Light-load maximal lifting velocity full squat training program improves important physical and skill characteristics in futsal players

A comparative study of 8-week complex training and resistance training on athletic performance of amateur futsal players

Background: Despite the acknowledged importance of resistance training (RT) in enhancing physical performance in futsal players., the comparative effectiveness of RT and complex training (CT) on both physical and technical performance in futsal players remains underexplored. This study aimed to compare the effects of RT vs. CT on physical and technical performance in amateur futsal players. Method: Players from two amateur futsal teams were assigned to RT (one team of 16 players; 18 years) and CT (one team of 16 players; 18 years) to perform an 8-week intervention with two weekly sessions. The RT performed the squat and deadlift (6 sets of 6-10 repetitions at 75%-85% one-repetition maximum (1RM), while the CT performed the squat + squat jump and deadlift + high pull (3 sets of 4-6 + 10-12 repetitions at 75%-85% 1RM). Pre- and post-intervention assessments included the Futsal Special Performance Test (FSPT), repeated sprint ability (RSA), sprint decrement (Sdec), sprint times at 10-m (T10), 10-20-m (T10-20), and 20-m (T20), 1RM back squat (1RM BS), isometric mid-thigh pull (IMTP), and countermovement jump (CMJ). Results: At baseline, no significant differences between groups were observed for any variable analyzed (p > 0.05). After 8 weeks, there were significant differences between CT vs. RT on FSPT (-10.8% vs. -3.4%; p < 0.05), T10 (-5.2% vs. -0.1%; p < 0.05), IMTP (7.8% vs. 5.1%; p < 0.05), and CMJ (10.2% vs. 4.5%; p < 0.05). On the other hand, no significant differences between CT vs. RT were observed for RSA (-2.0% vs. -1.2%; p > 0.05), Sdec (-7.6% vs. -3.5%; p > 0.05), T10-20 (-0.9% vs. -0.9%; p > 0.05), T20 (-1.8% vs. -1.7%; p > 0.05), and 1RM BS (5.7% vs. 4.5%; p > 0.05) after the training program. Both groups significantly improved FSPT, T20, 1RM BS, and IMTP, while only CT significantly improved RSA, Sdec, T10, and CMJ. Conclusion: The results suggest that CT may be valuable for improving specific performance parameters in amateur futsal players, with some advantages over RT in enhancing strength and power. These findings support tailored training protocols for futsal players to optimize performance.

Load monitoring, strength training, and recovery in futsal: Practitioners' perspectives

This study aimed to describe the current practices in futsal regarding a variety of topics related to performance and injury risk mitigation. Thirty-seven coaches from Spain and Portugal completed a questionnaire consisting of 28 closed questions organized in four categories: a) background information; b) training load (TL) monitoring and assessment of players' physical qualities; c) strength training (ST) practices; and d) recovery (REC) methods. The results showed that coaches varied in experience (1-8 years) and age (from 20 years to >50 years). Overall, 97.3% of the participants declared monitoring TL, with rating of perceived exertion, heart rate monitors, and wearable technology being used by 86.5%, 40.5%, and 37.8%, respectively. Neuromuscular and strength testing are the most common practices to evaluate performance and fatigue during the season. ST is a significant component of futsal, being performed 3 times/week during the pre- and in-season. ST is prescribed via %1RM - XRM (59.5%), velocity-based training (21.7%), repetitions in reserve (18.9%), until failure (10.8%), and circuit training (2.7%). 'Better Monitoring', 'More Individualized', 'Better Facilities', 'More Staff', and 'More Time' were the main aspects to improve ST. Multiple post-match REC strategies are used, with durations ranging from 0-15 to 16-30 min independently of game location.

Comparison of 10% vs. 30% Velocity Loss during Squat Training with Low Loads on Strength and Sport-Specific Performance in Young Soccer Players

The aim of this study was to compare the effects of two velocity-based resistance training (RT) programs using moderate loads (45-60% 1RM) but different magnitudes of velocity loss (VL) limits (10% vs. 30%) on the changes in physical performance in young soccer players. Twenty young soccer players were randomly allocated into two groups: VL10% (n = 10) and VL30% (n = 10). All participants were assessed before and after the 8-week RT program (twice a week) involving the following tests: 20 m running sprint (T20), countermovement jump (CMJ), kicking a ball (KB), and progressive loading test in the full squat (SQ) exercise. The RT program was conducted using only the SQ exercise and movement velocity was monitored in all repetitions. Significant 'time × group' interaction (p < 0.05) was observed for sprint performance, KB and 1RM in the SQ exercise in favor of VL10%. No significant changes between groups at post-test were observed. The VL10% resulted in significant (p < 0.05-0.001) intra-group changes in all variables analyzed, except for KB, whereas VL30% only showed significant (p < 0.05) performance increments in a sprint test and 1RM in the SQ exercise. The percentage of change and the intra-group's effect size were of greater magnitude for VL10% in all variables analyzed compared to VL30%. In conclusion, our results suggest that, for non-trained young soccer players, squat training with low to moderate relative loads and 10%VL is sufficient to elicit significant increases in muscle strength and sport-specific actions compared to 30%VL in the set.

Linear and Change of Direction Repeated Sprint Ability Tests: A Systematic Review

ABSTRACT

Kyles, A, Oliver, JL, Cahill, MJ, Lloyd, RS, and Pedley, J. Linear and change of direction repeated sprint ability tests: a systematic review. J Strength Cond Res 37(8): 1703-1717, 2023-The ability to repeatedly sprint is important in many sports, but there is no established protocol for measuring repeated sprint ability (RSA). The purpose of this review was to identify overground RSA protocols previously reported in the literature and to recommend standardized protocols. A systematic review of the literature was used to identify studies that have used an RSA test, with data describing protocol design extracted. One hundred eight studies were included in the review, across which 47 unique protocols were identified. Eighteen protocols included at least one change of direction (COD), and this increased mean sprint time compared with linear RSA tests (7.26 ± 1.84 vs. 4.48 ± 1.02 seconds). There was considerable variability across protocols regarding sprint distance (20-40 m), sprint repetitions (3-15), recovery duration (10-60 seconds), recovery type (active vs. passive), and work-to-rest ratio (≤1:1.4-19.2). Separate protocols are needed for linear and COD tests, and these should reflect the brief nature of intense periods of competition and stress the ability to recover. Based on data across studies for protocol design and to ensure a demanding work-to-rest ratio, it is suggested that a linear RSA should comprise 6 × 30 m sprints separated by 15 seconds of active recovery. To provide some parity to linear tests, to keep work duration brief and to maintain a demanding work-to-rest ratio, a COD RSA should comprise 6 × 30 m shuttle sprints (15 + 15 m), providing one change of direction (180° COD), and maintaining a 15-second active recovery.

Strength and Power Performance Changes During an In-Season Resistance Training Program in Elite Futsal Players: A Case Study

In this study, we aimed to analyze (i) the strength and power changes after resistance training (RT) in elite futsal players, and (ii) the associations between the session rate of perceived exertion (sRPE) and perceived total quality recovery (TQR), and the sRPE and TQR with the volume load of the RT program. Ten elite futsal players (24.8 ± 5.4 years; 76.2 ± 7.1 kg; 1.77 ± 0.05 m) performed an in-season 8-week RT program twice per week. RT consisted of 2-3 sets x 3-6 reps at 45-65% of one-repetition maximum (1RM) with maximal velocities in the full squat and complementary exercises with the same volume. We assessed the TQR before every session, while the sRPE was calculated after each RT session. One week before and after the intervention, we measured the countermovement jump (CMJ) height, isometric hip adduction strength (IHAS), 1RM, and peak power (PP) in the full squat progressive loading test. After the 8-week training program, there was a significant improvement in most outcomes, yet the gains (%Δ) remained below the minimal detectable change (MDC), except for IHAS (CMJ: p < 0.05, %Δ = 6.7, MDC% = 7.2; IHAS: p < 0.001, %Δ = 19.1, MDC% = 14.6; 1RM: p > 0.05, %Δ = 9.2, MDC% = 21.5; PP: p < 0.05; %Δ = 14.4, MDC% = 22.4). We also found a significant negative correlation between TQR and the sRPE (r = -0.45, p < 0.001). Our data suggest that RT based on low-volume and low-to-moderate loads may not produce a sufficient stimulus to induce meaningful dynamic strength and power gains in elite futsal players, although it improves isometric strength. Furthermore, monitoring TQR before sessions may show coaches how the elite futsal player will perceive the session's intensity.

The Effects of Different Relative Loads in Weight Training on Acceleration and Acceleration from Flying Starts

The purpose of this review was to examine how different relative loads in weight training can improve acceleration over 10 m from a standing or flying start. A systematic review of the literature was undertaken using the following databases: PubMed, MedLine, Google Scholar, and SPORTDiscus. Studies were eligible if they met the following criteria: (1) participants were at least 15 years or older and healthy and injury free, (2) the study included at least one exercise for the lower body with a strength training frequency of at least once a week and included a training period of at least four weeks, and (3) interventions with clear pre- and post-test results on 10 m sprint or 10 m flying start are stated. Non-English-language articles were excluded. Percent change and between-group effect size (ES) were calculated to compare the effects of different training interventions. Forty-nine studies met the inclusion criteria. The results were categorized into four groups: (1) explosive weight training with light loads at 30–60% of 1-RM, (2) explosive weight training with moderate loads at 60–85% of 1-RM, (3) maximal weight training at 85–100% of 1-RM, and (4) hypertrophy training at 60–85% of 1-RM. At 10 m, all methods of weight training demonstrated improvements, and maximal weight training demonstrated the highest results with a large ES, while other approaches varied from very small to moderate ES. Weight training showed little progression with a significantly lower effect on flying start across all training methods, except for one group that trained power cleans (hypertrophy) where progress was large. To improve acceleration over the first 10 m, this review demonstrated maximal weight training as the preferred training method. For athletes with a pre-existing high level of strength, it could be more appropriate to use explosive training with light loads or a combination of the two. To a lesser extent, acceleration from a flying start could be improved using both training methods as well.

Can the Supido Radar Be Used for Measuring Ball Speed during Soccer Kicking? A Reliability and Concurrent Validity Study of a New Low-Cost Device

The aim was to analyze the reliability and validity of a low-cost instrument, based on a radar system, to quantify the kicking ball speed in soccer. A group of 153 male soccer players (under-13, n = 53; under-15, n = 54; under-18, n = 46) participated in this study. Each player performed three kicks on the goal in a standardized condition while the ball speed was measured with three different devices: one Radar Stalker ATS II^® (reference criterion) and two Supido Radar^® (Supido-front of the goal and Supido-back of the goal). The standard error of measurement (SEM) expressed as a coefficient of variation (CV) and the intraclass correlation coefficient (ICC) were employed for assessing the reliability of each instrument. Stalker and Supido-back showed very high absolute (CV = 4.0-5.4%) and relative (ICC = 0.945-0.958) reliability, whereas Supido-front resulted in moderate to low reliability scores (CV = 7.4-15%, ICC = 0.134-0.693). In addition, Lin's concordance correlation coefficient (CCC) values revealed an 'almost perfect' agreement between Stalker and Supido-back for the average (r = 0.99) and maximal (r = 0.98) ball speed, regardless of the ball speed range analyzed. However, Supido-front resulted in a poor degree of concordance (CCC = 0.688) and a high magnitude of error (17.0-37.5 km·h^-1) with the reference Stalker radar gun. The Supido Radar^® placed behind the goal could be considered a reliable and valid device for measuring ball speed in soccer.

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

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

Internal Validity in Resistance Training Research: A Systematic Review

Ensuring internal validity is the key procedure when planning the study design. Numerous systematic reviews have demonstrated that considerations for internal validity do not receive adequate attention in the primary research in sport sciences. Therefore, the purpose of this study was to review methodological procedures in current literature where the effects of resistance training on strength, speed, and endurance performance in athletes were analyzed. A computer-based literature searches of SPORTDiscus, Scopus, Medline, and Web of Science was conducted. The internal validity of individual studies was assessed using the PEDro scale. Peer-reviewed studies were accepted only if they met all the following eligibility criteria: (a) healthy male and female athletes between the ages of 18-65 years; (b) training program based on resistance exercises; (c) training program lasted for at least 4 weeks or 12 training sessions, with at least two sessions per week; (d) the study reported maximum strength, speed, or endurance outcomes; and (e) systematic reviews, cohort studies, case-control studies, cross-sectional studies were excluded. Of the 6,516 articles identified, 133 studies were selected for rating by the PEDro scale. Sixty-eight percent of the included studies used random allocation to groups, but only one reported concealed allocation. Baseline data are presented in almost 69% of the studies. Thirty-eight percent of studies demonstrated adequate follow-up of participants. The plan to follow the intention-to-treat or stating that all participants received training intervention or control conditions as allocated were reported in only 1.5% of studies. The procedure of blinding of assessors was also satisfied in only 1.5% of the studies. The current study highlights the gaps in designing and reporting research in the field of strength and conditioning. Randomization, blinding of assessors, reporting of attrition, and intention-to-treat analysis should be more fully addressed to reduce threats to internal validity in primary research.

Changes in Muscle Strength, Jump, and Sprint Performance in Young Elite Basketball Players: The Impact of Combined High-Speed Resistance Training and Plyometrics

ABSTRACT

Yáñez-García, JM, Rodríguez-Rosell, D, Mora-Custodio, R, and González-Badillo, JJ. Changes in muscle strength, jump, and sprint performance in young elite basketball players: the impact of combined high-speed resistance training and plyometrics. J Strength Cond Res 36(2): 478-485, 2022-This study aimed to compare the effect of a combined resistance training (RT) and plyometrics on strength, sprint, and jump performance in basketball players of different ages. Thirty three elite basketball players from the same academy were categorized into 3 groups by chronological age: under-13 (U13, n = 11); under-15 (U15, n = 11); and under-17 (U17, n = 11). Players participated in a 6-week strength training program that included 2 sessions each week and consisted of full squats with low loads (45-60% 1 repetition maximum) and low volume (2-3 sets and 4-8 repetitions), jumps, and sprint exercises. All repetitions were performed at maximal intended velocity. In addition to strength training sessions, subjects performed 4 on court basketball training sessions plus 2 official matches per week. After training program, all 3 experimental groups resulted in significant improvements (p < 0.05-0.001) in maximal strength (Δ: 9.2-27.3%; effect size [ES]: 0.38-0.82), countermovement jump height (Δ: 6.6-11.6%; ES: 0.37-0.95), and sprint time in 10 and 20 m (Δ: -3.9 to -0.3%; ES: 0.09-0.69) for all experimental groups. Comparison between groups showed that training program was more effective in inducing improvements in most variables assessed for U13 compared with U15 (ES: 0.11-0.42) and U17 (ES: 0.20-0.43), whereas differences between U15 and U17 were relevant in jump and strength parameters (ES: 0.20-0.35). Therefore, these findings suggest that high-speed RT combined with plyometrics produces increments in several important variables, including strength, jump, and sprint, to yield high performance during a match in young basketball players. However, training program used seems to be generally less effective as the age of the basketball players increased.

The effect of post-match resistance training on recovery in female footballers; when is best to train?

OBJECTIVE

This study examined the effects of resistance training (RT) performed at 24 or 48h post-match on recovery in female soccer players.

METHODS

In a randomized cross-over design, 10 professional female soccer players undertook matches followed by three conditions: Control (no RT), RT-24h and RT-48h post-match. RT was a high-speed and low-load session, consisting of 3 sets of 6 repetitions of lower-body exercises at 50%1RM. During training, one exercise (half-squat) was performed on a force platform to determine mean and peak forces. Tests were undertaken pre, 24, 48 and 72h post-match including countermovement jump (CMJ), 20m sprint, C-reactive protein (CRP) and delayed onset muscle soreness (DOMS). Two-way repeated-measures ANOVA and Effect size (ES) analyses compared the time-course of recovery.

RESULTS

Despite no significant differences between conditions, ES for changes from pre to 72h were larger for CMJ, 10 and 20m sprint time, and DOMS in RT48h (ES=0.38-2.13) than in RT24h (ES=0.08-0.66) and in Control (ES=0.09-0.36). No differences in forces of half-squat exercise existed between conditions (p>0.05; ES=0.05-0.06).

CONCLUSION

The trend for suppressed recovery of speed, power and perceptual responses at 72h post-match suggests RT48h is less ideal in female soccer players, particularly during congested micro-cycles.

Effects of Concurrent Training on 1RM and VO2 in Adults: Systematic Review with Meta-analysis

The purpose of this systematic review was to analyze the effects of concurrent training on one repetition maximum (1RM), maximum oxygen consumption (VO₂max), and peak oxygen consumption (VO₂peak) in healthy adults. The review followed PRISMA recommendations using randomized controlled trials in nine databases. Twenty-one studies met the inclusion criteria, totaling a sample of 796 subjects to perform the meta-analysis. As result, concurrent training provides similar increases in 1RM as strength training for upper limbs (standardized mean difference [SMD]: 0.12; 95% IC: [-0.18; 0.41]; p=0.43) and for the lower limbs (SMD: -0.32; 95% IC: [-0.79; 0.15]; p=0.19). Similarly, no difference was found in the aerobic capacity between the concurrent training vs. aerobic training groups ([SMD - VO₂max]: -0.19; 95% IC: [-0.71; 0.33]; p=0.48 and [SMD - VO₂peak]: -0.24; 95% IC: [-0.57; 0.08]; p=0.14). Based on the results found, we can affirm that a) similar to strength training, concurrent training provides maximum strength development for upper and lower limbs; and b) cardiorespiratory capacity is not impaired by concurrent training in relation to aerobic training, demonstrating the compatibility of the two training sessions.

Differences between adjusted vs. non-adjusted loads in velocity-based training: consequences for strength training control and programming

Strength and conditioning specialists commonly deal with the quantification and selection the setting of protocols regarding resistance training intensities. Although the one repetition maximum (1RM) method has been widely used to prescribe exercise intensity, the velocity-based training (VBT) method may enable a more optimal tool for better monitoring and planning of resistance training (RT) programs. The aim of this study was to compare the effects of two RT programs only differing in the training load prescription strategy (adjusting or not daily via VBT) with loads from 50 to 80% 1RM on 1RM, countermovement (CMJ) and sprint. Twenty-four male students with previous experience in RT were randomly assigned to two groups: adjusted loads (AL) (n = 13) and non-adjusted loads (NAL) (n = 11) and carried out an 8-week (16 sessions) RT program. The performance assessment pre- and post-training program included estimated 1RM and full load-velocity profile in the squat exercise; countermovement jump (CMJ); and 20-m sprint (T20). Relative intensity (RI) and mean propulsive velocity attained during each training session (V_session) was monitored. Subjects in the NAL group trained at a significantly faster V_session than those in AL (p < 0.001) (0.88-0.91 vs. 0.67-0.68 m/s, with a ∼15% RM gap between groups for the last sessions), and did not achieve the maximum programmed intensity (80% RM). Significant differences were detected in sessions 3-4, showing differences between programmed and performed V_session and lower RI and velocity loss (VL) for the NAL compared to the AL group (p < 0.05). Although both groups improved 1RM, CMJ and T20, NAL experienced greater and significant changes than AL (28.90 vs.12.70%, 16.10 vs. 7.90% and -1.99 vs. -0.95%, respectively). Load adjustment based on movement velocity is a useful way to control for highly individualised responses to training and improve the implementation of RT programs.

The Training of Short Distance Sprint Performance in Football Code Athletes: A Systematic Review and Meta-Analysis

Background

Short-sprint (≤ 20 m) performance is an important quality for success in the football codes. Therefore, developing an evidence base for understanding training methods to enhance short-sprint performance is key for practitioners. However, current systematic reviews are limited by (1) a lack of focus on football code athletes, (2) a lack of consideration of all training modalities and (3) a failure to account for the normal training practices undertaken by intervention groups within their analysis. Therefore, this review aimed to (1) conduct a systematic review of the scientific literature evaluating training interventions upon short-sprint performance within football code athletes, (2) undertake a meta-analysis to assess the magnitude of change of sport-sprint performance following training interventions and (3) identify how moderator variables affect the training response.

Methods

A systematic search of electronic databases was conducted. A random-effects meta-analysis was performed to establish standardised mean difference with 95% confidence intervals. This identified the magnitude and direction of the individual training effects of intervention subgroups (primary, secondary, combined-specific, tertiary and combined training methods) on short-sprint performance while considering moderator variables (i.e., football code, sex, age, playing standard, phase of season).

Results

121 studies met the inclusion criteria, totalling 3419 athletes. Significant improvements (small-large) were found between pre- and post-training in short-sprint performance for the combined, secondary, tertiary and combined-specific training methods. No significant effect was found for primary or sport only training. No individual mode was found to be the most effective. Between-subgroup analysis identified that football code, age, playing standard and phase of season all moderated the overall magnitude of training effects.

Conclusions

This review provides the largest systematic review and meta-analysis of short-sprint performance development methods and the only one to assess football code athletes exclusively. Practitioners can apply combined, secondary and tertiary training methods to improve short-sprint performance within football code athletes. The application of sport only and primary methods does not appear to improve short-sprint performance. Regardless of the population characteristics, short-sprint performance can be enhanced by increasing either or both the magnitude and the orientation of force an athlete can generate in the sprinting action.

Trial Registration

OSF registration https://osf.io/kshqn/.

Electronic supplementary material

The online version of this article (10.1007/s40279-020-01372-y) contains supplementary material, which is available to authorized users.

Association of strength and plyometric exercises with change of direction performances

The change of direction (COD) ability is an important task-specific skill for success in team sports, dependent on both strength and reactive strength. The sprint approaching the COD and degrees of the turn are factors influencing the specificity of the COD. Thus, CODs have been suggested to be categorized as force- (> 90°) and velocity-dominant (< 90°) dependent on the degree of the turn. When training programmes fail to provide a significant increase in COD performance, it is often due to neglecting the task-specific demands of the COD. As such, 23 male football players volunteered to complete a randomized controlled trial, investigating the association of maximal strength and power performance with performance in a force- (180°) and velocity-dominant (45°) COD, with a 4 m and 20 m sprint approach. Three strength and three plyometric exercises, matched in movement patterns, were used. Muscle activity of the different conditions was also compared. The correlational analysis revealed that better performance in the plyometric tests were associated with less time to complete both force- and velocity-dominant CODs, supported by similarities in muscle activation. None of the performances in strength exercises correlated to COD performance, due to the slow contraction velocity of maximal lifts. It was concluded that plyometrics share more physical similarities with CODs than the strength exercises.

Effects of Resistance Training on Change-of-Direction Speed in Youth and Young Physically Active and Athletic Adults: A Systematic Review with Meta-Analysis

BACKGROUND

Change-of-direction (CoD) speed is a physical fitness attribute in many field-based team and individual sports. To date, no systematic review with meta-analysis available has examined the effects of resistance training (RT) on CoD speed in youth and adults.

OBJECTIVE

To aggregate the effects of RT on CoD speed in youth and young physically active and athletic adults, and to identify the key RT programme variables for training prescription.

DATA SOURCES

A systematic literature search was conducted with PubMed, Web of Science, and Google Scholar, with no date restrictions, up to October 2019, to identify studies related to the effects of RT on CoD speed.

STUDY ELIGIBILITY CRITERIA

Only controlled studies with baseline and follow-up measures were included if they examined the effects of RT (i.e., muscle actions against external resistances) on CoD speed in healthy youth (8-18 years) and young physically active/athletic male or female adults (19-28 years).

STUDY APPRAISAL AND SYNTHESIS METHODS

A random-effects model was used to calculate weighted standardised mean differences (SMD) between intervention and control groups. In addition, an independent single training factor analysis (i.e., RT frequency, intensity, volume) was undertaken. Further, to verify if any RT variable moderated effects on CoD speed, a multivariate random-effects meta-regression was conducted. The methodological quality of the included studies was assessed using the physiotherapy evidence database (PEDro) scale.

RESULTS

Fifteen studies, comprising 19 experimental groups, were included. The methodological quality of the studies was acceptable with a median PEDro score of 6. There was a significant large effect size of RT on CoD speed across all studies (SMD = - 0.82 [- 1.14 to - 0.49]). Subgroup analyses showed large effect sizes on CoD speed in males (SMD = - 0.95) contrasting with moderate improvements in females (SMD = - 0.60). There were large effect sizes on CoD speed in children (SMD = - 1.28) and adolescents (SMD = - 1.21) contrasting with moderate effects in adults (SMD = - 0.63). There was a moderate effect in elite athletes (SMD = - 0.69) contrasting with a large effect in subelite athletes (SMD = - 0.86). Differences between subgroups were not statistically significant. Similar improvements were observed regarding the effects of independently computed training variables. In terms of RT frequency, our results indicated that two sessions per week induced large effects on CoD speed (SMD = - 1.07) while programmes with three sessions resulted in moderate effects (SMD = - 0.53). For total training intervention duration, we observed large effects for ≤ 8 weeks (SMD = - 0.81) and > 8 weeks (SMD = - 0.85). For single session duration, we found large effects for ≤ 30 min and ≥ 45 min (both SMD = - 1.00). In terms of number of training sessions, we identified large effects for ≤ 16 sessions (SMD = - 0.83) and > 16 sessions (SMD = - 0.81). For training intensity, we found moderate effects for light-to-moderate (SMD = - 0.76) and vigorous-to-near maximal intensities (SMD = - 0.77). With regards to RT type, we observed large effects for free weights (SMD = - 0.99) and machine-based training (SMD = - 0.80). For combined free weights and machine-based training, moderate effects were identified (SMD = - 0.77). The meta-regression outcomes showed that none of the included training variables significantly predicted the effects of RT on CoD speed (R2 = 0.00).

CONCLUSIONS

RT seems to be an effective means to improve CoD speed in youth and young physically active and athletic adults. Our findings indicate that the impact of RT on CoD speed may be more prominent in males than in females and in youth than in adults. Additionally, independently computed single factor analyses for different training variables showed that higher compared with lower RT intensities, frequencies, and volumes appear not to have an advantage on the magnitude of CoD speed improvements. In terms of RT type, similar improvements were observed following machine-based and free weights training.

Relationship of Performance Measures and Muscle Activity between a 180° Change of Direction Task and Different Countermovement Jumps

The ability to rapidly perform change of direction (COD) is crucial for performance in Soccer. COD speed is thought to share similarities with countermovement jumps in kinematics and muscle activation. Thus, the objective of the current study was to investigate the relationship between muscle activities in performance measures of a modified 505-agility test and different countermovement jumps. Twenty-one experienced soccer players performed a COD test including the 505-agility test and uni- and bi-lateral horizontal and vertical countermovement jumps. The main findings were that the vertical bilateral and horizontal unilateral countermovement jump were able to predict total time to complete the COD, but not 505-agility time. Muscle activity in the COD and countermovement jumps was only distinguished by a higher peak muscle activity for the adductor longus, semitendinosus and biceps femoris in the COD to stabilize the hip and decelerate knee joint movements when turning compared with the jumps. Conclusively, the relationship between performance in countermovement jumps and total time to complete the COD test was due to longer sprint distances, which makes the distinction between performances bigger. Peak muscle activity of most muscles is similar between the jumps and the COD step, indicating similar muscular demands between these activities.

EFFECTS OF PUBERTY ON JUMP AND SPRINT PERFORMANCE IN YOUNG FUTSAL PLAYERS

ABSTRACT Futsal is a sport that involves motor actions with high intensity and short duration, especially vertical jumps and sprints, which require fast application of strength and speed. The evaluation and training of these physical capacities is a routine practice of coaches, especially in the base categories, which are the entry point for many children and adolescents aiming for a professional career in futsal. With regard to the training of this public, puberty is a factor that must be considered, as a natural biological process involving several bodily transformations that can influence the performance of these physical capacities, especially considering that the categories are divided by chronological age, which does not always correspond to pubertal age. The objective of this study was to conduct a literature review of body modifications during puberty, and how these can affect the aspects that determine good performance in jumps and sprints. It was verified that this phase is associated with hormonal changes, an increase in muscle mass, and anthropometric aspects, as well as the maturation of the neuromuscular functions and refinement of the more complex motor activities, such as locomotion. Together, these factors can favor the fast application of force, and better performance of these players in terms of motor activities. However, it is important to emphasize that although these factors increase and naturally favor the players' performance in terms of strength and speed, it is a phase in which specific types of training focused on the aspects that determine good performance are fundamental to increase these capacities and diminish other aspects that also occur with the bodily development, such as a transient decrease in motor coordination and balance due to the rapid growth spurt, and tissue stiffness, which can sometimes occur during this period. Level of evidence V; Expert Opinion.

Effect of Different Physical Training Forms on Change of Direction Ability: a Systematic Review and Meta-analysis

Background

The ability to perform a rapid change of direction (COD) is a critical skill in numerous court- and field-based sports. The aim of this review is to investigate the effect of different physical training forms on COD performance.

Methods

A systematic review of the literature was undertaken using the following databases: PubMed, SPORTDiscus and Google Scholar. Studies were eligible if they met the following criteria: (1) a COD test measuring performance before and after the training intervention, with specific description of the test in terms of length and number of changes in a direction with specified angles, (2) involve training intervention like plyometric, strength, sprint, specific COD training, or a combination of these training forms targeting the lower extremities, (3) the study had to state training background in terms of which sport they participated in and their competitive level and a detailed methodological description. Non-English articles were excluded. Percentage difference and effect sizes were calculated in order to compare the effects of different training interventions.

Results

A range of studies performing plyometrics, strength, sprint, specific COD training, training with post-activation potentiation or a combination of these training forms were examined. The percentage of change and effect size (ES) were calculated. Seventy-four studies met the inclusion criteria, comprising 132 experimental groups and 1652 unique subjects. The review revealed no clear consensus on which training form is optimal to develop COD performance. All training forms resulted in an increase in performance from almost no ES to large ES.

Conclusions

The results of the study indicate that COD ability is a specific skill, whereas the COD task, the sports require determines which training form is the most effective to develop COD ability. Training targeting improvement in COD performance should address the duration of the training in line with which energy system is utilized. The complexity of the COD task with respect to the individual athlete must be considered. Consequently, the number of changes in direction and the angles of the task are relevant when organizing training.

Reliability and Criterion Validity of the Assess2Perform Bar Sensei

The Assess2Perform Bar Sensei is a device used to measure barbell velocity for velocity-based training that has not yet been validated. The purpose of this study was to determine criterion validity and reliability of the Assess2Perform Bar Sensei in barbell back squats by comparing it against the GymAware PowerTool, a previously validated instrument. Sixteen injury-free, resistance-trained subjects (eleven males and five females) were recruited. Subjects were tested for their back squat one repetition maximum (1RM). Then, on two separate days, subjects performed two sets of three repetitions at loads of 45%, 60% and 75% 1RM. The GymAware PowerTool and Bar Sensei were attached to the barbell in similar locations for concurrent collection of mean concentric velocity (MCV) and peak concentric velocity (PCV). The Bar Sensei and PowerTool showed generally fair to poor agreement for MCV and PCV when subjects lifted 45% of 1RM (intraclass correlation;ICC 0.4–0.59), and they showed poor agreement when subjects lifted 60% and 75% of 1RM (ICC 0.3–0.4). Inter-repetition/within-set reliability for the Bar Sensei ranged between ICC = 0.273–0.451 for MCV and PCV compared to the far more reliable PowerTool (ICC = 0.651–0.793). Currently, the Bar Sensei is not a reliable or valid tool for measuring barbell velocity in back squats.

Effects of Resisted Sprints With Changes of Direction Through Several Relative Loads on Physical Performance in Soccer Players

PURPOSE

To compare the effects of resisted change-of-direction (COD) movements, using several relative loads, on soccer players' physical performance.

METHODS

Fifty-four male soccer players were randomly assigned to 1 of the following 3 groups, which differed only in the magnitude of the external load used during the COD training: COD training without external load (COD-0; n = 16), COD training with a 12.5% body-mass external load (COD-12.5; n = 19), and COD training with a 50% body-mass external load (COD-50; n = 19). Participants performed the specific COD training twice per week for 6 wk. Before and after the training period, a battery of tests was completed: countermovement jump, 30-m running sprint (time in 10 m [T10], 20 m [T20], and 30 m [T30]), L-run test, and V-cut test.

RESULTS

Within-group comparisons showed substantial improvements in countermovement jump and T10 (likely) in COD-0, whereas countermovement jump, T10, and T20 were substantially enhanced (possibly to likely) in COD-50. COD-12.5 induced substantial improvements in all analyzed variables (likely to most likely). Between-groups comparisons showed better effects on all analyzed variables for COD-12.5 than for COD-0 (possibly to very likely), whereas COD-50 only showed possibly better effects than COD-0 on T10. In addition, COD-12.5 induced a better effect on L-run and V-cut tests than COD-50 (possibly to likely).

CONCLUSIONS

These results indicate that COD training, especially moderate load (12.5% body mass) resisted COD training, may have a positive effect on COD skills, running sprint performance, and jumping ability in young soccer players.

The Relationship of Age and BMI with Physical Fitness in Futsal Players

The aim of this study was to examine the relationship of age and body mass status with field and laboratory measures of physical fitness in futsal players. Futsal players (n = 65, age 12.9 ± 2.8 years), who were classified into U11 (n = 28, 9-11 years), U13 (n = 21, 11-13 years), and adults (n = 16, >18 years), performed a physical fitness battery consisting of both laboratory and field tests. A similar prevalence of overweight (25%) was observed in all age groups (χ² = 1.94, p = 0.380, φ = 0.17). Age groups differed for all parameters, except body fat percentage, with adult players showing higher values than the younger groups (p < 0.05). U13 was heavier, taller, and had larger fat-free mass than U11 (p < 0.05). Adult players had superior values than their younger counterparts for all physical fitness parameters (p < 0.05). Body mass index (BMI) correlated inversely with aerobic capacity (U13), jumping ability, relative isometric muscle strength, and relative mean power in the Wingate anaerobic test (WAnT) (U11) (p < 0.05). Also, it correlated directly with absolute isometric muscle strength (U11) and peak power, mean power (all groups), and fatigue index (U11, U13) in WAnT (p < 0.05). Considering the results of this study, it was concluded that the prevalence of overweight in futsal players should be an important concern for practitioners working in this team sport. Optimizing BMI should be considered as a training and nutrition goal in order to improve sport performance.

Effects of Low-Moderate Load High-Velocity Resistance Training on Physical Performance of Under-20 Futsal Players

Resistance training (RT) is an effective methodology to improve physical performance of athletes. However, up to now, no studies have addressed the RT benefits in under-20 futsal players. The purpose of this study was to evaluate the effects of six weeks of RT with high-velocity movements, low-to-moderate loads, and low volume on physical performance of under-20 futsal players. A total of 21 players were divided into two groups: A control group (CG, n = 10) and a RT group (RTG, n = 11). The RTG performed two weekly training sessions constituted by leg-press, jumps, and sprints, along with three futsal training sessions, while the CG only performed the futsal training. Before and after the intervention, the sprint time in 0–10 m (T₁₀), 10–20 m (T_10–20), and 0–20 m (T₂₀), the countermovement jump (CMJ) height, the T-Test time, the kicking ball speed (KBS), and the maximum dynamic strength in the leg-press, were assessed. In post-test, significant improvements in CMJ, T-Test, KBS, and leg-press were found for the RTG, whilst a significant decrease in T_10–20 was evidenced in the CG. The present results suggested that RT based on high velocity movements, low-to-moderate loads, and low volume produce positive effects on physical performance of under-20 futsal players.

Reliability and Accuracy of Ball Speed During Different Strokes in Young Tennis Players

This study aimed to examine the relationship between anthropometric and sport level (SL) variables and both ball speed and accuracy in young male competitive tennis players. A secondary aim of this study was to analyze the possible differences in ball speed and accuracy between players of different competitive levels. A total of 85 players (age: 14.7±2.4 years; height: 1.65±0.12 m; body weight: 56.3±13.4 kg) were divided into five groups according to their positions in the ranking list. To measure stroke performances, the goal was to hit 20 balls at the maximum possible speed inside the court, with the opportunity of hitting a maximum of 30 balls for each groundstroke and 40 for serve. Accuracy was calculated by dividing the number of balls inside the default surface by the total number of hits. The ball speed showed high reliability for all three strokes assessed. The ball speed progressively increased as SL increased for all strokes, whereas accuracy remained unchanged across SL groups. All independent variables presented significant relationships (r=0.59-0.85, p<0.05-0.001) with ball speed for all strokes. However, after applying partial correlations these relationships decreased substantially (r=0.02-0.51). The accuracy showed significant relationships with SL only in the serve (r=0.31, p<0.05) and backhand (r=0.26, p<0.05) strokes. In conclusion, the results of the present study suggest that tennis performance depends on increasing ball speed while maintaining a relatively stable level of accuracy.