fifteen male collegiate athletes participated in three BP tasks set at 65% of their one-repetition maximum. The RPE, spectral fatigue index (SFI), and velocity loss were measured across different experimental conditions. RESULTS: Significant effects were observed across different experimental conditions for the overall RPE, average velocity loss, and average SFI (all p< 0.001). As the lifting tasks progressed, there were significant increases in the RPE, velocity loss, and SFI (p< 0.001). Additionally, significant differences were observed between the experimental conditions in the RPE (p< 0.001), SFI (p< 0.001), and velocity loss (p< 0.01). A significantly stronger (p< 0.05) correlation was observed between the RPE and SFI (r= 0.68, df= 117, p< 0.001) than between the velocity loss and SFI (r= 0.51, df= 117, p< 0.001). CONCLUSIONS: The corresponding changes observed in the RPE, velocity loss, and SFI suggest that both the RPE and velocity loss can be used as indicators of muscle fatigue during non-explosive BP exercise. However, due to the strong correlation between the RPE and SFI, RPE is more effective for reflecting muscle fatigue in non-explosive resistance exercise settings. Regarding ease of use, the RPE is more suitable than velocity loss for assessing muscle fatigue in training scenarios.
This study assessed the reliability of mean concentric bar velocity from 3- to 0-repetitions in reserve (RIR) across four sets in different exercises (bench press and prone row) and with different loads (60 and 80% 1-repetition maximum; 1RM). Whether velocity values from set one could be used to predict RIR in subsequent sets was also examined. Twenty recreationally active males performed baseline 1RM testing before two randomised sessions of four sets to failure with 60 or 80% 1RM. A linear position transducer measured mean concentric velocity of repetitions, and the velocity associated with each RIR value up to 0-RIR. For both exercises, velocity decreased between each repetition from 3- to 0-RIR (p ≤ 0.010). Mean concentric velocity of RIR values was not reliable across sets in the bench press (mean intraclass correlation coefficient [ICC] = 0.40, mean coefficient of variation [CV] = 21.3%), despite no significant between-set differences (p = 0.530). Better reliability was noted in the prone row (mean ICC = 0.80, mean CV = 6.1%), but velocity declined by 0.019-0.027 m·s-1 (p = 0.032) between sets. Mean concentric velocity was 0.050-0.058 m·s-1 faster in both exercises with 60% than 80% 1RM with (p < 0.001). At the individual level, the velocity of specific RIR values from set one accurately predicted RIR from 5- to 0-RIR for 30.9% of repetitions in subsequent sets. These findings suggest that velocity of specific RIR values vary across exercises, loads and sets. As velocity-based RIR estimates were not accurate for 69.1% of repetitions, alternative methods to should be considered for autoregulating of resistance exercise in recreationally active individuals.
This study aimed to investigate the recovery of neuromuscular performance using mechanical parameters collected during jump (vertical and horizontal) and strength- power exercises in youth soccer players after official soccer matches. Twenty-one outfield highly trained youth male soccer athletes (age: 18.23 ± 0.73 years; weight: 72.12 33 ± 6.99 kg; height: 1.78 ± 0.08 m) from two teams competing in the 1 st division of U-19 Portuguese National Championship participated in this study. Players completed a battery of physical tests at-2h, +30 min, +24h, and +48h in relation to the match. Countermovement jump height, horizontal jump distance, and bar velocity during the half-squat, bench press, and hip-thrust exercises, at fixed loads, were recorded. Countermovement jump was impaired until 24h post-match (-1.7% from pre to 24h post, p=0.050; ES=-0.82). Half-squat bar velocity was reduced immediately following the match (-6.8 % from pre-p=0.004; ES=-0.64) but recovered at +24h (+2.9%, p=1.00; ES=0.02). Hip-thrust bar velocity was reduced for up to 48h post-match (-7.4% from pre to 48h post, p<0.001; ES=-0.80). No impairments were found in the horizontal jump and bench press at any moment. Our findings show prolonged decrements in strength of the posterior chain following a soccer match, measured in the hip-thrust exercise, while the other exercises displayed faster recovery dynamics.
Capsinoids may exert ergogenic effects on resistance exercises. However, the acute effects of capsinoids on neuromuscular performance in humans are unknown. Here, we aimed to investigate the acute effects of dihydrocapsiate on lower- and upper-body neuromuscular performance parameters in resistance-trained individuals. 25 young adults (n=6 women; age = 26 ± 3 years; body mass index = 24.3 ± 2.8 kg/m2) with ≥ 1-year resistance training experience were included in this triple-blind (participants, intervention researchers, and data analysts were blinded), placebo-controlled, crossover study. Lower- and upper-body ballistic strength (countermovement jump [CMJ] height and bench press throw [BPT] peak velocity), maximum dynamic strength (estimated 1 repetition maximum in squat and bench press [BP]), and strength-endurance (mean set velocity [squat] and number of repetitions to failure [bench press]) were assessed in 2 independent sessions (≥7 days separation). Participants ingested 12 mg of dihydrocapsiate or placebo 30 min before each trial. We found no significant differences between dihydrocapsiate and placebo conditions in ballistic strength, (CMJ height 33.20 ± 8.07 vs 33.32 ± 7.85 cm; BPT peak velocity 2.82 ± 0.77 vs 2.82 ± 0.74 m/s) maximal dynamic strength (estimated squat 1RM: 123.76 ± 40.63 vs 122.66 ± 40.97 kg; estimated BP 1RM: 99.47 ± 43.09 vs 99.60 ± 43.34 kg), and strength-endurance (squat mean set velocity 0.66 ± 0.07 vs 0.66 ± 0.05 m/s; number BP repetitions to failure 13.00 ± 3.56 vs 13.00 ± 4.78) (all P ≥ 0.703). We conclude that dihydrocapsiate does not acutely improve neuromuscular performance in trained young adults.
Problem Statement: Resistance training with intra-repetition rest (IRR) may lead to the maintenance of peak velocity (PV), reduce fatigue, induce lower blood-lactate concentration, and enhance the technical performance of exercises compared to continuous repetitions. Several studies have investigated the effect of various IRR on various resistance exercises, but the acute effects of IRR on jump-shrug exercise PV remain unexplored. Purpose: This study examined whether different IRR configurations may contribute to maintaining velocity using fast velocity loads in the jump-shrug exercise. Methods: The study involved 12 resistance-training participants (age: 23.4±3.7 years, body mass: 70.3±12.7 kg, body height: 1.70±0.08 m) with 4.3±2.1 years of experience in resistance training. Participants performed the jump-shrug exercise on three different days using three different fast velocity loads of 15, 20, and 25% calculated from the maximum isometric mid-thigh pull dynamometer (IMTPd) test with a randomized order. For each training load, three sets were performed with three different IRR intervals of 2 (IRR2), 6 (IRR6), and 12 (IRR12) seconds with 10 minutes of rest between sets. Measurements included anthropometric characteristics, the maximum IMTPd score, and the PV evaluation across 12 repetitions during the three different load conditions. Results: Significant differences were found for 15, 20, and 25% load conditions for PV between IRR2 and IRR12 configurations (p<0.05). In addition, significant differences were found for the 20% load condition between IRR2 and IRR6 configurations (p<0.05). The percentage of PV loss was significantly lower for the IRR12 configuration than IRR2 across all training loads (p<0.05), while the percentage of PV loss was significantly lower for IRR6 compared to IRR2 for only the 20% load condition. Conclusions: These results suggest that an IRR configuration equal to or greater than 6 seconds during jump-shrugs may contribute to maintaining PV and the percentage of PV loss. Consequently, when fast velocity loads are used for jump-shrugs during power training, IRR equal to or greater than 6 seconds (ideally 12 seconds) should be applied to better maintain PV during repetitions.
The vertical jump is one of the most used testing movements to assess athlete's physical performance and fatigue status in several sports. However, low-cost, portable, field-based, and reliable methods are needed to measure jumping performance. The aim of the current investigation was to assess the validity and reliability of a new photoelectric cells device (ADR) for measuring the vertical jump height. Twenty-three trained male participants (age: 24.8 6 5.2 years, body mass: 74.2 6 7.3 kg; height: 1.76 6 0.04 m) performed four maximal countermovement jumps (CMJ). Flight time-derived jump height was extracted simultaneously from three devices including a force plate (FP) (Kistler Quattro-Jump, criterion measurement) and two photoelectric cells (PC) devices (ADR and Optojump). The ADR mean CMJ height measurements demonstrated substantial validity compared to both FP and Optojump (r = 0.98 p \ 0.01). Intraclass correlation coefficients (ICCs) for reliability were classified as good to excellent for the three devices (0.986-0.994). All devices showed similar coefficients of variation (CV%), classified as very good (3.21-3.85), whereas observed standardized typical error values (STE) were small (1.29-1.39). The ADR Jumping device can be considered an affordable, reliable, and valid method to measure vertical jump height thereby making it a practical resource for coaches when monitoring the training process.
Kettlebell training provides multiple health benefits, including the generation of power. The primary purpose of this study was to examine the kinematics and kinetics of lower-body joints during a repeated, maximum effort kettlebell swing protocol. Sixteen resistance and kettlebell swing experienced males performed 10 rounds of a kettlebell swing routine (where one round equates to 30s of swings followed by 30s of rest). Kinematic (i.e., swing duration and angular velocities) and kinetic (i.e., normalised sagittal plane ground reaction force, resultant joint moment [RJM] and power) variables were extracted for the early portion and late portion of the round. Average swing duration and the magnitude of normalised ground reaction forces (GRF) increased within rounds, while hip joint power decreased. Changes in swing duration were minimal, but consistent due to an increase in overall fatigue. An increase in the magnitude of GRF was observed at the end of rounds, which is a potential concern for injury. Hip joint power decreased primarily due to a slower angular velocity. This protocol may be an effective routine for those who are resistance trained with kettlebell swing experience, and who want to optimise power in their exercise program.
This study aimed to test the reliability and criterion validity of the Ergonauta encoder to assess countermovement jump (CMJ) performance, considering jump height and mean propulsive velocity metrics. Twenty-three recreationally active men participated in this study. The participants were positioned on a force plate with the Ergonauta individually connected through a belt. Two CMJs were performed, and the jump height and mean propulsive velocity metrics were analyzed. The intraclass correlation coefficient (ICC) and typical error (TE) were used as relative and absolute reliability indicators, respectively. The Pearson correlation was used to verify the relationship between the Ergonauta and force plate derived-metrics, and the Bland-Altman plot was used to verify the agreement between the metrics ( Ergonauta encoder and force plate), with the level of significance set at p < 0.05. The results show excellent relative reliability for both metrics, considering the two evaluation devices (ICC = 0.95–0.99, TE = 1.02–2.46). The jump height and mean propulsive velocity obtained by the Ergonauta encoder and the force plate were strongly correlated ( r = 0.95; r = 0.90, respectively, p < 0.01). The Bland-Altman plot showed good agreement for both metrics (jump height and mean propulsive power) and equipment (close to 0). We concluded that the Ergonauta encoder is reliable and valid for assessing CMJ performance, particularly the jump height and mean propulsive velocity metrics.
Different laboratory-based variables are individually associated with cycling performance, but scarce evidence exists on which of them, when all assessed in combination, could best explain cycling performance. The present study aimed to examine the combined association between laboratory-based endurance, strength/ power and body composition indicators with time trial performance iṅhigh-level cyclists. Ninety-four male cyclists were recruited (age: 20 ± 3.5 years, maximum oxygen uptake [VO2max]: 77.7 ± 5.4 ml · kg−1 · min−1). Participants performed a maximal incremental cycling test for the assessment of endurance indicators (peak power output [PPO], V̇ O2max, ventilatory threshold [VT] and respiratory compensation point [RCP]), and an incremental loading test to assess muscle strength and power-related outcomes (1-repetition maximum, mean maximal power) in the squat, lunge and hip-thrust exercises. Body composition was assessed by dual energy X-ray absorptiometry. On a separate visit, participants performed a simulated 8-minute time trial to assess cycling performance (determined as the mean power output attained). Strong-to-very-strong correlations were found between all endurance indicators and time trial performance (most r-values ranging between 0.68–0.92), whereas weaker correlations were found for strength/power (r-values < 0.5) or body composition (r-values < 0.7) indicators. Multivariate regression analyses revealed that VT, RCP and PPO explained together 92% of the variance in time trial performance (p < 0.001), with no significant contribution of the remaining variables. Although different endurance, strength/power and body composition individually correlate with simulated time trial performance in high-level cyclists, the former (and particularly VT, RCP and PPO) show the strongest association when all studied in combination. These findings underscore the importance of endurance capabilities (above strength/power or body composition) for maximizing time trial performance.
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.
Much is known about the physiological impairments that can cause muscle fatigue. It is known that fatigue can be caused by many different mechanisms, ranging from the accumulation of metabolites within muscle fibres to the generation of an inadequate motor command in the motor cortex, and that there is no global mechanism responsible for muscle fatigue. Rather, the mechanisms that cause fatigue are specific to the task being performed. The development of muscle fatigue is typically quantified as a decline in the maximal force or power capacity of muscle, which means that submaximal contractions can be sustained after the onset of muscle fatigue. There is even evidence that the duration of some sustained tasks is not limited by fatigue of the principal muscles. Here we review experimental approaches that focus on identifying the mechanisms that limit task failure rather than those that cause muscle fatigue. Selected comparisons of tasks, groups of individuals and interventions with the task-failure approach can provide insight into the rate-limiting adjustments that constrain muscle function during fatiguing contractions.
Drinkwater, E.J., T.W. Lawton, R.P. Lindsell, D.B. Pyne, P.H. Hunt, and M.J. McKenna. Training leading to repetition failure contributes to bench press strength gains in elite junior athletes. J. Strength Cond. Res. 19(2):382-388. 2005. The purpose of this study was to investigate the importance of training leading to repetition failure in the performance of 2 different tests: 6 repetition maximum (6RM) bench press strength and 40-kg bench throw power in elite junior athletes. Subjects were 26 elite junior male basketball players (n 12; age = 18.6 +/- 0.3 years; height = 202.0 +/- 11.6 cm; mass = 97.0 +/- 12.9 kg; mean SD) and soccer players (n = 14; age = 17.4 +/- 0.5 years; height = 179.0 +/- 7.0 cm; mass = 75.0 +/- 7.1 kg) with a history of greater than 6 months' strength training. Subjects were initially tested twice for 6RM bench press mass and 40-kg Smith machine bench throw power output (in watts) to establish retest reliability. Subjects then undertook bench press training with 3 sessions per week for 6 weeks, using equal volume programs (24 repetitions X 80-105% 6RM in 13 minutes 20 seconds). Subjects were assigned to one of two experimental groups designed either to elicit repetition failure with 4 sets of 6 repetitions every 260 seconds (RF4x6) or allow all repetitions to be completed with 8 sets of 3 repetitions every 113 seconds (NF8x3). The RF4X6 treatment elicited substantial increases in strength (7.3 +/- 2.4 kg, + 9.5%, p < 0.001) and power (40.8 +/- 24.1 W, + 10.6%, p < 0.001), while the NF8X3 group elicited 3.6 +/- 3.0 kg (+ 5.0%, p < 0.005) and 25 +/- 19.0 W increases (+ 6.8%, p < 0.001). The improvements in the RF4x6 group were greater than those in the repetition rest group for both strength (p < 0.005) and power (p < 0.05). Bench press training that leads to repetition failure induces greater strength gains than nonfailure training in the bench press exercise for elite junior team sport athletes.
Recent advances in molecular biology have elucidated some of the mechanisms that regulate skeletal muscle growth. Logically, muscle physiologists have applied these innovations to the study of resistance exercise (RE), as RE represents the most potent natural stimulus for growth in adult skeletal muscle. However, as this molecular-based line of research progresses to investigations in humans, scientists must appreciate the fundamental principles of RE to effectively design such experiments. Therefore, we present herein an updated paradigm of RE biology that integrates fundamental RE principles with the current knowledge of muscle cellular and molecular signalling. RE invokes a sequential cascade consisting of: (i) muscle activation; (ii) signalling events arising from mechanical deformation of muscle fibres, hormones, and immune/inflammatory responses; (iii) protein synthesis due to increased transcription and translation; and (iv) muscle fibre hypertrophy. In this paradigm, RE is considered an ‘upstream’ signal that de