The Importance of Muscular Strength in Athletic Performance

Effects of variable resistance training with different load ratios on lower-limb strength and power in male college students

Objective

The optimum relationship combination of variable to constant resistance within variable resistance training (VRT) for enhancing lower-limb strength and power remains unclear. This study aimed to investigate how different ratios of variable to constant resistance in VRT affect lower-limb strength and power.

Methods

Forty-five male college students (age: 21.65 ± 2.20 years; height: 179.65 ± 4.98 cm; body mass: 77.21 ± 6.77 kg; resistance training experience: 3.00 ± 0.96 years) were randomly assigned to three groups: 20 % VRT (n = 15), 35 % VRT (n = 15), and constant resistance training (CRT, n = 15). All groups trained squats twice weekly for 6 weeks at 80 % 1RM total load (20 % VRT: 20 % variable resistance combined 80 % constant resistance; 35 % VRT: 35 % variable resistance combined 65 % constant resistance; CRT: 100 % constant resistance). Pre- and post-experiment tests included squat 1RM, countermovement jump (CMJ), squat jump (SJ), standing broad jump (SBJ), 20-m sprint, and rectus femoris cross-sectional area (RFCSA). A mixed-design ANOVA (group × time) was used for data analysis.

Results

The 20 % VRT group surpassed CRT in maximal strength cross-sectionally (F = 3.565, p = 0.037) but not longitudinally (p = 0.079). All groups improved strength over time (p < 0.001; Cohen's d = 0.87-0.94). A significant interaction (F = 3.407, p = 0.043) indicated SJ improvement for 35 % VRT vs. CRT (p < 0.05, Cohen's d = 0.43), with no CMJ, SBJ, sprint, or RFCSA differences (p > 0.05).

Conclusion

VRT and CRT yield equivalent long-term strength gains. Different combinations of variable to constant resistance ratios in VRT (20 % and 35 %) led to distinct task-specific adaptations in lower-limb performance. Practitioners should prioritize 35 % VRT for static explosive tasks, use 20 % VRT as a supplementary strength tool.

Impact of a 6-week foot tapping training program on lower limb strength, sprinting, jumping, and change of direction ability in soccer players

This study aimed to evaluate the effects of a 6-week foot tapping training program (TAP-Training) on enhancing lower limb strength, sprinting, jumping, and change of direction ability in soccer players. Twenty-two soccer players were randomly assigned to either the TAP-Training group (TAP-TG, N = 11), which underwent the 6-week TAP-Training program, or the control group (CG, N = 11). Pre- and post-training assessments included jumps, sprints, the foot tapping test (TAP-test), and the change of direction test (MICOD), which were compared within and between groups. Significant improvements were observed post-training only in TAP score (p < 0.01) and MICOD performance (p < 0.05) within the TAP-TG. This indicates a positive impact of the neuromuscular frequency training program on TAP scores and change of direction performance. Conversely, no significant differences were noted in any parameters for the CG (p > 0.05) between pre-and post-training assessments. Furthermore, post-training comparisons between groups revealed statistically significant differences favoring the TAP-TG in TAP score and MICOD performance (p < 0.01). In conclusion, a 6-week TAP neuromuscular training program positively influences the change of direction performance and TAP scores in soccer players.

Comparison of physical characteristics among english professional and semi-professional soccer players across different leagues

The purpose of the present study was to investigate if differences exist in neuromuscular qualities between different leagues in English male soccer. Twenty soccer players (age: 23.3 ± 5.2 years, stature: 180.3 ± 7.0 cm, mass: 82.5 ± 7.7 kg) from English football league two (EFL2). 34 soccer players (age: 25.8 ± 4.3 years, stature: 180.9 ± 5.6 cm, mass: 81.4 ± 8.6 kg) from National league (NL) and 23 soccer players (age: 27.5 ± 4.3 years, stature: 182.1 ± 5.5 cm, mass: 84.1 ± 8.0 kg) from National league North (NLN). Each player completed three to five repetitions of the countermovement jump (CMJ), countermovement rebound jump (CMJRJ) and isometric mid-thigh pull (IMTP). Trivial to small differences were observed in CMJ jump height, CMJ momentum, relative average braking and propulsion force, time to take-off and modified reactive strength index (RSI) (p > 0.265, d = 0.05-0.55). However, moderate to large (p ≤ 0.009, d = 0.94-1.25) differences were observed in countermovement depth. Trivial to moderate differences were observed in absolute and relative peak net force and force at 100 and 250 ms (p ≥ 0.092, d = 0.13-0.63). Trivial to moderate differences were observed in CMJRJ rebound jump height and rebound jump momentum (p ≥ 0.440, d = 0.17-0.41). NLN players had longer rebound contact time and lower rebound RSI, rebound average relative braking and propulsion forces to a large magnitude (p ≤ 0.001, d = 1.18-1.85), with small differences between ELF2 and NL (p > 0.536, d = 0.11-0.39). Lower reactive qualities of NLN players could explain observed leagues, considering their relationship with match scoring situations. All players would be considered weak (<30 N/kg) and practitioners should prioritise lower limb strength across all leagues.

Maximizing sprint performance among adolescent sprinters: a controlled evaluation of functional, traditional, and combined training approaches

Background

Sprint performance plays a crucial role in competitive sports, particularly among adolescent athletes. Training methodologies such as Functional Training (FT), Traditional Training (TT), and a Combined Training (CT) approach have been widely implemented to improve sprinting ability, agility, and coordination. However, the comparative effectiveness of these methods remains inconclusive. This study aims to evaluate the differential impact of FT, TT, and CT on key physiological and skill-related performance variables in adolescent sprinters.

Methods

A total of 52 national-level adolescent sprinters (aged 15-18 years) were randomly assigned to four groups: Functional Training Group (FTG, n = 13), Traditional Training Group (TTG, n = 13), Combined Training Group (CTG, n = 13), and Control Group (CG, n = 13). The intervention lasted for 8 weeks, with training sessions conducted 6 days a week. Sprint performance, agility, coordination, VO₂ max, muscular strength, and body fat percentage were assessed pre- and post-intervention. A repeated-measures ANOVA was used to analyze within- and between-group differences, with significance set at p < 0.05.

Results

Combined Training Group demonstrated the most significant improvements across all performance variables, including VO₂ max (+4.32%), muscular strength (+8.93%), and sprinting ability (-4.71%). FTG showed substantial gains in agility (-2.16%) and coordination (+4.40%), whereas TTG exhibited moderate improvements in strength (+1.43%) and sprint time (-2.18%). The CG group showed no significant changes. Statistical analysis confirmed a significant main effect of training interventions (F = 72.34, p < 0.001, η 2 p = 0.81), highlighting the superior efficacy of CTG.

Discussion

The findings suggest that a combined approach integrating FT and TT yields optimal improvements in sprint performance by enhancing both neuromuscular coordination and force production. While FT alone is effective in refining agility and coordination, TT primarily contributes to strength gains. The absence of structured training in the CG reinforces the necessity of targeted interventions for performance enhancement. These results provide valuable insights for coaches and sports scientists in designing sprint training programs for adolescent athletes. Future studies could explore the long-term effects of combined FT and TT interventions across different age groups and genders to assess their generalizability.

The impact of core training on overall athletic performance in different sports: a comprehensive meta-analysis

BACKGROUND AND OBJECTIVES

Despite widespread implementation of core training in athletic preparation, evidence regarding its effectiveness across different sports and performance domains remains fragmented. This meta-analysis examined the effects of core training on athletic performance across multiple sports, addressing limitations of previous analyses that focused on single sports or limited performance measures.

METHODS

Following PRISMA guidelines, we conducted a systematic review across five databases (PubMed, Web of Science, Scopus, SPORTDiscus, and Google Scholar). We assessed methodological quality using the PEDro scale and risk of bias using the Cochrane tool. Eligibility criteria included randomized controlled trials published between 2014-2024 involving healthy athletes aged 15-25 years, with core training as the primary intervention.

RESULTS

From an initial 1,670 records identified, 29 studies met rigorous inclusion criteria, comprising 956 athletes aged 15-23 years. Core training demonstrated significant improvements in general athletic performance (SMD = 1.38, 95% CI [0.85, 1.82], p < 0.001), with notably strong effects on core endurance (SMD = 1.32, 95% CI [0.57, 2.08], p < 0.004) and balance (SMD = 0.99, 95% CI [0.29, 1.69], p = 0.01). Core training revealed a moderate but insignificant effects on sport-specific performance (SMD = 0.62, 95% CI [-0.08, 1.31], p = 0.084). The analysis revealed non-significant effects sport-specific outcomes: speed (SMD = -0.28 [-0.86, 0.31], p = 0.28); maximal strength (SMD = 7.57 [-7.75, 22.89], p = 0.27); flexibility (SMD = 0.48 [-0.76, 1.73], p = 0.3); change of direction (SMD = 0.10 [-0.56, 0.76], p = 0.69); technical skill performance (SMD = 0.71 [-4.38, 5.81], p = 0.75); throwing velocity/distance (SMD = 1.52 [-0.43, 3.48], p = 0.1) and vertical jump height (SMD = 0.90 [-0.23, 2.03], p = 0.1). The high heterogeneity across outcomes (I2 = 37-100%) indicates that training responses vary substantially depending on competitive level, intervention duration, and sport-specific contexts, suggesting the need for carefully tailored core training approaches.

CONCLUSION

This analysis demonstrates that core training effectively improves foundational athletic qualities but shows variable effects on sport-specific performance measures. The findings suggest core training should be integrated with sport-specific training for optimal performance enhancement. Future research should address the high heterogeneity observed by implementing standardized protocols and examining long-term training effects.

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.

Exploring the Use of 5 Different Yo-Yo Tests in Evaluating V ̇ O 2 max $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$ and Fitness Profile in Team Sports: A Systematic Review and Meta-Analysis

This review aims to examine the relationship between five different Yo-Yo tests andV ̇ O 2 max $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$ as well as performance in various fitness tests, to provide practical guidance for fitness assessment. Thirty-three studies (n = 1362) were analyzed to qualitatively score correlation magnitude (r-values) between five different Yo-Yo tests withV ̇ O 2 max $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$ . The association between Yo-Yo tests and physical fitness tests were examined including 36 studies (n = 1262 participants). Large correlations were found betweenV ̇ O 2 max $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$ and Yo-Yo Intermittent Endurance level 1 (r = 0.67), and level 2 (r = 0.67), Yo-Yo Intermittent Recovery level 1 (r = 0.65), and level 2 (r = 0.55). Yo-Yo tests showed moderate correlations with the jump tests (r = 0.40). Large associations were reported between Yo-Yo tests performance and treadmill endurance test (r = 0.59) and the field-based endurance tests (r = 0.66), respectively. These findings confirm Yo-Yo tests as reliable and valid tests for estimatingV ̇ O 2 max $$ \dot{\mathrm{V}}{\mathrm{O}}_{2\max } $$ and endurance performance in team sports, supporting their integration in structured testing batteries. Coaches should supplement Yo-Yo tests with specific strength and sprint assessments for a comprehensive fitness evaluation of the team sport athletes.

Can the velocity profile in the bench press and the bench pull sufficiently estimate the one repetition maximum in youth elite cross-country ski and biathlon athletes?

INTRODUCTION

In recent years, load-velocity profiles (LVP) have been frequently proposed as a highly reliable and valid alternative to the one-repetition maximum (1RM) for estimating maximal strength and prescribing training loads. However, previous authors commonly report intraclass correlation coefficients (ICC) while neglecting to calculate the measurement error associated with these values. This is important for practitioners, especially in an elite sports setting, to be able to differentiate between small but significant changes in performance and the error rate.

METHODS

49 youth elite athletes (17.71±2.07 years) were recruited and performed a 1RM test followed by a load-velocity profiling test using 30%, 50% and 70% of the 1RM in the bench press and bench pull, respectively. Reliability analysis, ICCs and the coefficient of variability, were calculated and supplemented by an agreement analysis including the mean absolute error (MAE) and mean absolute percentage error (MAPE) to provide the resulting measurement error. Furthermore, validity analyses between the measured 1RM and different calculation models to estimate 1RM were performed.

RESULTS

Reliability values were in accordance with current literature (ICC = 0.79-0.99, coefficient of variance [CV] = 1.86-9.32%), however, were accompanied by a random error (mean absolute error [MAE]: 0.05-0.64 m/s, mean absolute percentage error [MAPE]: 2.7-9.5%) arising from test-retest measurement. Strength estimation via the velocity-profile overestimated the bench pull 1RM (limits of agreement [LOA]: -9.73 - -16.72 kg, MAE: 9.80-17.03 kg, MAPE 16.9-29.7%), while the bench press 1RM was underestimated (LOA: 3.34-6.37 kg, MAE: 3.74-7.84 kg, MAPE: 7.5-13.4%); dependent on used calculation model.

DISCUSSION

Considering the observed measurement error associated with LVP-based methods, it can be posited that their utility as a programming strategy is limited. The lack of accuracy required to discriminate between small but significant changes in performance and error, coupled with the potential risks of under- and overestimating 1RM, can result in insufficient stimulus or increased injury risk, respectively. This further diminishes the practicality of these methods, particularly in elite sports settings.

Exploring turn demands of an English Premier League team across league and knockout competitions over a full season

Turns are key performance actions in soccer, but can also induce high mechanical loads resulting in tissue damage or injury. This study aimed to quantify the turn demands of an elite English Premier League soccer team. Turning data were obtained from 49 soccer matches (2022-23 season), from a single team that played 35 Premier League, 5 UEFA Europa League, 5 League Cup and 4 FA Cup matches using Sportlight LiDAR technology. Turns were analysed from 29 players who were categorised in playing position groups: goalkeeper (GK), central defenders (CD), full-backs (FB), central-midfielders (CM), wide-midfielders (WM), central-forwards (CF). Turn categories: high (120-180°), medium (60-119°) and low (20-60°) angled, and very high (>7.0ms-1), high (5.5-7.0ms-1), medium (3.0-5.5ms-1), and low (<3.0ms-1) entry speed (ES) was analysed. Primary findings show, on average, per match, CM performed more total turns (~35), than all other playing positions. Additionally, CM performed significantly more low and medium entry speed and high angled turns than other outfield positions. There were no significant differences between turn frequencies and turn characteristics in different competitions (p >0.05). The turning demands of soccer appear to vary significantly between player position. These findings may help inform position-specific return-to-play protocols, physical preparation strategies, drill design and rehabilitation programmes.

Acute effects of optimal power load flywheel half-squat training on lower limb explosive power under different load volumes

Background

To explore the effects of flywheel half-squat interventions with different volumes of optimal power load (OPL) on post-activation performance enhancement (PAPE) in countermovement jump (CMJ) height and 30 m sprint performance among collegiate athletes.

Methods

A randomized crossover design was employed, recruiting 20 collegiate athletes to participate in the experiment. After determining each participant's OPL, four different training load schemes were arranged for eight formal experiments, including four CMJ tests and four 30 m sprint tests. The differences between baseline and post-intervention at 0, 4, 8, and 12 min were compared. A two-factor repeated measures ANOVA was used for data analysis, with a significance level set at P < 0.05, and Cohen's d value was used to represent the effect size (ES).

Results

(1) The improvement in CMJ height for different flywheel half-squat load volumes peaked at 8 min of recovery. In terms of ES, the improvement was Group B > Group C > Group A. (2) The improvement in 30 m sprint speed for Group A peaked at 4 min post-intervention, while the improvement for Groups B and C peaked at 8 min post-intervention. In terms of ES, the improvement was Group B > Group C > Group A.

Conclusion

Using two sets × six repetitions of OPL flywheel half-squat arrangement can induce a more reliable PAPE effect compared to higher load volumes. However, when using half-squats as a pre-stimulation exercise, the PAPE effect on CMJ height is superior to that on 30 m sprint speed.

Effect of 6-week single leg countermovement jump training on force time metrics in elite female youth footballers

Female football participation has grown exponentially. Unfortunately, females exhibit greater injury risk than male athletes, and experience increased mechanical stress during adolescence. Force plates provide accurate and reliable force-time characteristics enabling profiling of injury risk and benchmarking using a variety of jump and isometric tasks. The purpose of this study was to determine whether test-retest reliability and force-time characteristics of SLCMJ, bilateral countermovement jump (CMJ), countermovement rebound jump (CMJ-R) and isometric mid-thigh pull (IMTP) change with six weeks of SLCMJ training. Twenty-eight elite youth female footballers (13.7 ± 1.1 years, 53.27 ± 8.82 kg, 162.20 ± 5.37 cm) completed six weeks of SLCMJ as part of a routine strength and plyometric training program. SLCMJ training did not influence test-retest reliability and resulted in favourable adaptations indicated through small to large changes in force-time characteristics for SLCMJ. Significant (p < 0.05) yet trivial to small favourable changes were observed for the CMJ and CMJ-R, with small increases observed for IMTP. The results of this study demonstrate that six weeks of SLCMJ training does not influence phase-specific test-rest reliability (i.e. braking and propulsion) and causes weekly fluctuations in force-time characteristics leading to improvements in SLCMJ, CMJ, CMJ-R and IMTP. Practitioners can use such information to inform training design and monitor athlete performance.

The Role of High-Intensity Interval Training (HIIT) in Neuromuscular Adaptations: Implications for Strength and Power Development-A Review

High-intensity Interval Training (HIIT) is increasingly recognized for enhancing neuromuscular function, strength, power, and overall athletic performance. This review systematically examined peer-reviewed studies published between 2000 and 2025, focusing on HIIT's impact on motor unit recruitment, muscle fiber composition, neuromuscular efficiency, maximal strength, rate of force development (RFD), muscle hypertrophy, and power output. Findings indicate that HIIT significantly improves neuromuscular activation by increasing motor unit recruitment and synchronization, particularly in fast-twitch fibers essential for explosive movements. HIIT also promotes shifts toward Type II and hybrid Type IIa fibers, enhancing strength and endurance. However, despite its effectiveness in boosting RFD and explosive power, HIIT is less efficient than traditional resistance training for maximizing absolute strength and hypertrophy due to insufficient progressive overload. Integrating resistance-based and plyometric-based HIIT protocols emerged as an effective strategy to enhance strength and power concurrently. Effective periodization and recovery strategies, including active recovery and targeted nutrition, help mitigate fatigue and optimize adaptations. Notable research gaps include the long-term impacts of HIIT on neuromuscular function and the efficacy of individualized HIIT protocols based on specific athlete characteristics. Future research should focus on refining HIIT protocols for different sports, exploring its synergy with traditional resistance training, and assessing long-term adaptations to sustain strength and power gains. HIIT presents a valuable, time-efficient complement to conventional training methods for improving strength, power, and neuromuscular efficiency.

Influence of Resistance Training Variables and the Nordic Hamstring Exercise on Biceps Femoris Architectural Adaptations in Soccer Players: A Systematic Review

CONTEXT

Manipulation of resistance training variables influences the structural and functional adaptations of muscle, having a great impact on sport performance and hamstring injury prevention.

OBJECTIVE

To analyze how the main resistance training variables affect the biceps femoris long head architecture in soccer players.

DATA SOURCES

Five databases were searched from inception to January 2024.

STUDY SELECTION

Studies that included training intervention groups and measured muscle architecture adaptations before and after the training program in soccer players were included.

STUDY DESIGN

Systematic review with meta-analysis.

LEVEL OF EVIDENCE

Level 2.

DATA EXTRACTION

Muscle thickness, fascicle length, and pennation angle were extracted from included studies as main outcomes.

RESULTS

Six studies and 12 training groups (168 participants) were analyzed. The effects of Nordic hamstring exercise (NHE) against soccer interventions, volume of training, and frequency of training as independent variables were analyzed. NHE significantly improved biceps femoris long head fascicle length (P = 0.01). Training twice a week did not show significant differences compared with training once a week. Higher volumes of training (ie, >290 repetitions) in a period of 6 to 12 weeks with 57 repetitions per week demonstrated significant effects.

CONCLUSION

NHE lengthens the fascicle, especially if a sufficient volume (ie, >290 repetitions) and 2 days per week are performed. It is still unknown how the programming of some fundamental variables such as intensity, degree of effort, or exercise selection affects the muscle architecture of the biceps femoris long head.

Effect of two training modalities on sprint performance in young American football players

Background

Time to perform 40-yard dash (40-yd) is a performance criterion in American football. Sprinting ability is strongly correlated with maximal values of horizontal power (PHmax), Force (FH0) and Velocity (VH0). While numerous methods for developing sprint speed exist, few studies have focused on the effects of periodizations on the sprinting mechanical variables in young talented American football players.

Objective

this study aimed to compare the effects of block (BP) and undulating (UP) training periodization modalities on 40-yard dash performance.

Method

27 players from the Young French League of American football (17.1 ± 0.9 y, 179.9 ± 5.5 cm, 81.1 ± 14.9 kg) were randomly assigned in either the BP (n = 15) or UP (n = 12) group. Anthropometric characteristics, 40-yd performance, maximal velocity (Vmax), PHmax, FH0 and VH0 were assessed before and after 10-wk intervention period.

Results

Training resulted in the 40-yd performance increase of 3.72% (p < 0.001) and significant changes in Vmax (+ = 6.13 ± 5.62%, p < 0.001) and VH0 values (+2.68 ± 4.14%, p = 0.004). BP intervention leaded higher improvements in time to perform 40-yd (4.45 ± 2.06 vs. 3.02 ± 1.93%, p < 0.001) and Vmax (7.30 ± 6.63% vs. 4.54 ± 4.10%, p = 0.002,) compared to UP. No periodization effect was found in changes of VH0 (BP: 3.42 ± 4.31% vs. UP: 1.48 ± 3.88, p = 0.214).

Conclusion

Our results showed that BP and UP were effective to increase sprint performance. Despite a similar training load, the block periodization of training had better effects on 40-yd performance compared to undulating training periodization in this population of talented young American football 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.

Blood Flow Restriction Training: A Tool to Enhance Rehabilitation and Build Athlete Resiliency

Blood flow restriction training (BFRT) is a tool utilized in rehabilitation and injury prevention to improve muscle strength and size, particularly in load-compromised individuals. BFRT facilitates gains in muscular strength and hypertrophy at lower loads, allowing for accelerated recovery and less disuse atrophy. BFRT must be applied appropriately and with caution, particularly in individuals with cardiovascular concerns. There are applications for BFRT across a wide spectrum of human performance training and in rehabilitation of both lower and upper extremity conditions, providing a high-quality adjunct to improve muscle strength, power, and endurance.

Level of Evidence

Level V, expert opinion.

Comparison of Optimal Drop Heights in 2 Drop-Jump Exercises for Basketball Athletes With Differing Strength Levels

PURPOSE

Previous research has primarily focused on bounce drop jump (BDJ) rather than countermovement drop jump (CDJ) in studying optimal drop heights for drop jump. This study explored the biomechanic parameters of both BDJ and CDJ and their relationship with performance across varying drop heights based on the percentage of squat-jump height (SJH).

METHODS

Twenty-four college basketball athletes were recruited and divided into low- and high-strength groups. Participants performed BDJ and CDJ at 50%, 75%, 100%, 125%, 150%, and 175% of SJH. The point or zone with the largest reactive strength index (RSI) corresponds to the optimal drop height for a drop jump.

RESULTS

Optimal drop heights were determined to be 84.7% of SJH for BDJ low strength and 84.1% of SJH for BDJ high strength, with no significant difference between groups (P = .213). For CDJ, relative optimal drop heights were 104.6% of SJH for CDJ low strength and 106.1% of SJH for CDJ high strength, also with no significant difference (P = .717). Mechanical power with RSI exhibited a coefficient close to 1 (r = .98-.99), while average propulsive force demonstrated a very strong positive correlation with RSI (r = .72-.77).

CONCLUSIONS

It is recommended that basketball athletes incorporate particular percentages of SJH into drop jump, with 75% to 100% of SJH for BDJ and 100% to 125% of SJH for CDJ, as these heights are associated with achieving an optimal RSI and mechanical power. Tailoring the inclusion of BDJ or CDJ in training should account for the specific demands of on-court positions and task objectives for basketball players.

The relationship between countermovement jump force-time characteristics and 2,000-m rowing ergometer performance

Background

Rowing is a strength-endurance sport. The Olympic race distance of 2,000-m (2k) requires extensive aerobic and anaerobic energy system contributions, along with sustained high force output.

Aims

The primary aim of this study was to evaluate the relationship between rowing ergometer (erg) performance and the force-time curve characteristics of a counter-movement jump (CMJ), and to determine if rowing-related low back pain (LBP) affected these relationships.

Methods

Athletes completed a 2k time trial at the 2023 USRowing Atlantic City Indoor National Championships as well as a CMJ on force plates. Data from the 2k (n = 27) time trial was analyzed to determine significant relationships between CMJ force-time characteristics and 2k rowing ergometer performance. Partial correlations were used to determine the effects rowing-related LBP has on the relationship between 2k erg and CMJ force-time curve characteristics.

Results

Positive Take-off Impulse had the strongest correlation with 2k erg performance (r = 0.71, p < 0.001). Jump height was not significantly related to 2k erg performance (r = -0.13, p = 0.518). Current LBP changed the relationship for Concentric Mean Force (r = 0.74, p < 0.001).

Conclusion

Positive Take-off Impulse has a strong, positive relationship to 2k erg performance. CMJ variables related to impulse and force should be monitored longitudinally to see if changes in these variables coincide with improved 2k rowing erg performance and the assessment of neuromuscular fatigue. Coaches can utilize these findings to individualize strength and power training for potential 2k erg performance improvements.

Quantifying the Effects of Detraining on Female Basketball Players Using Physical Fitness Assessment Sensors

This study leverages physical fitness assessment sensors to investigate the effects of a brief in-season break (detraining period) on the physical performance of female basketball players. Sixty-seven players (Senior (n = 19), U18 (n = 19), and U14 (n = 29)) were evaluated before and after a 3-week break using sensor-derived data from a countermovement jump (CMJ), an Abalakov jump (ABK), a linear speed test (20 m sprint), a seated medicine ball throw test (SMBT), and a Basketball-Specific Agility Test (TEA-Basket). The Total Score of Athleticism (TSA), computed as the mean Z-Score across tests, served as a composite indicator of physical fitness. Data obtained from performance sensors revealed significant interactions between time and category for the CMJ, ABK, 20 m sprint, and SMBT, while TEA-Basket measurements showed no significant changes. Time and baseline fitness level interactions were also significant for the CMJ, ABK, and SMBT but not for sprint time or the TEA-Basket. Despite observed declines in explosive strength, speed, and upper-body power across all groups, TSA scores remained stable. These findings underscore the utility of sensor-based evaluation methods in highlighting the adverse effects of short-term detraining and emphasize the necessity of tailored training strategies during competitive breaks.

Lower body strength and body composition in female football

Lower-body strength plays a crucial role in football performance and injury prevention, and thus, monitoring of strength variables has become crucial in the training process. This study aims to (1) assess knee muscle strength performance through intra- and inter-limb asymmetries and (2) examine the relationships between knee muscle strength, body composition, and vertical jump performance (squat jump and countermovement jump). Twenty-seven semiprofessional female football players (21.5 ± 4.9 years) were evaluated for body composition, isokinetic knee muscle strength (60º/s and 180º/s), and vertical jump tasks. Peak torque (PT), peak torque/body weight (PT/BW), bilateral strength deficit, and the hamstring-to-quadriceps strength ratio (H/Q) for knee extensors (KE) and flexors (KF) in both the preferred and non-preferred legs. The H/Q ratio and the bilateral strength deficit revealed no significant intra- or inter-limb asymmetries in knee muscle strength. Strong correlations were found between vertical jump performance and KE strength at both 60º/s (p ≤ 0.01) and 180º/s (p ≤ 0.01). Additionally, a significant negative correlation was observed between vertical jump performance and body fat percentage (p ≤ 0.01). These findings highlight the critical role of knee muscle strength in explosive tasks and underline the negative impact of higher body fat on lower-body strength performance.

Twenty-five years of blood flow restriction training: What we know, what we don't, and where to next?

Blood flow restriction is a technique that involves inflating a cuff at the proximal portion of the limb with the goal of reducing arterial inflow into the muscle and venous outflow from the muscle. Low-load or low-intensity exercise in combination with blood flow restriction has been consistently shown to augment adaptations over the same/similar exercise without restriction, with changes in muscle size and strength being two of the most commonly measured adaptations. The purpose of this manuscript is to provide an updated narrative review on blood flow restriction. Blood flow restriction's history, methodology, safety, and efficacy are highlighted. We discuss the effects of blood flow restriction on changes in muscle size and strength, and also review work completed on other variables (e.g. bone, resting blood flow, tendon, pain sensitivity, cognition, orthostatic intolerance). We finish by highlighting six possible areas for future research: 1) identifying mechanisms for growth and strength; 2) sex differences in the effects of blood flow restriction; 3) individual responses to blood flow restriction; 4) influence of pressure versus amount of blood flow restricted; 5) application of blood flow restriction with higher-loads; and 6) what considerations should be made to test the effects of blood flow restriction.

Effect of Post-Activation Performance Enhancement in Combat Sports: A Systematic Review and Meta-Analysis-Part I: General Performance Indicators

Background/Objectives: Post-activation performance enhancement (PAPE) has been explored for its potential to improve general performance in combat sports. This systematic review and meta-analysis investigated the effects of PAPE protocols on physical performance, focusing on differences across disciplines, competitive levels, and testing methods. Methods: A PRISMA-guided search (2010-2023) identified 19 studies examining PAPE protocols in combat sports athletes. The inclusion criteria required human trials using defined PAPE protocols, with outcomes of general performance indicators such as countermovement jumps (CMJs). A meta-analysis was conducted on data from 866 athletes using random effects modeling. Results: The PAPE protocols yielded a pooled effect size of 0.136 (95% CI, 0.008-0.263) across 866 athletes. Taekwondo athletes exhibited the most pronounced improvements in CMJ performance, particularly when using protocols that combined repeated vertical jumps with heavy-resistance cluster sets, and with dynamic, sport-specific movements such as the bandal chagui protocol achieving an effect size of 1.19 (p < 0.001). Conversely, Muay Thai athletes experienced performance declines when the protocols incorporated highly specific techniques, such as roundhouse kicks (ES = -1.36, p = 0.009). Analysis by competitive level revealed pooled effect sizes of 0.14 (95% CI, -0.01 to 0.29) for amateur athletes and 0.13 (95% CI, -0.11 to 0.38) for elite athletes, with no statistically significant differences observed between these groups. Conclusions: PAPE's effectiveness depends on tailoring protocols to the competitive level and discipline. Short rest intervals support plyometric protocols for amateurs, while heavy-resistance exercises enhance elite performers. Further research is needed to standardize PAPE protocols and explore discipline-specific adaptations.

Biomechanical Changes and the Time Course of Recovery in Lower Extremities of Recreational Runners Following a Simulated Treadmill Half-Marathon

BACKGROUND

Providing runners with injury prevention suggestions from a biomechanical perspective is crucial in light of the increased incidence of running-related injuries forecasted with the rising popularity of the half-marathon. Previous research has demonstrated associations between running injuries and patterns of lower extremity biomechanics, as well as indicating that inadequate rest between training sessions can result in injuries and underperformance. However, whether half-marathon running elicits lower extremity biomechanical changes and the recovery time remains largely unclear. This study aimed to investigate the acute changes (pre-run and immediately post-run) and the time course of recovery (pre-run, day 1, and day 2) in neuromuscular function, landing strategies, and lower extremity joint mechanics of recreational runners following a simulated half-marathon protocol on a treadmill.

RESULTS

Compared to pre-half-marathon measurements, we observed significant reductions in concentric (Flexors: Pre: 1.49 ± 0.50Nm/kg, Post: 1.34 ± 0.54Nm/kg, p < 0.001; Extensors: Pre: 2.19 ± 0.73Nm/kg, Post: 2.00 ± 0.82Nm/kg, p < 0.001) and eccentric (Flexors: Pre: 1.67 ± 0.68Nm/kg, Post: 1.34 ± 0.62Nm/kg, p < 0.001; Extensors: Pre: 2.44 ± 0.13Nm/kg, Post: 1.96 ± 0.12Nm/kg, p < 0.001) torques of the knee flexors and extensors, reductions in eccentric knee flexor to concentric knee extensor torque ratios (Pre: 0.78 ± 0.27, Post: 0.68 ± 0.22, p < 0.001), and impaired knee (Pre: 1.6 ± 0.1°, Post: 3.0 ± 0.2°, p < 0.001) and hip (Pre: 1.5 ± 0.2°, Post: 2.6 ± 0.2°, p < 0.001) joint position sense immediately post running. Additionally, we observed an increase in contact time (p = 0.006), decreases in peak vertical ground reaction force (p < 0.001) and impulse (p < 0.001), and changes in lower extremity joint kinematics and kinetics during the stance phase of running immediately after the half-marathon. Most measured parameters recovered within one day, except hip joint position sense, which was restored within two days. By the second day, we also observed super-compensation in thigh muscle torques.

CONCLUSION

The study revealed that simulated treadmill half-marathon induces alterations to neuromuscular function, impacts landing strategies, and elicits changes in lower extremity joint mechanics. However, these effects are temporary and resolve within two days post-run. These findings provide valuable insights to optimize training responses and prevent overtraining in recreational runners.

Predicting Multijoint Maximal Eccentric and Concentric Strength With Force-Velocity Jump Mechanics in Collegiate Athletes

PURPOSE

Maximal muscle strength is often assessed with single-joint or repetition-maximum testing. The purpose of this study was to evaluate the reliability of countermovement-jump (CMJ) velocity-load testing and assess the relationship between CMJ velocity-load kinetics and concentric-isometric-eccentric multijoint leg-extension strength tested on a robotic servomotor leg press in trained athletes.

METHODS

University athletes (N = 203; 52% female) completed 3 concentric, isometric, and eccentric maximum voluntary leg-extension contractions on the robotic leg press, followed by CMJ velocity-load testing with an additional external load of 0% (CMJBW), 30% (CMJ30), and 60% (CMJ60) of body mass. A linear model was fit for the CMJ takeoff velocity-load relationship to obtain the load intercept. Force-velocity parameters were obtained for the CMJ eccentric deceleration and concentric phases. Linear mixed-effects models were constructed to predict concentric, isometric, and eccentric leg-press force using the CMJ takeoff velocity-load relationship and CMJ kinetics.

RESULTS

Isometric leg-press strength was predicted by load intercept and sex (P < .001, R2 = .565, prediction error = 14%). Concentric leg-press strength was predicted by load intercept, CMJ60 concentric impulse, and sex (P < .001, R2 = .657, prediction error = 10%). Eccentric leg-press strength was predicted by minimum downward velocity, CMJ60 eccentric deceleration impulse, and sex (P < .001, R2 = .359, prediction error = 14%).

CONCLUSIONS

Given the relevance of muscle-strength testing for sport performance and injury prevention, assessing force-velocity mechanics with loaded CMJ testing is a reliable and viable approach to predict maximal concentric, isometric, and eccentric leg-press strength in competitive athletes.

Trends in body mass between finalist teams in the Japanese collegiate rugby union championship: a 15-year analysis

This study examined the relationship between body mass and match outcomes among university rugby players in a Japanese collegiate rugby union championship over a 15-year period (2008-2022). Using data from 680 players across 30 finalist teams, we analyzed trends in body mass by playing position and their impact on match outcomes. No interaction was observed for body mass in matches over 15 years for all registered players (interaction [year × match], p = 0.85). Although no significant annual increase in body mass was observed across the period, the winning teams consistently had heavier players, with an average difference of 2.2 kg. The forwards of the winning teams were, on average, 3.6 kg heavier, and their reserve players for forward positions were 4.2 kg heavier than those of the losing teams. These findings emphasize that body mass is a crucial factor in determining success at university level, particularly in forward positions. This study highlights the need for further investigation of the role of body composition, physical assessments, and game-related factors to better understand the determinants of rugby performance.

A Comparison of Bilateral vs. Unilateral Flywheel Strength Training on Physical Performance in Youth Male Basketball Players

Background/objectives: This study aimed to compare the effects of bilateral and unilateral flywheel training programs on leg strength, sprint performance, jumping, and change of direction ability in young basketball players. Methods: Twenty-two youth male basketball players were randomly assigned to two groups: the unilateral group (UG; n = 11; age = 15.5 ± 0.5 years) and the bilateral group (BG; n = 11; age = 15.2 ± 0.4 years). Both groups participated in a six-week flywheel training intervention (UG: split squat; BG: half squat) alongside their regular basketball activities. Performance measures included change of direction ability (5-0-5 test), knee extension 60 degrees/s leg strength (EX60), bilateral and unilateral countermovement jump heights (CMJ, CMJL, and CMJD), reactive strength index (RSI), and 5 m and 20 m sprint times (SPR5m and SPR20m). A 2 × 2 ANOVA was used to evaluate pre- to post-intervention changes. Results: Significant interaction effects were observed for the 5-0-5 test (F = 13.27; p = 0.02), with pre-post improvements of 8.4% and 13.3% for the BG and UG, respectively. Both groups showed significant CMJ improvements (11.4%, ES = 0.69 for the BG; 14.6%, ES = 1.4 for the UG). The UG demonstrated greater unilateral jump improvements compared to the BG. Significant RSI improvements were found for both groups (BG: 19.6%, ES = 0.95; UG: 19.6%, ES = 0.77). Both groups improved on sprint performance, with the UG showing slightly larger effect sizes. Conclusions: Unilateral flywheel strength training appeared to be a more effective strategy than bilateral training for enhancing strength, sprinting, jumping, and change of direction ability in youth basketball players.

Estimation of maximum lower limb muscle strength from vertical jumps

Determining the one-repetition maximum (1RM) is crucial for organizing training loads, but it also is time-consuming, physically demanding, and poses a risk of injury. Vertical jumps are a less demanding and well-established method to test the ability of the lower limbs to generate great forces over a short time, which may allow for the estimation of 1RM in squatting. The purpose of this study was to develop a model for estimating 1RM back squat from ground reaction forces during vertical jumps. Thirteen healthy participants completed a 1RM back squat test, countermovement jumps, and squat jumps. Five kinematic and kinetic variables (e.g., peak and mean power, relative net impulse, jump height, and peak kinetic energy during various phases) were derived from ground reaction forces collected via a Kistler force plate (1000 Hz). Five out of 5 variables correlated with 1RM in countermovement jump and squat jump (ICC = .96-.98, r = .88-.95, p < .001 and ICC = .97-.99, r = .76-.90, p < .05, respectively). The most accurate stepwise regression model (adjusted R2 = .90, SEE =  13.24 kg, mean error =  7.4% of mean 1RMm, p < .001) estimated 1RM back squat based on peak kinetic energy during countermovement jumps. Estimation errors ranged from 7.4% to 10.7% of mean measured 1RM, with no differences between estimated and measured values (d <  0.01, p = .96-1.00). Estimating 1RM via jump tests may offer a practical alternative to traditional methods, reducing injury risks, testing intervals, and effort. Our study proposes a new possible approach for estimating 1RM back squat from jump forces, providing coaches and sports professionals with a more efficient tool to monitor and adjust training loads.

The effects of normobaric hypoxic resistance training on muscle strength in healthy adults

Normobaric hypoxic resistance training (NHRT) has emerged as a novel approach to enhancing muscle strength, potentially offering advantages over conventional resistance training. However, its efficacy in healthy adults remains uncertain. This systematic review and meta-analysis aimed to evaluate the effects of NHRT on muscle strength indicators, including one-repetition maximum (1RM), isometric strength, and isokinetic strength, in healthy adults.

METHODS

Following PRISMA 2020 guidelines, four databases (PubMed, Web of Science, SportDiscus, and CNKI) were searched from inception to October 25, 2024, for randomized controlled trials. Study quality was assessed using the Cochrane Risk of Bias tool. Effect sizes were calculated using Review Manager 5.4.

RESULTS

A total of 22 RCTs involving 487 healthy adults were included. The meta-analysis revealed a significant small-to-moderate improvement in 1RM (SMD = 0.22, 95% CI [0.06, 0.38]) but no statistically significant effects on isometric strength (SMD = 0.32, 95% CI [-0.05, 0.70]) and isokinetic strength (SMD = 0.25, 95% CI [-0.11, 0.62]). Subgroup analyses indicated that oxygen concentrations of 14-16% and training loads of 60-80% 1RM produced the most substantial gains, particularly among untrained participants.

CONCLUSIONS

NHRT is a promising strategy for enhancing 1RM in healthy adults, with its effectiveness influenced by hypoxic levels, training load, and baseline training status. Optimal outcomes were observed at oxygen concentrations of 14-16% and moderate training loads (60-80% 1RM), particularly in untrained individuals. Further high-quality studies are warranted to confirm these outcomes and explore the underlying mechanisms.Registration number on PROSPEROCRD42024547100.

Comparing the Effects of Integrative Neuromuscular Training and Traditional Physical Fitness Training on Physical Performance Outcomes in Young Athletes: A Systematic Review and Meta-Analysis

BACKGROUND

Enhancing youth's physical fitness levels during childhood and adolescence through prior training programs can significantly optimize their athletic performance. The integrative neuromuscular training (INT) model is designed to improve neuromuscular function and prevent athletic injuries, and is superior to the traditional physical training method. This systematic review and meta-analysis aims to compare the effects of INT versus traditional physical fitness training (PT) on physical performance-related outcomes in young athletes.

METHODS

Six online databases (PubMed, MEDLINE, Embase, SPORTDiscus, Web of Science, PsycINFO) searched from inception through 15 January 2024. Meta-analysis was performed when data were available from two or more trials. Physical performance-related outcomes were analyzed using standardized mean differences (SMDs) and mean differences (MDs) with 95% confidence intervals (CIs). The certainty of evidence and quality of the included studies were rated using the GRADE scale and the revised Cochrane risk-of-bias tool respectively.

RESULTS

Seventeen randomized controlled trials with 649 young athletes were included in the systematic review. Of those, 1 study showed a low risk of bias, 1 showed a high risk, and 15 showed some concerns. Compared to the PT group, INT significantly improved dynamic balance (MD = 7.29%, 95%CI 3.31 to 11.28, p < 0.001, I2 = 64.7%), static balance (SMD = -0.54, 95%CI -0.84 to -0.24, p < 0.001, I2 = 0.0%), jumping performance (SMD = 0.53, 95%CI 0.32 to 0.73, p < 0.001, I2 = 0.0%), sprinting capacity (SMD = -0.76, 95%CI -1.13 to -0.39, p < 0.001, I2 = 57.6%) and maximal strength (SMD = 1.01, 95%CI 0.35 to 1.67, p = 0.002, I2 = 81.9%%). No significant between-group differences were identified for agility and flexibility.

CONCLUSION

Our findings suggest that INT has the potential to be an effective training method to improve physical performance in young athletes. Moreover, further research is needed to determine the effects and associated doses for young athletes of different age groups.

Confirmation Bias in Sport Science: Understanding and Mitigating Its Impact

PURPOSE

Confirmation bias, a cognitive phenomenon deeply ingrained in human thinking, shapes our perception of reality. It leads individuals to favor information that aligns with their preexisting beliefs while dismissing or undervaluing the contrary evidence. In sport science, where precision and evidence-based practices are critical aspects to optimize performance, confirmation bias can decisively impact decision-making processes. In this context, practitioners rely on both objective and subjective data to be interpreted to enhance athletic performance. However, confirmation bias introduces a subtle yet powerful distortion, which is difficult to control and quantify. We usually believe that our observations can justify expectations or predictions about future observations, as well as broader generalizations beyond what we have directly observed-inductive inferences. Researchers and practitioners may therefore unknowingly seek out evidence that confirms their beliefs, inadvertently overlooking alternative viewpoints and interpretations.

CONCLUSIONS

This paper explores the concept of confirmation bias in sport science, providing practical examples in the contexts of testing, training, and monitoring. By understanding how confirmation bias operates (ie, heuristic of decision making), we may develop strategies to mitigate its effects and promote more accurate and effective decision making in sport science (eg, performance).

A Chinese Knowledge Graph Dataset in the Field of Scientific Fitness

To promote the development of scientific fitness research and practice, we propose the Chinese Knowledge Graph Dataset in the Field of Scientific Fitness (FitKG-CN). This knowledge graph contains over 10,000 fitness-related terms, categorized into eight main groups: body parts, items of exercise, fitness movement, equipment and tools, exercise goals, anatomical structures, nutrients, and technical terms. The construction of FitKG-CN is based on authoritative data sources, undergoing rigorous preprocessing, including noise removal, format standardization, and normalization of entities and relationships. The data is manually annotated on a professional platform and ultimately stored in a Neo4j graph database for visualization. Additionally, we trained a Chinese SpERT model using the manually annotated data to enhance the automation of data processing. The experimental results show that the model achieved an F1 score of 94.05% in entity recognition tasks and 82.00% in relation extraction tasks, validating the effectiveness of the model and improving the scalability of the dataset.

Cluster Versus Rest-Redistribution Training: Similar Improvements in Neuromuscular Capacities in Female Team-Sport Athletes

PURPOSE

This study's purpose was to investigate the midterm effects of alternative set configurations (cluster [CL] and rest redistribution [RR]) on lower- and upper-body neuromuscular capacities in female athletes.

METHOD

Twenty team-sport female athletes were randomly assigned to a CL (n = 10) or RR (n = 10) training group. The study protocol comprised 2 pretests, 12 training sessions, and a posttest. Both groups engaged in identical exercises (squat and bench press), load intensity (75% of 1-repetition maximum), and volume (18 repetitions per exercise). The distinction between the groups lay in the total session rest time: The CL group had 23 minutes (3 sets of 6 repetitions with 30 s of intraset rest every 2 repetitions and 3 min of interset rest), whereas the RR group had 17 minutes (9 sets of 2 repetitions with 45 s of interset rest). Countermovement-jump height and load-velocity relationship variables (load-intercept, velocity-intercept, and area under the load-velocity relationship line) were assessed during the squat and bench-press exercises.

RESULTS

All dependent variables revealed greater values at posttest compared with pretest (P ≤ .040; averaged Hedges g = 0.35 for CL and 0.60 for RR), but time × group interactions never reached statistical significance (P ≥ .144). Likewise, the comparison of the magnitude of changes between the 2 groups revealed only trivial differences, except for a small greater change in bench-press area under the load-velocity relationship line for RRG (Hedges g = 0.40).

CONCLUSIONS

RR is a more efficient strategy than CL for inducing strength gains in female athletes.

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

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

Effectiveness Index of Mechanical Energy Utilization in Male 400-m Sprinters and the Relation Between Muscle Cross-Sectional Area of the Trunk and the Lower Limb

The purpose of this study was to identify the morphological characteristics of trunk and lower limb muscles associated with 400-m sprint performance and "effectiveness index of mechanical energy utilization (EI)." Twelve male 400-m sprinters (age: 21.4 ± 1.7 years, 400-m best time: 48.38 ± 1.80 s) participated in this study. Using a 3-T magnetic resonance imaging system, we measured muscle cross-sectional area (CSA) of the key trunk and lower limb muscles, including the rectus abdominis, lateral abdominal wall, erector spinae, psoas major, adductors, quadriceps femoris, hamstrings, dorsiflexors, and plantar flexors. The CSA of the trunk muscles was summed bilaterally, while the CSA of the lower limb muscles was assessed on the right leg. In addition to absolute CSA, relative CSA, normalized by the two-thirds power of lean body mass, was used in the analysis to account for individual body size differences. Participants completed a 400-m sprint on an official outdoor track, with running motion in early phase (around the 160-m point) analyzed using high-speed video cameras. Our findings indicate that the specific muscle groups' relative CSA, particularly the lateral abdominal wall and adductors, were significantly correlated with 400-m sprint time (r = -0.604 to -0.748, p = 0.005-0.038) and EI (r = 0.598-0.599, p = 0.040). Additionally, the thigh-to-lower leg CSA ratio was significantly correlated with 400-m sprint time (r = -0.643, p = 0.024) and EI (r = 0.577, p = 0.049). These results suggest that the relative size of proximal muscles plays a crucial role in economical sprinting in 400-m sprinters. Thus, optimizing the development of proximal muscles relative to distal muscles may enhance 400-m sprint economy, providing a valuable reference for designing training programs focused on economical running techniques.

Changes in H-reflex, V-wave, and contractile properties of the plantar flexors following concurrent exercise sessions-the acute interference effect

The interaction between muscle strength and endurance impacts athletic performance. Integrating both modalities into concurrent exercise (CE) is challenging due to the interference effect. This study explored the acute effects of resistance-only (R), endurance-only (E), and CE sessions on voluntary muscle strength, evoked neurophysiological parameters, and contractile properties of the plantar flexors. We also explored whether the sequence of CE (E-R vs. R-E) affects these parameters. Ten males (23.5 ± 2.4 yr) experienced in resistance and endurance training underwent neuromuscular baseline assessments, including plantarflexion maximal voluntary isometric contraction (MVIC) and soleus evoked responses (M-wave, H-wave, V-wave, evoked octet, and twitch contractile properties). Then, participants completed four different exercise sessions in a randomized manner (e.g., E, R, E-R, and R-E), separated by 72 h. Exercise sessions were immediately followed by the same assessments completed at baseline. MVIC and the rate of torque development (RTD) were reduced after all sessions. The E session induced a greater decrease in RTD compared with R. Although the V-wave amplitude decreased after all sessions, the electromyographic activity of the soleus muscle remained unchanged during MVIC. The normalized amplitude of the H-reflex was reduced after E and both CE sessions. The gain of the H-reflex ascending limb (Hslope) exhibited a larger decrease after CE, irrespectively of exercise sequence. The twitch contractile properties were similarly impaired after all sessions. The E session induced a larger reduction of the evoked octet response. These findings provide new insights into the neuromuscular etiology of the acute interference effect resulting from CE.NEW & NOTEWORTHY All exercise modalities reduced maximal isometric strength; however, endurance exercise led to greater decreases in the rate of torque development. Resistance exercise negatively impacted supraspinal central neural drive, whereas both endurance and concurrent exercise significantly impaired spinal motoneuron responsiveness. Endurance and concurrent exercise also significantly reduced twitch contractile properties and evoked octet responses, with the most pronounced impairments observed following endurance-only exercise.

Comparative Effects of the Free Weights and Smith Machine Squat and Bench Press: The Important Role of Specificity for Strength Adaptations

PURPOSE

Although previous studies have compared strength-training adaptations between free weights (FW) and machine-guided exercises, those studies did not use a Smith machine (SM), which most closely replicates the exercises performed with FW. Thus, the aim of the present study was to investigate the chronic effects of strength-focused, velocity-based training regimens using FW versus SM.

METHODS

Thirty-seven sport-science students (14 female) were assigned, balanced by sex and relative strength, to either an FW or SM training group. The training program lasted 8 weeks (2 sessions/wk), and participants performed 4 sets per exercise (back squat and bench press) at 70% of their 1-repetition maximum with moderate effort levels (20%-25% velocity loss). Load-velocity profile parameters (load-axis intercept, velocity-axis intercept, and area under the load-velocity relationship line), cross-sectional areas of the vastus lateralis and pectoralis major muscles, and the number of repetitions to failure in the bench-press exercise were assessed before and after the training program. Mechanical variables were assessed using both FW and SM.

RESULTS

All variables, with the exception of back-squat velocity-axis intercept (P = .124), improved in both training groups. The changes in load-axis intercept and area under the load-velocity relationship line were more pronounced when the training and testing conditions matched. Failure in the bench-press exercise and cross-sectional areas of the vastus lateralis and pectoralis major showed comparable improvements for both training groups, while velocity-axis intercept tended to improve more in the SM group.

CONCLUSIONS

The general population, unconcerned with the specificity of strength adaptations, can choose a training modality (FW or SM) based on personal preferences.

Effects of Kefir Consumption on Gut Microbiota and Athletic Performance in Professional Female Soccer Players: A Randomized Controlled Trial

BACKGROUND/OBJECTIVES

This study aimed to determine the impact of the daily consumption of kefir on the gut microbiome, body composition, and athletic performance of professional female soccer players.

METHODS

The participants encompassed 21 females aged 18-29 years who were assigned to one of the two groups: the experimental group, which comprised females who consumed 200 mL of kefir daily for 28 days, and the control group, which comprised females who continued with their normal diet. Anthropometric measurements, dietary intake, the composition of the gut microbiome through 16S rRNA gene sequencing, and an athletic performance test known as the 30-15 Intermittent Fitness Test were performed before and after the intervention.

RESULTS

The results of this study revealed that the consumption of kefir increased the microbial diversity (Shannon and Chao1 indices), wherein a significant increase was noted in the abundance of Akkermansia muciniphila and Faecalibacterium prausnitzii, microorganisms that regulate energy metabolism and have anti-inflammatory effects. Furthermore, the athletic performance variables, including VO2max (mL.kg-1.min-1) and finishing speed (km/h), were strongly related to the abundance of these short-chain fatty acid-producing bacteria. A link between the microbiota profile and the dietary intake of fiber and protein as well as the body composition measurements was also established.

CONCLUSIONS

This study indicated that kefir consumption can positively affect the gut microbiota, which could in turn affect the athletes' performance. Therefore, to determine the effects of kefir as a functional food in sports nutrition over a longer period, more research should be conducted.

A meta-analysis of the effects of plyometric training on muscle strength and power in martial arts athletes

BACKGROUND

Plyometric training (PT) was explored as an effective intervention for enhancing muscle strength and power. However, its specific impact on these attributes in martial arts athletes had not been systematically evaluated. Therefore, the objective of this meta-analysis was to provide a quantitative assessment of the impact of PT on muscle strength and power in martial arts athletes. Additionally, it aimed to investigate potential moderators that could influence this relationship.

METHODS

A systematic literature search was conducted across several databases, including SPORTDiscus, PubMed, CNKI, Scopus, and Web of Science Core Collection. Studies were included if they were controlled trials that examined the effects of PT on measures of muscle strength and/or muscle power in martial arts athletes. Effect sizes (ESs) were calculated using a random-effects model based on weighted and averaged standardized mean differences. Moderator analyses were performed for variables related to age and training. The ROB2 and ROBINS-I tools were used to assess the methodological quality of the included studies. Publication bias was evaluated using funnel plots and the extended Egger's test.

RESULTS

The analysis included fifteen studies with a total of 499 participants aged 12 to 24 years. The findings indicated that PT had a small-to-moderate effect on muscle strength (ES = 0.62; 95% CI = 0.38 to 0.87, p < 0.001) and power (ES = 0.45; 95% CI = 0.20 to 0.71, p = 0.001). Furthermore, neither age nor training parameters significantly moderated the effect of PT on muscle strength and power.

CONCLUSIONS

The findings of the present study indicated that PT effectively enhanced muscle strength and power in martial arts athletes. However, additional trials are recommended to determine the optimal training doses and further explore the interactions among training variables to improve muscle strength and power in these athletes.

TRIAL REGISTRATION

https//www.crd.york.ac.uk/prospero/display_record.php? Record ID = 579,901, identifier CRD42024579901.

Maximal strength, sprint and jump performance in elite kumite karatekas

BACKGROUND

Both maximal muscle strength and muscle power are independently important for karatekas. However, the relationship between strength and power in elite male kumite karatekas is under researched. This study aimed to determine the relationship between back-leg-chest (BLC) isometric muscle strength with sprint and jump variables in elite male karatekas.

METHODS

Male elite/international level (tier 4) kumite karatekas (n = 14; age, 20.79 ± 1.67 year; height, 1.77 ± 0.06 m; weight, 72.21 ± 5.20 kg) were recruited. BLC strength, sprint and jump values were measured with a dynamometer, a photocell, and an application, respectively. Pearson correlation (trivial r < 0.1; small r < 0.3; moderate r < 0.5; large r < 0.7; very large r < 0.9; nearly perfect/perfect r ≥ 0.9) and linear regression analyses were performed to determine the relationship and shared variance between BLC strength, sprint, and jump performance.

RESULTS

There were large to very large correlations between BLC strength and sprint time (r = - 0.930, p < 0.01), velocity (r = 0.918; p < 0.01), acceleration (r = 0.913; p < 0.01) and running momentum (r = 0.721; p < 0.01). Additionally, BLC strength correlated with jump height (moderate, r = 0.550, p < 0.05), peak anaerobic power (moderate, r = 0.672, p < 0.01) and power to body mass ratio (moderate, r = 0.545, p < 0.05). BLC strength and sprint variables showed an r2 = 0.52-0.86 (p < 0.01), while BLC strength and jump variables showed an r2 = 0.29-0.45 (p < 0.05).

CONCLUSIONS

BLC strength is related to jump and sprint performance in male elite karate athletes. This relationship underscores the importance of including strength training that targets BLC muscle strength in training programs for coaches and athletes.

Current trends in physical and physiological profile of elite WKF karate athletes: a systematic review

BACKGROUND

This qualitative analysis aimed to: identify the physical and physiological factors that characterize elite WKF kumite and kata athletes, identify testing protocols that are used to examine the above mentioned profiles of WKF karatekas and indicate the variables that are significant for elite-level performance.

METHODS

A search of electronic databases (PubMed, EBSCO, Scopus) was conducted to identify all studies on physical and physiological profile in elite karatekas from 2012 to 2024. A JBI Qualitative Data Extraction Tool for systematic reviews of qualitative evidence was fulfilled in order to determine which variables should be extracted. The quality of the included studies was assessed based on the JBI Critical Appraisal Checklist.

RESULTS

164 full-text articles were evaluated to determine eligibility, while 20 met the inclusion criteria and were subjected to detailed analysis, including risk of bias assessment. Finally, 17 full-text articles were included in the qualitative analysis. The following motor abilities and physiological components were evaluated by researchers: muscular strength (n = 8) muscular power (n = 11), speed (n = 8), agility (n = 6), flexibility (n = 6), aerobic metabolism (n = 9), anaerobic metabolism (n = 5).

CONCLUSIONS

The force-velocity characteristics with the dominant effect of the velocity component seem to be crucial in regard to performance outcomes in WKF karatekas. Moreover, elite karatekas are characterized by high flexibility of the hamstring muscles and well developed speed and agility abilities. The efficiency of aerobic and anaerobic metabolism is significant for high-performance in elite WKF kumite athletes, however aerobic capacity may be crucial. It is difficult to confirm the impact of the above mentioned energy systems on kata performance. Athlete's age category and sex-related variables may affect the level of the analyzed motor abilities.

Human motor performance assessment with lower limb exoskeletons as a potential strategy to support healthy aging-a perspective article

With increasing age, motor performance declines. This decline is associated with less favorable health outcomes such as impaired activities of daily living, reduced quality of life, or increased mortality. Through regular assessment of motor performance, changes over time can be monitored, and targeted therapeutic programs and interventions may be informed. This can ensure better individualization of any intervention approach (e.g. by considering the current motor performance status of a person) and thus potentially increase its effectiveness with regard to maintaining current performance status or delaying further decline. However, in older adults, motor performance assessment is time consuming and requires experienced examiners and specific equipment, amongst others. This is particularly not feasible in care facility/nursing home settings. Wearable robotic devices, such as exoskeletons, have the potential of being used to assess motor performance and provide assistance during physical activities and exercise training for older adults or individuals with mobility impairments, thereby potentially enhancing motor performance. In this manuscript, we aim to (1) provide a brief overview of age-related changes of motor performance, (2) summarize established clinical and laboratory test procedures for the assessment of motor performance, (3) discuss the possibilities of translating established test procedures into exoskeleton-based procedures, and (4) highlight the feasibility, technological requirements and prerequisites for the assessment of human motor performance using lower limb exoskeletons.

The Prevalence of and Factors Associated with Disordered Eating Among Adult Athletes in Italy and Lebanon

BACKGROUND/OBJECTIVES

Disordered eating (DE) is a wide-spectrum condition, represented by altered eating patterns, behaviors, and attitudes aimed at controlling food intake, body weight, and shape, which does not necessarily satisfy the diagnostic criteria for an eating disorder of clinical severity. DE is frequently reported among athletes, but its prevalence and associated factors have not been fully elucidated. In this study, we intended to assess the prevalence of DE among adult athletes from different sports disciplines in Italy and Lebanon and to identify the factors associated with DE.

METHODS

A validated questionnaire (Eating Attitude Test [EAT-26]) was administered to determine the prevalence of DE, which was indicated by a score ≥ 17. Sport-related information, such as the type of sport, level of competition, training volume, and years of athletic experience, was also collected.

RESULTS

Among the total sample of 881 athletes, 78 were identified as having DE, with a prevalence of 6.1% (7.8% of females and 4.9% of males) in Italian athletes and 21.3% (27.3% of females and 17.0% of males) in Lebanese athletes. In addition, among male athletes, the risk of having DE was more than threefold in those practicing weightlifting or bodybuilding (odds ratio [OR] = 3.23; 95% confidence interval [CI] = 1.03-10.08, and p < 0.05), while females with more athletic experience had almost 10% less risk of having DE (OR = 0.92; 95%CI = 0.86-0.98, and p < 0.05).

CONCLUSIONS

DE is a prevalent condition among athletes. Therefore, it is crucial that sports federations and committees consider adopting standardized practical guidelines that focus on routinely screening for the early identification of DE in this population and implementing strategies for its timely management. In the future, longitudinal studies are also needed to clarify the impact of DE on athletes' clinical condition as well as their physical fitness and sports performance.

An investigation into the relationships between technical collision behaviours and physical characteristics in world-class, international female rugby players

This study first investigated how the probability of winning collision events is affected by technical characteristics among world-class, international female rugby union players, and second, whether enhanced performance of these technical characteristics was related to physical attributes. Carry and tackle events from 16 international matches played by a top-two world ranking team were coded according to technical characteristics and performance outcomes. Binary classification tree models revealed that carry performance was successfully predicted (p < 0.01) by combinations of the variables: carrier velocity at the line, change of direction and straightening angle, leg drive, body mass and system mass (carrier combined with assistance from team-mate(s)). Tackle performance was predicted by combinations of the variables: initial line-speed, tackle direction, tackle type, collision zone entry, body mass, system mass, arm use and leg drive. Cumulative link mixed effects models subsequently revealed that performance increases of ~2% in single-leg isometric squat, counter-movement jump, bench press, single-leg drop jump, 10 m acceleration momentum and velocity, and skinfolds and body mass; were associated with increasing and decreasing likelihoods of superior technical performance, depending on the investigated variable. These findings may increase the precision of practices, physical training and assessment methods, among elite-standard female rugby union players.

Dileucine ingestion, but not leucine, increases lower body strength and performance following resistance training: A double-blind, randomized, placebo-controlled trial

BACKGROUND

The essential amino acid leucine (LEU) plays a crucial role in promoting resistance-training adaptations. Dileucine (DILEU), a LEU-LEU dipeptide, increases MPS rates, however its impact on resistance training outcomes remains unexplored. This study assessed the effects of DILEU supplementation on resistance training adaptations.

METHODS

Using a randomized, double-blind, placebo-controlled approach, 34 resistance-trained males (age: 28.3 ± 5.9 years) consumed 2 grams of either DILEU monohydrate (RAMPS™, Ingenious Ingredients, L.P.), LEU, or placebo (PLA) while following a 4-day per week resistance training program for 10 weeks. Changes in body composition, 1-repetition maximum (1RM) and repetitions to failure (RTF) for leg press (LP) and bench press (BP), anaerobic capacity, countermovement jump (CMJ), and maximal voluntary contraction (MVC) were assessed after 0 and 10 weeks.

RESULTS

Significant main effects for time (p < 0.001) were realized for LP and BP 1RM and RTF. A significant group × time interaction was identified for changes in LP 1RM (p = 0.02) and LP RTF (p = 0.03). Greater increases in LP 1RM were observed in DILEU compared to PLA (p = 0.02; 95% CI: 5.8, 73.2 kg), and greater increases in LP RTF in DILEU compared to LEU (p = 0.04; 95% CI: 0.58, 20.3 reps). No significant differences were found in other measures.

CONCLUSIONS

DILEU supplementation at 2 grams daily enhanced lower body strength and muscular endurance in resistance-trained males more effectively than LEU or PLA. These findings suggest DILEU as a potentially effective supplement for improving adaptations to resistance training. NCT06121869 retrospectively registered.

A Comparison of Three Protocols for Determining Barbell Bench Press Single Repetition Maximum, Barbell Kinetics, and Subsequent Measures of Muscular Performance in Resistance-Trained Adults

BACKGROUND

One repetition maximum (1RM) is a vital metric for exercise professionals, but various testing protocols exist, and their impacts on the resulting 1RM, barbell kinetics, and subsequent muscular performance testing are not well understood. This study aimed to compare two previously established protocols and a novel self-led method for determining bench press 1RM, 1RM barbell kinetics, and subsequent muscular performance measures.

METHODS

Twenty-four resistance-trained males (n = 12, 24 ± 6.1 years) and females (n = 12, 22.5 ± 5.5 years) completed three laboratory visits in a randomized crossover fashion. During each visit, a 1RM was established using one of the three protocols followed by a single set to volitional fatigue using 80% of their 1RM. A Sex:Protocol repeated measures ANOVA was used to determine the effects of sex and differences between protocols.

RESULTS

No significant differences were observed between the protocols for any measure, except for 1RM peak power (p = 0.036). Post hoc pairwise comparisons failed to identify any differences. Males showed significantly higher 1RM, average, and peak power (ps < 0.001), while females demonstrated a greater average concentric velocity (p = 0.031) at 1RM.

CONCLUSIONS

These data suggest the protocol used to establish 1RM may have minimal impact on the final 1RM, 1RM barbell kinetics, and subsequent muscular endurance in a laboratory setting.

Joint-level determinants of the dynamic strength index: implications for testing and monitoring

The aims of this study were to determine the associations and differences between the traditional dynamic strength index (DSIGRF, calculated from ground reaction force [GRF] data) and joint-level dynamic strength indices (DSINJM, calculated from net joint moment [NJM] data). Eight female NCAA Division I lacrosse players performed three maximal effort isometric mid-thigh pulls (IMTP) and countermovement jumps (CMJ). GRF and motion capture data were recorded and used to calculate hip, knee, and ankle NJM. The ratio between peak forces during the IMTP and CMJ tests was used to calculate the DSIGRF and the ratio of peak NJM was used to calculate ankle, knee, and hip DSINJM. Associations and differences between DSIGRF and DSINJM were examined with Pearson's correlation coefficients, paired t-tests and Hedge's g effect sizes. The results showed that only the hip DSINJM was correlated with DSIGRF (hip: p = 0.037; r = 0.738). In addition, athletes exhibited significantly greater DSINJM than DSIGRF. Although these results suggest DSIGRF are associated with hip DSINJM, the fact that joint-level DSINJM were generally greater than DSIGRF suggests the ratio between peak NJM during the CMJ and IMTP may not provide intuitive or useful data for strength and conditioning coaches or sport scientists.

Methodological considerations for assessing whole-body strength capacity through isometric dynamometry

The present study aimed to explore the possibility of comprehensively assessing whole-body muscle strength by testing as few muscle groups as possible, using a single testing method (isometric or isokinetic dynamometry) and a single variable (maximal force or rate of force development). Knee, hip, shoulder and elbow extensors and flexors were evaluated in males with high (n = 26) and low strength levels (n = 32). The principal component analysis revealed three factors that explained 62.5% of the total variance, while the main factors were loaded by the different testing methods and strength variables for the muscles acting on the knee (first component), hip (second component) and arm joints (third component). These results were confirmed by a three-way ANOVA which revealed a significant factor of group (P < 0.001) and the interaction test type × group (P = 0.002), but not of test type (P = 0.644), muscle group (P = 0.999), or their interactions (P > 0.205). The correlations of strength outcomes across the muscles ranged from trivial to very large (r range = -0.17, 0.84), being generally higher for the antagonistic muscles. Overall, a comprehensive assessment of whole-body muscle strength can be obtained using isometric dynamometry and maximal force, but it should consider at least one muscle group from the antagonistic pair.

Skating sprint performance and the influence of lower-body strength and power in professional and junior elite ice hockey athletes

Skating sprint performance is essential for competitive success in ice hockey; however, it is unknown which component of a skating sprint is most critical for development throughout the performance pathway. Fifty-seven Swiss male ice hockey athletes were subjects (National League [NL], n = 22; Under 20 [U20], n = 20; Under 17 [U17], n = 15). Athletes performed: on-ice 30 m skating sprint, countermovement jump (CMJ), squat jump (SJ), and isometric mid-thigh pull (IMTP) tests in a single day. Linear mixed models, effect sizes and 95% confidence intervals were used to compare sprint performance and CMJ, SJ and IMTP between each performance level, with a correlation matrix used to determine the influence of lower-body strength and power on sprint performance. The NL and U20 athletes were significantly faster and had greater performance in most CMJ, SJ and IMTP variables compared to the U17 athletes, indicating minimum standards of lower-body strength and power are required to optimise technical performance. Significant differences were observed between NL and U20 for 10-20 m skating sprint split time and CMJ concentric relative peak and mean force, and reactive strength index-modified. Therefore, flying acceleration (10-20 m) is likely the most critical variable for pathway progression, with relative concentric force production the greatest influence.

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.

Elastic Bands During Half-Squats as A Re-Warm-Up Strategy for Youth Soccer Players' Performance

The study aimed to assess the immediate effects of re-warm-up strategies using half-squats with elastic looped bands on the performance of youth soccer players. A cross-over study design with repeated measures was implemented in field youth male soccer players (n = 20, age 15.7 ± 0.8 years). Following the first 45-min of match play, players were subjected to one of four re-warm-up (Re-w) interventions of equal duration: no Re-w (PAS), half-squat without elastic looped bands (SQ), half-squat with bands placed on the thighs (SQT), and half-squat with bands placed on the lower legs (SQL). These interventions were compared against a control condition (CON). The Re-w protocols were initiated 10-min after half-time, and players' performance was evaluated through vertical and horizontal jump tests, 20-m linear sprint, and T-agility test. Statistical analysis using ANOVA revealed that the SQT and SQL interventions significantly improved (p < 0.001) several performance metrics compared to the PAS and SQ conditions. These improvements were observed in squat jumps, unilateral squat jumps (both dominant and non-dominant legs), countermovement jumps, horizontal jumps, triple horizontal jumps, the 20-m linear sprint, and T-agility performance. In conclusion, SQT and SQL are equally effective to enhance performance as Re-w strategies after the 1st-half of a soccer match. However, the lack of physiological data and 2nd-half assessments suggests the need for further research to confirm the persistence of these effects.