The Adaptations to Strength Training

A pilot randomized controlled trial examining the feasibility of perioperative rehabilitation for inguinal hernia repair surgery

BACKGROUND

Despite the high frequency of inguinal hernia repair (IHR) surgery, there is little research investigating pre- or post-operative exercise and education in this population. Recommendations regarding perioperative physical activity are inconsistent and largely based on clinical opinion. We conducted a pilot randomized controlled trial to examine the feasibility of perioperative rehabilitation for inguinal hernia repair surgery in terms of recruitment rate, assessment, and protocol implementation.

METHODS

Participants were randomized into an intervention group and control group. Descriptive and patient-reported data were collected through online surveys at baseline, post-prehabilitation (prehab), 1-week post-operative (post-op), and 12-week post-op. Eligible participants completed a performance-based modified Short Form Functional Capacity Evaluation conducted by a masked observer at baseline, after 6 weeks of exercise and/or education, and at 12-week post-op. Participants in the intervention group received 6 weeks of exercise and education prior to and then after surgery. The control group received care as usual.

RESULTS

Thirty-one participants awaiting IHR with a mean age of 49 years were recruited (recruitment rate of 51.7%). Thirty participants were randomized into control (n = 16) and intervention groups (n = 14), while 1 dropped out prior to beginning the study due to being unable to take time off work for assessment. Twenty-four participants completed the final 12-week post-op follow-ups. Twenty-one participants returned to work by the 12-week post-op follow-up. Sixty-seven percent of participants in the intervention group exercised at least 3 times per week post-operatively. One participant in each group experienced exacerbations of hernia symptoms that were unrelated to study activities. Functional testing resulted in minimal symptom exacerbation in either group, but the intervention group reported less pain at 12-week post-op than controls.

CONCLUSION

A randomized trial of perioperative rehabilitation for patients undergoing inguinal hernia repair appears feasible, but protocol adjustments are needed to improve recruitment rate, assessment, and participant retention. Trial Registration: This trial is registered with ClinicalTrials.gov Identifier: NCT05069142.

Integration of resistance exercise into a multimodal approach to prehabilitation for patients with sarcopenia prior to surgery: a narrative review

Introduction

Sarcopenia describes the process of progressive, generalised loss of skeletal muscle mass and strength, and has been recognised as a predictor of postoperative complications and mortality. Prehabilitation represents a clinical strategy where patients undergo both physical and psychological strategies in order to improve their functional capacity prior to surgery. Importantly, prehabilitation programs have been considered as an area of perioperative optimisation to address sarcopenia. However, the optimal prehabilitation program regimen remains poorly characterised. Instead of suggesting a novel prehabilitation strategy for sarcopenic patients, this review seeks to characterise the best-practice modalities and methods of resistance training as a component of multimodal prehabilitation to improve patient outcomes following surgery.

Methods

A narrative review was performed following a search of Medline and Embase databases.

Results

There is significant heterogeneity in the literature regarding best-practive resistance exercise regimens for patients with sarcopenia who are awaiting surgery. Overall, the literature highlights that programs with early involvement of clinicians, dietitians, nutritionists, and psychological support programs have been shown to improve patient outcomes compared to programs that did not. Additionally, asides from muscular hypertrophy, resistance exercise programs have been shown to have a multifactorial impact on sarcopenia, synergistically improving the domains of nutrition, mental health, hormonal imbalance, and chronic inflammation. The ideal approach to resistance exercise remains poorly understood, with a paucity of evidence surrounding the best methods for delivering such regimens. Despite this, key considerations revealed by this review include the need for prehabilitation clinicians to consider key aspects of resistance training including training volume, intensity with consideration into periodisation and progressive overload. Collaboration with multidisciplinary networks such as physiotherapists, exercise physiologists and personal trainers should be considered to ensure a safe and injury-free approach to resistance exercise in prehabilitation.

Conclusion

While there remains a lack of standardisation of prehabilitation protocols, the evidence suggests that multimodal prehabilitation should be considered in evidence-based frameworks to improve patient outcomes following surgery. In particular, the ability of resistance exercises to address multiple domains relevant to sarcopenia, thereby enhancing patient outcomes beyond pure hypertrophy and playing a key role in prehabilitation.

The effects of two preseason periodizations on peak torque of knee extensors and flexors of a Polish first league soccer team

The study aimed to compare the effectiveness of two resistance training load progression methods-linear and step-on peak torque and power of knee extensors and flexors during the preseason of a Polish First League soccer team across two seasons. Differences between dominant and non-dominant limbs were analyzed, with progression tracked by tempo of movement and time under tension. Velocity-based training with a linear transducer ensured standardized intensity. Sixteen players from the same club participated in both seasons: 2021/2022 (linear) and 2022/2023 (step). Three-way ANOVA showed a significant leg × training × mesocycle interaction in the knee extensor and flexor peak torque. The post hoc test showed significant differences in peak torque between the dominant and nondominant legs during both progressive load methods - 2021/2022 and 2022/2023 seasons, both before and after the training intervention (p < 0.05). Knee extensors: The dominant leg showed higher values ​​compared to the non-dominant leg. However, there were no significant differences during the 2022/2023 season (p > 0.05). Knee flexors: No difference in peak torque values ​​between the dominant and non-dominant legs before the training intervention - 2022/2023 season. The conducted studies clearly indicate a greater effectiveness of the step load progression, however it also significantly affected bilateral asymmetry.

Impact of Overnight Fasted State Versus Fed State on Adaptations to Resistance Training: A Randomized Clinical Trial

The aim was to verify the effects of 12 weeks of resistance training (RT) performed in the fasted state compared with the fed state on body composition and physical performance in young adults. Participants were randomly assigned into fasting RT group (Fast-RT, n = 15) and fed RT group (Fed-RT, n = 13). Both groups trained two weekly resistance exercise sessions after an overnight fast or between 1 and 2 hr after consumption of a carbohydrate-rich meal, associated with isocaloric nutritional guidance. Assessments of body composition (dual-energy X-ray absorption), quadriceps muscle thickness (ultrasonography), maximum dynamic strength (one repetition maximum test), and muscle power in bench press and knee-extension exercises were performed before and after 12 weeks of intervention. Both Fast-RT and Fed-RT groups showed increases (p time ≤ .01) in quadriceps muscle thickness (1.21 and 1.18 cm, respectively; p group = .371; p Group × Time = .871), maximum dynamic strength (bench press: 10.53 and 4.89 kg, respectively; p group = .251; p Group × Time = .268; knee extension: 28.53 and 29.31 kg, respectively; p group = .919; p Group × Time = .846), and muscle power (knee extension mean power 70% one repetition maximum: 59.28 and 46.21 W, respectively; p group = .833; p Group × Time = .616; knee extension maximal power 70% one repetition maximum: 100.65 and 54.76 W, respectively; p group = .812; p Group × Time = .409). Regardless of food consumption prior to the sessions (fasted state and fed state), RT performed twice weekly across 12 weeks was associated with improvements in muscle hypertrophy and neuromuscular performance in young adults.

Task Specificity of Dynamic Resistance Training and Its Transferability to Non-trained Isometric Muscle Strength: A Systematic Review with Meta-analysis

BACKGROUND

Resistance training (RT) specificity has been confirmed for movement patterns (e.g., multi-joint or single joint), movement velocities, ranges of motion, and contraction types (e.g., dynamic vs isometric). However, a systematic analysis of the effects of dynamic mass-loaded (e.g., isoinertial) RT on dynamic versus isometric strength tests is lacking.

OBJECTIVE

We aimed to examine the specific effects of dynamic RT on dynamic (isoinertial) versus isometric muscle strength, including possible moderating factors (e.g., training length, single joint and multi-joint, upper body and lower body, RT status) and mechanisms (e.g., hypertrophy, muscle activation).

METHODS

A systematic literature search was conducted in MEDLINE (EBSCO), Web of Science, and Scopus up to March 2024. The included interventions contained at least ten training sessions, both dynamic and isometric muscle strength assessments before and after the training period, and healthy participants aged 16-60 years (encompassing untrained and trained individuals). Advanced RT approaches, such as electrical stimulation, isokinetic training, velocity-based training, and blood flow restriction training, were excluded. Within-subject, weighted standardized mean differences (SMDs) of the pre-intervention to post-intervention tests were calculated for both dynamic and isometric muscle strength measures using a random-effects model. Univariate sub-group analyses of RT status, intervention length, complexity (i.e., single-joint or multi-joint exercises), and body segments (i.e., upper and lower body) were independently computed. Random-effects meta-regressions were computed to examine if dynamic RT effects on dynamic and isometric muscle strength are predicted by RT effects on muscle hypertrophy or muscle activity.

RESULTS

Overall, 43 studies with 1660 participants across 72 different RT interventions were eligible for inclusion. The overall effect on dynamic strength was significant and moderate magnitude (SMD = 0.98, 95% confidence interval 0.91-1.06, p < 0.001), whereas the transfer to non-trained isometric strength measures was significant but small (SMD = 0.42, 95% confidence interval 0.35-0.49, p < 0.001). Sub-analyses demonstrated moderate-to-large task-specific effects (range SMD; 95% confidence interval 0.75-1.30) of conducting dynamic RT and only small-to-medium effects (range SMD; 0.29-0.70) of the transferability of muscle strength to the non-trained isometric contraction form. Muscle hypertrophy and activity changes did not significantly predict dynamic RT effects on dynamic and isometric muscle strength (p ≥ 0.222).

CONCLUSIONS

Our findings demonstrated task specificity of dynamic RT, as dynamic strength increased with a two-fold larger effect size than non-trained isometric muscle strength. Medium-to-large effects were observed for the dynamic strength improvements in the different sub-group analyses with small-to-medium effects in the isometric improvements. The limited transferability of dynamic (task-specific) strength to non-trained isometric contractions suggests that these two strength outcomes represent different neuromuscular domains.

Development of the rehabilitation interventions for people with an acute patellar dislocation in the Physiotherapy Rehabilitation Post Patellar Dislocation (PRePPeD) pilot randomized controlled trial

Aims

To develop the rehabilitation interventions for people with an acute patellar dislocation in the Physiotherapy Rehabilitation Post Patellar Dislocation (PRePPeD) pilot randomized controlled trial (RCT), and to describe how these interventions are delivered.

Methods

We developed the interventions drawing on a range of established intervention development approaches and frameworks. We selected intervention components after reviewing the existing evidence, clinical guidelines, UK NHS practice, and relevant scientific theory. We then created early versions of the interventions, and discussed these with clinical experts and patient and public partners. We finalized the interventions considering their feedback, findings from our preliminary study, and what would be acceptable and deliverable in the UK NHS.

Results

Upon randomization, all participants receive a workbook containing advice and initial exercises to implement before their first physiotherapy session. Self-managed rehabilitation then involves a single one-to-one session with a physiotherapist who provides advice, introduces a structured home exercise programme, and uses strategies to support exercise adherence. Participants then continue their recovery independently. Supervised rehabilitation involves four to six one-to-one physiotherapy sessions over a maximum of six months. Physiotherapists also provide advice, prescribe home exercise, and use exercise adherence strategies. Routine follow-up sessions enable physiotherapists to reassess participants and tailor the advice and exercises accordingly.

Conclusion

The interventions were developed and are currently being assessed in the PRePPeD pilot RCT. This will determine whether a full-scale RCT comparing these interventions is feasible. Results are anticipated in Summer 2025.

Effects of inspiratory muscle training on 1RM performance and body composition in professional natural bodybuilders

Background

The effect of inspiratory muscle training on upper limbs One Rep Maximum (1RM) in professional natural bodybuilders is still unclear. Our aim of this study is to investigate the effects of a 6 weeks inspiratory muscle training on 1RM results.

Methods

This study included 14 athletes, that had participated in international bodybuilding competitions. Each athlete had been training for minimum of 5 years and at least 5 h per week. The participants were randomly divided into two groups: inspiratory muscle training (IMT) and control (CON) groups. The IMT group and CON group consisted of seven subjects. While the control group continued with the normal training regime, the IMT group additionally performed inspiratory muscle training with the resistance setting of the PowerBreathe® Classic device set to 40% of the participant's MIP. Prior to and during the 6-week training period, the bench press 1 RM, anthropometry, pulmonary function tests, and maximal inspiratory (MIP) and expiratory (MEP) pressure measurements were obtained. A nutrition protocol developed by a qualified dietician was implemented for each athlete.

Results

The mean maximal strength of the respiratory muscle training group changed by 14.39%, whereas that of the control group changed by 9.43% (p = 0.012). The changes in the mean FVC (p = 0.000), FEV1 (p = 0.001), PEF (p = 0.064), MIP (p = 0.001), and maximal expiratory pressure (p = 0.017) were greater in the IMT group. The mean circumferences of the shoulder (p = 0.004), chest (p = 0.008), arm (p = 0.004), and neck (p = 0.003) improved more in the IMT group than in the CON group. A reduction in abdominal measurement was observed in the IMT group (p = 0.039), whereas no notable discrepancy was identified in body fat percentage (p = 0.295).

Conclusion

In conclusion we identified that the addition of progressive loading inspiratory muscle training for competition preparation programs in professional natural bodybuilders will further improve their respiratory function, respiratory muscle strength, maximal strength, and muscle development. This research provides valuable insights into how IMT influences bodybuilding training outcomes, potentially guiding future interventions and program designs to better support strength development and body composition in bodybuilding training contexts.

Effects of Neuromuscular Training Applied During Ramadan on Physical Fitness and Injury Prevention in Highly-Trained Male Youth Soccer Players

BACKGROUND

The intermittent fasting period of Ramadan is associated with reductions in training volumes and intensities to maintain physical fitness levels and reduce injury occurrence. Accordingly, it might be beneficial to include neuromuscular training (NMT) applied during Ramadan to avoid detraining and promote injury prevention in soccer players. This study aimed to analyze NMT effects on physical fitness and injury prevention during the Ramadan fasting period in young soccer players.

METHODS

Forty young highly-trained male soccer players (U17/U19) were randomly assigned to a NMT (n = 20) or a traditional soccer-specific training group (TT, n = 20). NMT was conducted during Ramadan, lasted four weeks, and included two weekly sessions with exercises to promote muscle strength, power (plyometrics), speed, balance. TT contents were similar to the training period before Ramadan and comprised two weekly sessions including endurance and sprint-based exercises. The training volume was similar between groups. Body composition (body fat), linear sprint (5-m, 10-m, 30-m sprint), and change-of-direction (CoD) speed (T-test with and without ball), muscle power (squat [SJ], countermovement jump [CMJ]), peak isokinetic torque of the knee flexors, extensors, and soccer-specific performance (Loughborough soccer passing test [LSPT], Yoyo intermittent test level 1 [YYIRT L1], repeated-shuttle-sprint ability test [RSSA]) were determined before and after the Ramadan period. The overall injury rate per 1000 h of exposure (training, match) was carried out during and after the four-week Ramadan period and until the end of the soccer season (overall 8 weeks).

RESULTS

No significant between group baseline differences were noted. Group-by-time interactions were significant for most assessed variables (0.001 < p < 0.004, 0.22 < d < 0.76) in favor of NMT. Variations in body mass, body fat, and BMI determined by post-hoc tests indicated significant decreases in NMT but not TT (0.026 < p < 0.047, 0.65 < d < 0.73). Moreover, post-hoc tests showed that NMT provided linear and COD speed improvements, enhanced muscle power (SJ, CMJ) and improved soccer-specific performance (p < 0.001, 0.71 < d < 2.53). Additionally, post-hoc tests revealed significant isokinetic strength increases in favor of NMT for all peak torque variables (0.015 < p < 0.049, 0.64 < d < 0.81). The overall injury rate was significantly lower in NMT (8.00/1000 h exposure) compared to TT (13.33/1000 h exposure) (p = 0.049; d = 0.66).

CONCLUSIONS

Findings suggest that a four-week NMT conducted during Ramadan fasting helped to maintain or even improve measures of physical fitness including isokinetic strength. In addition, significant NMT-related reductions in injury occurrence were noted in highly-trained young male soccer players.

Concurrent training effects on H reflex, V wave and contractile properties of the plantar flexors: insights into different resistance training types

PURPOSE

This study explored neuromuscular adaptations following 11 weeks of concurrent training (CT) compared to resistance-only (R) and endurance-only (E) in trained men.

METHODS

Thirty participants were randomized into three groups (E, R, CT), training three times per week. Neuromuscular assessments involved plantar-flexion maximal voluntary isometric contraction (MVIC), rate of torque development (RTD), evoked potentials (H reflex and V wave) and contractile properties at baseline, mid-training (week 5), and post-training. Resistance training for R and CT groups involved two phases: weeks 1-5 (maximal strength development) and weeks 6-11 (explosive/reactive strength and muscle power development). Endurance training for the E and CT groups involved 30-min of running on the heavy-intensity domain.

RESULTS

MVIC increased similarly in the R and CT groups. The R group significantly improved peak and sequential RTD, soleus electromyographic (EMG) activity, V wave and contractile properties. Conversely, the CT group exhibited an interference effect during the first phase with no improvements in RTD or neuromuscular parameters. During the second phase, the CT group exhibited significant enhancements in sequential RTD, soleus EMG activity, H- and V-wave amplitude. The improvements in the E group were limited to H-reflex excitability.

CONCLUSION

These findings suggest that the magnitude of CT interference is modulated by the focus of resistance training (maximal vs explosive strength) being performed. However, it is relevant to note that contractile impairments seem to persist, likely due to endurance training in the heavy-intensity domain.

Effects of resistance training vs high intensity interval training on body composition, muscle strength, cardiorespiratory fitness, and quality of life in survivors of breast cancer: a randomized trial

PURPOSE

Breast cancer treatments often lead to unfavourable changes in body composition, physical fitness, and quality of life (QoL). We compared the effects of resistance training (RT) and high-intensity interval training (HIIT) on these outcomes in survivors of breast cancer.

METHODS

Twenty-eight survivors of breast cancer, post-treatment (Stage I-III), aged 55.5 ± 8.8 years and body mass index 27.9 ± 5 kg/m2 were randomly allocated to a 12-week supervised RT (n = 14) or HIIT (n = 14) intervention, 3 days per week. Body composition (dual energy x-ray absorptiometry), upper and lower body muscle strength (1-repetition maximum), cardiorespiratory fitness (CRF) (Ekblom Bak Cycle Test), and QoL domains (EORTC QLQ-C30 and EORTC QLQ-BR45) were assessed at baseline and 12 weeks.

RESULTS

There were no significant differences between groups at baseline. Exercise attendance ranged from 81 to 85%. Between groups, there were significant differences (p ≤ 0.001) after 12 weeks in chest press strength for RT (mean difference [MD] = 4.7 kg) and CRF for HIIT (MD = 1.9 ml/min/kg). Within groups, there were significant improvements (p < 0.05) for % lean mass and % fat mass in both RT and HIIT, as well as for upper and lower body muscle strength, CRF, and QoL domains. No major adverse events were noted.

CONCLUSION

Both exercise groups improved body composition, physical fitness, and QoL domains over 12 weeks of RT or HIIT, although mode-specific benefits were apparent with more substantial improvements in lean mass and muscle strength with RT and reductions in % fat mass and improved CRF with HIIT. Tailored exercise programs should address the specific health needs of each patient.

Development and delivery of the rehabilitation interventions for older adults with an ankle fracture in the AFTER (Ankle Fracture Treatment Enhancing Rehabilitation) trial

OBJECTIVES

Describe the development and delivery of the interventions in the Ankle Fracture Treatment Enhancing Rehabilitation (AFTER) trial, a randomised controlled trial comparing the effectiveness of supervised versus self-directed rehabilitation for adults aged ≥50 years with an ankle fracture.

DESIGN

Intervention development.

SETTING

UK National Health Service (NHS) hospitals.

METHOD

We developed the interventions in stages. First, we reviewed two UK clinical guidelines and the existing research evidence. We then conducted a clinical practice survey (n = 59 physiotherapists) to inform a stakeholder meeting which identified key intervention components. Subsequently, we designed the interventions, tested them in a pilot trial (n = 61 participants), then refined them for the definitive AFTER trial.

RESULTS/FINDINGS

The definitive AFTER trial interventions start after randomisation, which occurs when the participant's cast/boot is removed and weightbearing and ankle movement restrictions are lifted. Participants allocated to self-directed rehabilitation receive a high-quality advice workbook, a progressively challenging self-directed exercise programme that they follow to self-manage their recovery, and strategies to encourage exercise adherence. Supervised rehabilitation participants receive a high-quality workbook, then 4 to 6 one-to-one face-to-face/remote sessions with a physiotherapist. The physiotherapist provides specific advice, home exercises, and uses strategies to facilitate adherence to prescribed exercises. The supervised rehabilitation intervention is tailored to individual participants during review sessions.

CONCLUSIONS

The definitive AFTER trial will provide high-quality evidence to guide rehabilitation provision for older adults with an ankle fracture. Results are anticipated in 2025.

TRIAL REGISTRATION NUMBER

ISRCTN registry (identifier: ISRCTN11830323). CONTRIBUTION OF THE PAPER.

Partial versus full range of motion triceps strength training on shooting accuracy among recreational basketball players: a randomized controlled trial

BACKGROUND

The benefits of strength training on shooting accuracy in football players and other athletes are well known, but its effectiveness in improving shooting accuracy among basketball players remains unclear. Therefore, this study aimed to determine the effect of partial range of motion (PROM) and full range of motion (FROM) triceps strength training on stationary three-point shooting test (S3P) among recreational basketball players.

METHODS

This was a single-blinded randomized controlled trial. 30 participants were randomly assigned into 3 equal groups; FROM, PROM, and control (CON). Triceps strength training was carried out using an adjustable overhead cable crossover machine. With shoulders over-head flexed to 160-180° for both experimental groups, the FROM group performed strength training from full elbow flexion to full extension. In contrast, the PROM group worked at a restricted range, between 60°-110° elbow flexion/extension. Both groups engaged in 4 sets of 10 repetitions, 2 sessions/week for 4-weeks at 67% of 1 repetition maximum, while the CON group did not participate in any exercise program. S3P was assessed at baseline and at the end of 4-weeks intervention.

RESULTS

Participants mean age (20.20 ± 1.54 years), height (1.74 ± 0.61 m), and body mass index (22.55 ± 3.31) were descriptively analysed. Within group analysis showed a significant improvement of S3P in both FROM (p = 0.0345, 95% CI = -1.50 to -0.07, ES = 0.81) and PROM (p = 0.005, 95% CI = -2.44 to -0.97, ES = 2.40) compared to CON group (p = 0.8995, 95% CI = -0.61 to 0.68, ES = 0.05). Group-by-time interaction demonstrated PROM to be more promising (p = 0.0102, 95% CI = -1.70 to 0.21) than the FROM and CON groups.

CONCLUSIONS

PROM triceps strength training improves shooting accuracy and is a time-efficient technique highly recommended for basketball players.

TRIAL REGISTRATION

clinicaltrials.gov, NCT04128826, registered on 14/10/2019 - retrospectively, https://clinicaltrials.gov/study/NCT04128826 .

Multimodal Adaptations to Expiratory Musculature-Targeted Resistance Training: A Preliminary Study in Healthy Young Adults

PURPOSE

Exercise-induced adaptations, including neuroplasticity, are well studied for physical exercise that targets skeletal muscles. However, little is known about the neuroplastic potential of targeted speech and swallowing exercises. The current study aimed to gather preliminary data on molecular and functional changes associated with the neuroplastic effects of 4-week expiratory musculature-targeted resistance training in healthy young adults.

METHOD

Five healthy young adult men aged between 19 and 35 years, M (SD) = 28.8 (2.68) years, underwent 4 weeks of expiratory muscle strength training (EMST). We measured changes in maximum expiratory pressure (MEP), serum brain-derived neurotrophic factor (BDNF), and insulin-like growth factor 1 (IGF-1) levels at baseline and posttraining conditions. Furthermore, functional and structural magnetic resonance images were obtained to investigate the neuroplastic effects of EMST. We analyzed the effects of training using a linear mixed model for each outcome, with fixed effects for baseline and posttraining.

RESULTS

MEP and serum BDNF levels significantly increased posttraining. However, this effect was not observed for IGF-1. A significant increase in functional activation in eight regions was also observed posttraining. However, we did not observe significant changes in the white matter microstructure.

CONCLUSIONS

Preliminary data from our study suggest targeted resistance training of expiratory muscles results in molecular and neuroplastic adaptations similar to exercise that targets skeletal muscles. Additionally, these results suggest that EMST could be a potential intervention to modulate (or prime) neurotrophic signaling pathways linked to functional strength gains and neuroplasticity.

A mechanically consistent muscle model shows that the maximum force-generating capacity of muscles is influenced by optimal fascicle length and muscle shape

Muscle forces are difficult to measure in vivo, so the force-generating capacity of muscles is commonly inferred from muscle architecture. It is often assumed, implicitly or explicity, that a muscle's maximum force-generating capacity is proportional to physiological cross-sectional area (PCSA), and that a muscle's operating range is proportional to mean optimal fascicle length. Here, we examined the effect of muscle architecture (PCSA and fascicle length) on muscle function (maximal isometric force and operating range) using a three-dimensional finite element model which accounts in a mechanically consistent way for muscle deformation and other complexities of muscle contraction. By varying architectural properties independently, it was shown that muscle force-generating capacity does not scale by the same factor as PCSA, and that operating range does not scale by the same factor as optimal fascicle length. For instance, 3-fold independent variation of mean optimal fascicle length caused the maximum isometric force-generating capacity of the muscle to vary from 83% to 105% of the force predicted by PCSA alone. Non-uniformities in fascicle length that develop as the muscle deforms during contraction reduce muscle force and operating range. Thus, a three-dimensional finite element model that satisfies fundamental physical constraints predicts that the maximum force-generating capacity of skeletal muscle depends on factors other than PCSA, and that operating range depends on factors other than optimal fascicle length. These findings have implications for how the force-generating properties of animal muscles are scaled to human muscles, and for how the functional capacity of muscles is predicted from muscle architecture.

The Acute Effects of Antagonist Static Stretching on Agonist Performance

Stretching the antagonist muscle to enhance agonist performance has gained considerable attention. However, most studies have focused on one stretching duration. Hence, the aim of this study was to compare varying durations (40-, 80-, and 120-seconds) of antagonist (dorsiflexors) static stretching (SS) on agonist (plantar flexors: PF) muscle performance. In this randomized crossover study, 16 participants (six females) underwent four sessions (40-, 80-, 120-s dorsiflexors SS and control), with pre- and post-intervention measurements of slow (600/s) and fast (2400/s) PF isokinetic, isometric peak torque, total work, stiff leg drop jump (SDJ) performance (height, reactive strength index (RSI) and peak power), and tibialis anterior and soleus electromyography (EMG). Dorsiflexors SS protocol involved 1x40-s (40-s), 2x40-s (80-s), and 3x40-s (120-s). There were no significant pre- to post-intervention changes in any parameter. A main effect for time demonstrated an overall decrease in fast (p < 0.0001, 5.9%, d = 0.24) and slow (p = 0.05, 6.6%, d = 0.24) isokinetic peak torque, total work (p = 0.02, 5.1%, d = 0.20) and all SDJ measures (SDJ height: p = 0.02, 2.7%, d = 0.15, RSI: p < 0.0001, 5.9%, d = 0.23, peak power: p = 0.002, 4.4%, d = 0.22). Soleus EMG decreased from pre- to post-SS after 120-s in both isometric (p = 0.002, 13.6%, d = 0.73) and slow isokinetic (p = 0.002, 12.3%, d = 0.91) peak torque as well as 80-s with slow isokinetic peak torque (p = 0.02, 6.6%, d = 0.75). In summary, different durations of dorsiflexors SS (40-s, 80-s, 120-s) did not significantly influence PF performance. However, deficits associated with a main effect for time suggested possible testing effects as detected with the control condition.

What are the potential mechanisms of fatigue-induced skeletal muscle hypertrophy with low-load resistance exercise training?

High-load resistance exercise (>60% of 1-repetition maximum) is a well-known stimulus to enhance skeletal muscle hypertrophy with chronic training. However, studies have intriguingly shown that low-load resistance exercise training (RET) (≤60% of 1-repetition maximum) can lead to similar increases in skeletal muscle hypertrophy as compared with high-load RET. This has raised questions about the underlying mechanisms for eliciting the hypertrophic response with low-load RET. A key characteristic of low-load RET is performing resistance exercise to, or close to, task failure, thereby inducing muscle fatigue. The primary aim of this evidence-based narrative review is to explore whether muscle fatigue may act as an indirect or direct mechanism contributing to skeletal muscle hypertrophy during low-load RET. It has been proposed that muscle fatigue could indirectly stimulate muscle hypertrophy through increased muscle fiber recruitment, mechanical tension, ultrastructural muscle damage, the secretion of anabolic hormones, and/or alterations in the expression of specific proteins involved in muscle mass regulation (e.g., myostatin). Alternatively, it has been proposed that fatigue could directly stimulate muscle hypertrophy through the accumulation of metabolic by-products (e.g., lactate), and/or inflammation and oxidative stress. This review summarizes the existing literature eluding to the role of muscle fatigue as a stimulus for low-load RET-induced muscle hypertrophy and provides suggested avenues for future research to elucidate how muscle fatigue could mediate skeletal muscle hypertrophy.

The assessment of myopenia and muscle biopsy in pediatric patients with liver disease awaiting liver transplantation-A cross-sectional analysis

Little is known about the skeletal muscle characteristics (fiber type proportion and size, location of nuclei, presence of fat infiltration) in children with liver disease with radiologically determined myopenia (low muscle mass). During liver transplantation (LTx) surgery, biopsies from the rectus abdominis muscle were collected. Muscle fiber types (I, I/IIA, IIA, IIA/X, IIX) and cross-sectional area index (µm/m 2 ) were determined using immunofluorescence staining. Triacylglycerol and phospholipid content of muscle was determined using gas chromatography. Myopenia was defined using study-specific cutoffs (skeletal muscle index <-2 SD) from age-sex-matched healthy control scans. Myopenia was prevalent in 41% of children. Children also had a high prevalence of high muscle adiposity (37%). Children with myopenia were older (8.4 vs. 0.7 y; p <0.001), had smaller total (median 595 vs. 844 µm/m 2 ; p =0.04) and hybrid IIA/X (612±143 vs. 993±341 µm/m 2 ; p =0.04) muscle fiber size index, lower prevalence of type I fibers (53% vs. 64%; p =0.01) and higher prevalence of type IIA/X hybrid fibers (median 7.5% vs. 0%; p =0.04). Children with myopenia also had a higher prevalence of elevated triacylglycerol content (>75 percentile) within the muscle compared to children without myopenia (36% vs. 0%; p =0.009). Percent of muscle fibers with centralized nuclei was not different between groups. In conclusion, children with myopenia experience differences in skeletal muscle biological characteristics when compared to children without myopenia at LTx, and these findings may have implications for dietary and exercise rehabilitation pre-LTx and post-LTx.

Immediate Effects of High-Intensity Blood Flow Restriction Training on Muscle Performance and Muscle Soreness

Purpose: The aim was to investigate the immediate effects of high-intensity resistance training with blood flow restriction (HIRT-BFR) on rectus femoris (RF) muscle activity, reaction time, muscular performance, and delayed onset muscle soreness (DOMS) in healthy young adults. Methods: Twenty-four healthy young adults were randomized into the HIRT-BFR group or HIRT group. Both groups performed a single session of training with 80% of 1RM, 8 repetitions, 2 sets, and 3 minutes rest to RF muscle. The activity and reaction time of the dominant extremity RF muscle were evaluated by superficial electromyography (sEMG), muscular performance by single-leg squat test, and DOMS by the Visual Analog Scale. Results: Single-leg squat performance was significantly increased in HIRT-BFR (p = .001) and HIRT group (p = .04). Additionally, in HIRT group resting average (p = .03), resting maximal voluntary contraction % (p = .04), and relaxation minimum (p = .02) values of RF were significantly increased. DOMS level decreased significantly in HIRT-BFR (p < .001) and HIRT group (p = .019). The differences were similar in the groups for sEMG parameters, muscle performance, and DOMS level. Conclusion: We observed that HIRT-BFR and HIRT were similar in terms of muscle activation, reaction time, muscular performance of the RF, and DOMS level.Trial registration number: This study is registered at www.clinicaltrails.gov (NCT05274542).

Resistance exercise training improves disuse-induced skeletal muscle atrophy in humans: a meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis aimed to determine whether resistance exercise training (RET) can attenuate the loss of muscle volume and function in anti-gravitational muscles, especially quadriceps and calf muscles, during immobilization/disuse conditions.

METHODS

A comprehensive literature search was conducted to identify randomized controlled trials comparing RET vs. no exercise during immobilization/disuse. Searches were conducted in databases including Web of Science, PubMed, EBOSCO, and Cochrane Library, without imposing a time limit until 20 March, 2023. Studies reporting outcomes related to muscle volume, MVC, peak power, concentric peak force, eccentric peak force, isometric MVC torque of knee extension, isometric MVC torque of knee flexion were included. Data were pooled using random-effects models.

RESULTS

Eleven randomized controlled trials were finally included. RET elicited substantial benefits for preserving quadriceps muscle volume (n = 5, MD = 252.56, 95% CI = 151.92, 353.21, p < 0.001). RET demonstrated a statistically significant preventive effect on the reduction of MVC in both quadriceps (n = 4, MD = 338.59, 95% CI = 247.49, 429.69, p < 0.001) and calf muscles (n = 3, MD = 478.59, 95% CI = 160.42, 796.77, p < 0.01). Peak power of quadriceps muscles (n = 4, MD = 166.08, 95% CI = 28.44, 303.73, p < 0.05) and calf muscles (n = 2, MD = 176.58, 95% CI = 102.36, 250.79, p < 0.001) were elevated after RET intervention. RET significantly ameliorated the weakening of both concentric and eccentric peak force in quadriceps (concentric: n = 2, MD = 470.95, 95% CI = 355.45, 586.44, p < 0.001; eccentric: n = 1, MD = 351.51, 95% CI = 254.43, 448.58, p < 0.001) and calf muscles (concentric: n = 2, MD = 867.52, 95% CI = 548.18, 1186.86, p < 0.001; eccentric: n = 1, MD = 899.86, 95% CI = 558.17, 1241.55, p < 0.001). Additionally, the diminishing of isometric MVC torques of knee extension (n = 6, MD = 41.85, 95% CI = 20.93, 62.77, p < 0.001) and knee flexion (n = 4, MD = 13.20, 95% CI = 8.12, 18.77, p < 0.001) were enhanced significantly after RET intervention.

CONCLUSIONS

RET effectively minimized deterioration of muscle volume and muscle function during immobilization/disuse, particularly in anti-gravitational muscles. RET should be recommended to maintain muscle and neuromuscular health for spaceflight, bed rest, immobilization/disuse conditions. Further research is needed to explore the effects of RET in more diverse populations and under various disuse conditions. More high-quality research will be required to demonstrate the aforementioned benefits conclusively.

Succinate Regulates Exercise-Induced Muscle Remodelling by Boosting Satellite Cell Differentiation Through Succinate Receptor 1

BACKGROUND

Skeletal muscle remodelling can cause clinically important changes in muscle phenotypes. Satellite cells (SCs) myogenic potential underlies the maintenance of muscle plasticity. Accumulating evidence shows the importance of succinate in muscle metabolism and function. However, whether succinate can affect SC function and subsequently coordinate muscle remodelling to exercise remains unexplored.

METHODS

A mouse model of high-intensity interval training (HIIT) was used to investigate the effects of succinate on muscle remodelling and SC function by exercise capacity test and biochemical methods. Mice with succinate receptor 1 (SUCNR1)-specific knockout in SCs were generated as an in vivo model to explore the underlying mechanisms. RNA sequencing of isolated SCs was performed to identify molecular changes responding to succinate-SUCNR1 signalling. The effects of identified key molecules on the myogenic capacity of SCs were investigated using gain- and loss-of-function assays in vitro. To support the translational application, the clinical efficacy of succinate was explored in muscle-wasting mice.

RESULTS

After 21 days of HIIT, mice supplemented with 1.5% succinate exhibited striking gains in grip strength (+0.38 ± 0.04 vs. 0.26 ± 0.03 N, p < 0.001) and endurance (+276.70 ± 55.80 vs. 201.70 ± 45.31 s, p < 0.05), accompanied by enhanced muscle hypertrophy and neuromuscular junction regeneration (p < 0.001). The myogenic capacity of SCs was significantly increased in gastrocnemius muscle of mice supplemented with 1% and 1.5% succinate (+16.48% vs. control, p = 0.008; +47.25% vs. control, p < 0.001, respectively). SUCNR1-specific deletion in SCs abolished the modulatory influence of succinate on muscle adaptation in response to exercise, revealing that SCs respond to succinate-SUCNR1 signalling, thereby facilitating muscle remodelling. SUCNR1 signalling markedly upregulated genes associated with stem cell differentiation and phosphorylation pathways within SCs, of which p38α mitogen-activated protein kinase (MAPK; fold change = 6.7, p < 0.001) and protein kinase C eta (PKCη; fold change = 12.5, p < 0.001) expressions were the most enriched, respectively. Mechanistically, succinate enhanced the myogenic capacity of isolated SCs by activating the SUCNR1-PKCη-p38α MAPK pathway. Finally, succinate promoted SC differentiation (1.5-fold, p < 0.001), ameliorating dexamethasone-induced muscle atrophy in mice (p < 0.001).

CONCLUSIONS

Our findings reveal a novel function of succinate in enhancing SC myogenic capacity via SUCNR1, leading to enhanced muscle adaptation in response to exercise. These findings provide new insights for developing pharmacological strategies to overcome muscle atrophy-related diseases.

The efficacy of high load-volume exercise versus low load-volume exercise for rotator cuff tendinopathy: A pilot and feasibility trial

BACKGROUND

The most effective exercise variables for rotator cuff tendinopathy are unknown.

OBJECTIVE

Determine feasibility of a fully powered trial comparing high load-volume versus low load-volume exercise for adults with rotator cuff tendinopathy.

DESIGN

Two arm, multi-centre pilot and feasibility randomised controlled trial.

METHODS

Participants aged over 18 were recruited via social media and randomised into 12 weeks of either high load-volume exercise (i.e. with dumbbell resistance) or low load-volume exercise (i.e. without added resistance). Feasibility outcomes were rates of recruitment, retention, questionnaire completion, adverse events and adherence to prescribed exercise.

RESULTS

Fifteen participants were randomised to high load-volume and 16 to low load-volume (18/31 were female). Retention rate was 84% at 6 weeks, and 81% at 12 and 26 weeks. Five participants withdrew and one participant was lost to follow up. Questionnaire completion rate was 78%. Adherence to the prescribed exercise sets was 77%. Recruitment, conversion and retention rates were above the pre-defined success criterion. There were no serious adverse events.

CONCLUSION

A fully powered multi-centre randomised trial is feasible with minor amendments addressing exercise adherence and questionnaire response rate. Future trials should utilise outcomes that consider participants baseline physical activity levels and adequately measure pain disparate from performance.

Previous short-term disuse dictates muscle gene expression and physiological adaptations to subsequent resistance exercise

Short-term unloading experienced following injury or hospitalisation induces muscle atrophy and weakness. The effects of exercise following unloading have been scarcely investigated. We investigated the functional and molecular adaptations to a resistance training (RT) programme following short-term unloading. Eleven males (22.09 ± 2.91 years) underwent 10 days of unilateral lower limb suspension (ULLS) followed by 21 days of knee extensor RT (three times/week). Data collection occurred at Baseline (LS0), after ULLS (LS10) and at active recovery (AR21). Knee extensor maximum voluntary contraction (MVC) was evaluated. Quadriceps volume was estimated by ultrasonography. Muscle fibre cross-sectional area, fibre type distribution, glycogen content and succinate dehydrogenase (SDH) activity were measured from vastus lateralis biopsies. Mitochondrial-related proteins were quantified by western blot and transcriptional responses were assessed by RNA sequencing. Following ULLS, quadriceps volume and MVC decreased significantly (3.7%, P < 0.05; 29.3%, P < 0.001). At AR21 (vs. LS10), MVC was fully restored (42%) and quadriceps volume increased markedly (18.6%, P < 0.001). Glycogen content and whole-body water increased at AR21 (14%, P < 0.001; 3.1%, P < 0.05). We observed a marked increase in fibre type I at AR21 (38%, P < 0.05). SDH immunoreactivity increased significantly after exercise (20%, P < 0.001). Mitochondrial fusion (MFN1, MFN2 and OPA1) and fission (DRP1) proteins were markedly increased by RT, and the most differentially expressed genes belonged to oxidative phosphorylation pathways. In contrast with what is usually observed after RT, oxidative metabolism, slow fibre type and mitochondrial dynamics were enhanced beyond expected. We propose that prior exposure to short-term muscle unloading may drive the nature of molecular adaptations to subsequent RT. KEY POINTS: Short-term unloading is often experienced during recovery from injuries and hospitalisation, leading to loss of muscle mass and strength. Although exercise can be beneficial in mitigating/reversing such alterations during disuse, only a few studies have focused on the effects of exercise following muscle unloading. With an integrative physiological approach, we aimed to elucidate the basic mechanisms of muscle function recovery in response to 21 days of resistance exercise that followed 10 days of unilateral lower limb suspension (ULLS), assessing whether the mechanisms underlying recovery are defined by a specific reversal of those that occurred during disuse. Resistance training was successful in recovering functional and structural muscle properties after 10 days of ULLS, but in contrast with what is usually observed in response to this training modality, oxidative metabolism and slow fibre type were mostly enhanced. We propose that prior exposure to short-term muscle unloading may drive the adaptations to subsequent exercise.

Cross-education: motor unit adaptations mediate the strength increase in non-trained muscles following 8 weeks of unilateral resistance training

Introduction

Early increases in muscle strength following unilateral resistance training are typically accompanied by strength gains in the contralateral untrained muscles, a phenomenon known as cross-education. However, the specific motor unit adaptations responsible for this gain transfer remain poorly understood. To address this gap, we recorded myoelectrical activity from the biceps brachii using high-density electromyography.

Methods

Nine participants performed 8-week unilateral resistance training and were compared to nine control individuals who did no intervention. Discharge characteristics of longitudinally tracked motor units were assessed during maximal voluntary contractions and isometric ramp contractions at 35% and 70% of the maximal voluntary force (MVF) at baseline (T0), 4 weeks (T1), and 8 weeks (T2) post-intervention.

Results

MVF increased by 7% in untrained muscles at T1 and 10% at T2 (p < 0.05). These gains were accompanied by significant decreases in motor unit recruitment thresholds (p < 0.01) and higher net discharge rate (i.e., gain in discharge rate from recruitment to peak) following intervention (p < 0.05). Trained muscles presented greater MVF (+11%, T1; +19%, T2) with similar motor unit adaptations, including a lower recruitment threshold (p < 0.01) and a higher net discharge rate (p < 0.01).

Discussion

Our findings indicate that higher strength in untrained muscles is associated with a higher net discharge rate, implying a greater spinal motoneuron output to muscles. The present results underscore the role of motor unit adaptations in the transfer of strength gains to non-trained muscles, offering novel insights into the neural mechanisms underlying cross-education.

Resilience capacity in older women engaged in resistance training: physiological and functional adaptations to training interruption imposed by the COVID-19 pandemic followed by retraining

NOVELTY

Two years of training interruption imposed by the COVID-19 pandemic impair physiological and functional outcomes in older women engaged in resistance training. Retraining led to resilience capacity only in muscular strength gains.

Exercise snacks and physical fitness in sedentary populations

Physical inactivity remains a pressing global public health concern. Prolonged periods of sedentary behavior have been linked to heightened risks of non-communicable diseases such as cardiovascular diseases and type 2 diabetes, while engaging in any form of physical activity can elicit favorable effects on health. Nevertheless, epidemiological research indicates that people often struggle to meet recommended physical activity guidelines, citing time constraints, lack of exercise equipment, and environmental limitations as common barriers. Exercise snacks represents a time-efficient approach with the potential to improve physical activity levels in sedentary populations, cultivate exercise routines, and enhance the perception of the health benefits associated with physical activity. We review the existing literature on exercise snacks, and examine the effects of exercise snacks on physical function and exercise capacity, while also delving into the potential underlying mechanisms. The objective is to establish a solid theoretical foundation for the application of exercise snacks as a viable strategy for promoting physical activity and enhancing overall health, particularly in vulnerable populations who are unable to exercise routinely.

Reliability of direct and indirect measures of intrinsic foot muscle strength in adults: A systematic review

BACKGROUND

The aim of this systematic review was to summarize the existing literature on evaluation methods developed to measure intrinsic foot muscle strength in both symptomatic and asymptomatic individuals. The specific objectives was to provide an overview of the evaluation methods with their protocols and reliability.

METHODS

Five databases (PubMed, Embase, Web of Science, Cochrane Library and SPORTDiscus) were searched up to August 2023. Studies reporting direct or indirect measures of intrinsic foot muscle evaluation with no limitation to sex, BMI or ethnicity were included. The inclusion criteria were applied systematically, and the methodological quality of the selected articles was assessed using The Downs and Black Checklist.

FINDINGS

Sixteen studies provided results of direct measures of intrinsic foot muscle strength, while indirect measures were reported in 19 articles. Direct measurement methods such as dynamometry (ICC 0.75-0.99) and plantar pressure (ICC 0.75-0.95) show high reliability. Among the indirect methods, both MRI (ICC 0.99) and ultrasound showed mostly high (ICC 0.66-0.99) reliability values.

INTERPRETATION

Direct methods like dynamometry and plantar pressure show excellent reliability, but validity is uncertain. MRI is considered gold standard among indirect measurement techniques. However, portable ultrasound devices have gained popularity due to their strong agreement with MRI.

Molecular biomarkers of dysphagia targeted exercise induced neuroplasticity: A review of mechanistic processes and preliminary data on detraining effects

While molecular adaptations accompanying neuroplasticity during physical exercises are well-established, little is known about adaptations during dysphagia-targeted exercises. This research article has two primary purposes. First, we aim to review the existing literature on the intersection between resistance (strength) training, molecular markers of neuroplasticity, and dysphagia rehabilitation. Specifically, we discuss the molecular mechanisms of two potential molecular markers: brain-derived neurotrophic factor (BDNF) and insulin-like growth factor-1 (IGF-1) in exercise-induced neuroplasticity. Second, we present preliminary data on the effects of two weeks of detraining on circulating serum BDNF, IGF-1 levels, and expiratory muscle strength. This subset is a part of our more extensive studies related to dysphagia-targeted resistance exercise and neuroplasticity. Five young adult males underwent four weeks of expiratory muscle strength training, followed by two weeks of detraining. We measured expiratory strength, circulating levels of BDNF, and IGF-1 at post-training and detraining conditions. Our results show that expiratory muscle strength, serum BDNF, and IGF-1 levels decreased after detraining; however, this effect was statistically significant only for serum BDNF levels. Oropharyngeal and upper airway musculature involved in swallowing undergoes similar adaptation patterns to skeletal muscles during physical exercise. To fully comprehend the mechanisms underlying the potential neuroplastic benefits of targeted exercise on swallowing functions, mechanistic studies (models) investigating neuroplasticity induced by exercises addressing dysphagia are critical. Such models would ensure that interventions effectively and efficiently achieve neuroplastic benefits and improve patient outcomes, ultimately advancing our understanding of dysphagia-targeted exercise-induced neuroplasticity.

Is it truly impossible to strengthen the vastus medialis in isolation from the entire quadriceps muscle group?

Background

To date, no specific exercises have been designed to selectively strengthen the vastus medialis muscle. Therefore, the purpose of this research is to provide a clear answer to the question: Is it truly impossible to strengthen the vastus medialis independently of the entire quadriceps muscle group? Methods: Thirty-three females with lateral patellar compression syndrome were randomly divided into 2 groups: one focused on selective strengthening of the vastus medialis (n = 16) and the other on general strengthening of the quadriceps (n = 17). The intervention lasted 8 weeks. Muscles cross-sectional area and electrical activity were assessed using ultrasound and electromyography, respectively. Data analysis was done using independent and dependent t-tests.

Results

In the selective strengthening group, significant increases were observed in the activity and cross-sectional area of the vastus medialis, as well as in the ratios of vastus medialis/vastus lateralis activity and cross-section from pre-to post-intervention (P < 0.01). In the general strengthening group, significant increases were noted in the cross-sectional area of the vastus lateralis and the activity of both muscles, with a greater increase in the vastus lateralis (P < 0.01).

Conclusions

Contrary to previous evidence, our findings demonstrate that preferential activation and selective strengthening of the vastus medialis muscle, independent of the other quadriceps components, is achievable through the training protocol employed in this study.

Optimizing concurrent training programs: A review on factors that enhance muscle strength

The purpose of this study is to explore the factors that should be considered when designing concurrent training programs to minimize the "interference effect." This study provides a comprehensive summary of various perspectives from existing studies on factors such as the ability level of the target group, the frequency and intensity of concurrent training, the order and interval time of resistance and endurance training, nutritional arrangements during training, and gender differences in concurrent training. The results of this study suggest that the emergence of the "interference effect" in concurrent training is influenced by several factors, with a particular emphasis on the adaptation status of muscle fitness when compared to resistance training alone. However, it is important to note that the current understanding of this theory remains somewhat ambiguous. The ability level of participants plays a crucial role in training adaptation and the specificity of post-training skeletal muscle molecular responses. Therefore, the participant's capacity level is likely a key determinant of the extent of the interference effect in concurrent training. In addition to training-related factors such as frequency, duration, intensity, volume, training sequence, recovery time, and nutritional intake, non-training-related variables, including the methodology used to assess various metrics, also significantly impact the design of concurrent training programs. These factors collectively influence the overall outcomes and provide insight into the extent of the "interference effect" in concurrent training. Understanding these aspects is essential for comprehending the phenomenon of the "interference effect" in concurrent training.

The effects of exercise on neuromuscular function in people with chronic neck pain: A systematic review and meta-analysis

BACKGROUND

Differences in cervical neuromuscular function are commonly observed between people with and without chronic neck pain. Exercise may improve cervical neuromuscular function of people with neck pain although the evidence for this has not been systematically reviewed.

OBJECTIVE

To systematically review the existing evidence on the effect of exercises targeting the neck muscles on neuromuscular function in people with chronic non-specific neck pain.

METHODS

This systematic review was conducted based on a registered protocol (CRD42021298831) with searches conducted on the following databases from inception to 21st October 2023: MEDLINE, CINAHL, Web of Science, Scopus, AMED, Google Scholar, Open Grey and Zetoc. Studies of interest were trials investigating neuromuscular adaptations to a program of exercise targeting the neck muscles (>2 weeks) in people with chronic non-specific neck pain. Two reviewers independently screened the studies and performed data extraction, risk of bias assessment, and rated the overall certainty of the evidence (GRADE).

RESULTS

Fourteen articles from 2110 citations were included. There is moderate certainty of evidence that the use of craniocervical flexion training (either in isolation or in combination with resistance training) can induce neural adaptations within the neck muscles. A meta-analysis showed a reduction in sternocleidomastoid muscle activity after neck exercise interventions compared to control interventions.

CONCLUSION

The articles included in this systematic review confirmed that exercise can result in neuromuscular adaptations within neck muscles, as measured by electromyography. Specificity of training was seen to be relevant for the type of neuromuscular adaptations induced.

The Validity and Reliability of the My Jump Lab App for the Measurement of Vertical Jump Performance Using Artificial Intelligence

The countermovement jump (CMJ) is a widely used test to assess lower body neuromuscular performance. This study aims to analyze the validity and reliability of an iOS application using artificial intelligence to measure CMJ height, force, velocity, and power in unloaded and loaded conditions. Twelve physically active participants performed 12 CMJs with external loads ranging from 0% to 70% of their body mass while being simultaneously monitored with a pair of force platforms and the My Jump Lab application. The scores for jump height, mean propulsive force, velocity, and power between devices were compared for validity and reliability purposes. The force platform and the application showed a high association (r > 0.91, p < 0.05) for measuring CMJ height, force, velocity, and power. Small and no statistically significant differences (p < 0.05) were observed in most loading conditions. Both instruments showed high reliability (Cronbach's α > 0.93, Coefficient of variation < 6%) for measuring the different trials performed by each participant. The My Jump Lab application was shown to be valid and reliable for measuring CMJ height, force, velocity, and power in both loaded and unloaded jumps, eliminating the problems associated with the cost and portability of force plates for daily practice.

Impact of Five Weeks of Strengthening Under Blood Flow Restriction (BFR) or Supplemental Oxygen Breathing (Normobaric Hyperoxia) on the Medial Gastrocnemius

Background and Objectives: This study investigates the effects of a five-week training program on the medial gastrocnemius muscle, comparing two approaches: blood flow restriction (BFR) training and normobaric hyperoxia (oxygen supplementation). It evaluates three strengthening modalities (dynamic, isometric, and the 3/7 method) analyzing their impact on maximal voluntary contraction (MVC), muscle architecture, and perceived exertion. Methods: A total of 36 young healthy participants (21 females, 15 males) were randomized into six subgroups (n = 6 each) based on the type of contraction and oxygen condition. Training sessions (three per week) were conducted for five weeks at 30% of MVC. Measurements of MVC, muscle circumference, pennation angle, fascicle length, and perceived exertion were taken at baseline (T0), mid-protocol (T1), and post-protocol (T2). Results: All groups demonstrated significant increases in MVC after five weeks, with no notable differences between BFR and oxygen conditions. Structural changes were observed in specific subgroups: the BFR-isometric group showed increased calf circumference (p < 0.05), and the 3/7 groups exhibited significant fascicle length gains (p < 0.05). Perceived exertion was consistently higher in BFR groups compared to oxygen supplementation, particularly in dynamic exercises. Conclusions: Both BFR and oxygen supplementation are effective in enhancing strength with light loads, though they elicit different structural and perceptual responses. Oxygen supplementation may be more comfortable and less strenuous, offering a viable alternative for populations unable to tolerate BFR. Future research should focus on optimizing training parameters and exploring applications tailored to specific athletic or clinical contexts.

Myofascial force transmission between latissimus dorsi and contralateral gluteus maximus in runners: a cross-sectional study

The anatomical connection between latissimus dorsi (LD), thoracolumbar fascia, and contralateral gluteus maximus (GM) enables myofascial force transmission (MFT) between the shoulder, trunk, and hip. This study investigates whether regular sports practice, specifically running, influences this MFT pathway. Given the potential changes in tissue stiffness from sports practice and the importance of this property for MFT, we hypothesize that runners may exhibit greater MFT between the LD and GM, resulting in altered passive properties of the lumbar and hip regions during LD contraction. This study aimed to investigate whether runners present a higher modification in lumbar stiffness and passive properties of the contralateral hip due to LD contraction than sedentary individuals. The lumbar stiffness, hip resting position, passive hip torque, and stiffness of fifty-four individuals were assessed using an indentometer and an isokinetic dynamometer, respectively, in two conditions: LD relaxed, and LD contracted. The main and interaction effects were assessed using a two-way ANOVA. The LD contraction increased lumbar stiffness (p < 0.001; ηp2 = 0.50), externally rotated the hip resting position and increased the passive hip torque and stiffness (p < 0.05; ηp2 > 0.1) in both groups. In addition, runners presented higher lumbar stiffness compared to sedentary in the LD contracted condition (p = 0.017, ESd = 0.54). Although runners exhibited increased lumbar stiffness during LD contraction, the MFT from the shoulder to the hip joint occurred similarly in both groups.

Effects of 5-Wk Repeated Sprint Training in Hypoxia on Global Inspiratory and Core Muscle Functions

Repeated-sprint training in hypoxia (RSH) has been shown to boost team-sport players' repeated-sprint ability (RSA). Whether players' global inspiratory muscle (IM) and core muscle (CM) functions would be altered concomitantly with RSH was not reported. This study was designed to compare the concomitant alternations in players' RSA and their IM and CM functions during a team-sport-specific intermittent exercise protocol (IEP) before and after the intervention. Twenty players were assigned into either RSH or control (CON) groups (n = 10 for each). RSH players participated in 5-wk RSH (15 sessions, 3 sets 5x5-s all-out treadmill sprints interspersed with 25-s passive recovery under the hypoxia of 13.5%) while CON players had no corresponding training. The changes in RSA between pre- and post-intervention, and the alterations in IM and CM functions that were revealed by maximum inspiratory mouth pressure (PImax) and sport-specific endurance plank test (SEPT) performance, respectively, between pre- and post-IEP and across pre- and post-intervention in the RSH group were compared with that of CON. Following the 5-wk RSH, players' RSA improved significantly (>6%, p < 0.05) while PImax and SEPT performance did not alter (P > 0.05). Nevertheless, PImax which declined markedly in pre-intervention IEP (pre-IEP 155.4 ± 22.7 vs post-IEP 140.6 ± 22.8 cmH2O, p < 0.05) was alleviated significantly in post-intervention IEP (152.2 ± 27.4 vs 152.6 ± 31.8, p > 0.05), while the concomitant declined SEPT performance in the pre-intervention IEP (155 ± 24.6 vs 98.1 ± 21.7 s, p < 0.05) was retained post intervention (170.7 ± 38.1 vs 100.5 ± 33.4, p < 0.05). For the CON, all variables were unchanged (p > 0.05). Such findings suggest that 5-wk RSH could enhance players' RSA but not global IM and CM functions. Nonetheless, the decline in PImax in pre-intervention IEP alleviated significantly post intervention led to a postulation that players' IM endurance, rather than strength, might improve with the 5-wk RSH regimen, while the possible improved IM endurance did not advance the fatigue resistance of CM.

Effects of Low-Load Blood Flow Restriction Training on Muscle Volume After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis

Background

After anterior cruciate ligament (ACL) reconstruction (ACLR), the function and strength of the quadriceps muscle are essential for a successful recovery. Low-load blood flow restriction training (LL-BFRT) is believed to reduce muscle atrophy and restore muscle function.

Purpose

To systematically analyze the evidence on the effectiveness of LL-BFRT in early rehabilitation after ACLR.

Study Design

Systematic review; Level of evidence, 1.

Methods

A systematic review and meta-analysis were conducted consistent with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Comprehensive literature searches were performed in several electronic databases-including Cochrane Library (trials), PubMed, Embase, Web of Science, China National Knowledge Infrastructure, WanFang, China Science and Technology Journal Database, and Sinomed-from inception to October 1, 2023. Included were randomized controlled trials in Chinese and English comparing LL-BFRT within 6 weeks after ACLR with conventional rehabilitation training. Bias risk was assessed using the Cochrane Risk-of-Bias 2 tool. The outcomes measured were quadriceps muscle size, knee joint functional scores, balance function, and complications. The effects of LL-BFRT versus conventional rehabilitation were analyzed using standardized mean differences (SMDs) or weighted mean differences (WMDs).

Results

A total of 362 studies were initially identified, and 8 were included for analysis. LL-BFRT was significantly more effective in improving quadriceps muscle volume (SMD, 0.37 [95% CI, 0.08 to 0.66]; P = .01) and Lysholm scores (SMD, 0.74 [95% CI, 0.43 to 1.05]; P < .0001) compared with conventional rehabilitation training. However, no significant improvements were observed in the 3 directions of the Y-balance test: anterior (WMD, 0.55 [95% CI, -6.37 to 7.46]; P = .88), posteromedial (WMD, -2.24 [95% CI, -8.76 to 4.29]; P = .50), and posterolateral (WMD, 0.02 [95% CI, -13 to 13.03]; P = 1.0). No complications were reported in any of the included studies.

Conclusion

The results of this meta-analysis suggested that LL-BFRT within 6 weeks after ACLR has a more pronounced effect on increasing quadriceps muscle volume and improving Lysholm scores compared with conventional rehabilitation training, with no apparent complications.

Quadriceps Architectural Adaptations in Team Sports Players: A Meta-analysis

Resistance training is the most effective strategy to modify muscle architecture, enhancing sport performance and reducing injury risk. The aim of this study was to compare the effects of high loads (HL) versus lower loads (LL), maximal versus submaximal efforts, and high frequency (HF) versus low frequency (LF) on quadriceps architectural adaptations in team sports players. Five databases were searched. Vastus lateralis thickness, fascicle length and pennation angle, and rectus femoris thickness were analyzed as main outcomes. Overall, resistance training significantly improved muscle thickness and pennation angle, but not fascicle length. LL led to greater fascicle length adaptations in the vastus lateralis compared to HL (p=0.01), while no substantial differences were found for other load comparisons. Degree of effort and training frequency did not show meaningful differences (p>0.05). In conclusion, LL lengthen the fascicle to a greater extent than HL, and training with LL twice a week could maximize architectural adaptations, whereas the degree of effort does not appear to be a determinant variable on quadriceps architectural adaptations.

Greater motor unit discharge rate during rapid contractions in chronically strength-trained individuals

Though similar motor unit (MU) discharge properties have been observed during slow sustained contractions between chronically strength-trained (ST) and untrained (UT) individuals, it is currently unknown whether differences between these groups exist for when maximal in vivo MU discharge rate is assessed during rapid, maximal rate of force development (RFD) contractions. Therefore, we compared MU discharge characteristics and RFD during rapid contractions in chronic ST and UT individuals. The investigations were performed in two independent cohorts of chronically ST men, with trained elbow flexors (experiment 1, n = 13, 6 ± 4 yr of training experience) or knee extensors (experiment 2, n = 11, 9 ± 4 yr of experience), and compared with those of UT (n = 12 and n = 10, respectively). ST individuals had greater absolute elbow flexion and knee extension RFD throughout the first 150 ms of rapid contractions compared with UT, but this difference was absent for relative RFD. ST exhibited higher initial MU discharge rate in both biceps brachii (74 [68, 80] vs. 56 [50, 63] pulses per second (pps), P < 0.0001) and vastus lateralis (102 [90, 115] vs. 76 [63, 90] pps, P = 0.0025) and a greater average number of MU discharges per second in both trained muscles in the early phase of rapid contractions. We provide novel evidence for a higher maximal MU discharge rate in strength-trained individuals. Interestingly, despite the augmented output of the spinal cord, no differences in relative RFD were observed, which suggests either greater maximal force enhancement of ST compared with UT and/or slowing of the intrinsic contractile properties by prolonged strength training.NEW & NOTEWORTHY Chronically strength-trained and untrained individuals show similar motor unit discharge rates during slow sustained contractions, however, potential differences in motor unit discharge rates during rapid contractions remained unclear. Here, we show greater maximal motor unit discharge rates during rapid contractions of chronically strength-trained individuals. However, the augmented spinal cord output of strength-trained individuals did not lead to greater relative maximal rate of force development compared with untrained men.

Optimizing Resistance Training for Sprint and Endurance Athletes: Balancing Positive and Negative Adaptations

Resistance training (RT) triggers diverse morphological and physiological adaptations that are broadly considered beneficial for performance enhancement as well as injury risk reduction. Some athletes and coaches therefore engage in, or prescribe, substantial amounts of RT under the assumption that continued increments in maximal strength capacity and/or muscle mass will lead to improved sports performance. In contrast, others employ minimal or no RT under the assumption that RT may impair endurance or sprint performances. However, the morphological and physiological adaptations by which RT might impair physical performance, the likelihood of these being evoked, and the training program specifications that might promote such impairments, remain largely undefined. Here, we discuss how selected adaptations to RT may enhance or impair speed and endurance performances while also addressing the RT program variables under which these adaptations are likely to occur. Specifically, we argue that while some myofibrillar (muscle) hypertrophy can be beneficial for increasing maximum strength, substantial hypertrophy can lead to macro- and microscopic adaptations such as increases in body (or limb) mass and internal moment arms that might, under some conditions, impair both sprint and endurance performances. Further, we discuss how changes in muscle architecture, fiber typology, microscopic muscle structure, and intra- and intermuscular coordination with RT may maximize speed at the expense of endurance, or maximize strength at the expense of speed. The beneficial effect of RT for sprint and endurance sports can be further improved by considering the adaptive trade-offs and practical implications discussed in this review.

Electrocortical activity during resistance exercises in healthy young adults-a systematic review

Introduction

Resistance training (RT) is known to induce both peripheral and central adaptations, resulting in enhanced strength, sports performance, and health benefits. These adaptations are specific to the training stimuli. The acute cortical mechanisms of single sessions resistance exercise (RE) are not yet understood. Therefore, this review investigates the electrocortical activity during acute RE regarding the specific RE stimuli.

Methods

A systematic literature search was conducted across three databases, focusing on the acute electrocortical activity associated with the muscle contraction type, load, and volume of RE in healthy young adults.

Results

Out of an initial 1,332 hits, 19 studies were included for data synthesis. The findings from these studies show that the RE load, contraction type, and volume during RE significantly affect brain activity. The current literature exhibits methodological heterogeneity attributed to variations in study quality, differences in the location of cortical sources, the cortical outcome parameter and the use of diverse training interventions.

Discussion

Despite inconsistencies in the current literature, this review highlights the need to investigate time and frequency-specific characteristics when examining electrocortical activity during RE. More research is necessary to further explore the acute cortical mechanisms related to resistance exercise. Future research could improve our understanding of acute neural responses to RE and provide insights into mechanism underlying more long-term neuroplastic adaptations to RT.

Endurance and electromyographic assessment of abdominopelvic motor control in women with primary dysmenorrhea: a cross-sectional study

Primary dysmenorrhea (PD), a prevalent menstrual condition characterized by pelvic pain during the menstrual cycle, significantly impacts the quality of life of women and produces increased pain sensitivity that can persist throughout the menstrual cycle. However, scientific literature has not studied whether there are implications for alterations in muscle function and endurance in the abdominopelvic region during the non-painful phases of the menstrual cycle. The aim of this study was to compare muscle function and endurance capacity in the abdominopelvic region in women with PD versus women without this condition. An observational, cross-sectional study was designed to analyze muscle activation and endurance capacity using electromyography (EMG) during McGill exercises. Forty-four women were included, 22 with PD and 22 without dysmenorrhea. The results did not indicate significant differences in muscle activation and endurance of the abdominopelvic musculature between the two groups (p > 0.05). However, the analysis suggests that women with primary dysmenorrhea might develop compensatory strategies that allow them to maintain physical function despite their condition. These results suggest that the approach to PD could focus more on pain management rather than physical functionality, and more studies are needed from a comprehensive approach to more accurately evaluate the relationship between PD and muscle function.

Effects of Extrinsic and Intrinsic Motivation on Selective Activation of Shoulder Girdle Muscles During the Barbell Bench Press Exercise

Background/Objectives: This study aimed to investigate the effects of intrinsic and extrinsic motivation on selective muscle activation of the shoulder girdle during the barbell bench press. Specifically, this research focused on how attentional focus on individual muscles, such as the anterior deltoid (AD), pectoralis major (PM), and triceps brachii long (TBL), could influence their electromyographic (EMG) activity during the exercise. Methods: Twelve male participants, with at least five years of strength training experience, performed bench press exercises under two conditions: with extrinsic motivation (no specific focus on muscle activity) and with intrinsic motivation (internal focus on specific muscles). Surface electromyography (sEMG) was used to measure muscle activity during three sets of bench presses at 60% of one repetition maximum (1RM). Participants were instructed to focus on the activation of specific muscles in a randomized sequence. Results: The intrinsic motivation condition significantly increased muscle activation compared to extrinsic motivation. Electromyographic activity of the AD, PM, and TBL muscles was notably higher when participants focused their attention on these muscles. AD activation increased from 71.78 ± 11.13%MVC (extrinsic) to 88.03 ± 8.84%MVC (intrinsic) (p = 0.0019), while PM and TBL activation also demonstrated significant increases under intrinsic focus. Conclusions: The study concludes that intrinsic motivation, or an internal focus on specific muscle activation, can significantly enhance EMG activity in target muscles during the bench press exercise. This finding has important implications for resistance training and rehabilitation, where focused muscle activation can be utilized to improve training outcomes and muscle engagement.

Does acute dehydration affect the neuromuscular function in healthy adults?-a systematic review

The effects of acute dehydration on neuromuscular function have been studied. However, whether the mechanisms underpinning such function are central or peripheral is still being determined, and the results are inconsistent. This systematic review aims to elucidate the influence of acute dehydration on neuromuscular function, including a novel aspect of investigating the central and peripheral neuromuscular mechanisms. Three databases were used for the article search: PubMed, Web of Science, and Scopus. Studies were included if they had objective measurements of dehydration, muscle performance, and electromyography data or transcranial magnetic stimulation or peripheral nerve stimulation measurements with healthy individuals aged 18-65 years. Twenty-three articles met the eligibility criteria. The studies exhibited considerable heterogeneity in the methods used to induce and quantify dehydration. Despite being inconsistent, the literature shows some evidence that acute dehydration does not affect maximal strength during isometric or moderate-speed isokinetic contractions. Conversely, acute dehydration significantly reduces maximal strength during slow-speed isokinetic contractions and fatigue resistance in response to endurance tasks. The studies report that dehydration does not affect the motor cortical output or spinal circuity. The effects occur at the peripheral level within the muscle.

Neuromuscular Adaptations Related to Medial Knee Osteoarthritis and Influence of Unloader Braces on Neuromuscular Activity in Knee Osteoarthritis Subjects-A Systematic Review

ABSTRACT

Unloader braces are a treatment modality for medial compartment knee osteoarthritis. The functional mechanisms involved are not yet fully understood. Therefore, this two-part systematic review examines the following research questions: How is muscle activation altered by medial compartment knee osteoarthritis, and do medial tibio-femoral compartment unloader braces alter muscle activation? If so, could this alteration be part of the unloading mechanism by affecting the altered muscle activity in medial compartment knee osteoarthritis?A systematic literature search was conducted using PubMed, LIVIVO, Web of Science, Google Scholar, and CENTRAL for articles published until August 2023. The first systematic review, examining neuromuscular alterations, identified 703 articles, with a final inclusion of 20. The second systematic review, which evaluated the neuromuscular effects of unloader braces, identified 123 articles with the final inclusion of 3. Individuals with medial compartment knee osteoarthritis demonstrated increased activity and co-contraction of the periarticular knee muscles, whereas medial tibio-femoral compartment unloader braces seemed to reduce activity and co-contraction. In contrast to the belief that unloader braces result in muscle weakness as they decrease muscle activity and co-contraction, our limited insights indicate that they rather might reduce the pathological increase. This may result in joint load reduction due to lower compressive forces. However, further investigation is required.

Research on the effect of post-activation potentiation under different velocity loss thresholds on boxer's punching ability

This study was conducted in accordance with the principles of velocity-based training theory, with the objective of investigating the effects of post-activation potentiation (PAP) induced by different velocity loss (VL) thresholds (10% vs. 20%) on the punching ability of boxers. In addition, the aim was to determine the velocity loss thresholds and time nodes that produced the optimal activation effect. Twenty-four male elite boxers were randomly assigned to three groups: CON, 10 VL, and 20 VL. All subjects in the three groups underwent an activation intervention involving an 85% of the one-repetition maximum (1RM) squat, with 6-8 repetitions performed in the CON. The number of repetitions in the 20%VL and 10 VL was determined based on the velocity loss monitored by the GymAware PowerTool system. Four time points were selected for observation: the 4th, 8th, 12th and 16th minutes. These were chosen to test the subjects' punching ability. The results demonstrated that activation training at different VL induced a post-activation potentiation in boxers, improving punching ability bilaterally and to a greater extent than in the CON. The dominant side demonstrated the greatest efficacy at the 12th minute under the 20% velocity loss threshold, while the non-dominant side exhibited the greatest efficacy at the 8th minute under the 10% velocity loss threshold.

Five weeks of dynamic finger flexor strength training on bouldering performance and climbing-specific strength tests. A randomized controlled trial

The aim of the study was to examine the effects of a 5-week dynamic finger flexor strength training program on bouldering performance and climbing-specific strength tests. Advanced to elite level boulderers (n = 31) were randomized to a dynamic finger strength training group (DFS) or a control group (CON). The DFS training program consisted of 3 weekly sessions (3-5 sets, 4-10 repetitions per session). Both groups continued bouldering training as usual throughout the intervention period. Pre- and post-intervention measures included bouldering performance, maximal dynamic finger strength, isometric finger strength (peak and average force), and rate of force development (RFD). The DFS demonstrated greater improvement in dynamic finger strength (11.5%, 3.9 kg) than the CON (5.3%, 1.7 kg; p = 0.075, ES = 0.90), but there were no differences between the groups in 1RM (p = 0.075, ES = 0.67), bouldering performance (p = 0.39, ES = 0.35), isometric finger strength (p = 0.42-0.56, ES = 0.20-0.22) or RFD (p = 0.30, ES = 0.46). The DFS improved dynamic (p < 0.01, ES = 1.83) and isometric peak and average (p < 0.01, ES = 0.98, and p < 0.01, ES = 0.75, respectively) finger strength, while the CON only increased dynamic finger strength (p < 0.05, ES = 0.58). None of groups improved bouldering performance or RFD (p = 0.07-0.58). In conclusion, 5 weeks of DFS training improving dynamic strength to a greater extent than bouldering alone in addition to improving isometric finger strength among advanced boulderers. Isolated bouldering improved dynamic finger flexor strength, but importantly, increased finger strength (dynamic or isometric) did not improve bouldering performance.

Comprehensive assessment of heavy slow resistance training and high-dose therapeutic ultrasound in managing patellar tendinopathy, a randomized single-blind controlled trial

BACKGROUND

Patellar tendinopathy (PT) is a common sport injury prone to recurrence. Heavy Slow Resistance Training (HSR) and High-Dose Therapeutic Ultrasound (TUS) are frequently used interventions for PT. However, the combined effectiveness of these therapies remains unclear. This study investigated the impact of combination therapy on functional outcomes in patients with PT.

METHODS

Fifty-one college students aged 18-25, diagnosed with PT via musculoskeletal ultrasound, were randomly assigned to one of three groups (n = 17 per group): combined HSR and high-dose TUS, HSR training alone, or high-dose TUS alone. The eight-week intervention included assessments using the Victorian Institute of Sport Assessment-Patella (VISA-P), Visual Analogue Scale (VAS), Y-balance Test (YBT), Modified Thomas Test (MTT), Horizontal Jumping Distance, Maximum Isometric Muscle Strength Test, and musculoskeletal ultrasound for patellar tendon thickness and blood flow. Assessments were conducted at baseline and post-intervention, with a follow-up VISA-P assessment at week 16. This randomized, single-blind controlled trial was registered on ISRCTN11447397 ( www.ISRCTN.com ) on February 17, 2024 (retrospectively registered).

RESULTS

All groups demonstrated significant improvements in VISA-P scores at the end of the intervention compared to baseline (p < 0.01), with the combined group showing the greatest improvement (21 points). Follow-up at week 16 revealed continued improvement in VISA-P scores for the combined and HSR groups, while the TUS group showed a slight decrease (from 74 to 70). All groups displayed significantly reduced VAS scores post-intervention (p < 0.01) compared to baseline, indicating decreased pain. While no significant between-group differences were observed in pre-intervention VAS scores, post-intervention results revealed significant differences between the combined and HSR groups (p < 0.05), as well as between the combined and TUS groups (p < 0.01).

CONCLUSION

Both exercise intervention and high-dose TUS appear effective in reducing pain and improving motor function in individuals with PT. However, the therapeutic effect of high-dose TUS alone seems limited compared to exercise intervention. The combined application of both methods yielded the most significant improvements in pain relief and motor function enhancement.

Effect of two quadriceps strengthening protocols on morphological characteristics of knee vastus muscles in patients with lateral patellar compression syndrome

INTRODUCTION

The purpose of this study is to compare the effect of two types of quadriceps strengthening protocols on morphological characteristics of the knee vastus muscles in patients with lateral patellar compression syndrome.

METHODS

48 female patients were randomly divided into 3 groups: selective (16), general (17) and control (15). The selective group participated in an isokinetic knee extension training protocol at the last 30° knee extension arc with maximum leg external rotation at high speed with the aim of selectively strengthening the vastus medialis muscle. The general group participated in an exercise protocol aimed at strengthening the entire quadriceps muscle. Both these protocols lasted 8 weeks. The control group did not receive any intervention. The vastus medialis and lateralis muscles cross-sections and fibers angles were measured using an ultrasound device. The data were analyzed using repeated-measures ANOVA and dependent t tests.

RESULTS

At pre-intervention, there were no differences between groups in muscles cross-sections and fiber angles (P > 0.05), but after interventions, in selective group, the vastus medialis cross-section and fiber angle, as well as vastus medialis to vastus lateralis cross-section ratio, were significantly higher than other groups (P < 0.01). Also, compared to pre-intervention, the vastus medialis cross-section and fiber angle increased only in selective group (P = 0.001), and the vastus lateralis cross-section increased only in general group (P = 0.001).

DISCUSSION AND CONCLUSION

Use of isokinetic extension exercises targeting selectively strengthening the vastus medialis can improve the activity and involvement of this muscle-which is impaired in chronic patellofemoral joint disorders - by changing its morphology.

Molecular mechanisms of cancer cachexia. Role of exercise training

Cancer-associated cachexia represents a multifactorial syndrome mainly characterized by muscle mass loss, which causes both a decrease in quality of life and anti-cancer therapy failure, among other consequences. The definition and diagnostic criteria of cachexia have changed and improved over time, including three different stages (pre-cachexia, cachexia, and refractory cachexia) and objective diagnostic markers. This metabolic wasting syndrome is characterized by a negative protein balance, and anti-cancer drugs like chemotherapy or immunotherapy exacerbate it through relatively unknown mechanisms. Due to its complexity, cachexia management involves a multidisciplinary strategy including not only nutritional and pharmacological interventions. Physical exercise has been proposed as a strategy to counteract the effects of cachexia on skeletal muscle, as it influences the mechanisms involved in the disease such as protein turnover, inflammation, oxidative stress, and mitochondrial dysfunction. This review will summarize the experimental and clinical evidence of the impact of physical exercise on cancer-associated cachexia.

Long-Term Resistance Trained Human Muscles Have More Fibers, More Myofibrils, and Tighter Myofilament Packing Than Untrained

INTRODUCTION

Increases in skeletal muscle size occur in response to prolonged exposure to resistance training that is typically ascribed to increased muscle fiber size. Whether muscle fiber number also changes remains controversial, and a paucity of data exists about myofibrillar structure. This cross-sectional study compared muscle fiber and myofibril characteristics in long-term resistance-trained (LRT) versus untrained (UNT) individuals.

METHODS

The maximal anatomical cross-sectional area (ACSAmax) of the biceps brachii muscle was measured by magnetic resonance imaging in 16 LRT (5.9 ± 3.5 yr' experience) and 13 UNT males. A muscle biopsy was taken from the biceps brachii to measure muscle fiber area, myofibril area, and myosin spacing. Muscle fiber number, and myofibril number in total and per fiber were estimated by dividing ACSAmax by muscle fiber area or myofibril area, and muscle fiber area by myofibril area, respectively.

RESULTS

Compared with UNT, LRT individuals had greater ACSAmax (+70%, P < 0.001), fiber area (+29%, P = 0.028), fiber number (+34%, P = 0.013), and myofibril number per fiber (+49%, P = 0.034) and in total (+105%, P < 0.001). LRT individuals also had smaller myosin spacing (-7%, P = 0.004; i.e., greater packing density) and a tendency toward smaller myofibril area (-16%, P = 0.074). ACSAmax was positively correlated with fiber area ( r = 0.526), fiber number ( r = 0.445), and myofibril number (in total r = 0.873 and per fiber r = 0.566), and negatively correlated with myofibril area ( r = -0.456) and myosin spacing ( r = -0.382) (all P < 0.05).

CONCLUSIONS

The larger muscles of LRT individuals exhibited more fibers in cross-section and larger muscle fibers, which contained substantially more total myofibrils and more packed myofilaments than UNT participants, suggesting plasticity of muscle ultrastructure.

Muscle hypertrophy response across four muscles involved in the bench press exercise: Randomized 10 weeks training intervention

BACKGROUND AND PURPOSE

Resistance training exercise provides increases in muscle size and is used by coaches and health care professional as a tool to improve functional performance. The aim of the present study was to investigate the effect of 10 weeks of resistance training program performed on the bench press (BP) exercise on the hypertrophic responses of four different muscles (pectoralis major, anterior and medial deltoid, brachii, and pectoralis minor) involved in the task compared to controls.

METHODS

Twenty-four healthy males were recruited, and thirteen performed a resistance training intervention while eleven were control. RT group trained for 10 weeks and the protocol consisted of a time under tension for each set of 36s (3-4 sets) with 12 repetitions with an intensity of 50-55% of the 1RM, a training frequency of 3 times a week, with a 3 min rest between sets. Muscle cross-sectional area (CSA) was measure by magnetic resonance imaging.

RESULTS

Individuals in the RT group demonstrated higher changes in CSA of the pectoralis major, pectoralis minor, anterior deltoid, and triceps brachii (P ≤ 0.019) than in the Control group. It was identified in the RT group higher increases in CSA of all muscles compared to medial deltoid (P ≤ 0.016), while pectoralis major demonstrated larger increases in CSA than pectoralis minor and triceps brachii (P ≤ 0.030).

CONCLUSIONS

We demonstrated that 10 weeks of resistance training performed on the BP exercise led to increases in muscle size of the muscles involved in the task, but not in the same magnitude.