Effects of maximal effort strength training with different loads on dynamic strength, cross-sectional area, load-power and load-velocity relationships

Is Boccia XR an enjoyable and effective rehabilitation exercise for older adults?

BACKGROUND AND OBJECTIVES

Maintaining activities of daily living (ADL) in older adults requires muscle strength and physical activity. However, exercise motivation often declines with age. Enjoyable activities can enhance motivation and effectiveness. Boccia is a recreational sport with rehabilitation potential but requires substantial space. This study evaluated the enjoyment and lower limb muscle activity of "Boccia XR," a virtual adaptation designed for limited spaces, comparing it with traditional Boccia and treadmill walking.

METHODS

Eighteen healthy older adults (mean age 73.3 ±  5.4 years) participated. Each performed Boccia XR, traditional Boccia, and treadmill walking in random order. Mood changes were assessed using the Profile of Mood States 2nd Edition (POMS2), and lower-limb muscle activity was measured via electromyography (EMG).

RESULTS

Both Boccia XR and traditional Boccia significantly improved positive mood (Vigor-Activity) and reduced negative mood (Total Mood Disturbance) as compared to treadmill walking. Muscle activity analysis revealed that Boccia XR and traditional Boccia imposed muscle loads comparable to treadmill walking. Rectus femoris activity exceeded that of treadmill walking, and medial gastrocnemius activation was sufficient for strengthening in sedentary older adults during Boccia tasks.

CONCLUSION

Boccia XR is an enjoyable and effective physical activity for older adults, requiring less space, than traditional Boccia while providing physical benefits similar to treadmill walking. It may enhance exercise adherence and overall function in space-limited settings.

Neuromuscular Adaptations to Same Versus Separate Muscle-Group Concurrent Aerobic and Strength Training in Recreationally Active Males and Females

Combining aerobic and strength training may attenuate neuromuscular adaptations, particularly when both target the same muscle group. This study assessed whether separating the training modalities by muscle groups mitigates this interference. Ninety-six participants (56 males and 40 females) completed a 12-week intervention, divided into three groups: (1) LHLS (lower-body high-intensity interval (HIIT) and strength training), (2) LHUS (lower-body HIIT and upper-body strength training), and (3) LSUS (lower- and upper-body strength training). Maximal (1RM) and explosive strength were assessed using load-velocity profiling, with mean propulsive velocity (MPV) at 30%, 50%, 70%, and 90% of 1RM as a measure of explosive strength. Muscle cross-sectional area (CSA) of the M. vastus lateralis and M. pectoralis major was measured using panoramic ultrasound. Lower-body adaptations were compared between LHLS and LSUS, and upper-body adaptations were compared between LHUS and LSUS. MPV at 70% and 90% of 1RM for the squat (LHLS and LSUS) and bench press (LHUS and LSUS) showed improvements (p < 0.050), with no significant between-group differences. Squat 1RM improved in both LHLS and LSUS, and bench press 1RM increased in both LHUS and LSUS (all p < 0.001). M. vastus lateralis CSA increased in LHLS (p = 0.029) but not in LSUS, whereas M. pectoralis major CSA increased in both LHUS and LSUS (p < 0.001), with no between-group differences. No sex-based differences were observed. Concurrent aerobic and strength training does not impair explosive strength, maximal strength, or muscle hypertrophy, regardless of whether the same or separate muscle groups are targeted.

A narrative review of velocity-based training best practice: the importance of contraction intent versus movement speed

Explosive movements requiring high force and power outputs are integral to many sports, posing distinct challenges for the neuromuscular system. Traditional resistance training can improve muscle strength, power, endurance, and range of motion; however, evidence regarding its effects on athletic performance, such as sprint speed, agility, and jump height, remains conflicting. The specificity of resistance training movements, including velocity, contraction type, and joint angles affects performance outcomes, demonstrates advantages when matching training modalities with targeted sports activities. However, independent of movement speed, the intent to contract explosively (ballistic) has also demonstrated high velocity-specific training adaptations. The purpose of this narrative review was to assess the impact of explosive or ballistic contraction intent on velocity-specific training adaptations. Such movement intent may predominantly elicit motor efferent neural adaptations, including motor unit recruitment and rate coding enhancements. Plyometrics, which utilize rapid stretch-shortening cycle movements, may augment high-speed movement efficiency and muscle activation, possibly leading to improved motor control through adaptations like faster eccentric force absorption, reduced amortization periods, and quicker transitions to explosive concentric contractions. An optimal training paradigm for power and performance enhancement might involve a combination of maximal explosive intent training with heavier loads and plyometric exercises with lighter loads at high velocities. This narrative review synthesizes key literature to answer whether contraction intent or movement speed is more critical for athletic performance enhancement, ultimately advocating for an integrative approach to resistance training tailored for sports-specific explosive action.

FHOD-1 and profilin protect sarcomeres against contraction-induced deformation> in C. elegans

Formin HOmology Domain 2-containing (FHOD) proteins are a subfamily of actin-organizing formins important for striated muscle development in many animals. We showed previously that absence of the sole FHOD protein, FHOD-1, from Caenorhabditis elegans results in thin body wall muscles with misshapen dense bodies that serve as sarcomere Z-lines. We demonstrate here that mutations predicted to specifically disrupt actin polymerization by FHOD-1 similarly disrupt muscle development, and that FHOD-1 cooperates with profilin PFN-3 for dense body morphogenesis, and with profilins PFN-2 and PFN-3 to promote body wall muscle growth. We further demonstrate that dense bodies in worms lacking FHOD-1 or PFN-2/PFN-3 are less stable than in wild-type animals, having a higher proportion of dynamic protein, and becoming distorted by prolonged muscle contraction. We also observe accumulation of actin and actin depolymerization factor/cofilin homologue UNC-60B in body wall muscle of these mutants. Such accumulations may indicate targeted disassembly of thin filaments dislodged from unstable dense bodies, possibly accounting for the abnormally slow growth and reduced body wall muscle strength in fhod-1 mutants. Overall, these results implicate FHOD protein-mediated actin assembly in forming stable sarcomere Z-lines, and identify profilin as a new contributor to FHOD activity in striated muscle development.

Resistance training leading to repetition failure increases muscle strength and size, but not power-generation capacity in judo athletes

Strength-trained athletes has less trainability in muscle size and function, because of their adaptation to long-term advanced training. This study examined whether resistance training (RT) leading to repetition failure can be effective modality to overcome this subject. Twenty-three male judo athletes completed a 6-week unilateral dumbbell curl training with two sessions per week, being added to in-season training of judo. The participants were assigned to one of three different training programs: ballistic light-load (30% of one repetition maximum (1RM)) RT to repetition failure (RFLB) (n = 6), traditional heavy-load (80% of 1RM) RT to repetition failure (RFHT) (n = 7), and ballistic light-load (30% of 1RM) RT to non-repetition failure (NRFLB) (n = 10). Before and after the intervention period, the muscle thickness (MT) and the maximal voluntary isometric force (MVC) and rate of force development (RFDmax) of elbow flexors were determined. In addition, theoretical maximum force (F0), velocity (V0), power (Pmax), and slope were calculated from force-velocity relation during explosive elbow flexion against six different loads. For statistical analysis, p < 0.05 was considered significant. The MT and MVC had significant effect of time with greater magnitude of the gains in RFHT and NRFLB compared to RFLB. On the other hand, all parameters derived from force-velocity relation and RFDmax did not show significant effects of time. The present study indicates that ballistic light-load and traditional heavy-load resistance training programs, leading to non-repetition failure and repetition failure, respectively, can be modalities for improving muscle size and isometric strength in judo athletes, but these do not improve power generation capacity.

Light load jump squat and plyometric training enhance jumping, sprinting, change of direction, and balance performance of male soccer players (U-19): a randomized controlled trial

BACKGROUND

In sports science, optimizing athletic performance is pursued through an emerging approach that combined light-loaded squat (LLS) training and plyometric jump training (PJT), targeting strength, power, and neuromuscular adaptations, particularly beneficial for the dynamic demands of youth soccer. The aim of this study was to examine the effect of a combined LLS training and PJT program on athletic performance and balance in youth soccer players.

METHODS

Thirty-two male players were randomly assigned to two groups: an experimental group (EG: N.=16; age: 18.56±0.51 years; body mass: 66.87±4.99 kg; height: 1.78±0.07 m) and a control group (CG: N.=16; age: 18.68±0.47 years; body mass: 67.93±4.58 kg; height: 1.77±0.07 m) from the same U19 team of a professional club voluntarily participated in the study. Squat jump (SJ), countermovement jump (CMJ), horizontal jump (HJ), drop jump (DJ), 30 m sprint (30 mS), change of direction ability (4×5 m sprint test [S 4×5 m]) and static balance (the stork balance) performance tests were carried out in the week before and the week after the 8 weeks with combined LLS and PJT period. The two-way analysis of variance (ANOVA) was used for all tests.

RESULTS

The results of this study show that the EG had significantly greater improvements than the CG in all tests (all P<0.001). Also, EG experienced higher performance between preintervention and post intervention measures (all P<0.05). There was no significant difference between the two groups in the 4×5mS performance (P>0.05).

CONCLUSIONS

We conclude that coaches may be advised to use the combined LLS and PJT since it is as effective as traditional methods and perfect for sports and activities requiring fast, explosive movements during the in-season period than regular training.

FHOD-1/profilin-mediated actin assembly protects sarcomeres against contraction-induced deformation in C. elegans

Formin HOmology Domain 2-containing (FHOD) proteins are a subfamily of actin-organizing formins important for striated muscle development in many animals. We showed previously that absence of the sole FHOD protein, FHOD-1, from C. elegans results in thin body-wall muscles with misshapen dense bodies that serve as sarcomere Z-lines. We demonstrate here that actin polymerization by FHOD-1 is required for its function in muscle development, and that FHOD-1 cooperates with profilin PFN-3 for dense body morphogenesis, and profilins PFN-2 and PFN-3 to promote body-wall muscle growth. We further demonstrate dense bodies in fhod-1 and pfn-3 mutants are less stable than in wild type animals, having a higher proportion of dynamic protein, and becoming distorted by prolonged muscle contraction. We also observe accumulation of actin depolymerization factor/cofilin homolog UNC-60B in body-wall muscle of these mutants. Such accumulations may indicate targeted disassembly of thin filaments dislodged from unstable dense bodies, and may account for the abnormally slow growth and reduced strength of body-wall muscle in fhod-1 mutants. Overall, these results show the importance of FHOD protein-mediated actin assembly to forming stable sarcomere Z-lines, and identify profilin as a new contributor to FHOD activity in striated muscle development.

Preoperative respiratory muscle training reduces the risk of pulmonary complications and the length of hospital stay after cardiac surgery: a systematic review

QUESTIONS

What is the effect of preoperative respiratory muscle training (RMT) on the incidence of postoperative pulmonary complications (PPCs) after open cardiac surgery? What is the effect of RMT on the duration of mechanical ventilation, postoperative length of stay and respiratory muscle strength?

DESIGN

Systematic review of randomised trials with meta-analysis.

PARTICIPANTS

Adults undergoing elective open cardiac surgery.

INTERVENTION

The experimental groups received preoperative RMT and the comparison groups received no intervention.

OUTCOME MEASURES

The primary outcomes were PPCs, length of hospital stay, respiratory muscle strength, oxygenation and duration of mechanical ventilation. The methodological quality of studies was assessed using the PEDro scale and the overall certainty of the evidence was assessed using the GRADE approach.

RESULTS

Eight trials involving 696 participants were included. Compared with the control group, the respiratory training group had fewer PPCs (RR 0.51, 95% CI 0.38 to 0.70), less pneumonia (RR 0.44, 95% CI 0.25 to 0.78), shorter hospital stay (MD -1.7 days, 95% CI -2.4 to -1.1) and higher maximal inspiratory pressure values at the end of the training protocol (MD 12 cmH2O, 95% CI 8 to 16). The mechanical ventilation time was similar in both groups. The quality of evidence was high for pneumonia, length of hospital stay and maximal inspiratory pressure.

CONCLUSION

Preoperative RMT reduced the risk of PPCs and pneumonia after cardiac surgery. The training also improved the maximal inspiratory pressure and reduced hospital stay. The effects on PPCs were large enough to warrant use of RMT in this population.

REGISTRATION

CRD42021227779.

Exercise prescription and strategies to promote the cross-education of strength: a scoping review

The cross-education of strength is moderated by exercise design and prescription in clinical and non-clinical populations. This review synthesizes the available evidence regarding exercise design strategies for unilateral resistance training and provides evidence-based recommendations for the prescription of unilateral training to maximize the cross-education of strength. Greater insights regarding the timing and effectiveness of cross-education interventions in clinical scenarios will strengthen the use of unilateral resistance training for individuals who may benefit from its use.

Influence of muscle strength, power, and rapid force capacity on maximal club head speed in male national level golfers

This study investigated the relationships between maximal club head speed (CHS) and physiological and anthropometric parameters in 21 national-level male golfers (age: 21.9 ± 3.9 years; handicap: +1.1 ± 1.7). Maximal isometric strength (MVC) was measured during isometric mid-thigh pull and bench press, while MVC and rate of force development (RFD) were measured during isometric leg press. Power, lower limb stiffness, positive impulse, jump height and RFDdyn were measured during countermovement jump (CMJ). Moreover, rotational trunk power, active range of motion (AROM) and anthropometrics were determined. Comparisons were made between participants with high (FTG) and low (STG) CHS, respectively. FTG demonstrated greater isometric mid-thigh pull and isometric bench press MVC, leg press RFD, rotational trunk power, and CMJ parameters (except RFDdyn) as well as reduced hip AROM compared to STG (P < 0.01). CHS was positively correlated to isometric mid-thigh pull and isometric bench press MVC, leg press RFD, rotational trunk power and CMJ parameters (P < 0.01). In conclusion, strong positive correlations were observed between maximal CHS and maximal strength and power parameters. Consequently, improving maximal neuromuscular strength and power may be considered of importance for golfers, as greater CHS and accompanying driving distance may lead to competitive advantages.

National Strength and Conditioning Association Position Statement on Weightlifting for Sports Performance

ABSTRACT

Comfort, P, Haff, GG, Suchomel, TJ, Soriano, MA, Pierce, KC, Hornsby, WG, Haff, EE, Sommerfield, LM, Chavda, S, Morris, SJ, Fry, AC, and Stone, MH. National Strength and Conditioning Association position statement on weightlifting for sports performance. J Strength Cond Res XX(X): 000-000, 2022-The origins of weightlifting and feats of strength span back to ancient Egypt, China, and Greece, with the introduction of weightlifting into the Olympic Games in 1896. However, it was not until the 1950s that training based on weightlifting was adopted by strength coaches working with team sports and athletics, with weightlifting research in peer-reviewed journals becoming prominent since the 1970s. Over the past few decades, researchers have focused on the use of weightlifting-based training to enhance performance in nonweightlifters because of the biomechanical similarities (e.g., rapid forceful extension of the hips, knees, and ankles) associated with the second pull phase of the clean and snatch, the drive/thrust phase of the jerk and athletic tasks such as jumping and sprinting. The highest force, rate of force development, and power outputs have been reported during such movements, highlighting the potential for such tasks to enhance these key physical qualities in athletes. In addition, the ability to manipulate barbell load across the extensive range of weightlifting exercises and their derivatives permits the strength and conditioning coach the opportunity to emphasize the development of strength-speed and speed-strength, as required for the individual athlete. As such, the results of numerous longitudinal studies and subsequent meta-analyses demonstrate the inclusion of weightlifting exercises into strength and conditioning programs results in greater improvements in force-production characteristics and performance in athletic tasks than general resistance training or plyometric training alone. However, it is essential that such exercises are appropriately programmed adopting a sequential approach across training blocks (including exercise variation, loads, and volumes) to ensure the desired adaptations, whereas strength and conditioning coaches emphasize appropriate technique and skill development of athletes performing such exercises.

Impaired regenerative capacity contributes to skeletal muscle dysfunction in chronic obstructive pulmonary disease

Locomotor skeletal muscle dysfunction is a relevant comorbidity of chronic obstructive pulmonary disease (COPD) and is strongly associated with worse clinical outcomes including higher mortality. Over the last decades, a large body of literature helped characterize the process, defining the disruptive muscle phenotype caused by COPD that involves reduction in muscle mass, force-generation capacity, fatigue-tolerance, and regenerative potential following injury. A major limitation in the field has been the scarcity of well-calibrated animal models to conduct mechanistic research based on loss- and gain-of-function studies. This article provides an overall description of the process, the tools available to mechanistically investigate it, and the potential role of mitochondrially driven metabolic signals on the regulation muscle regeneration after injury in COPD. Finally, a description of future avenues to further expand on the area is proposed based on very recent evidence involving mitochondrial metabolic cues affecting myogenesis.

Relationship between Dynamic and Isometric Strength, Power, Speed, and Average Propulsive Speed of Recreational Athletes

The purpose of this study was to examine the type of relationship between measures of maximal force (dynamic and isometric), maximal power, and mean propulsive velocity. In total, 355 recreational athletes, 96 women (age 20.5 ± 2.5 years; height 158.2 ± 17.3 cm; weight 61.8 ± 48.4 kg) and 259 men (age 21.0 ± 2.6 years; height 170.5 ± 12.6 cm; weight 65.9 ± 9.2 kg) were evaluated in three sessions separated by 72 h each in isometric midthigh pull exercise (ISOS) (kg), bench press maximum strength (1RM MSBP) (kg), jump height (CMJ) (m), and maximum pedaling power (WT) the maximum squat strength (1RM MSS) (kg), the mean propulsive velocity in the bench press (MPVBP) (m·s^-1), and the peak power (PPBP) (w), mean propulsive squat velocity (MPVS) (m·s^-1), peak power (PP) (w), maximum handgrip force (ISOHG) (kg), and 30 m movement speed (V30) (s). Significant correlations (p ≤ 0.01) were identified between 95% of the various manifestations of force, and only 5% presented a significance of p ≤ 0.05; however, when the magnitude of these correlations is observed, there is great heterogeneity. In this sense, the dynamic strength tests present the best correlations with the other strength and power tests used in the present study, followed by PPBP and PP. The results of this study complement what is reported in the literature regarding the correlation between different types of force manifestations being heterogeneous and contradictory.

The effect of high and low velocity-based training on the throwing performance of collegiate handball players

Background

The intensity of strength training exercise is generally regarded to be the most essential element in developing muscle strength and power. The exercise intensity of strength training is known as one-repetition maximum (1RM). Velocity-based training (VBT) has been proposed as a different approach for determining training intensity. VBT relies on the use of linear position transducers and inertial measurement units, providing real-time feedback to objectively adjust the exercise intensity based on an athlete's velocity zone.

Methods

This study investigated the effects of two different training interventions based on individualized load velocity profiles (LVP) on maximal bench press strength (i.e., 1RM), maximum throwing velocity (TV), and skeletal muscle mass (SKMM). Twenty-two university handball players were randomly assigned to Group 1 (low-movement speed training) or Group 2 (high-movement speed training). Group 1 exercised with a bar speed of 0.75-0.96 m/s, which corresponds to a resistance of approximately 60% 1RM, whereas Group 2 trained at 1.03-1.20 m/s, corresponding to a resistance of approximately 40% 1RM. Both groups exercised three times a week for five weeks, with strength and throwing tests performed at baseline and post-intervention.

Results

A two-way repeated measures ANOVA was applied, and the results showed the interaction between group and time was not statistically significant for SKMM (p = 0.537), 1RM (p = 0.883), or TV (p = 0.774). However, both groups significantly improved after the five weeks of training: SKMM (3.1% and 3.5%, p < 0.01), 1RM (15.5% and 15.0%, p < 0.01), and throwing velocity (18.7% and 18.3%, p < 0.01) in Group 1 and 2 respectively. Training at both prescribed velocities in this study elicited similar changes in strength, muscle mass, and throwing velocity.

Toward a New Paradigm in Resistance Training by Means of Velocity Monitoring: A Critical and Challenging Narrative

For more than a century, many concepts and several theories and principles pertaining to the goals, organization, methodology and evaluation of the effects of resistance training (RT) have been developed and discussed between coaches and scientists. This cumulative body of knowledge and practices has contributed substantially to the evolution of RT methodology. However, a detailed and rigorous examination of the existing literature reveals many inconsistencies that, unless resolved, could seriously hinder further progress in our field. The purpose of this review is to constructively expose, analyze and discuss a set of anomalies present in the current RT methodology, including: (a) the often inappropriate and misleading terminology used, (b) the need to clarify the aims of RT, (c) the very concept of maximal strength, (d) the control and monitoring of the resistance exercise dose, (e) the existing programming models and (f) the evaluation of training effects. A thorough and unbiased examination of these deficiencies could well lead to the adoption of a revised paradigm for RT. This new paradigm must guarantee a precise knowledge of the loads being applied, the effort they involve and their effects. To the best of our knowledge, currently this can only be achieved by monitoring repetition velocity during training. The main contribution of a velocity-based RT approach is that it provides the necessary information to know the actual training loads that induce a specific effect in each athlete. The correct adoption of this revised paradigm will provide coaches and strength and conditioning professionals with accurate and objective information concerning the applied load (relative load, level of effort and training effect). This knowledge is essential to make rational and informed decisions and to improve the training methodology itself.

Effectiveness of individualized training based on force-velocity profiling on physical function in older men

The study aimed to investigate the effectiveness of an individualized power training program based on force–velocity (FV) profiling on physical function, muscle morphology, and neuromuscular adaptations in older men. Forty‐nine healthy men (68 ± 5 years) completed a 10‐week training period to enhance muscular power. They were randomized to either a generic power training group (GPT) or an individualized power training group (IPT). Unlike generic training, individualized training was based on low‐ or high‐resistance exercises, from an initial force–velocity profile. Lower‐limb FV profile was measured in a pneumatic leg‐press, and physical function was assessed as timed up‐and‐go time (TUG), sit‐to‐stand power, grip strength, and stair‐climbing time (loaded [20kg] and unloaded). Vastus lateralis morphology was measured with ultrasonography. Rate of force development (RFD) and rate of myoelectric activity (RMA) were measured during an isometric knee extension. The GPT group improved loaded stair‐climbing time (6.3 ± 3.8 vs. 2.3% ± 7.3%, p = 0.04) more than IPT. Both groups improved stair‐climbing time, sit to stand, and leg press power, grip strength, muscle thickness, pennation angle, fascicle length, and RMA from baseline (p < 0.05). Only GPT increased loaded stair‐climbing time and RFD (p < 0.05). An individualized power training program based on FV profiling did not improve physical function to a greater degree than generic power training. A generic power training approach combining both heavy and low loads might be advantageous through eliciting both force‐ and velocity‐related neuromuscular adaptions with a concomitant increase in muscular power and physical function in older men.

Strength Training in Swimming

This narrative review deals with the topic of strength training in swimming, which has been a controversial issue for decades. It is not only about the importance for the performance at start, turn and swim speed, but also about the question of how to design a strength training program. Different approaches are discussed in the literature, with two aspects in the foreground. On the one hand is the discussion about the optimal intensity in strength training and, on the other hand, is the question of how specific strength training should be designed. In addition to a summary of the current state of research regarding the importance of strength training for swimming, the article shows which physiological adaptations should be achieved in order to be able to increase performance in the long term. Furthermore, an attempt is made to explain why some training contents seem to be rather unsuitable when it comes to increasing strength as a basis for higher performance in the start, turn and clean swimming. Practical training consequences are then derived from this. Regardless of the athlete's performance development, preventive aspects should also be considered in the discussion. The article provides a critical overview of the abovementioned key issues. The most important points when designing a strength training program for swimming are a sufficiently high-load intensity to increase maximum strength, which in turn is the basis for power, year-round strength training, parallel to swim training and working on the transfer of acquired strength skills in swim training, and not through supposedly specific strength training exercises on land or in the water.

Movement velocity as a determinant of actual intensity in resistance exercise

This study aimed to analyze the acute mechanical, metabolic and EMG response to five resistance exercise protocols (REP) in the full squat (SQ) exercise performed with 2 velocity conditions: maximal intended velocity (MaxV) vs. half-maximal velocity (HalfV). Eleven resistance-trained men performed 10 REP (5 with each velocity conditions) in random order (72-96 h apart). The REP consisted of 3 sets of 8-3 repetitions against 45-65% 1RM. The percent change in countermovement jump (CMJ) height, velocity attained with the load that elicited a ~1.00 m·s-1 (V1-load), surface EMG variables and blood lactate concentration were assessed pre- vs. post-exercise protocols. MaxV resulted in greater percent changes (Δ: 12-25%) and intra-condition effect sizes (ES: 0.76-4.84) in loss of V1-load and CMJ height compared to HalfV (Δ: 10-16%; ES: 0.65-3.90) following all REP. In addition, MaxV showed higher post-exercise lactate concentration than HalfV (ES: 0.46-0.83; p<0.05). For EMG variables, only the Dimitrov index resulted in relevant changes after each REP, with MaxV showing greater magnitude of changes (23-38%) than HalfV (12-25%) across all REP. These results suggest that voluntary movement velocity is a key aspect to consider since it clearly determines the overall training intensity during resistance exercise.

The Effects of Resistance Training on Architecture and Volume of the Upper Extremity Muscles: A Systematic Review of Randomised Controlled Trials and Meta-Analyses

To systematically review the effects of exercise on fascicle geometry and muscle size parameters of the upper extremity muscles, the CENTRAL, CINAHL, PubMed and OpenGrey databases were searched on 31 July 2021. Finally, 17 randomised controlled trials (RCTs) were included in this systematic review. High-intensity bench press training (g = 1.03) and 12 RM bench press exercises (g = 1.21) showed a large effect size on increasing pectoralis major muscle size. In the elbow extensors, large effects were reported for an increase in muscle size with isometric maximal voluntary co-contraction training (g = 1.97), lying triceps extension exercise (g = 1.25), and nonlinear periodised resistance training (g = 2.07). In addition, further large effects were achieved in the elbow flexors via traditional elbow flexion exercises (g = 0.93), concentric low-load forearm flexion-extension training (g = 0.94, g = 1), isometric maximal voluntary co-contraction training (g = 1.01), concentric low-load forearm flexion-extension training with blood flow restriction (g = 1.02, g = 1.07), and nonlinear periodised resistance training (g = 1.13, g = 1.34). Regarding the forearm muscles, isometric ulnar deviation training showed a large effect (g = 2.22) on increasing the flexor carpi ulnaris and radialis muscle size. Results show that these training modalities are suitable for gaining hypertrophy in the relevant muscles with at least four weeks of training duration. Future RCTs should investigate the effects of exercise modalities on the triceps brachii fascicle geometry, the infraspinatus muscle thickness (MT) and the subscapular MT due to their associations with sports performance.

Isolated Joint Block Progression Training Improves Leaping Performance in Dancers

The purpose of this study was to investigate the effect of a 12-week ankle-specific block progression training program on saut de chat leaping performance [leap height, peak power (PP), joint kinetics and kinematics], maximal voluntary isometric plantar flexion (MVIP) strength, and Achilles tendon (AT) stiffness. Dancers (training group n = 7, control group n = 7) performed MVIP at plantarflexed (10◦) and neutral ankle positions (0◦) followed by ramping isometric contractions equipped with ultrasound to assess strength and AT stiffness, respectively. Dancers also performed saut de chat leaps surrounded by 3-D motion capture atop force platforms to determine center of mass and joint kinematics and kinetics. The training group then followed a 12-week ankle-focused program including isometric, dynamic constant external resistance, accentuated eccentric loading, and plyometric training modalities, while the control group continued dancing normally. We found that the training group's saut de chat ankle PP (59.8%), braking ankle stiffness (69.6%), center of mass PP (11.4%), and leap height (12.1%) significantly increased following training. We further found that the training group's MVIP significantly increased at 10◦ (17.0%) and 0◦ (12.2%) along with AT stiffness (29.6%), while aesthetic leaping measures were unchanged (peak split angle, mean trunk angle, trunk angle range). Ankle-specific block progression training appears to benefit saut de chat leaping performance, PP output, ankle-joint kinetics, maximal strength, and AT stiffness, while not affecting kinematic aesthetic measures. We speculate that the combined training blocks elicited physiological changes and enhanced neuromuscular synchronization for increased saut de chat leaping performance in this cohort of dancers.

Impact of Reverse Triggering Dyssynchrony During Lung-Protective Ventilation on Diaphragm Function: An Experimental Model

RATIONALE

Reverse triggering is a patient-ventilator interaction where a respiratory muscle contraction is triggered by a passive mechanical insufflation. Its impact on diaphragm structure and function is unknown.

OBJECTIVE

To establish an animal model of reverse triggering with lung injury receiving lung-protective ventilation and to assess its impact on structure and function of the diaphragm.

METHODS

Lung injury was induced by surfactant depletion and high stress ventilation in 32 ventilated pigs. Animals were allocated to receive passive mechanical ventilation or a lung-protective strategy with adjustments facilitating the occurrence of reverse triggering for 3 hours. Diaphragm function (transdiaphragmatic pressure (Pdi) during phrenic nerve stimulation [Force/frequency curve]) and structure (biopsies) were assessed. The impact of reverse triggering on diaphragm function was analyzed according to the breathing effort.

RESULTS

Compared to passive ventilation, the protective ventilation group with reverse triggering received significantly lower tidal volume (7 vs 10 ml/kg) and higher respiratory rate (45 vs 31 bpm). An entrainment pattern of 1:1 was frequent. Breathing effort induced by reverse triggering was highly variable across animals. Reverse triggering with the lowest tercile of breathing effort was associated with 23% higher twitch Pdi compared to passive ventilation, whereas reverse triggering with high breathing effort was associated with a 10% lower twitch Pdi and a higher proportion of abnormal muscle fibers.

CONCLUSION

In a reproducible animal model of reverse triggering with variable levels of breathing effort and entrainment patterns, reverse triggering with high effort is associated with impaired diaphragm function whereas reverse triggering with low effort is associated with preserved diaphragm force.

Should we individualize training based on force-velocity profiling to improve physical performance in athletes?

The present study aimed to examine the effectiveness of an individualized training program based on force-velocity (FV) profiling on jumping, sprinting, strength, and power in athletes. Forty national level team sport athletes (20 ± 4years, 83 ± 13 kg) from ice-hockey, handball, and soccer completed a 10-week training intervention. A theoretical optimal squat jump (SJ)-FV-profile was calculated from SJ with five different loads (0, 20, 40, 60, and 80 kg). Based on their initial FV-profile, athletes were randomized to train toward, away, or irrespective (balanced training) of their initial theoretical optimal FV-profile. The training content was matched between groups in terms of set x repetitions but varied in relative loading to target the different aspects of the FV-profile. The athletes performed 10 and 30 m sprints, SJ and countermovement jump (CMJ), 1 repetition maximum (1RM) squat, and a leg-press power test before and after the intervention. There were no significant group differences for any of the performance measures. Trivial to small changes in 1RM squat (2.9%, 4.6%, and 6.5%), 10 m sprint time (1.0%, -0.9%, and -1.7%), 30 m sprint time (0.9%, -0.6%, and -0.4%), CMJ height (4.3%, 3.1%, and 5.7%), SJ height (4.8%, 3.7%, and 5.7%), and leg-press power (6.7%, 4.2%, and 2.9%) were observed in the groups training toward, away, or irrespective of their initial theoretical optimal FV-profile, respectively. Changes toward the optimal SJ-FV-profile were negatively correlated with changes in SJ height (r = -0.49, p < 0.001). Changes in SJ-power were positively related to changes in SJ-height (r = 0.88, p < 0.001) and CMJ-height (r = 0.32, p = 0.044), but unrelated to changes in 10 m (r = -0.02, p = 0.921) and 30 m sprint time (r = -0.01, p = 0.974). The results from this study do not support the efficacy of individualized training based on SJ-FV profiling.

Influence of resistance training load on measures of skeletal muscle hypertrophy and improvements in maximal strength and neuromuscular task performance: A systematic review and meta-analysis

This systematic review and meta-analysis determined resistance training (RT) load effects on various muscle hypertrophy, strength, and neuromuscular performance task [e.g., countermovement jump (CMJ)] outcomes. Relevent studies comparing higher-load [>60% 1-repetition maximum (RM) or <15-RM] and lower-load (≤60% 1-RM or ≥ 15-RM) RT were identified, with 45 studies (from 4713 total) included in the meta-analysis. Higher- and lower-load RT induced similar muscle hypertrophy at the whole-body (lean/fat-free mass; [ES (95% CI) = 0.05 (-0.20 to 0.29), P = 0.70]), whole-muscle [ES = 0.06 (-0.11 to 0.24), P = 0.47], and muscle fibre [ES = 0.29 (-0.09 to 0.66), P = 0.13] levels. Higher-load RT further improved 1-RM [ES = 0.34 (0.15 to 0.52), P = 0.0003] and isometric [ES = 0.41 (0.07 to 0.76), P = 0.02] strength. The superiority of higher-load RT on 1-RM strength was greater in younger [ES = 0.34 (0.12 to 0.55), P = 0.002] versus older [ES = 0.20 (-0.00 to 0.41), P = 0.05] participants. Higher- and lower-load RT therefore induce similar muscle hypertrophy (at multiple physiological levels), while higher-load RT elicits superior 1-RM and isometric strength. The influence of RT loads on neuromuscular task performance is however unclear.

The Effectiveness of Two Methods of Prescribing Load on Maximal Strength Development: A Systematic Review

Background

Optimal prescription of resistance exercise load (kg) is essential for the development of maximal strength. Two methods are commonly used in practice with no clear consensus on the most effective approach for the improvement of maximal strength.

Objective

The primary aim of this review was to compare the effectiveness of percentage 1RM (% 1RM) and repetition maximum targets (RM) as load prescription methods for the development of maximal strength.

Methods

Electronic database searches of MEDLINE, SPORTDiscus, Scopus, and CINAHL Complete were conducted in accordance with PRISMA guidelines. Studies were eligible for inclusion if a direct measure of maximal strength was used, a non-training control group was a comparator, the training intervention was > 4 weeks in duration and was replicable, and participants were defined as healthy and between the ages of 18–40. Methodological quality of the studies was evaluated using a modified Downs and Black checklist. Percentage change (%) and 95% confidence intervals (CI) for all strength-based training groups were calculated. Statistical significance (p < 0.05) was reported from each study.

Results

Twenty-two studies comprising a total of 761 participants (585 males and 176 females) were found to meet the inclusion criteria. 12 studies were returned for % 1RM, with 10 for RM. All studies showed statistically significant improvements in maximal strength in the training groups (31.3 ± 21.9%; 95% CI 33.1–29.5%). The mean quality rating for all studies was 17.7 ± 2.3. Four studies achieved a good methodological rating, with the remainder classified as moderate.

Conclusions

Both % 1RM and RM are effective tools for improving maximal strength. % 1RM appears to be a better prescriptive method than RM potentially due to a more sophisticated management of residual fatigue. However, large heterogeneity was present within this data. Lower body and multi-joint exercises appear to be more appropriate for developing maximal strength. Greater consensus is required in defining optimal training prescriptions, physiological adaptations, and training status.

Electronic supplementary material

The online version of this article (10.1007/s40279-019-01241-3) contains supplementary material, which is available to authorized users.

Evidence that ageing does not influence the uniformity of the muscle-tendon unit adaptation in master sprinters

Differences in the adaptation processes between muscle and tendon in response to mechanical loading can lead to non-uniform mechanical properties within the muscle-tendon unit (MTU), potentially increasing injury risk. The current study analysed the mechanical properties of the triceps surae (TS) MTU in 10 young (YS; 22 ± 3 yrs) and 10 older (OS; age 65 ± 8 yrs; i.e. master) (inter)national level sprinters and 11 young recreationally active adults (YC; 23 ± 3 yrs) to detect possible non-uniformities in muscle and tendon adaptation due to habitual mechanical loading and ageing. Triceps surae muscle strength, tendon stiffness and maximal tendon strain were assessed in both legs during maximal voluntary isometric plantarflexion contractions via dynamometry and ultrasonography. Irrespective of the leg, OS and YC in comparison to YS demonstrated significantly (P < 0.05) lower TS muscle strength and tendon stiffness, with no differences between OS and YC. Furthermore, no group differences were detected in the maximal tendon strain (average of both legs: OS 3.7 ± 0.8%, YC 4.4 ± 0.8% and YS 4.3 ± 0.9%) as well as in the inter-limb symmetry indexes in muscle strength, tendon stiffness and maximal tendon strain (range across groups: -5.8 to 4.9%; negative value reflects higher value for the non-preferred leg). Thus, the findings provide no clear evidence for a disruption in the TS MTU uniformity in master sprinters, demonstrating that ageing tendons can maintain their integrity to meet the increased functional demand due to elite sports.

Effects of resistance training intensity on sleep quality and strength recovery in trained men: a randomized cross-over study

Resistance training (RT) variables can affect sleep quality, strength recovery and performance. The aim of this study was to examine the acute effect of RT leading to failure vs. non-failure on sleep quality (SQ), heart rate variability (HRV) overnight and one-repetition maximum (1-RM) performance 24 hours after training. Fifteen resistance-trained male athletes (age: 23.4 ± 2.4 years; height 178.0 ± 7.6 cm; weight: 78.2 ± 10.6 kg) performed two training sessions in a randomized order, leading to failure (4x10) or non-failure (5x8(10) repetitions), with 90 seconds for resting between sets at 75% 1-RM in bench press (BP) and half squat (HS). The day after, the participants completed the predicted 1-RM test for both exercises. In addition, the subjective and actigraphic SQ and HRV during sleep were measured after each training session. The day after the training protocol leading to failure, the 1-RM of BP (MD = 7.24 kg; -7.2%; p < 0.001) and HS (MD = 20.20 kg; -11.1%; p < 0.001) decreased. However, this parameter did not decrease after a non-failure RT session. No differences were observed between failure and non-failure training sessions on SQ and HRV; therefore, both types of training sessions similarly affected the SQ and the autonomic modulation during the night after the training session. This study provides an insight into the influence of different training strategies on SQ, strength performance and recovery after moderate- to high-demand training. This information could be useful especially for professional coaches, weightlifters and bodybuilders, due to the potential influence on the programming processes.

Changes in Bench Press Velocity and Power After 8 Weeks of High-Load Cluster- or Traditional-Set Structures

Davies, TB, Halaki, M, Orr, R, Helms, ER, and Hackett, DA. Changes in bench press velocity and power after 8 weeks of high-load cluster- or traditional-set structures. J Strength Cond Res 34(10): 2734-2742, 2020-This study investigated the effects of high-load cluster- vs. traditional-set structures using the bench press on velocity and power. Twenty-one resistance-trained individuals (male = 12, female = 9) performed a 3-week familiarization block followed by randomization into 1 of 2 upper- and lower-body split training routines performed for 8 weeks. The bench press was the only exercise manipulated with subjects using either cluster-set (CLUS, n = 11) or traditional-set (TRAD, n = 10) structures during training sessions. Subjects performed 4 sets of 5 repetitions at 85% 1 repetition maximum (1RM) with CLUS having a 30-second inter-repetition, and 3-minute interset rest while TRAD had a 5-minute interset rest. A load-velocity profile of relative loads derived from a 1RM test was used to assess velocity and power (absolute and relative to body mass) on the bench press. Significant improvements over time were found across various loads ranging from 45 to 75% 1RM for absolute and relative peak power (p = 0.006-0.041), and mean power (p = 0.001-0.032). Significant decreases over time were found at 55% 1RM and 65% 1RM for peak velocity (p = 0.027 and p = 0.012, respectively) and mean velocity (p = 0.047 and p = 0.022, respectively). There were no significant group or group by time interactions found for all outcomes. Within the context of high-load resistance training, set structure seems to be of less importance for changes in bench press velocity and power provided there is an intention to lift with maximal concentric velocity.

Morphological and functional assessment of the flexor carpi radialis brevis using conventional ultrasound and elastography

PURPOSE

The flexor carpi radialis brevis (FCRB) is a supernumerary musculotendinous structure of the wrist that has been the focus of some interest in the last decade. While its anatomy is well known, its in vivo function remains unknown as it has never been studied.

METHODS

Eleven cases of FCRB underwent a multimodal ultrasound consisting of B-mode, color Doppler and shear wave elastography.

RESULTS

A pennate shape was observed in all cases and the mean value of the cross-sectional area was 0.8 cm² (SD 0.3 cm²). Young's modulus was significantly (p < 0.01) different between the resting position and active flexion or passive extension.

CONCLUSION

Our study demonstrates that the FCRB shows biomechanics of a typical skeletal muscle and is voluntarily controlled by flexing the wrist. Absent in other vertebrate taxa, the FCRB probably plays a role in active stability of the wrist in Human.

Load-velocity Profiles Change after Training Programs with Different Set Configurations

This study explored the changes in load-velocity relationship of bench press and parallel squat exercises following two programs differing in the set configuration. A randomized controlled trial was carried out in a sample of 39 physically active individuals. Participants were assigned to rest redistribution set configuration, traditional set configuration, or control groups. Over 5 weeks, the experimental groups completed 10 sessions with the 10 repetitions maximum load of both exercises. Rest redistribution sets consisted in 16 sets of 2 repetitions with 60 s of rest between sets, and 5 min between exercises, whereas traditional sets entailed 4 sets of 8 repetitions with 5 min of rest between sets and exercises. The load-velocity relationships of both exercises were obtained before and after the training period. For bench press, an increase of the velocity axis intercept, and a decrease of the slope at post-test were observed in both rest redistribution (p<0.001, G=1.264; p<0.001; G=0.997) and traditional set (p=0.01, G=0.654; p=0.001; G=0.593) groups. For squat, the slope decreased (p<0.001; G=0.588) and the velocity axis intercept increased (p<0.001; G=0.727) only in the rest redistribution group. These results show that rest redistribution sets were particularly efficient for inducing changes in the load-velocity relationship.

Monitoring Muscle-Tendon Adaptation Over Several Years of Athletic Training and Competition in Elite Track and Field Jumpers

Differences in muscle and tendon responsiveness to mechanical stimuli and time courses of adaptive changes may disrupt the interaction of the musculotendinous unit (MTU), increasing the risk for overuse injuries. We monitored training-induced alterations in muscle and tendon biomechanical properties in elite jumpers over 4 years of athletic training to detect potential non-synchronized adaptations within the triceps surae MTU. A combined cross-sectional and longitudinal investigation over 4 years was conducted by analyzing triceps surae MTU mechanical properties in both legs via dynamometry and ultrasonography in 67 elite track and field jumpers and 24 age-matched controls. Fluctuations in muscle and tendon adaptive changes over time were quantified by calculating individual residuals. The cosine similarity of the relative changes of muscle strength and tendon stiffness between sessions served as a measure of uniformity of adaptive changes. Our cross-sectional study was unable to detect clear non-concurrent differences in muscle strength and tendon stiffness in elite jumpers. However, when considering the longitudinal data over several years of training most of the jumpers demonstrated greater fluctuations in muscle strength and tendon stiffness and hence tendon strain compared to controls, irrespective of training period (preparation vs. competition). Moreover, two monitored athletes with chronic Achilles tendinopathy showed in their affected limb lower uniformity in MTU adaptation as well as higher fluctuations in tendon strain over time. Habitual mechanical loading can affect the MTU uniformity in elite jumpers, leading to increased mechanical demand on the tendon over an athletic season and potentially increased risk for overuse injuries.

Emphasizing Task-Specific Hypertrophy to Enhance Sequential Strength and Power Performance

While strength is indeed a skill, most discussions have primarily considered structural adaptations rather than ultrastructural augmentation to improve performance. Altering the structural component of the muscle is often the aim of hypertrophic training, yet not all hypertrophy is equal; such alterations are dependent upon how the muscle adapts to the training stimuli and overall training stress. When comparing bodybuilders to strength and power athletes such as powerlifters, weightlifters, and throwers, while muscle size may be similar, the ability to produce force and power is often inequivalent. Thus, performance differences go beyond structural changes and may be due to the muscle's ultrastructural constituents and training induced adaptations. Relative to potentiating strength and power performances, eliciting specific ultrastructural changes should be a variable of interest during hypertrophic training phases. By focusing on task-specific hypertrophy, it may be possible to achieve an optimal amount of hypertrophy while deemphasizing metabolic and aerobic components that are often associated with high-volume training. Therefore, the purpose of this article is to briefly address different types of hypertrophy and provide directions for practitioners who are aiming to achieve optimal rather than maximal hypertrophy, as it relates to altering ultrastructural muscular components, to potentiate strength and power performance.

Myosin heavy chain expression relationships to power-load and velocity-load curves

BACKGROUND

Velocity- and power-based training are popular methods of determining training session loads and volumes. One factor that may influence load-velocity and load-power properties of an individual is the myosin heavy chain (MHC) composition of the muscle. The aim of this study was to examine the relationship between MHC composition and both load-velocity and load-power properties of muscle performance.

METHODS

Forty-two men with a variety of training backgrounds took part in this study (mean±SD; age=22.4±3.5 yrs, hgt=1.78±0.07 m, BW=78.7±13.3 kg). After testing leg extension one repetition maximum (1 RM), subjects performed maximal effort leg extensions at loads from 30% to 90% 1 RM. Muscle biopsies from the vastus lateralis were analyzed via SDS-PAGE electrophoresis technique for MHC content (IIx=13.8±12.9%, IIa=49.4±10.3%, I=36.8±11.3%). Leg extension rotational velocity and power were plotted against relative loads for all subjects.

RESULTS

Significant correlations (P<0.05) were observed for MHC IIa with all performance variables (i.e. slopes, intercepts, peaks and relative loads). Relationships indicated that greater %MHC IIa was associated with greater velocity intercepts, more negative load-velocity slopes, greater maximal power, and with maximal power occurring at a lower relative intensity (% 1 RM).

CONCLUSIONS

These data indicate that muscle velocity and power characteristics appear to be partially influenced by MHC content in a manner consistent with single muscle fiber contractile properties.

Mechanical properties of muscle and tendon at high strain rate in sprinters

The aim of the present study was to compare the mechanical properties of muscles and tendons at high strain rates between sprinters and untrained men. Fifteen sprinters and 18 untrained men participated in this study. Active muscle stiffness of the medial gastrocnemius muscle was calculated according to changes in the estimated muscle force and fascicle length during fast stretching at five different angular velocities (100, 200, 300, 500, and 600 deg·s-1 ) after submaximal isometric contractions. Stiffness and hysteresis of tendon structures were measured during ramp and ballistic contractions. Active muscle stiffness at 500 deg·s-1 (p = .070) and 600 deg·s-1 (p = .041) was greater in sprinters than untrained men, whereas no differences in those at 100, 200, and 300 deg·s-1 were found between the two groups. There were no differences in stiffness or hysteresis of tendon structures measured during ramp and ballistic contractions between the two groups. These results suggest that, for sprinters, greater active muscle stiffness at a high angular velocity is caused by exercising with a high angular velocity that is typical of their training.

Movement Velocity as A Measure of Exercise Intensity in Persons with Multiple Sclerosis: A Validity Study

Objectives: This study aims to analyse the validity (agreement between two methods) of the movement propulsive velocity (MPV) as an indicator of relative load in leg press (LP) and bench press (BP) exercises in persons with multiple sclerosis (MS). Methods: 18 persons with MS (sex = 55% male; age (mean ± SD) = 44.88 ± 10.62 years; body mass = 67.19 ± 10.63 kg; height = 1.66 ± 0.07 m; Expanded Disability Status Scale (EDSS) = 3.12 ± 1.73) performed an incremental loading test in BP and LP exercises in two separate sessions. Individual determination of the one-repetition maximum (1RM) and full load-velocity profile were obtained for each participant. Results: a significant linear relationship was observed between the %1RM load and the MPV in LP (%1RM = −133.58 × MPV + 117.44; r² = 0.84; standard error of the estimate (SEE) = 9.38%1RM) and BP (%1RM = −95.66 × MPV + 115.26; r² = 0.86; SEE = 9.82%1RM). In addition, no significant differences were found between the %1RM achieved directly and the %1RM obtained by the equation calculated from the linear regression (LP, p = 0.996; BP, p = 0.749). Conclusions: these results indicate that movement velocity can estimate the relative load in bench press and leg press exercises in persons MS.

Anatomical and Neuromuscular Determinants of Strength Change in Previously Untrained Men Following Heavy Strength Training

This study examined whether changes in strength following a moderate-duration strength training program were associated with changes in specific combinations of anatomical and neuromuscular variables. 36 men (18-40 y) completed 10 weeks of lower-limb heavy resistance (6-RM) strength training. Measurements included cross-sectional area (CSA), fascicle length (l_f) and fascicle angle (θ_f) from proximal, middle and distal regions of the four quadriceps components; agonist (EMG:M), antagonist (EMG) muscle activities and percent voluntary quadriceps activation (%VA; interpolated twitch technique); patellar tendon moment arm distance; and maximal isometric, concentric and eccentric (60° s^-1) torque. Multiple regression models were developed to quantify the relationship between the change in maximum torque and the changes in combinations of anatomical and neuromuscular variables. The best model for each contraction mode was determined using Akaike's Information Criterion (AIC_c), an information-theoretic approach for model selection. Strength increased significantly following training (mean range = 12.5-17.2%), and moderate relationships were observed between modeled data (using best-fit prediction models) and the change in torque for each contraction mode. The change in isometric torque was best (although weakly) predicted by the linear combination of the change in proximal-region vastus lateralis (VL) CSA and fascicle angle (R ² = 0.27, p < 0.05; AIC_c w_i = 0.52, i.e., the probability the model would be selected as the "best model"). The models best predicting the change in concentric and eccentric torque both included the combination of the change in quadriceps (i.e., mean of all muscles) EMG:M and the change in vastus intermedius fascicle angle combined with either a change in proximal-region VL (R ² = 0.40, p < 0.001; AIC_c w_i = 0.15) or whole quadriceps (R ² = 0.41, p < 0.001; AIC_c w_i = 0.30) CSA (concentric and eccentric, respectively). Models incorporating the change in proximal CSA typically received substantial support (AIC_C < 2) for concentric torque prediction models, and the change in % VA and pre-training moment arm distance had substantial support for use in eccentric torque prediction models. In conclusion, adaptations varied between individuals, however strength training programs targeted to improve a group of variables that particularly includes agonist muscle activation might yield the greatest improvements in concentric and eccentric knee extension strength, whereas proximal muscle size and fascicle angle appear most important for isometric torque improvements.

Evidence of a Uniform Muscle-Tendon Unit Adaptation in Healthy Elite Track and Field Jumpers: A Cross Sectional Investigation

Different adaptive responses to mechanical loading between muscle and tendon can lead to non-uniform biomechanical properties within the muscle-tendon unit. The current study aimed to analyze the mechanical properties of the triceps surae muscle-tendon unit in healthy male and female elite track and field jumpers in order to detect possible inter-limb differences and intra-limb non-uniformities in muscle and tendon adaptation. The triceps surae muscle strength and tendon stiffness were analyzed in both limbs during maximal voluntary isometric plantar flexion contractions using synchronous dynamometry and ultrasonography in sixty-seven healthy young male (n = 35) and female (n = 32) elite international level track and field jumpers (high jump, long jump, triple jump, pole vault). Triceps surae muscle-tendon unit intra-limb uniformity was assessed using between limb symmetry indexes in the muscle strength and tendon stiffness. Independent from sex and jumping discipline the take-off leg showed a significantly higher (p < 0.05) triceps surae muscle strength and tendon stiffness, suggesting different habitual mechanical loading between legs. However, despite these inter-limb discrepancies no differences were detected in the symmetry indexes of muscle strength (5.9 ± 9.4%) and tendon stiffness (8.1 ± 11.5%). This was accompanied by a significant correlation between the symmetry indexes of muscle strength and tendon stiffness (r = 0.44; p < 0.01; n = 67). Thus, the current findings give evidence for a uniform muscle-tendon unit adaptation in healthy elite track and field jumpers, which can be reflected as a protective mechanism to maintain its integrity to meet the functional demand.

Effect of Strength on Velocity and Power During Back Squat Exercise in Resistance-Trained Men and Women

Askow, AT, Merrigan, JJ, Neddo, JM, Oliver, JM, Stone, JD, Jagim, AR, and Jones, MT. Effect of strength on velocity and power during back squat exercise in resistance-trained men and women. J Strength Cond Res 33(1): 1-7, 2019-The purpose was to examine load-velocity and load-power relationships of back squat in resistance-trained men (n = 20, 21.3 ± 1.4 years, 183.0 ± 8.0 cm, 82.6 ± 8.0 kg, 11.5 ± 5.0% total body fat) and women (n = 18; 20.0 ± 1.0 years; 166.5 ± 6.9 cm; 63.9 ± 7.9 kg, 20.3 ± 5.0% body fat). Body composition testing was performed followed by determination of back squat 1 repetition maximum (1RM). After at least 72 hours of recovery, subjects returned to the laboratory and completed 2 repetitions at each of 7 separate loads (30, 40, 50, 60, 70, 80, and 90% 1RM) in a random order. During each repetition, peak and average velocity and power were quantified using a commercially available linear position transducer. Men produced higher absolute peak and average power and velocity at all loads. When power output was normalized for body mass, significant differences remained. However, when normalizing for strength, no significant differences were observed between sexes. Furthermore, when subjects were subdivided into strong and weak groups, those above the median 1RM produced higher peak power, but only at loads greater than 60% 1RM. It was concluded that differences between men and women may be a result of strength rather than biological sex. Furthermore, training for maximal strength may be an appropriate method to augment maximal power output in those athletes who exhibit low levels of strength.

Protein intake in the early recovery period after exhaustive exercise improves performance the following day

The aim of the present study was to investigate the effect of protein and carbohydrate ingestion during early recovery from exhaustive exercise on performance after 18-h recovery. Eight elite cyclists (V̇o2max: 74.0 ± 1.6 ml·kg−1·min−1) completed two exercise and diet interventions in a double-blinded, randomized, crossover design. Participants cycled first at 73% of V̇o2max (W73%) followed by 1-min intervals at 90% of V̇o2max until exhaustion. During the first 2 h of recovery, participants ingested either 1.2 g carbohydrate·kg−1·h−1 (CHO) or 0.8 g carbohydrate + 0.4 g protein·kg−1·h−1 (CHO + PROT). The diet during the remaining recovery period was similar for both interventions and adjusted to body weight. After an 18-h recovery, cycling performance was assessed with a 10-s sprint test, 30 min of cycling at W73%, and a cycling time trial (TT). The TT was 8.5% faster (41:53 ± 1:51 vs. 45:26 ± 1:32 min; P < 0.03) after CHO + PROT compared with CHO. Mean power output during the sprints was 3.7% higher in CHO + PROT compared with CHO (1,063 ± 54 vs. 1,026 ± 53 W; P = 0.01). Nitrogen balance in the recovery period was negative in CHO and neutral in CHO + PROT (−82.4 ± 11.5 vs. 7.0 ± 15.4 mg/kg; P < 0.01). In conclusion, TT and sprint performances were improved 18 h after exhaustive cycling by CHO + PROT supplementation during the first 2 h of recovery compared with isoenergetic CHO supplementation. Our results indicate that intake of carbohydrate plus protein after exhaustive endurance exercise more rapidly converts the body from a catabolic to an anabolic state than carbohydrate alone, thus speeding recovery and improving subsequent cycling performance.

NEW & NOTEWORTHY Prolonged high intensity endurance exercise depends on glycogen utilization and high oxidative capacity. Still, exhaustion develops and effective recovery strategies are required to compete in multiday stage races. We show that coingestion of protein and carbohydrate during the first 2 h of recovery is superior to isoenergetic intake of carbohydrate to stimulate recovery, and improves both endurance time-trial and 10-s sprint performance the following day in elite cyclists.

Comparison of Periodized and Non-Periodized Resistance Training on Maximal Strength: A Meta-Analysis

BACKGROUND

Periodization is a logical method of organizing training into sequential phases and cyclical time periods in order to increase the potential for achieving specific performance goals while minimizing the potential for overtraining. Periodized resistance training plans are proposed to be superior to non-periodized training plans for enhancing maximal strength.

OBJECTIVE

The primary aim of this study was to examine the previous literature comparing periodized resistance training plans to non-periodized resistance training plans and determine a quantitative estimate of effect on maximal strength.

METHODS

All studies included in the meta-analysis met the following inclusion criteria: (1) peer-reviewed publication; (2) published in English; (3) comparison of a periodized resistance training group to a non-periodized resistance training group; (4) maximal strength measured by 1-repetition maximum (1RM) squat, bench press, or leg press. Data were extracted and independently coded by two authors. Random-effects models were used to aggregate a mean effect size (ES), 95% confidence intervals (CIs) and potential moderators.

RESULTS

The cumulative results of 81 effects gathered from 18 studies published between 1988 and 2015 indicated that the magnitude of improvement in 1RM following periodized resistance training was greater than non-periodized resistance training (ES = 0.43, 95% CI 0.27-0.58; P < 0.001). Periodization model (β = 0.51; P = 0.0010), training status (β = -0.59; P = 0.0305), study length (β = 0.03; P = 0.0067), and training frequency (β = 0.46; P = 0.0123) were associated with a change in 1RM. These results indicate that undulating programs were more favorable for strength gains. Improvements in 1RM were greater among untrained participants. Additionally, higher training frequency and longer study length were associated with larger improvements in 1RM.

CONCLUSION

These results suggest that periodized resistance training plans have a moderate effect on 1RM compared to non-periodized training plans. Variation in training stimuli appears to be vital for increasing maximal strength, and longer periods of higher training frequency may be preferred.

Weekly Training Frequency Effects on Strength Gain: A Meta-Analysis

Background

The current recommendations for resistance training (RT) frequency range from 2 to 5 days per week (days week^− 1) depending on the subjects’ training status. However, the relationship between RT frequency and muscular strength remains controversial with reported variances existing across different population groups. We conducted a meta-analysis that (1) quantified the effects of low (LF; 1 day week^− 1), medium (MF; 2 days week^− 1), or high (HF; ≥ 3 days week^− 1) RT frequency on muscular strength per exercise; (2) examined the effects of different RT frequency on one repetition maximum (1RM) strength gain profiles (multi-joint exercises and single joint exercises); (3) examined the effects of different RT frequency on 1RM strength gain when RT volume is equated; and (4) examined the effects of different RT frequency on 1RM strength gains on upper and lower body.

Methods

Computerised searches were performed using the terms ‘strength training frequency’, ‘resistance training frequency’, ‘training frequency’, and ‘weekly training frequency’. After review, 12 studies were deemed suitable according to pre-set eligibility criteria. Primary data were pooled using a random-effects model. Outcomes analysed for main effects were pre- to post strength change with volume-equated studies that combined multi-joint and isolation exercise; isolation-only exercise and untrained subjects only. Heterogeneity between studies was assessed using I² and Cochran’s Q statistics with funnel plots used to assess publication bias and sensitivity analyses calculated for subgroups.

Results

Pre- versus post-training strength analysis comprised of 74 treatment groups from 12 studies. For combined multi-joint and isolation exercises, there was a trend towards higher RT frequency compared with lower frequency [mean effect size (ES) 0.09 (95% CI − 0.06–0.24)] however not significant (p = 0.25). Volume-equated pre- to post-intervention strength gain was similar when LF was compared to HF [mean ES 0.03 (95% CI − 0.20–0.27); p = 0.78]. Upper body pre- to post-intervention strength gain was greater when HF was compared with LF [mean ES 0.48 (95% CI 0.20–0.76)] with significant differences between frequencies (p < 0.01). Upper body pre- to post-intervention strength gain was similar when MF was compared with LF (ES 0.12; 95% CI − 0.22–0.47); p = 0.48]. There was no significant difference in lower body mean ES between HF and LF [mean ES 0.21(95% CI − 0.55–0.13); p = 0.22]. There was a trend towards a difference in mean ES between MF and HF [mean ES 0.41(95% CI − 0.26–1.09); however, the effect was not significant (p = 0.23).

Conclusions

The existing data does not provide a strong correlation between increased weekly training frequency (HF) and maximal strength gain in upper and lower body resistance exercises for a mixed population group. When RT is volume-equated for combined multi-joint and isolation exercises, there is no significant effect of RT frequency on muscular strength gain. More investigations are required to explore the effects of varying weekly training frequencies adequately.

Effect of Lower-Body Resistance Training on Upper-Body Strength Adaptation in Trained Men

Bartolomei, S, Hoffman, JR, Stout, JR, and Merni, F. Effect of lower-body resistance training on upper-body strength adaptation in trained men. J Strength Cond Res 32(1): 13-18, 2018-The aim of this study was to examine the effect of 2 different lower-body strength training schemes on upper-body adaptations to resistance training. Twenty resistance-trained men (4.25 ± 1.6 years of experience) were randomly assigned to either a high intensity (HI; n = 9; age = 24.9 ± 2.9 years; body mass = 88.7 ± 17.2 kg; height = 177.0 ± 5.6 cm) or a mixed high volume and HI resistance training program (MP; n = 11; age = 26.0 ± 4.7 years; body mass = 82.8 ± 9.1 kg; height = 177.54 ± 5.9 cm). High-intensity group followed a HI training for both upper and lower body (4-5 reps at 88%-90% of 1 repetition maximum (1RM)), whereas the MP group performed high-volume training sessions focused on muscle hypertrophy for lower body (10-12 reps at 65%-70% of 1-RM) and a HI protocol for the upper body. Maximal strength and power testing occurred before and after the 6-week training program. Analysis of covariance was used to compare performance measures between the groups. Greater increases in MP groups compared with HI groups were observed for bench press 1RM (p = 0.007), bench press power at 50% of 1RM (p = 0.011), and for arm muscle area (p = 0.046). Significant difference between the 2 groups at posttest were also observed for fat mass (p = 0.009). Results indicated that training programs focused on lower-body muscle hypertrophy and maximal strength for upper body can stimulate greater strength and power gains in the upper body compared with HI resistance training programs for both the upper and lower body.

Influence of Maximal Strength on In-Water and Dry-Land Performance in Young Water Polo Players

Keiner, M, Rähse, H, Wirth, K, Hartmann, H, Fries, K, and Haff, GG. Influence of maximal strength on in-water and dry-land performance in young water polo players. J Strength Cond Res 34(7): 1999-2005, 2020-Water polo is a multifaceted sport that is characterized by explosive actions, including sprint swimming, jumping, throwing, and struggling against opponents. Based on these factors, maximal and speed strength may be important characteristics to develop in-water polo players. However, more research is needed to further understand the relationship between various strength characteristics and water polo performance. Therefore, the primary purpose of this study was to examine the relationships between strength, speed strength, and markers of water polo performance in youth water polo players. Sixty-one male youth water polo players (10-14 years, 11.9 ± 1.3 years) had their 1-repetition maximum (1RM) bench press and squat, dry-land speed-strength performance (squat jump [SJ], countermovement jump [CMJ], and medicine ball throw), in-water performance (sprint swim and water jump), and anthropometric measurements assessed. Fifty to 60% of the variance in sprint performance was explained by the 1RM bench press and arm span. The influence of the bench press 1RM was more than twice that of the anthropometric factors. Maximum strength in the squat and speed-strength (jump height in SJ, CMJ) variables explained 18-25% variance in the eggbeater kick (a leg strike technique to stay above and jump out of water), and the bench press 1RM explained the 42% of the variance in loaded throws without the influence of anthropometric factors. This study suggests that upper- and lower-body maximal strength parameters are important predictors of the performance capacity of water polo players.

Effects of Different Relative Loads on Power Performance During the Ballistic Push-up

Wang, R, Hoffman, JR, Sadres, E, Bartolomei, S, Muddle, TWD, Fukuda, DH, and Stout, JR. Effects of different relative loads on power performance during the ballistic push-up. J Strength Cond Res 31(12): 3411-3416, 2017-The purpose of this investigation was to examine the effect of load on force and power performance during a ballistic push-up. Sixty (24.5 ± 4.3 years, 1.75 ± 0.07 m, and 80.8 ± 13.5 kg) recreationally active men who participated in this investigation completed all testing and were included in the data analysis. All participants were required to perform a 1 repetition maximum bench press, and ballistic push-ups without external load (T1), with 10% (T2) and 20% (T3) of their body mass. Ballistic push-ups during T2 and T3 were performed using a weight loaded vest. Peak and mean force, power, as well as net impulse and flight time were determined for each ballistic push-up. Peak and mean force were both significantly greater (p < 0.01) during T3 (1,062 ± 202 and 901 ± 154 N, respectively), than both T2 (1,017 ± 202 and 842 ± 151 N, respectively) and T1 (960 ± 188 and 792 ± 140 N, respectively). Peak and mean power were significantly greater (p < 0.01) during T1 (950 ± 257 and 521 ± 148 W, respectively), than both T2 (872 ± 246 and 485 ± 143 W, respectively) and T3 (814 ± 275 and 485 ± 162 W, respectively). Peak and mean power were greatest during T1, regardless of participants' strength levels. Significant (p < 0.01) greater net impulse and smaller peak velocity and flight time were also noted from T1 to T3. Results of this investigation indicated that maximal power outputs were achieved without the use of an external load when performing the ballistic push-up, regardless of the participants' level of strength.

High-Speed Resistance Training Modifies Load-Velocity and Load-Power Relationships in Parkinson's Disease

Muscle power is a major neuromuscular factor affecting motor function and independence in patients with Parkinson's disease (PD), and it is commonly targeted using high-speed exercise. This study examined the changes in velocities (Vpp) and percent loads (%1RMpp) at peak power and load-velocity (L-V) and load-power (L-P) relationships, resulting from resistance training because of exercise choice and loading in older patients with PD. Fourteen older adults with mild to moderate PD participated in a 12-week randomized controlled power training trial. Changes in L-V and L-P relationships for the biceps curl, chest press, leg press, hip abduction, and seated calf were assessed using pneumatic resistance machines at loads ranging from 30 through 90% of subjects' 1 repetition maximum for each exercise. Significant increases in Vpp were seen for biceps curl, leg press, hip abduction, and seated calf and decreases in %1RMpp were noted for biceps curl and hip abduction. Additionally, unique patterns of change were seen in these relationships across exercises, with biceps curl, chest press, and leg press showing the greatest shifts at the lower load end of the loading spectrum, and hip abduction and seated calf showing greatest responses at the higher end. The patterns of change in L-V and L-P relationships provide evidence for the unique responses of the specific muscle groups and joints to the exercises evaluated and offer a framework for more exacting exercise prescriptions in patients with PD.

Lower body blood flow restriction training may induce remote muscle strength adaptations in an active unrestricted arm

PURPOSE

We examined the concurrent characteristics of the remote development of strength and cross-sectional area (CSA) of upper body skeletal muscle in response to lower body resistance training performed with an applied blood flow restriction (BFR).

METHODS

Males allocated to an experimental BFR group (EXP; n = 12) or a non-BFR control group (CON; n = 12) completed 7-weeks of resistance training comprising three sets of unilateral bicep curls [50% 1-repetition maximum (1-RM)], then four sets of bilateral knee extension and flexion exercises (30% 1-RM). EXP performed leg exercises with an applied BFR (60% limb occlusion pressure). 1-RM strength was measured using bilateral leg exercises and unilateral bicep curls in both trained and untrained arms. Muscle CSA was measured via peripheral quantitative computed tomography in the dominant leg and both arms.

RESULTS

1-RM in the trained arm increased more in EXP (2.5 ± 0.4 kg; mean ± SEM) than the contralateral untrained arm (0.8 ± 0.4 kg), and the trained arm of CON (0.6 ± 0.3 kg, P < 0.05). The increase in knee extension 1-RM was twofold that of CON (P < 0.01). Knee flexion 1-RM, leg CSA, and trained arm CSA increased similarly between groups (P > 0.05), while untrained arm CSA did not change (P > 0.05).

CONCLUSION

Lower limb BFR training increased trained arm strength more than the contralateral untrained arm, and the trained arm of controls. However, there was no additional effect on muscle CSA. These findings support evidence for a BFR training-derived remote strength transfer that may be relevant to populations with localised movement disorders.

Effects of Variable Resistance Using Chains on Bench Throw Performance in Trained Rugby Players

Godwin, MS, Fernandes, JFT, and Twist, C. Effects of variable resistance using chains on bench throw performance in trained rugby players. J Strength Cond Res 32(4): 950-954, 2018-This study sought to determine the effects of variable resistance using chain resistance on bench throw performance. Eight male rugby union players (19.4 ± 2.3 years, 88.8 ± 6.0 kg, 1RM 105.6 ± 17.0 kg) were recruited from a national league team. In a randomized crossover design, participant's performed 3 bench throws at 45% one repetition maximum (1RM) at a constant load (no chains) or a variable load (30% 1RM constant load and 15% 1RM variable load; chains) with 7 days between conditions. For each repetition, the peak and mean velocity, peak power, peak acceleration, and time to peak velocity were recorded. Differences in peak and mean power were very likely trivial and unclear between the chain and no chain conditions, respectively. Possibly greater peak and likely greater mean bar velocity were accompanied by likely to most likely greater bar velocity between 50 and 400 ms from initiation of bench press in the chain condition compared with the no chain condition. Accordingly, bar acceleration was very likely greater in the chain condition compared with the no chain condition. In conclusion, these results show that the inclusion of chain resistance can acutely enhance several variables in the bench press throw and gives support to this type of training.