Analysis of repeated high-intensity running performance in professional soccer

Analysis of player speed and angle toward the ball in soccer

The study analyzes how the magnitude and angle of the speed of soccer players change according to the distance to the ball and the phases of the game, namely the defensive and attacking phases. We observed how the role played in the team (goalkeeper, defender, midfielder, or forward) strongly determines the speed pattern of players. As a general trend, the speed's modulus is incremented as their position is closer to the ball, however, it is slightly decreased when arriving at it. Next, we studied how the angle of the speed with the direction to the ball is related to the distance to the ball and the game phases. We observed that, during the defensive phase, goalkeepers are the players that run more parallel to the ball, while forwards are the ones running more directly to the ball position. Importantly, this behavior changes dramatically during the attacking phase. Finally, we show how the proposed methodology can be used to analyze the speed-angle patterns of specific players to understand better how they move on the pitch according to the distance to the ball.

Performance and healthcare analysis in elite sports teams using artificial intelligence: a scoping review

Introduction

In competitive sports, teams are increasingly relying on advanced systems for improved performance and results. This study reviews the literature on the role of artificial intelligence (AI) in managing these complexities and encouraging a system thinking shift. It found various AI applications, including performance enhancement, healthcare, technical and tactical support, talent identification, game prediction, business growth, and AI testing innovations. The main goal of the study was to assess research supporting performance and healthcare.

Methods

Systematic searches were conducted on databases such as Pubmed, Web of Sciences, and Scopus to find articles using AI to understand or improve sports team performance. Thirty-two studies were selected for review.

Results

The analysis shows that, of the thirty-two articles reviewed, fifteen focused on performance and seventeen on healthcare. Football (Soccer) was the most researched sport, making up 67% of studies. The revised studies comprised 2,823 professional athletes, with a gender split of 65.36% male and 34.64% female. Identified AI and non-AI methods mainly included Tree-based techniques (36%), Ada/XGBoost (19%), Neural Networks (9%), K-Nearest Neighbours (9%), Classical Regression Techniques (9%), and Support Vector Machines (6%).

Conclusions

This study highlights the increasing use of AI in managing sports-related healthcare and performance complexities. These findings aim to assist researchers, practitioners, and policymakers in developing practical applications and exploring future complex systems dynamics.

Analyzing ECG signals in professional football players using machine learning techniques

Background

Football player's health is important, and preventing sudden cardiac arrest may be a critical issue. Professional football players have different ECG signals than the average population, yet there are considerable gaps in study whereas the general population has been extensively studied.

Objectives

(a) Generate a reference and innovative resting 12-lead ECG database from 54 UEFA PRO level male football players from La Liga. This is a novel approach to cope the ECG and possible arrythmias in athletes. (b) Manage each XML athlete ECG data and develop a free-use program to visualize, denoise and filter the signal with the capacity to automate the labelling of the waves and save the reports. (c) Study the ECG wave shape and generate models through ML to analyse its utility to automate basic diagnosis.

Methods

The dataset collection is based on a prospective observational cohort and includes 10 s, 12-lead ECGs and rhythm and condition labels for each athlete. Physiological sport arrhythmias, T-Wave shape and other findings were studied and labelled. ECG Visualizer was developed and used for 3 machine learning (ML) methods to automate sinus bradycardia arrhythmia diagnosis.

Results

A dataset with 163 ECGs in XML format was collected comprising the Pro Football 12-lead Resting Electrocardiogram Database (PF12RED). "ECG Visualizer" software was developed, and ML was shown to be useful in detecting sinus bradycardia.

Conclusions

The study demonstrates that AI and machine learning can detect simple arrhythmias with accuracy, also it provides a valuable dataset and a free software application.

Normative data on horizontal power, acceleration, and change-of-direction ability in amateur youth female soccer players

BACKGROUND

Physical performance measures such as horizontal power, acceleration, and change-of-direction ability are related to performance in soccer, and may aid in talent selection, coaching decisions and the prescription of training programs. The purpose of this study was to describe the normative values of three performance tests in amateur female youth soccer players.

METHODS

A cross-sectional descriptive study design was employed with 151 amateur female youth soccer players (age 14.20±1.13 years). Physical performance measures included the standing broad jump, 10-meter sprint, and Pro-Agility Test. Time since peak height velocity (PHV) was calculated to represent physical maturity status. Descriptive statistics were sought, and Pearson's correlation coefficients were used to identify correlations between variables. One-Way Analysis of Variance with a Tukey post-hoc test was used to calculate the relationship between categorical groups of chronological ages and years since PHV. Significance was set at P<0.05.

RESULTS

Normative data for each physical performance measure are presented based on chronological age and physical maturity status for amateur female youth soccer players. Chronological age was significantly associated with improved performance in standing broad jump (R=0.558; 95% CI: 0.436, 0.658; P<0.01), 10-meter sprint time (R=-0.375; 95% CI: -0.495, -0.217; P<0.01), and Pro-Agility Test time (R=-0.424; 95% CI: -0.546, -0.284; P<0.01). Physical maturity status was also significantly associated with improved performance in standing broad jump (R=0.650; 95% CI: 0.426, 0.711; P<0.01), 10-meter sprint time (R=-0.430; 95% CI: -0.507, -0.232; P<0.01), and Pro-Agility Test time (R=-0.453; 95% CI: -0.554, -0.293; P<0.01).

CONCLUSIONS

The normative data from this study demonstrates differences in physical performances across chronological ages and physical maturity status. Physical maturity status had a slightly stronger association for all performance measures than chronological age. The variance and range tended to increase across performance measures with increasing age.

Influence of Maturation and Determinants of Repeated-Sprint Ability in Youth Basketball Players

ABSTRACT

Gonzalo-Skok, O, and Bishop, C. Influence of maturation and determinants of repeated-sprint ability in youth basketball players. J Strength Cond Res 38(2): 325-333, 2024-The main aims of the current study were (a) to determine the main predictors of general and specific repeated-sprint ability (RSA) tests, (b) to analyze the relationships between RSA tests and independent measures of physical performance, (c) to examine whether between-age differences exist, and (d) to assess whether maturation affects those mentioned above in young basketball players. Thirty-five young (U-14 to U-16), highly trained basketball players performed a linear sprint test (5, 10, and 25 m), an incremental running test, and 2 repeated-sprint tests (general [RSG]: 6 × 25 m; specific [RSS]: 6 × 5 + 5 m with a 45° change of direction and 20 seconds of passive recovery in both tests). Anthropometric variables were measured and used to calculate age at peak height velocity (APHV), which was used to determine maturation. The main determinants of RSA tests were aerobic performance and linear sprinting for RSS ( R2 = 0.84) and adding the percentage of body fat for RSG ( R2 = 0.94). Almost perfect relationships ( r = 0.93-0.99) were found between all RSA variables (i.e., the best [RSG b and RSS b ] and mean time [RSG m and RSS m ]). As age increased, performance in RSA was evident, as shown by improved best and mean scores. When APHV was controlled for, no significant differences were apparent in the comparison from U-14 and U-16 in 25 m, RSG b , and RSG m . By contrast, significant differences ( p < 0.05) were still evident with APHV controlled between U-14 and U-16 in 5 m, 10 m, RSS b , and RSS m . In conclusion, maturation positively affects linear sprinting and linear RSA performance, whereas specific (multidirectional) RSA seems to be related to other factors.

The "Worst-Case Scenario": Recovery Between Repeated High-Intensity Efforts in Rugby League Match-Play

BACKGROUND

Repeated high-intensity effort (RHIE) activity is known to be a critical component of high-intensity, intermittent team sports. Despite the importance of this quality, there are few studies comparing the RHIE activity of higher- and lower-ranked teams competing in the same competition. This study characterized the distribution of recovery times between RHIE in Top 4 and Bottom 4 semi-elite rugby league players.

HYPOTHESIS

Players from Top 4 teams will engage in a greater frequency of RHIE bouts than Bottom 4 teams, with shorter recovery periods between consecutive efforts.

STUDY DESIGN

Cohort study.

METHODS

A total of 104 semi-elite rugby league players from 11 teams wore global positioning system units during 28 Queensland Cup rugby league matches. Recovery between efforts was classified as <10, 11 to 20, 21 to 30, 31 to 60, and 61 to 120 seconds.

RESULTS

The majority of RHIE bouts were performed with ≤10 seconds recovery between efforts for both Top 4 and Bottom 4 teams. Top 4 teams performed a greater proportion of RHIE bouts with ≤10 seconds recovery between efforts than Bottom 4 teams (effect size [ES], 0.27 ± 0.19), while only trivial differences (ES, 0.17 ± 0.20) were found between Top 4 and Bottom 4 teams for the proportion of RHIE with 61 to 120 seconds recovery between efforts. Wide-running forwards from Top 4 teams performed a greater proportion of RHIE bouts with ≤10 seconds recovery between efforts (ES, 0.59 ± 0.40) and a smaller proportion of RHIE bouts with 61 to 120 seconds recovery between efforts (ES, 0.62 ± 0.38) than wide-running forwards from Bottom 4 teams.

CONCLUSION

Rugby league players perform proportionally more RHIE bouts with ≤10 seconds recovery between efforts than any other recovery duration. In addition, Top 4 teams are more likely to complete a greater proportion of short (≤10 seconds) recovery RHIE bouts than Bottom 4 teams.

CLINICAL RELEVANCE

These findings demonstrate the demanding nature of RHIE activity in rugby league. To be successful, teams should train for these demanding passages of play.

Testing the peak running speed in analytical and contextual-based scenarios: Applied research in young adult soccer players

The primary aim was to compare the peak running speed (PRS) attained in the 40-m linear sprint test, in an analytical-based soccer drill, in the 5-0-5 test, and a training match scenario. The secondary aim of the study was to evaluate the differences between the three assessment sessions and identify how the tests can vary from session to session. Additionally, we aimed to investigate the within-test variability to understand how consistent the performance is within each test format across the different sessions. Forty male under-19 players competing at the national level participated in this study. A training session was observed for each of the three study weeks in which the following tests/scenarios were monitored using a GPS. The 40-m linear sprint test and the analytical-based soccer drill presented the smallest within-subject coefficients of variation between the sessions. A large correlation (r = 0.742) was found between the PRS during the 40-m linear sprint test and the analytical-based soccer drill. The 40-m linear sprint test was the best method of those examined for measuring PRS. The analytical drill provides a reliable method for measuring PRS, although it differs from the 40-metre linear sprint test.

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.

The Acute Demands of Repeated-Sprint Training on Physiological, Neuromuscular, Perceptual and Performance Outcomes in Team Sport Athletes: A Systematic Review and Meta-analysis

BACKGROUND

Repeated-sprint training (RST) involves maximal-effort, short-duration sprints (≤ 10 s) interspersed with brief recovery periods (≤ 60 s). Knowledge about the acute demands of RST and the influence of programming variables has implications for training prescription.

OBJECTIVES

To investigate the physiological, neuromuscular, perceptual and performance demands of RST, while also examining the moderating effects of programming variables (sprint modality, number of repetitions per set, sprint repetition distance, inter-repetition rest modality and inter-repetition rest duration) on these outcomes.

METHODS

The databases Pubmed, SPORTDiscus, MEDLINE and Scopus were searched for original research articles investigating overground running RST in team sport athletes ≥ 16 years. Eligible data were analysed using multi-level mixed effects meta-analysis, with meta-regression performed on outcomes with ~ 50 samples (10 per moderator) to examine the influence of programming factors. Effects were evaluated based on coverage of their confidence (compatibility) limits (CL) against elected thresholds of practical importance.

RESULTS

From 908 data samples nested within 176 studies eligible for meta-analysis, the pooled effects (± 90% CL) of RST were as follows: average heart rate (HRavg) of 163 ± 9 bpm, peak heart rate (HRpeak) of 182 ± 3 bpm, average oxygen consumption of 42.4 ± 10.1 mL·kg-1·min-1, end-set blood lactate concentration (B[La]) of 10.7 ± 0.6 mmol·L-1, deciMax session ratings of perceived exertion (sRPE) of 6.5 ± 0.5 au, average sprint time (Savg) of 5.57 ± 0.26 s, best sprint time (Sbest) of 5.52 ± 0.27 s and percentage sprint decrement (Sdec) of 5.0 ± 0.3%. When compared with a reference protocol of 6 × 30 m straight-line sprints with 20 s passive inter-repetition rest, shuttle-based sprints were associated with a substantial increase in repetition time (Savg: 1.42 ± 0.11 s, Sbest: 1.55 ± 0.13 s), whereas the effect on sRPE was trivial (0.6 ± 0.9 au). Performing two more repetitions per set had a trivial effect on HRpeak (0.8 ± 1.0 bpm), B[La] (0.3 ± 0.2 mmol·L-1), sRPE (0.2 ± 0.2 au), Savg (0.01 ± 0.03) and Sdec (0.4; ± 0.2%). Sprinting 10 m further per repetition was associated with a substantial increase in B[La] (2.7; ± 0.7 mmol·L-1) and Sdec (1.7 ± 0.4%), whereas the effect on sRPE was trivial (0.7 ± 0.6). Resting for 10 s longer between repetitions was associated with a substantial reduction in B[La] (-1.1 ± 0.5 mmol·L-1), Savg (-0.09 ± 0.06 s) and Sdec (-1.4 ± 0.4%), while the effects on HRpeak (-0.7 ± 1.8 bpm) and sRPE (-0.5 ± 0.5 au) were trivial. All other moderating effects were compatible with both trivial and substantial effects [i.e. equal coverage of the confidence interval (CI) across a trivial and a substantial region in only one direction], or inconclusive (i.e. the CI spanned across substantial and trivial regions in both positive and negative directions).

CONCLUSIONS

The physiological, neuromuscular, perceptual and performance demands of RST are substantial, with some of these outcomes moderated by the manipulation of programming variables. To amplify physiological demands and performance decrement, longer sprint distances (> 30 m) and shorter, inter-repetition rest (≤ 20 s) are recommended. Alternatively, to mitigate fatigue and enhance acute sprint performance, shorter sprint distances (e.g. 15-25 m) with longer, passive inter-repetition rest (≥ 30 s) are recommended.

Relative Individual Sprint in Most Demanding Passages of Play in Spanish Professional Soccer Matches

(1) Background: The objective of this research was to analyse the most demanding passages (MDP) considering the sprint variable relative to the maximum level of sprint ability of each player as a function of player position, final outcome and part of the match during the competitive phase of a professional soccer season. (2) Methods: Global positioning system (GPS) data were collected from 22 players according to their playing position in the last 19 match days of the Spanish La Liga professional soccer in the 2020/2021 season. MDP were calculated from 80% of the maximum sprint speed of each player. (3) Results: Wide midfielders covered the greatest distance at >80% of the maximum speed (2.4 ± 1.63 seg) and the longest duration (21.91 ± 13.35 m) in their MDP. When the whole team was losing, it demonstrated greater distances (20.23 ± 13.04 m) and longer durations (2.24 ± 1.58 seg) compared to games in which it was winning. When the team ended up drawing, the relative sprint distance covered in the second half was significantly greater than in the first (16.12 ± 21.02; SD = 0.26 ± 0.28 (-0.03/-0.54). (4) Conclusions: Different demands of MDP, according to the sprint variable relative to the maximum individual capacity in competition, are required when contextual game factors are considered.

Performance Adaptations to Intensified Training in Top-Level Football

Because physical demands are surging in football (soccer, USA), clubs are more and more seeking players who have a high capacity to perform repeated intense exercise. High-intensity interval training (HIIT), comprising exercise performed at intensities near or exceeding the capacity of aerobic energy systems, effectively enhances the physical conditioning of players. But given that HIIT imposes high loads, it increases the risk of overload-associated match performance decline and injury. This makes some coaches inclined to conduct HIIT in the weeks leading up to the season and during the season. Therefore, the challenge is how to optimize and dose HIIT during these phases, as they can be decisive. Studies have highlighted the utility of conducting periods of intensified training to overcome the risk of overload while at the same time enhancing performance. During intensified training periods of typically a few weeks, intensity is increased by enlarging the amount of HIIT, for example, aerobic high-intensity training or speed endurance training, while volume at low-to-moderate intensity is significantly reduced. The outcome depends on training composition and prescription-most notably, intensity and duration of bouts and recovery. When work intervals are prescribed for a few minutes at intensities > 90% heart rate max (i.e., aerobic high-intensity training), then beneficial adaptations pertaining to aerobic power and capacity are apparent. But when work intervals are conducted at much higher intensities, as all-out efforts or sprinting of typically 10- to 40-s duration with longer recovery periods (i.e., speed endurance training), beneficial adaptations pertaining to anaerobic energy systems, ion handling, and fatigue resilience are commonly observed. In this review, we discuss the utility of conducting intensified training periods to enhance performance in elite football players during the late preparation phase and competitive season.

High-speed running and sprinting in professional adult soccer: Current thresholds definition, match demands and training strategies. A systematic review

The aims of this systematic review were (1) to summarize the evidence on absolute velocity thresholds used to classify high-speed running and sprinting, (2) to examine the existing evidence about the individualized thresholds approach, (3) to describe high-speed and sprint running distance match demands, and (4) to provide training strategies for eliciting HSR and sprinting during training sessions in professional adult soccer. This systematic review was conducted following the PRISMA 2020 guidelines. After the authors' screening, 30 studies were included in this review. This review found that, to date, there is no consensus on the absolute thresholds defining high-speed and sprint running in adult soccer players. Until international standards are defined, it is reasonable to set absolute thresholds considering the range of values found in the literature collected in this review. Relative velocity thresholds could be considered for specific training sessions whose goal is to reach near maximal velocity exposure. During official matches, high-speed and sprint running distances ranged from 911 to 1,063 m and 223-307 m, respectively, in professional female soccer players, while ranges from 618 to 1,001 m and 153-295 m, respectively, in professional male soccer players. During training, game-based drills designed in formats using relative areas per player greater than 225 m2 and 300 m2 appear to be adequate for achieving high-speed running and sprinting exposure, respectively, for male players. The combination of game-based, running exercises and soccer circuit-based drills is advisable to ensure adequate high-speed and sprint running exposure both at a team and individual level.

Quantifying Exposure and Intra-Individual Reliability of High-Speed and Sprint Running During Sided-Games Training in Soccer Players: A Systematic Review and Meta-analysis

BACKGROUND

Sided games (i.e., small sided, medium sided, large sided) involve tactical, technical, physical, and psychological elements and are commonly implemented in soccer training. Although soccer sided-games research is plentiful, a meta-analytical synthesis of external load exposure during sided games is lacking.

OBJECTIVE

The objective of this systematic review and meta-analysis was to: (1) synthesize the evidence on high-speed and sprint running exposure induced by sided games in adult soccer players, (2) establish pooled estimates and intra-individual reliability for high-speed and sprint running exposure, and (3) explore the moderating effects of game format and playing constraints.

METHODS

A literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Four databases (PubMed/MEDLINE, Scopus, SPORTDiscus, Web of Science Core Collection) were systematically searched up to 25 January, 2022. Eligibility criteria were adult soccer players (population); training programs incorporating sided games (intervention); game manipulations including number of players, pitch dimension, and game orientation (comparator); and high-speed, very high-speed, and sprint relative (m[Formula: see text]min^-1) running distances and associated intra-individual reliability (outcome). Eligible study risk of bias was evaluated using RoBANS. Pooled estimates for high-speed and sprint running exposure, and their intra-individual reliability, along with the moderating effect of tracking device running velocity thresholds, pitch dimension (i.e., area per player), and game orientation (i.e. score or possession), were determined via a multi-level mixed-effects meta-analysis. Estimate uncertainty is presented as 95% compatibility intervals (CIs) with the likely range of relative distances in similar future studies determined via 95% prediction intervals.

RESULTS

A total of 104 and 7 studies met our eligibility criteria for the main and reliability analyses, respectively. The range of relative distances covered across small-sided games, medium-sided games, and large-sided games was 14.8 m[Formula: see text]min^-1 (95% CI 12.3-17.4) to 17.2 m[Formula: see text]min^-1 (95% CI 13.5-20.8) for high-speed running, 2.7 m[Formula: see text]min^-1 (95% CI 1.8-3.5) to 3.6 m[Formula: see text]min^-1 (95% CI 2.3-4.8) for very high-speed running, and 0.2 m[Formula: see text]min^-1 (95% CI 0.1-0.4) to 0.7 m[Formula: see text]min^-1 (95% CI 0.5-0.9) for sprinting. Across different game formats, 95% prediction intervals showed future exposure for high-speed, very high-speed running, and sprinting to be 0-46.5 m[Formula: see text]min^-1, 0-14.2 m[Formula: see text]min^-1, and 0-2.6 m[Formula: see text]min^-1, respectively. High-speed, very high-speed running, and sprinting showed poor reliability with a pooled coefficient of variation of 22.8% with distances being moderated by device speed thresholds, pitch dimension, and game orientation.

CONCLUSIONS

This review is the first to provide a detailed synthesis of exposure and intra-individual reliability of high-speed and sprint running during soccer sided games. Our estimates, along with the moderating influence of common programming variables such as velocity thresholds, area per player, and game orientation should be considered for informed planning of small-sided games, medium-sided games, and large-sided games soccer training.

CLINICAL TRIAL REGISTRATION

Open Science Framework available through https://osf.io/a4xr2/ .

Dietary Supplement Use of Turkish Footballers: Differences by Sex and Competition Level

This study aimed to evaluate the consumption of dietary supplements (DS) and to determine related topics in Turkish football players of different sexes and competition levels. A total of 117 footballers (79 males and 38 females) completed a specific survey regarding DS consumption in athletes. The type of DS ingested was classified based on the level of scientific evidence by the Australian Institute of Sport (AIS): group A (high level of scientific evidence), group B (DS that could have a positive effect, but require more evidence), group C (evidence is against their use), and group D (prohibited substances). After a Kolmogorov−Smirnov test, a t-test or Mann−Whitney U test was performed for quantitative variables, while Pearson’s chi-square and odds ratio (with the confidence interval) were performed for qualitative variables. Of the sample, 87.2% reported having consumed DS, with a higher consumption rate in males (males: 93.7%, females: 73.7%; p = 0.006; OR = 5.3 [1.7−16.8]) and professional players (professional: 98.2%, non-professional: 77.4%; p < 0.001; OR = 7.9 [1.2−52.3]). Males and professional players consume more sports foods (p < 0.001), performance supplements (p < 0.001), and total group A supplements (p < 0.001) compared to females and non-professionals. In addition, males consume more medical supplements (p = 0.012) and total group C supplements (p < 0.001) than female footballers. The most consumed DS were sports drinks (63.2%), magnesium (52.1%), vitamin C (51.3%), vitamin D (46.2%), caffeine (38.5%), sports bars (37.6%), whey protein (28.2%), meat protein (25.6%), vitamin E (24.8%), and omega-3 fatty acids (24.8%). The supplement consumption was higher in male and professional footballers. According to the AIS classification, there were significant differences in the consumption of sports foods, medical supplements, performance supplements, and the total number of group A and group C supplements according to sex, and there were significant differences in the consumption of sports foods, performance supplements, and the total number of group A supplements according to competition level.

Anthropometric and Physiological Profiles of Hungarian Youth Male Soccer Players of Varying Ages and Playing Positions: A Multidimensional Assessment with a Critical Approach

BACKGROUND

This study aimed to create preliminary anthropometric and physiological profiles of Hungarian male soccer players belonging to different age categories (14, 15, 16, and 17-18-years) and assigned to different playing positions (forward, defender, midfielder, goalkeeper).

METHODS

Anthropometric and physiological profiles were created for four age groups: 14- (n = 20), 15- (n = 16), 16- (n = 22) and 17-18-year-olds (n = 23) representing the Hungarian soccer academy. Additionally, the variables were analyzed across the four player positions mentioned above.

RESULTS

The mean values of body mass, fat mass and BMI were within normal limits, although in some cases the anthropometric and body composition values were too high, particularly among the 17-18-year-olds. The mean values of HR_rest were lowest among the 15-year-olds. The highest mean and maximal values of rVO_2max and rVO₂/AT [57.6 ± 8.12 (43.8-68.3) and 51.2 ± 7.24 (38.9-60.8) mL/kg/min, respectively] were noted in 14-year-olds. Goalkeepers performed significantly better than the remaining soccer players in terms of the most anthropometric and physiological characteristics, except for the Yo-Yo test (p < 0.001).

CONCLUSIONS

The values of anthropometric parameters increased with age. As expected, the oldest group achieved the best results in the performance tests. Goalkeepers outperformed the players representing other playing positions in the tests when assessing lower limb strength, sprint performance (5- and 10-m distance), and agility tests. From a practical point of view, the presented anthropometric and physiological profiles of players representing different age groups and playing positions can be useful for soccer coaches, strength and conditioning specialists, and athletic trainers of other soccer clubs in terms of the individualization and optimalization of soccer training.

Physical and Mental Fatigue Reduce Psychomotor Vigilance in Professional Football Players

PURPOSE

Professional football players experience both physical and mental fatigue (MF). The main aims of this randomized crossover study were to investigate the effect of MF on repeated-sprint ability (RSA) and the effects of both physical fatigue and MF on psychomotor vigilance.

METHODS

Seventeen male professional football players performed 10 maximal 20-m shuttle sprints interspaced by incomplete recovery (RSA test). Running speed, heart rate, brain oxygenation, and rating of perceived exertion were monitored during each sprint. The RSA test was preceded by either a 30-minute Stroop task to induce MF or by watching a documentary for 30 minutes (control [CON]) in a randomized counterbalanced order. Participants performed a psychomotor vigilance test at baseline, after the cognitive task (MF or CON), and after the RSA test.

RESULTS

Heart rate and rating of perceived exertion significantly increased, while running speed and brain oxygenation significantly decreased over the repeated sprints (P < .001) with no significant differences between conditions. Response speed during the psychomotor vigilance test significantly declined after the Stroop task but not after CON (P = .001). Response speed during the psychomotor vigilance test declined after the RSA test in both conditions (P < .001) and remained lower in the MF condition compared to CON (P = .012).

CONCLUSIONS

MF does not reduce RSA. However, the results of this study suggest that physical fatigue and MF have negative and cumulative effects on psychomotor vigilance. Therefore, strategies to reduce both physical fatigue and MF should be implemented in professional football players.

Inter- and intra-microcycle external load analysis in female professional soccer players: A playing position approach

This study analyzes the inter- and intra-differences in external load across the microcycle in professional female soccer players. External load during four consecutive microcycles (i.e., M1, M2, M3, and M4) and training sessions (i.e., MD-4, MD-3, MD-2, and MD-1) and a match day (i.e., MD) were registered in seventeen female professional soccer players (age: 26.3 ± 4.6 years; height: 166.3 ± 6.1 cm; body mass: 59.8 ± 6.8 kg; and body mass index: 21.6 ± 1.7 kg·m^-2) who belonged to the same team in Spanish first division. A 10-Hz GPS that integrated a 100-Hz triaxial accelerometer was used to register external load. The results showed lower decelerations in M2 compared to M1 and M3 (p < 0.05), lower high-intensity distance (>16.0 km·h^-1) in M3 vs. M2, and greater relative sprint distance (>21.0 km·min^-1) in M4 vs. M1 and M3 (p < 0.05). MD-3 registered the highest load for all variables (p < 0.05). Forwards (FWs) performed (p < 0.05) significantly more sprints (meters and number > 21.0 km·h^-1) than central midfielders (CMs) and central defenders (CDs) in MD-2 and MD. Both, fitness and conditioning staff should pay special attention to the external loads for each playing position in training sessions to optimize the training process.

Impact of the Menstrual Cycle Phases on the Movement Patterns of Sub-Elite Women Soccer Players during Competitive Matches

The purpose of this study was to evaluate the influence of the menstrual cycle phases on the movement patterns of sub-elite women soccer players during competitive matches over three consecutive seasons. Individual movement data were analyzed and compared in eight players from the second French League at the early follicular (EF), late follicular (LF) and mid-luteal (ML) phases of their menstrual cycle, determined by the calendar method. The movement patterns, expressed as meters per minute, were recorded during competitive matches using devices placed on the player’s ankle. Our results showed significantly lower distances covered at moderate and high velocity in the EF phase than in the LF and ML phases (Cohen’s d effect size = 1.03 and 0.79, respectively). The total distance covered during matches and the number of sprints also were reduced during EF compared with LF (d = 0.78 and 0.7, respectively). Overall, the total distance and distance covered at low velocity were significantly lower during the second half-time of the matches (d = 1.51), but no menstrual cycle phase × game period interaction was noted. In conclusion, our study suggests that EF may impact the movement pattern of sub-elite women soccer players during competitive matches, without any modulation of this effect by the playing time. Despite the low sample size, these results can be useful for coaches and support staff to modulate training loads and player rotation during soccer games.

The validity and reliability of an integrated approach for quantifying match physical-tactical performance

This study aimed to: (1) develop an integrated approach to quantifying match physical-tactical performance and (2) comprehensively examine the validity and reliability of this novel approach. Both UEFA qualified coaches and performance analysts (n = 30) participated to verify the scientific robustness of this new method. The percentage of correct responses were used to verify the validity of the integrated approach and the minimum acceptable agreement was set at 80%. Two well-trained groups of observers analysed a randomly selected English Premier League match for inter- and intra-observer reliability using the kappa statistic. A high degree of validity was demonstrated as the mean percentage of correct responses by all participants, accounting for 91.8 ± 4.3% for all, 92.2 ± 4.7% for out-of-possession, and 91.6 ± 5.7% for in-possession physical-tactical variables. Inter- and intra-observer reliability were found to be strong (κ = 0.81) to almost perfect (κ = 0.94), respectively. Additional analyses demonstrated that there was a nearly perfect correlation between data derived from the novel filter used for the present study to capture high-intensity running and those obtained from the filter of the commercial data provider (r = 0.99; P < 0.01). The data demonstrates that the integrated approach is valid and reliable regarding the quantification of physical-tactical performances. Therefore, it is now possible to unveil unique high-intensity profiles of elite players related to key tactical actions. This may help coaches and practitioners better understand the physical-tactical performances of players, as well as effectively translate physical metrics into training.

Moving Toward a More Comprehensive Analysis of Acceleration Profiles in Elite Youth Football

In football, having greater acceleration ability may decide the most important moments within matches. Up to now, commonly used acceleration variables have typically been investigated in isolation, with each variable suffering from unique limitations. Subsequently, any findings may provide a limited representation of what specific acceleration demands had actually occurred. Without gaining a comprehensive understanding of acceleration demands in football, it appears difficult to identify how to best monitor and maximize the long-term development of acceleration ability in footballers, all whilst doing so in a safe, sport-specific manner. Moving toward a more comprehensive analysis of acceleration profiles addresses this, as it can provide a more robust, informative understanding of the unique acceleration demands of competitive match-play. This perspective article aims to discuss the benefits of adopting a more comprehensive analysis of the acceleration demands during competitive matches for football players, by simultaneously analyzing high-intensity accelerations, repeated high acceleration ability (RHAA), and average acceleration. We discuss examples of the calculation and application of a more comprehensive acceleration profile at a team level throughout the course of an entire elite youth football season, as well as on an individual level. Monitoring acceleration profiles more comprehensively not only appears important from a training load/injury prevention perspective, but also, equips coaches and conditioning staff with the specific information necessary to develop and prescribe individualized, acceleration-emphasized training protocols that are replicable to the demands of match-play. Examples of such protocols are provided.

Effects of Combined Plyometric and Short Sprints Training on Athletic Performance of Male U19 Soccer Players

This project investigated adding 8 weeks of biweekly plyometric and short sprints training into standard training in elite youth soccer players. An experimental group (EG, n = 18, age: 17.6 ± 0.6 years, body mass: 67.6 ± 5.8 kg, height: 1.75 ± 0.06 m, and body fat: 11.5 ± 1.6%) and control group (CG, n = 18, age: 17.5 ± 0.6 years, body mass: 68.8 ± 3.6 kg, height: 1.77 ± 0.04 m, and body fat: 11.7 ± 1.2%) participated. Pre-intervention and post-intervention measures were squat-jump (SJ), countermovement-jump (CMJ), standing long jump (SLJ), 5 and 20 m sprints, change-of-direction ability (4 × 5 m sprint test [S 4 × 5 m] and sprint 9-3-6-3-9 m with backward and forward running [SBF]), repeated change of direction (RCOD), and static balance (the stork balance test). For all parameters, significant (p < 0.001, ηp2 > 0.10) time and interaction (group × time) effects were observed. For three parameters (SBF, RCOD fastest time, and SLJ) no significant group effects were observed. The EG consistently showed a significantly higher performance level than the CG and a higher amount of effect sizes d (EG: d_range: 1.27–2.61; CG: d_range: 0.13–0.79) as an indicator for the development of performance between pre-intervention and post-intervention measures. Adding biweekly plyometric and short sprint training to standard training improves the athletic performance of young soccer players. Such plyometric and short sprint training conditioning can be highly recommended as part of the annual short training program for male elite under-19 (U19) soccer players.

The use of recovery strategies by Spanish first division soccer teams: a cross-sectional survey

OBJECTIVES

different active and passive post-exercise recovery techniques such as massage, foam rolling, stretching or ice baths among others, are used by elite athletes to promote effective physiological, physical, and mental restoration. However, limited research is available investigating the use of recovery strategies in professional soccer. As such, we aimed to explore and describe the use of strategies by professional teams throughout the season, describing competitive and preparatory phases.

METHODS

the present study collected data from all professional Spanish soccer teams who played in 'LaLiga' (The Spanish first division), during the season 2018-2019 (n = 20) and the ones promoted for the season 2019-2020 (n = 3). A six-section online survey was responded once.

RESULTS

teams used different recovery protocols and combinations, although natural and physical strategies such as sleep/nap, food/fluid replacement, cold/ice bath/shower/immersion, and massage were always present. However, there is no agreement in the protocols and timings employed. Three physical strategies showed a higher presence in the recovery protocols after competition: cold/ice bath/shower/immersion, massage and foam rolling; always used by seventeen teams (74%), sixteen (70%) and thirteen (57%) respectively. The design and supervision of recovery are multidisciplinary tasks in 87% of the teams. Our findings also demonstrate that although there is a body of scientific evidence on recovery, a gap between theory and practice exists with 13% of the teams acknowledging that insufficient logistics and economic resources limit the use of some strategies, and two teams (9%) not periodizing or individualizing recovery.

CONCLUSION

the investigation provided insight into the current use of recovery strategies by 'LaLiga' teams, highlighting that all clubs used them to one extent or another, but also that significant variability responding to individualized perceptions exists. Moreover, this study provides relevant contextual information that may be useful for professional soccer staff concerning the use of recovery strategies.

Quantifying Mean Peak Running Intensities in Elite Field Hockey

ABSTRACT

Delves, RIM, Bahnisch, J, Ball, K, and Duthie, GM. Quantifying mean peak running intensities in elite field hockey. J Strength Cond Res 35(9): 2604-2610, 2021-To replicate match demands in training, field hockey (FH) coaches typically prescribe intensities based on whole-match data. Such data may underestimate peak competition periods, potentially underpreparing athletes for competition. This study then aimed to quantify maximal mean running intensities during elite FH competition to facilitate enhanced training prescription. Ten-Hertz Global Positioning System data were collected from 17 male and 11 female FH athletes who competed in the 2016 and 2017 Australian Hockey League tournaments. Maximal mean values for speed, acceleration, and metabolic power (Pmet) were calculated over a 1- to 10-minute moving average by position. Summary match statistics were also analyzed. Linear mixed models were constructed to determine the effect of position on moving average and summary variables. Pairwise comparisons between groups were made using magnitude-based inferences. In female competition, speed and Pmet intensities were greater in midfielders, whereas defenders were lowest in acceleration demands over the 10-minute window and in corresponding intercepts. In male competition, acceleration was greater in defenders during the 10-minute window and in subsequent intercepts compared with midfielders, whereas defenders were lowest in speed intercepts. In comparison with previously reported summary match variables, intensities from the 1-minute moving average interval were 50-65% greater in male competition and 30-50% greater in female competition. The 10-minute moving average framework has identified FH running intensities that are greater than previously reported whole-match averages. This information enhances the understanding of the demands of FH, assisting practitioners to prepare their athletes for the most demanding instances of play.

The influence of thermal stress on the physical and technical activities of soccer players: lessons from the 2018 FIFA World Cup in Russia

The present study attempts to assess changes in soccer players' physical and technical activity profiles due to thermal stress, measured with the Universal Thermal Climate Index (UTCI), in training centres and during matches of the 2018 FIFA World Cup in Russia. The study also verifies the theoretical models of soccer players' physiological parameters. The study sample consisted of 945 observations of 340 players of national teams taking part in the World Cup in Russia. The measured variables included physical activities: total distance covered, distances covered with an intensity of 20-25 km/h, number of sprints; technical activities: number of shots, number of passes, pass accuracy and physiological indicators: evaporative water loss and heart rate. In addition, the final ranking places of each national team were also used in the study. The UTCI was calculated based on meteorological data recorded at training centres and during matches. The UTCI records were then classified into two ranges: NTS-no thermal stress (UTCI 9-26 °C) and TS-thermal stress (UTCI > 26 °C). Climatic conditions at soccer training centres assessed as involving "no thermal stress" are found to be more beneficial for increasing the total distance covered and the number of sprints performed by players during a match. The theoretical models for determining soccer players' physiological parameters used in the study reduce the players' heart rate effort and evaporative water loss, which is in line with findings in studies by other authors. The climatic conditions at soccer training centres and during tournament matches should be taken into account in planning preparations for future World Cup tournaments, especially those in hotter countries.

Ecological and Construct Validity of a Repeated Sprint Test in Male Youth Soccer Players

ABSTRACT

Fernandes-Da-Silva, J, Castagna, C, Teixeira, AS, Carminatti, LJ, Francini, L, Póvoas, SCA, and Antonacci Guglielmo, LG. Ecological and construct validity of a repeated sprint test in male youth soccer players. J Strength Cond Res 35(7): 2000-2009, 2021-This study aimed to examine the relationship between a repeated sprint ability (RSA) test (5 bouts of 30-m sprints interspersed by 30 seconds of recovery) and match-related physical performance in male youth soccer players. Although 60 outfield players were evaluated, only data from players who participated in the full matches (n = 39) were retained (8 central defenders, 7 external defenders, 8 central midfielders, 8 external midfielders, and 8 forwards). To verify the ecological validity of this RSA protocol, the association between the best (RSAbest) and mean (RSAmean) sprint time in the 5 × 30-m and physical match performance during friendly youth soccer games was examined. Physical match demands were assessed using global positioning system technology (10 Hz) considering distance covered in selected arbitrary speed categories. The absolute speed thresholds were the same for all the players. Players were categorized into 2 groups based on the 5 × 30-m performance: RSAmean times below (i.e., faster) and above (i.e., slower) the median value. Players with faster RSAmean times covered significantly more distance sprinting during friendly matches (606 ± 204 m, +47.0%; t = 4.953; effect size = 1.88, 1.24; 2.52, p ≤ 0.001) compared to their slower counterparts (322 ± 145 m). A large negative correlation (r = -0.63, -0.77; -0.44, p ≤ 0.001) was found between RSAbest time (4.59 ± 0.27 seconds) and match sprint distance (457 ± 229 m). Likewise, RSAmean time (4.76 ± 0.25 seconds) was also largely associated (r = -0.60, -0.75; -0.39; p ≤ 0.001) with in-game sprinting performance. The results of this study provided evidence to support the construct and ecological validity of the 5 × 30-m protocol in male youth soccer players. Furthermore, differences in 5 × 30-m performance explained the amount of sprinting activity performed during the match.

Maximal Oxygen Consumption Requirements in Professional North American Ice Hockey

ABSTRACT

Ferland, P-M, Marcotte-L'Heureux, V, Roy, P, Carey, V, Charron, J, Lagrange, S, Leone, M, and Comtois, AS. Maximal oxygen consumption requirements in professional North American ice hockey. J Strength Cond Res 35(4): 1586-1592, 2021-This study was designed to measure preseason on-ice relative V̇o2max of professional ice-hockey players (n = 101 National Hockey League [NHL], 42 American Hockey League [AHL], 4 East Coast Hockey League [ECHL], and 15 Canadian Hockey League [CHL]) throughout 17 years and compare it between generations, league level, and position, and to verify if it was related to season and NHL career statistics. Relative V̇o2max was measured on ice with a portable metabolic analyzer (K4b2, Cosmed, Rome) with full hockey equipment, except for the helmet with either the Skating Multistage Aerobic Test or the 30-15 intermittent ice test tests. Relative V̇o2max results from both tests were compared between players of the same generation with an independent-samples T-test and were not significantly different. A one-way analysis of variance and post hoc pairwise tests were performed to detect significant differences between groups. Pearson correlations (two-tailed) were also performed between selected variables. All statistical significance was set at p < 0.05. Results show that there are no significant differences for relative V̇o2max between generations (2001-2003 vs. 2006 vs. 2015-2017), league level (NHL vs. AHL vs. ECHL vs. CHL), and position (winger, center, and defense), other than the ECHL being lower. There are also no significant relationships between V̇o2max values and hockey season and NHL career statistics. Thus, the results show that there is a minimal relative V̇o2max requirement to play North American ice hockey at the elite level (55.9 ± 5.2 ml·kg-1·min-1; n = 162). Future research should be directed toward comparing V̇o2max of elite and amateur ice-hockey players to confirm the minimal relative V̇o2max requirement to play North American ice hockey at the elite level.

Acute Effects of Warm-Up, Exercise and Recovery-Related Strategies on Assessments of Soccer Kicking Performance: A Critical and Systematic Review

BACKGROUND

A number of reviews have collated information on the impact of warming-up, physical exertion and recovery strategies on physical, subjective and physiological markers in soccer players yet none have solely analyzed their potential effects on components of kicking performance.

OBJECTIVE

To systematically analyse the influence of warm-up, exercise and/or recovery-related strategies on kicking performance in male soccer players and provide a critical appraisal on research paradigm related to kicking testing constraints and data acquisition methods.

METHODS

A systematic literature search was performed (until July 2020) in PubMed, Web of Science, SPORTDiscus, Scopus and ProQuest. Studies in male soccer populations, which included the effects of warm-up routines, physical exercise and/or recovery-related interventions, reported on comparisons pre-post or between experimental conditions and that computed at least one measure of kicking kinematics and/or performance were considered. Methodological quality and risk of bias were determined for the included studies. Constraints related to kicking testing and data acquisition methods were also summarized and discussed.

RESULTS

Altogether, 52 studies were included. Of these, 10 examined the respective effects of a warm-up, 34 physical exercise, and 21 recovery-related strategies. The results of eight studies showed that lower limb kinematics, kicking accuracy or ball velocity were improved following warm-ups involving dynamic but not static stretching. Declines in ball velocity occurred notably following intermittent endurance or graded until exhaustion exercise (three studies in both cases) without inclusion of any ball skills. In contrast, conflicting evidence in five studies was observed regarding ball velocity following intermittent endurance exercise interspersed with execution of ball skills. Kicking accuracy was less frequently affected by physical exercise (remained stable across 14 of 19 studies). One investigation indicated that consumption of a carbohydrate beverage pre- and mid-exercise demonstrated benefits in counteracting the potentially deleterious consequences of exercise on ball velocity, while four studies reported conflicting results regarding kicking accuracy. Most evidence synthesized for the interventions demonstrated moderate level (77%) and unclear-to-high risk of bias in at least one item evaluated (98%). The main limitations identified across studies were kicks generally performed over short distances (50%), in the absence of opposition (96%), and following experimental instructions which did not concomitantly consider velocity and accuracy (62%). Also, notational-based metrics were predominantly used to obtain accuracy outcomes (54%).

CONCLUSIONS

The results from this review can help inform future research and practical interventions in an attempt to measure and optimise soccer kicking performance. However, given the risk of bias and a relative lack of strong evidence, caution is required when applying some of the current findings in practice.

PROSPERO ID

CRD42018096942.

Specific Absolute Velocity Thresholds during Male Basketball Games Using Local Positional System; Differences between Age Categories

The aim of this study was (I) to establish absolute specific velocity thresholds during basketball games using local positional system (LPS) and (II) to compare the speed profiles between various levels of competitions. The variables recorded were total distance (TD); meters per minute (m·min); real time (min); maximum speed (Km h−1), distance (m), percentage distance, and percentage duration invested in four speed zones (standing–walking; jogging; running; and high-speed running). Mean and standard deviation (±SD) were calculated, and a separate one-way analysis of variance was undertaken to identify differences between competitions. TD (3188.84 ± 808.37 m) is covered by standing–walking (43.51%), jogging (36.58%), running (14.68%), and sprinting (5.23%) activities. Overall, 75.22% of the time is invested standing–walking, jogging (18.43%), running (4.77%), and sprinting (1.89%). M·min (large effect size), % duration zone 2 (moderate effect size); distance zone 4 (large effect size), and % distance zone 4 (very large effect size) are significantly higher during junior than senior. However, % distance zone 1 (large effect size) and % duration zone 1 (large effect size) were largely higher during senior competition. The findings of this study reveal that most of the distance and play time is spent during walking and standing activities. In addition, the proportion of time spent at elevated intensities is higher during junior than in senior competition.

Distance and Intensity Profiles in Division I Women's Soccer Matches across a Competitive Season

Women’s participation in soccer has increased rapidly. The purpose of this study was to evaluate the physiological demands imposed on women’s NCAA Division I soccer players across a season according to speed, total distance traveled, and numbers of sprints measured via GPS (Polar Team Pro^®). Eighteen athletes (19.2 ± 1.1 years, 50.5 ± 6.5 mL/kg/min and 23.4 ± 3.6% fat) participated in this study. The analysis was obtained through 13 official matches. Speed zones were defined as Zone 1 (1.0 to 5.99 km·h⁻¹), Zone 2 (6.0 to 10.99 km·h⁻¹), Zone 3 (11.0 to 15.49 km·h⁻¹), Zone 4 (15.5 to 19.9 km·h⁻¹) and Zone 5 (sprint > 20 km·h⁻¹), with Zones 4–5 considered as high intensity running. Individual differences in playing time and total distance were highly variable due to substitutions. Average distance traveled per game in quartiles was 3.9 km, 5.6 km and 7.4 km in the 25th, 50th, and 75th quartiles, respectively. Relative to playing time, players travelled an average of 113.64 ± 17.12 m/min (range: 93.7 to 143.5 m/min) and ran one sprint every 4.12 ± 2.06 min. When distance was summated and analyzed for the entire team, significant difference between halves was found for speed Zones 2, 3 and 4, with greater values found in the first half. Total distance, high intensity running and sprint distance were significantly less than previously recorded in professional players. These findings suggest that coaches should consider the unique physiological demands and recovery opportunities present in NCAA play when constructing practices and conditioning programs.

Effects of Plyometric Jump Training on Repeated Sprint Ability in Athletes: A Systematic Review and Meta-Analysis

BACKGROUND

There is a growing body of research examining the effects of plyometric jump training (PJT) on repeated sprint ability (RSA) in athletes. However, available studies produced conflicting findings and the literature has not yet been systematically reviewed. Therefore, the effects of PJT on RSA indices remain unclear.

OBJECTIVE

To explore the effects of PJT on RSA in athletes.

METHODS

Searches for this review were conducted in four databases. We included studies that satisfied the following criteria: (1) examined the effects of a PJT exercise intervention on measures of RSA; (2) included athletes as study participants, with no restriction for sport practiced, age or sex; and (3) included a control group. The random-effects model was used for the meta-analyses. The methodological quality of the included studies was assessed using the PEDro checklist.

RESULTS

From 6367 search records initially identified, 13 studies with a total of 16 training groups (n = 198) and 13 control groups (n = 158) were eligible for meta-analysis. There was a significant effect of PJT on RSA best sprint (ES = 0.75; p = 0.002) and RSA mean sprint (ES = 0.36; p = 0.045) performance. We did not find a significant difference between control and PJT for RSA fatigue resistance (ES = 0.16; p = 0.401). The included studies were classified as being of "moderate" or "high" methodological quality. Among the 13 included studies, none reported injury or any other adverse events.

CONCLUSION

PJT improves RSA best and mean performance in athletes, while there were no significant differences between control and PJT for RSA fatigue resistance. Improvements in RSA in response to PJT are likely due to neuro-mechanical factors (e.g., strength, muscle activation and coordination) that affect actual sprint performance rather than the ability to recover between sprinting efforts.

Internal, external and repeated-sprint demands in small-sided games: A comparison between bouts and age groups in elite youth soccer players

This study investigated the activity profile during small-sided games (SSG) in elite youth soccer players. Internal load (IL) including heart rate (HR) and external load (EL) such as distance covered in different speed-zones (SZ) were collected from forty-eight players of three different teams (U15, U16, U18). The investigation included a total of eighteen 5vs.5 SSGs, each consisting of four 2-minute bouts on a 40x32m pitch during spring season. Total group results (n = 48) showed a reduction in total-distance (p = 0.001; ηp2 = 0.12), high-intensity-running (p = 0.009; ηp2 = 0.09), and low-intensity-running distance (p = 0.028; ηp2 = 0.07) between bouts. Similarly, a reduction in the number of both acceleration-low (p = 0.001; ηp2 = 0.12) and deceleration-high (p = 0.003; ηp2 = 0.11) values was observed. Additionally, time spent in HR-zones 3 and 4 (p≤0.007; ηp2 ≥ 0.10), increased, with a reduction in HR-zone 1 (p = 0.000, ηp2 = 0.25). Age group comparison showed less distance covered in SZ 1 (p≤0.000; ηp2 = 0.56) and greater deceleration-high values (p≤0.038; ηp2 = 0.32) in U15 players compared to other age groups. Further, U15 showed lower values in low-intensity-running compared to U18 (p = 0.038; ηp2 = 0.22). No age-related differences were found for IL and repeated sprint ability (RSA) values. The higher EL in younger age groups should be taken into account when implementing soccer specific SSGs. In addition, HRmean values between 80–85% of HRmax and RSA numbers, which are similar to match-play data, indicate SSGs as an effective training tool to prepare youth soccer athletes for the demands of competition.

The Accuracy of a Low-Cost GPS System during Football-Specific Movements

An affordable player monitoring solution could make the evaluation of external loading more accessible across multiple levels of football (soccer). The present study aimed to determine the accuracy of a newly designed and low-cost Global Positioning System (GPS) whilst performing match-specific movement patterns. Sixteen professional male football players (24 ± 3 years) were assigned a GPS device (TT01, Tracktics GmbH, Hofheim, Germany) and completed two experimental trials. In each trial, a continuous protocol including seven movements (sideways cornering, diagonal cornering, accelerating, decelerating, backwards jogging, shuttle running, and skipping) adding up to 500 m, was completed. Time-motion data was compared with criterion distance and velocity (photo-cell timing gates and radar). Validity was assessed through the standard error of the estimate (SEE) and reliability through the coefficient of variation (CV; both with 95% confidence limits). For the total distance covered during the protocol, the system was found to be valid (SEE = 3.1% [2.2; 5.8]) and reliable (intra-device CV = 2.0% [1.2; 7.6]). Similar results were found for velocity (SEE = 3.4% [2.6; 4.8], CV = 4.7% [3.2; 8.5]). In conclusion, the present GPS system, a low-cost solution, was found to be a valid and reliable tool for measuring physical loading during football-specific movements.

The Effect of High Volume Power Training on Repeated High-Intensity Performance and the Assessment of Repeat Power Ability: A Systematic Review

BACKGROUND

High volume power training (HVPT) involves high volumes of high-velocity resistance training, with the aim to improve repeated high-intensity efforts (RHIEs). Repeat power ability (RPA) is the ability to repeatedly produce maximal or near maximal efforts. Assessments of RPA using external loading may determine the ability to perform repeat RHIEs typical of many sports and, therefore, provide useful information on the effectiveness of training.

OBJECTIVES

(1) Identify the different HVPT protocols; (2) examine the acute responses and chronic adaptations to different HVPT protocols; (3) identify different lower body RPA assessment protocols and highlight similarities, differences and potential limitations between each protocol, and; (4) describe the reliability and validity of RPA assessments.

METHODS

An electronic search was performed using SPORTDiscus, PubMed, CINAHL and Embase for studies utilising HVPT protocols and assessments of RPA. Eligible studies included peer-reviewed journal articles published in English.

RESULTS

Twenty studies met the inclusion criteria of the final review. Of the eight longitudinal studies, three were rated as fair and five were rated as poor methodological quality, respectively. In contrast, all 12 cross-sectional studies were considered to have a low risk of bias. Preliminary evidence suggests that HVPT can enhance RHIE, RPA, anaerobic capacity, anaerobic power and aerobic performance. HVPT generally consists of 2-3 sessions per week, utilising loads of 30-40% 1 repetition maximum (RM), for 3-5 sets of 10-20 repetitions, with inter-set rest periods of 2-3 min. RPA assessments can be valid and reliable and may provide useful information on an athlete's ability to perform RHIE and the success of HVPT programmes.

CONCLUSIONS

HVPT can be used to improve a number of physical qualities including RPA and RHIE; while a variety of RPA assessments provide valid and reliable information regarding the athlete's ability to perform RHIEs. Considering the heterogeneity in the HVPT protocols currently used and the relatively low volume and quality of longitudinal publications in this area, further studies are needed to identify the effects of a variety of HVPT methods on RPA, RHIE and other performance outcomes and to identify the most valid and reliable RPA outcomes to use in such studies.

Muscular and Physical Response to an Agility and Repeated Sprint Tests According to the Level of Competition in Futsal Players

The aim of this study was to evaluate the neuromuscular response to an agility and repeated sprint ability (RSA) test according to the level of competition in futsal players. A total of 33 players from two elite teams and one amateur team participated in the study. The participants completed an agility t-test, a 30 m-speed test, and a RSA test. A countermovement jump (CMJ) test and a tensiomyography test of the rectus femoris (RF) and biceps femoris (BF) of both legs were carried out before and after the tests. RSA test revealed better sprint times in elite players compared to amateurs in the seven bouts, as well as in the 30 m sprint and in the agility test (p < 0.05). Before the tests, elite players showed higher sustain time (Ts) in RF (+31.03 ms; ES: 0.76) and BF (+28.73 ms; ES: 0.73), higher half-relaxation time (Tr) in BF (+20.79 ms; ES: 0.94), and lower delay time (Td) in BF (−2 ms; ES: 1.19) compared to amateur players. However, post-test values did not present any significant differences (p > 0.05). In conclusion, elite players showed greater performance in the RSA test, in the 30 m tests and in the agility test compared to amateur players. The contractile properties were not a key factor in the RSA performance of the futsal players.

Effects of acute wearable resistance loading on overground running lower body kinematics

Field-based sports require athletes to run sub-maximally over significant distances, often while contending with dynamic perturbations to preferred coordination patterns. The ability to adapt movement to maintain performance under such perturbations appears to be trainable through exposure to task variability, which encourages movement variability. The aim of the present study was to investigate the extent to which various wearable resistance loading magnitudes alter coordination and induce movement variability during running. To investigate this, 14 participants (three female and 11 male) performed 10 sub-maximal velocity shuttle runs with either no weight, 1%, 3%, or 5% of body weight attached to the lower limbs. Sagittal plane lower limb joint kinematics from one complete stride cycle in each run were assessed using functional data analysis techniques, both across the participant group and within-individuals. At the group-level, decreases in ankle plantarflexion following toe-off were evident in the 3% and 5% conditions, while increased knee flexion occurred during weight acceptance in the 5% condition compared with unloaded running. At the individual-level, between-run joint angle profiles varied, with six participants exhibiting increased joint angle variability in one or more loading conditions compared with unloaded running. Loading of 5% decreased between-run ankle joint variability among two individuals, likely in accordance with the need to manage increased system load or the novelty of the task. In terms of joint coordination, the most considerable alterations to coordination occurred in the 5% loading condition at the hip-knee joint pair, however, only a minority of participants exhibited this tendency. Coaches should prescribe wearable resistance individually to perturb preferred coordination patterns and encourage movement variability without loading to the extent that movement options become limited.

Fatigue Indices and Perceived Exertion Highlight Ergometer Specificity for Repeated Sprint Ability Testing

This study aimed to compare the time course of measures of performance, fatigue, and perceived exertion during repeated-sprint ability (RSA) testing performed on a non-motorized treadmill (NMT) and cycling ergometer (CE). Fourteen physically active participants performed two 10 ×6 s⁻¹ RSA tests with a 1:4 work-to-rest ratio (24 s recovery) on NMT and CE. Measures of performance [peak and mean power output (PPO and MPO), cadence, and the time to reach PPO (TTP)] and of fatigue (fatigue index and decrement score) and ratings of perceived exertion (RPE) were collected during each session. The level of significance was set at p < 0.05. Participants completed the RSA test at a MPO of 1,041 ± 141 W on CE and 431 ± 48 W on NMT, achieving PPO of 2,310 ± 339 W on CE and 1,763 ± 289 W on NMT. Participants' weight was significantly correlated with PPO and MPO on CE (p < 0.001) and with MPO on NMT (p < 0.001). PPO on CE and NMT was significantly correlated only for absolute measures of power (p < 0.01). Cadence was higher and decreased throughout the RSA on NMT compared to CE, where it decreased only at the seventh bout. TTP was significantly shorter and more affected by fatigue on NMT than on CE. Fatigue indices were significantly greater on NMT compared to CE, with significant correlations between the decrement score and absolute and relative PPO on CE and NMT, between the fatigue index and absolute and relative PPO only on NMT, and no significant correlations with MPO. During RSA, RPE increased more on NMT compared to CE from bouts 3 to 7. During recovery, RPE was consistently higher on NMT at 1, 3, and 5 min post exercise compared to CE. These findings indicate that RSA performed on NMT induces greater fatigue and physiological load than CE, which originated in the lower resistive torque typically used on NMT compared to CE, resulting in a front loaded power output profile from the greater acceleration and cadence. From these results, we discuss that despite providing highly correlated measures of power output, NMT and CE should not be used interchangeably to assess RSA as they elicit markedly different responses. We also discuss these results from the fundamental differences in active muscle mass and power application patterns between running and cycling, which could form the basis of future studies.

Change-of-Direction Ability of Para-Footballers With Cerebral Palsy Under a New Evidence-Based and Sport-Specific Classification System

PURPOSE

This study aimed (1) to explore the validity and reliability of a new and specific change-of-direction (COD) test that requires dribbling skills to classify international footballers with cerebral palsy (CP) and compare it with another valid and reliable COD test without ball dribbling and (2) to probe whether both tests can discriminate between the new CP football classes (ie, FT1, FT2, and FT3) established worldwide in 2018.

METHODS

This study involved 180 international para-footballers with CP from 23 national teams at the 3 regional competitions held in 2018. They performed 2 COD tests, the modified agility test (no dribbling skills) and the dribbling speed test (DST).

RESULTS

Reliability was excellent for both the modified agility test (intraclass correlation coefficient [ICC]2,1 = .91, SEM = 5.75%) and the DST (ICC2,1 = .92, SEM = 4.66%). The modified agility test and DST results were highly to very highly correlated to one another for the whole group and considering the sport classes (r = .60-.80; P < .001). A 1-way analysis of variance showed significant differences between sport classes in both tests (P < .001). However, among classes, there were significant differences between FT1 and FT2 and FT3 (P < .01, effect size = large) and low to moderate effect sizes between FT2 and FT3 for either test.

CONCLUSION

The DST appears to be valid and reliable to classify CP football players within the new classification system. Regression analysis revealed that 18.2% of the variance in the new sport classes could be explained by the 2 examined tests.

Validation of the alpine skiing 90 seconds box jump field test and prediction of power output

BACKGROUND

The purpose of this study was to validate the alpine ski racing 90 s box jump field-test (BJ90) with the 90 s Wingate test (W90).

METHODS

Fifteen elite alpine ski racers were tested on the BJ90 (0.45 m × 0.75 m × 0.9 m) and the W90 (Ergomedic 894 E Monark; Monark AB, Varberg, Sweden) test in a random order. The number of hits on the BJ90 was written down every 15 s and for the W90 the load (7.5% of body weight) was manually dropped once the subjects reached maximum RPM without resistance. Correlations and partial correlations were calculated with a 2-tailed Pearson correlation analysis. A stepwise forward regression analysis was also performed.

RESULTS

Results present significant (P<0.05) correlations and partial correlations adjusted for body weight between the total number of hits on the BJ90 and W90 peak W, peak W/kg, mean W and mean W/kg as well as with the number of hits and W90 Mean W and mean W/kg between each 15 s time slot. A linear regression predictive equation for mean relative power (W/kg) generated from the BJ90 was established: mean relative power (W/kg)=0.055*total hits+1.080 (r=0.79, P<0.001; total hits with mean W/kg). A stepwise forward regression equation for mean absolute power (W) generated from the BJ90 was also established: mean absolute power (W)=2.305*number of hits+5.081*body weight in kg^-1 -169.8 (R=0.964, P<0.001, SEE=23.56).

CONCLUSIONS

Practitioners could use the BJ90 to assess alpine skiers lower body power as previous research showed that both are correlated with performance and are able to discriminate skier level.

Effects of muscular injuries on the technical and physical performance of professional soccer players

Introduction: The aim of this study was to determine the effects of muscular injuries in the lower limbs on the technical and physical performance of professional soccer players when they return to the league competition. Methods: Seventy-six muscular injuries incurred by Spanish male professional soccer players (Age: 27.5 ± 3.5 years) were analyzed during two consecutive competitive seasons: 2014-2015 and 2015-2016. The players' performance was studied during Spanish First Division competitive matches using a multi-camera computerized tracking system (Mediacoach Desktop). Results: After muscular injury relative total distance covered in sprints decreased by 8.6 ± 30.2% (P = 0.013) in the first half and 7.7 ± 36.6% (P = 0.038) in the second half. Similarly, maximal running speed decreased by 2.78 ± 6.91 km.h^-1 (pre: 27.3 ± 6.4 km.h^-1vs. post: 24.5 ± 6.6 km.h^-1, P = 0.013) in the first half, and 1.50 ± 5.68 km.h^-1 (29.1 ± 3.9 km.h^-1vs. 27.6 ± 5.3 km.h^-1, P = 0.043) in the second half. Muscle injury also affected technical performance significantly decreasing successful passes (P = 0.045). There were no differences in the number of possession gains (P = 0.277), and possession losses (P = 0.178). Conclusions: After a moderate or severe muscular injury (causing >8 days lay off), player performance is significantly lower in high-intensity efforts and technical skills such as sprints, maximal running speed, or successful passes.

Post-competition recovery strategies in elite male soccer players. Effects on performance: A systematic review and meta-analysis

Aims

The main aim of the present review was to update the available evidence on the value interest of post-competition recovery strategies in male professional or semi-professional soccer players to determine its effect on post-game performance outcomes, physiological markers, and wellness indicators.

Methods

A structured search was carried out following the PRISMA guidelines using six online databases: Pubmed, Scopus, SPORTDiscus, Web of Science, CINAHL and Cochrane Central Register of Controlled Trials. The risk of bias was completed following the Cochrane Collaboration Guidelines. Meta-analyses of randomized controlled trials were conducted to determine the between and within-group effects of different recovery strategies on performance, physiological markers and wellness data. Final meta-analyses were performed using the random-effects model and pooled standardized mean differences (SMD).

Results

Five randomized controlled trials that used Compression Garments (n = 3), Cold Water Immersion (n = 1), and acute Sleep Hygiene Strategy (n = 1) were included. Greater CMJ values at 48h for the intervention group (SMD = 0.70; 95% CI 0.14 to 1.25; p = 0.001; I² = 10.4%) were found. For the 20-m sprint and MVC, the results showed no difference either at 24h or 48h. For physiological markers (CK and CRP) and wellness data (DOMS), small to large SMD were present in favor of the intervention group both at 24h (-0.12 to -1.86) and 48h (-0.21 to -0.85). No heterogeneity was present, except for MVC at 24h (I² = 90.4%; p = 0.0012) and CALF DOMS at 48h (I² = 93.7%; p = 0.013).

Conclusion

The use of recovery strategies offers significant positive effects only in jumping performance (CMJ), with no effects on the 20-m sprint or MVC. Also, the use of recovery strategies offers greater positive effects on muscle damage (physiological markers and wellness data), highlighting the importance of post-match recovery strategies in soccer.

Can Haematological and Hormonal Biomarkers Predict Fitness Parameters in Youth Soccer Players? A Pilot Study

The study aimed to investigate the correlations among immune, haematological, endocrinological markers and fitness parameters, and assess if the physiological parameters could be a predictor of fitness values. Anthropometric, physical evaluations (countermovement jump—CMJ, 10 m sprint, VO₂max, repeated sprint ability—RSA total time and index) and determination of blood (IL-6, IL-10, IL-17A and tumour necrosis factor) and salivary (testosterone and cortisol) samples parameters in 28 young male soccer players (age: 13.0 ± 0.2 years, body mass index (BMI): 19.5 ± 2.2 kg/m²) were analysed. To evaluate the dependence of the variables related to athletic performance, multiple linear regression with backward stepwise elimination was considered. A significant regression equation was found in CMJ (F_(5,16) = 9.86, p < 0.001, R² adjusted = 0.679) and in the RSA index (F_(5,16) = 15.39, p < 0.001, R² adjusted = 0.774) considering only five variables, in a 10 m sprint (F_(4,17) = 20.25, p < 0.001, R² adjusted = 0.786) and in the RSA total time (F_(4,17) = 15.31, p < 0.001, R² adjusted = 0.732) considering only four variables and in VO₂max (F_(9,12) = 32.09, p < 0.001, R² adjusted = 0.930) considering nine variables. Our study suggests the use of regression equations to predict the fitness values of youth soccer players by blood and saliva samples, during different phases of the season, short periods of match congestion or recovery from an injury.

Normative Data and Physical Determinants of Multiple Sprint Sets in Young Soccer Players Aged 11-18 Years: Effect of Maturity Status

Selmi, MA, Sassi, RH, Yahmed, MH, Giannini, S, Perroni, F, and Elloumi, M. Normative data and physical determinants of multiple sprint sets in young soccer players aged 11-18 years: Effect of maturity status. J Strength Cond Res 34(2): 506-515, 2020-The aims of the study were: (a) to establish normative data for repeated-sprint sets (RSS) test based on the maturity status (age at peak height velocity [PHV]) and (2) to investigate the relationship between anthropometrical variables (stature, sitting height, body mass, and body fat percentage), RSS (2 × 5 × 20 m with 15-second recovery between sprints and 1-minute recovery between sets), and fitness tests {squat jump, countermovement jump, standing long jump, standing triple jump, 5-jump test, and 20-m shuttle run (multistage shuttle run test [MSRT])}. Young male soccer players (n = 262; age: 14.5 ± 2.9 years) were evaluated and classified into 4 groups according to their maturity status: pre-PHV, circum-PHV1, circum-PHV2, post-PHV. An analysis of variance and Bonferroni post hoc were used to determine maturity group differences (p ≤ 0.05), whereas Pearson's correlation was used between variables. Repeated-sprint sets' indices (sum of sprint times [SST] and best sprint time [BST]) were significantly different between the maturity groups. Significant correlations between SST with body mass (from -0.73 to -0.33) and MSRT (from -0.49 to -0.30) among each maturity group were found. With the different maturity groups, correlations between SST (s), BST (s), and vertical jump (cm) (r = -0.63 to -0.25 and r = -0.68 to -0.23) and horizontal jump (m) (r = -0.70 to -0.38 and r = -0.63 to -0.43) were observed. Repeated-sprint sets' values improve during maturation of young soccer players and the correlations between RSS and fitness tests vary through the maturity groups. This information could be useful for the coach to identify talent and to prescribe specific physical training to improve performance.

Comparison between Two Different Device Models 18 Hz GPS Used for Time-Motion Analyses in Ecological Testing of Football

Background: The aim of this study was to compare the validity of two different GPS device models used for time–motion analyses in ecological testing of football. Methods: Ten healthy male players from a Spanish university football team participated in this study. The team sport simulation circuit (TSCC) used was based on previous research examining the validity and interunit reliability of different GPS systems. Participants were required to complete eight laps of the TSSC, resulting in a total distance of 1320 m. The GPS units used for the current study were the 18 Hz StatsSport Apex Pro and 18 Hz RealTrack WIMU Pro. Participants were required to wear either of the two GPS units during the test. To establish the construct validity of GPS as a measure of V_max, timing lights were used as a gold standard. Results: The results clearly suggest that it is not possible to use the same 18 Hz GPS model or interchange it. The measurement can be considered precise when the noise is at least equal to or lower than the smallest worthwhile change. In this case, all standard deviation in measurement error was higher than the smallest worthwhile change. This is due to an inconsistency in the data processing of each trademark. Conclusions: It is important to prevent a club using different GPS trademarks at the same time, since it is not possible to compare in any case any type of result obtained between different trademarks.