Hexagonal Barbell Deadlift One-repetition Maximum Estimation Using Velocity Recordings.

This study aimed to determine whether the optimal minimal velocity threshold (MVT) provides more precise estimates of one-repetition maximum (1RM) in the hexagonal barbell deadlift (HBD) than the general and individual MVTs. The 1RMs of 27 resistance-trained males were predicted using three types of MVT: (i) General MVT: averaged across subjects' velocity of the 1RM trial (0.25 m·s-1), (ii) individual MVT: velocity attained during the 1RM trial, and (iii) Optimal MVT: MVT that eliminated the differences between the actual and predicted 1RM. Two individual load-velocity relationships were modelled considering five (30-50-70-80%1RM) or six (30-50-70-80-90%1RM) loading conditions. Negligible differences (Effect size<0.20), low absolute errors (<5% of the actual 1RM), and extremely high correlations (r>0.90) were observed between the actual and six predicted 1RMs. The only significant difference was the lower raw errors for the 90%1RM condition (0.60±7.34 kg) compared to the 80%1RM condition (2.27±7.54 kg; p=0.013). These results suggest that the individual load-velocity relationship offers an accurate estimation of the HBD 1RM in resistance-trained males, and these estimates could maintain similar levels of precision across different types of MVT (general, individual, and optimal) and final tested loads (80%1RM and 90%1RM).

Comparison of external load measures per minute based on match seasonal periods and playing positions of a soccer Turkish super league team.

BACKGROUND: Turkish Super League teams need more information about the external load. Considering the specific country and the coaches' philosophies, the purpose of this study was to compare the external match load of a Turkish Super League team considering the different playing positions and in-season periods. METHODOLOGY: A longitudinal study design was employed by observing 29 official matches of the same team. A total of fifteen players, consisting of five defenders, five midfielders, and five forwards, were analyzed using the Sentio Sports Optical Tracking System. The following outcomes were extracted in each match: total distance (TD), walking [from 0 to 7.2 km/h], jogging [from 7.2 to 14.4 km/h], running [from 14.4 to 20 km/h], high speed running (HSR) [> 20 km/h], metabolic power (MP), maximum deceleration (Decmax) [Dec < -3 m/s2], total deceleration distance (Dectotal), maximum acceleration (Accmax) [Acc > 3 m/s2], and total acceleration distance (Acctotal). Statistical analysis consisted of ANOVA and Bonferroni correction post hoc tests. RESULTS: The main results showed that all variables were similar between periods of the season (p > 0.05) except for walking (p = 0.021 witha large effect size), which revealed lower values in the mid-season period. When analyzing periods of the season considering playing positions, there were several significant results for TD, walking, jogging, running, HSR, Dectotal and Acctotal (p < 0.05, with small to large effects). A tendency for higher values was noted in the mid and end-season. Considering the playing positions comparisons, midfielders showed higher values than defenders for TD, MP, Dectotal and Acctotal (p < 0.05 with large effect for all). Midfielders also showed higher values than forwards for TD, jogging, Dectotal and Acctotal (p < 0.05 with a large effect for all). CONCLUSIONS: The present study emphasizes the significance of analyzing data based on minute, playing position, and season period. Findings reveal that defenders consistently displayed the lowest values in all external load measures during matches compared to other positions throughout the season. Furthermore, midfielders demonstrated a higher activity profile during the initial and middle stages of the season compared to other positions, with a slight tendency to decrease load towards the end of the season.

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.

Relationships between training load and wellbeing measures across a full season: a study of Turkish national youth wrestlers.

The two aims of this study were: (i) to analyse the correlations between weekly acute workload (wAW), chronic workload, acute/chronic workload rate (wACWR), training monotony and strain and the weekly (w) reports of delayed onset muscle soreness, wFatigue, wStress, wSleep quality, and the Hooper indicator (wHI); (ii) to analyse the relationships between early, mid and end preparation season (PS) and the full PS. Ten elite young wrestlers participated in this study. The subjects who were included in this research were wrestlers participating in competitions organized by the National Turkish Wrestling Federation. The subjects were monitored for 32 weeks and were divided into three time periods: early PS, W1 to W11; mid PS, W12 to W22; and end PS, W23 to W32. Very large correlations were found for wAW and wACWR with wFatigue and wHI during end PS. Also, the same workload parameters were significantly correlated with wStress (r = 0.66; P = 0.03), wSleep (r = 0.78; P = 0.004), and wHI (r = 0.72; P = 0.01) during mid PS. The results of this study offer new perspectives for specialists regarding the perceived level of load and the variations of wellbeing during a PS at the level of elite young wrestlers.

Variability of peak speed and sprinting actions during the same small-sided games: within- and between-player variations inspected over four consecutive weeks.

This study aimed to analyze within- and between-player variations of peak speed and sprinting actions occurring in small-sided games (SSGs: 1 v 1 and 5 v 5). The study followed a cohort study design. Twenty male youth soccer players (age: 17 years old) from the same team were observed over four consecutive weeks. Each week, the players participated in two sessions (day one and day two) during which SSGs were applied. The 1 vs. 1 format was employed with four repetitions of thirty seconds interspaced with two-minute rest intervals, while the 5 vs. 5 format with four repetitions of four minutes and two-minute rest intervals between them. The players were monitored during all training sessions with the Polar Team Pro. The peak speed attained in each game, and the number of sprints were extracted as the primary outcomes. The between-player variability revealed a lower coefficient of variations for peak speed in the 1 vs. 1 (13.9%) and 5 vs. 5 (10.9%) formats than for sprints (1 v 1: 64.7%; 5 v 5: 65.5%). Considering the within-player variability, it was observed that sprints were more variable (1 vs. 1: 62.1%; 5 v 5: 65.7%) than peak speed (1 vs. 1: 16.4%; 5 v 5: 14.0%). The between-session analysis revealed that during week 1 (day 1), peak speed was significantly higher than during week 3 (day 1) in the 1 vs. 1 format (+3.0 km/h; p = 0.031; d = 1.296). Moreover, peak speed during week 3 (day 2) was considerably lower than during week 1 (-5.9 km/h; p < 0.001; d = 1.686) and week 2 (-5.0 km/h; p = 0.001; d = 1.639). The between-session analysis showed no significant differences in the sprint between the sessions on day 1 (p > 0.05). However, on day two, the sprint was substantially higher during week one than during week four in the 5 vs. 5 format (+5.40 n; p = 0.002; d = 2.571). In conclusion, this study revealed that peak speed presents lower within- and between-player variability than the number of sprints. Considering these two measures, there are no considerable variations between the weeks. Coaches should consider identifying strategies to stabilize the stimulus regarding the number of sprints if this represents one of the targets for employing SSGs.

Peak running speed can be used to monitor neuromuscular fatigue from a standardized running test in team sport athletes.

This study compared the sensitivity of peak running speed (PRS) measured during a submaximal run test (SRT) with a countermovement jump (CMJ) test to provide an alternate method of measuring neuromuscular fatigue (NMF). The study involved 20 semi-professional academy soccer players who performed a SRT and CMJ test, 24-hours pre-match, 24-, 48-, 72- and 96-hours post-match. Moderate decreases (effect-size (ES) ± 90% confidence intervals) were observed 24-hours post-match for CMJH; ES -0.70 ± 0.19, CMJPV; ES -0.92 ± 0.27 and PRS; ES -0.58 ± 0.11 with small decreases in CMJH; ES -0.36 ± 0.13 and PRS; ES -0.27 ± 0.23 still evident 48-hours post-match before returning to baseline 72-hours post-match. The results confirm PRS as an inexpensive alternate method of measuring NMF which, allows instantaneous real-time feedback on NMF. This can allow changes to be made immediately on-field within the post-match recovery phase without the need for further analysis or equipment.

Validity and Reliability of the Inertial Measurement Unit for Barbell Velocity Assessments: A Systematic Review.

The use of inertial measurement unit (IMU) has become popular in sports assessment. In the case of velocity-based training (VBT), there is a need to measure barbell velocity in each repetition. The use of IMUs may make the monitoring process easier; however, its validity and reliability should be established. Thus, this systematic review aimed to (1) identify and summarize studies that have examined the validity of wearable wireless IMUs for measuring barbell velocity and (2) identify and summarize studies that have examined the reliability of IMUs for measuring barbell velocity. A systematic review of Cochrane Library, EBSCO, PubMed, Scielo, Scopus, SPORTDiscus, and Web of Science databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From the 161 studies initially identified, 22 were fully reviewed, and their outcome measures were extracted and analyzed. Among the eight different IMU models, seven can be considered valid and reliable for measuring barbell velocity. The great majority of IMUs used for measuring barbell velocity in linear trajectories are valid and reliable, and thus can be used by coaches for external load monitoring.

Validity and Reliability of Mobile Applications for Assessing Strength, Power, Velocity, and Change-of-Direction: A Systematic Review.

This systematic review aimed to (1) identify and summarize studies that have examined the validity of apps for measuring human strength, power, velocity, and change-of-direction, and (2) identify and summarize studies that have examined the reliability of apps for measuring human strength, power, velocity, and change-of-direction. A systematic review of Cochrane Library, EBSCO, PubMed, Scielo, Scopus, SPORTDiscus, and Web of Science databases was performed, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From the 435 studies initially identified, 23 were fully reviewed, and their outcome measures were extracted and analyzed. In total, 11 mobile applications were analyzed and summarized for their validity and reliability to test movement velocity, movement time, movement displacement, power output, and workload. The present systematic review revealed that the tested apps are valid and reliable for measuring bar movement velocity during lower and upper body resistance exercises; however, systematic bias was detected with heavier loads.

Validity and reliability of velocity and power measures provided by the Vitruve linear position transducer.

This study aimed to determine the validity and between-day reliability of the mean velocity (MV), peak velocity (PV), mean power (MP), and peak power (PP) provided by the Vitruve linear position transducer at different submaximal loads in the free-weight and Smith machine back squat using GymAware as a reference point. Fourteen male sports science students (free-weight back squat one-repetition maximum [1RM]: 132.5 ± 28.5 kg, Smith machine back squat 1RM: 163.9 ± 30.4 kg) performed six experimental sessions, twice per week with 72 hours of rest. The first two included the assessment of the 1RM of both exercises. In the four remaining, both linear position transducers were simultaneously used to record MV, PV, MP, PP of each repetition during an incremental load test (i.e., 20, 40, 60, 80, 90% 1RM) with three minutes of rest between sets. Vitruve displayed both fixed and proportional bias for certain relative loads across all variables. Vitruve did not meet the validity criteria for all (MV, PP) or at least two (MP, PV) relative loads (Coefficient of variation [CV] > 10%; Pearson correlation < 0.70; Effect size > 0.60). MV, PV, MP, and PP recorded by Vitruve displayed acceptable reliability (CV < 10%) with superior reliability observed during a Smith Machine compared to free-weight back squat, and for velocity compared to power variables. Considering GymAware as a reference point, Vitruve was not valid for measuring velocity and power outcomes. Acceptable validity was observed only for PV in the Smith machine back squat, while the other variables-regardless of relative loads and exercise modes-were mostly inaccurate. All variables demonstrated acceptable reliability, with greater reliability noted in the Smith machine compared to the free-weight back squat exercise mode.

What We Do Not Know About Stretching in Healthy Athletes: A Scoping Review with Evidence Gap Map from 300 Trials.

BACKGROUND: Stretching has garnered significant attention in sports sciences, resulting in numerous studies. However, there is no comprehensive overview on investigation of stretching in healthy athletes. OBJECTIVES: To perform a systematic scoping review with an evidence gap map of stretching studies in healthy athletes, identify current gaps in the literature, and provide stakeholders with priorities for future research. METHODS: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 and PRISMA-ScR guidelines were followed. We included studies comprising healthy athletes exposed to acute and/or chronic stretching interventions. Six databases were searched (CINAHL, EMBASE, PubMed, Scopus, SPORTDiscus, and Web of Science) until 1 January 2023. The relevant data were narratively synthesized; quantitative data summaries were provided for key data items. An evidence gap map was developed to offer an overview of the existing research and relevant gaps. RESULTS: Of ~ 220,000 screened records, we included 300 trials involving 7080 athletes [mostly males (~ 65% versus ~ 20% female, and ~ 15% unreported) under 36 years of age; tiers 2 and 3 of the Participant Classification Framework] across 43 sports. Sports requiring extreme range of motion (e.g., gymnastics) were underrepresented. Most trials assessed the acute effects of stretching, with chronic effects being scrutinized in less than 20% of trials. Chronic interventions averaged 7.4 ± 5.1 weeks and never exceeded 6 months. Most trials (~ 85%) implemented stretching within the warm-up, with other application timings (e.g., post-exercise) being under-researched. Most trials examined static active stretching (62.3%), followed by dynamic stretching (38.3%) and proprioceptive neuromuscular facilitation (PNF) stretching (12.0%), with scarce research on alternative methods (e.g., ballistic stretching). Comparators were mostly limited to passive controls, with ~ 25% of trials including active controls (e.g., strength training). The lower limbs were primarily targeted by interventions (~ 75%). Reporting of dose was heterogeneous in style (e.g., 10 repetitions versus 10 s for dynamic stretching) and completeness of information (i.e., with disparities in the comprehensiveness of the provided information). Most trials (~ 90%) reported performance-related outcomes (mainly strength/power and range of motion); sport-specific outcomes were collected in less than 15% of trials. Biomechanical, physiological, and neural/psychological outcomes were assessed sparsely and heterogeneously; only five trials investigated injury-related outcomes. CONCLUSIONS: There is room for improvement, with many areas of research on stretching being underexplored and others currently too heterogeneous for reliable comparisons between studies. There is limited representation of elite-level athletes (~ 5% tier 4 and no tier 5) and underpowered sample sizes (≤ 20 participants). Research was biased toward adult male athletes of sports not requiring extreme ranges of motion, and mostly assessed the acute effects of static active stretching and dynamic stretching during the warm-up. Dose-response relationships remain largely underexplored. Outcomes were mostly limited to general performance testing. Injury prevention and other effects of stretching remain poorly investigated. These relevant research gaps should be prioritized by funding policies. REGISTRATION: OSF project ( https://osf.io/6auyj/ ) and registration ( https://osf.io/gu8ya ).

Relationship Between Training Load, Neuromuscular Fatigue, and Daily Well-Being in Elite Young Wrestlers.

Purpose: This study investigated acute workload (wAW), chronic workload (wCW), acute: chronic workload ratio (wACWR), training monotony (wTM), perceived load training strain indicators (wTS), and countermove- ment jump (CMJ) as indicators of wellness in one season and defined weekly variations. In addition, we analyzed the relationships between training load measurements and weekly reports. Methods: 16 elite young wrestlers were monitored daily with individual observations for 46 consecutive weeks throughout the season. Training load was obtained using the session rating of perceived effort. wSleep, wStress, wFatigue & wMuscle Soreness well-being were monitored daily using the Hooper index. Results: As a result of the analysis, it was found that there is a moderate relationship (r = 0.51, p = .003) between ACWR and w mean load (A.U.) and a high relationship (r = 0.81, p < .001) between monotony and strain. Conclusion: All variables other than ACWR, w mean load, strain, and monotony presented small and statistically insignificant relationships. These results provide coaches and practitioners with new insights into perceived loads and health changes during a season at the elite youth level.

Overhead squat assessment reflects treadmill running kinematics.

PURPOSE: Overhead squat assessment (OHSA) is a pre-activity dynamic movement analysis tool used to define deviations from an ideal motion pattern which known as compensation. Compensatory movements may result from abnormality in myofascial activity, length-tension relationships, neuro-motor control strategies, osteokinematics and arthrokinematics. The aim of this study is to identify the association between selected biomechanical variables of the ankle, knee, hip, pelvis, torso during OHSA and 16 km/h treadmill running tasks. METHODS: Thirteen national long distance male runners (17.3 ± 0.5 age (years); 5.89 ± 1.95 experience (years), 57.9 ± 3.7 body mass (kg); 175.4 ± 5.7 height (cm)) participated in this 2controlled laboratory study. Three-dimensional kinematics were collected at 250 Hz using a 9-camera Qualisys motion analysis system (Qualisys AB, Goteborg, Sweden) while participants performed 16 km/h treadmill running and OHSA tasks. RESULTS: Correlation coefficients demonstrated that OHSA pelvic anterior tilt angle was in a positive association with foot strike (FS), mid-stance (MS), and toe-off (TO) pelvic anterior tilt angles and MS tibial internal rotation on talus, MS ankle pronation, MS hip internal rotation. OHSA pelvic anterior tilt angle was in a negative association with TO hip extension. OHSA maximal hip adduction was positively correlated with MS and stance maximal knee adduction. FS, MS, stance maximal angular dorsiflexion values were positively correlated with OHSA dorsiflexion. Increased OHSA dorsiflexion angle was negatively associated with TO plantar flexion. OHSA pronation was positively associated with MS and stance pronation. MS hip internal rotation, MS hip adduction angles were increased, and MS ankle dorsiflexion was significantly decreased with the increase of trunk forward lean relative to tibia during OHSA. CONCLUSIONS: OHSA was associated with some important and dysfunction-related hip, knee and ankle kinematics. Running coaches, may use OHSA as an assessment tool before the corrective training plan to detect injury-related compensation patterns to reduce the risk of injury and improve running technique.

How does the increase in foreign players affect football?

BACKGROUND: In the study, we tried to analyze the effects of foreign players on Turkish Super League matches. For this purpose, in this long-term study, 1836 competition data played in 6 seasons between 2014 and 2020 was obtained from www.mackolik.com each year. METHOD: Pearson's correlation coefficient applied between 18 different variables (goal, shoot, pass, cross, corner, offside, foul, yellow card, red card, accurate shot, percentage of the precise pass, rate of accurate access on opponent's field, the difference of ball possession percentage, shot difference, pass difference, big team superiority, home team superiority) and the number of foreign players (NoFP, active foreign players in 90 min.). RESULT: In the Turkish Super League, within six seasons (2014-20), the NoFP in a match increased from 10.43 (38.06%) to 17.99 (64.26%). The increment was partially linear and statistically significant (F = 594.85) in all seasons. A positive association was found between NoFP several of passes (r = 0.219), percentage of accurate passes (r = 0.133), percentage of precise passes on the opponent's field (r = 0.139), exact pass difference between opponents (r = 0.114), and ball possession difference between opponents (r = 0.113). Fouls committed decreased with the increase of NoFP (r = -0.250). Although the win probability of the teams named The Big Three (Fenerbahçe, Galatasaray, and Besiktas) decreased from 67% (2014 season rate) to 50% in the last two seasons, no association was identified between the NoFP and big team superiority. CONCLUSIONS: Consequently, NoFP increment may improve the game quality by increasing accurate passes and passes in the opponent's field. The number of passes and the ball possession percentage difference between opponent teams may indicate that one team has control of the game by keeping possession or the other is tactically giving possession. These findings may suggest that the game evolved into half-field, tactical, set-play, possessioning competition. Analyzing variables such as game speed, intensity, the duration of the ball in play, running distance, energy consumption, and fatigue markers may light future studies.

Relative age effect and performance in elite youth male basketball.

The aims of the study were to (i) assess the Relative Age Effect (RAE) on elite young male basketball players, (ii) to analyze whether there is a difference between birth quarters (BQ) according to their minutes played and efficiency ratings as individual performance parameters and, (iii) to analyze the relationship between team efficiency, team success, and RAE with a new approach. The research was conducted on 678 players (Age:15.84 ± 0.42) from 53 teams in six different tournaments (from 2014 to 2019). Although, chi-square test showed that more players were born in first BQ than in all other BQs (p < 0.05), no significant difference between BQs and performance measures was found (p > 0.05). However, a relationship between team RAE score, tournament ranking, and team efficiency score was found (p < 0.05). Furthermore, there was a relationship between tournament rankings and team RAE rankings (p < 0.05). While players born in the first months of the year were more likely to be selected for the national youth teams, performance parameters did not show any significant difference when compared to other players who were born later in the same year. However, results showed that teams that have a higher number of athletes who were born in the earlier months of a year showed higher achievement in the tournaments.

Validity and reliability of Polar M400 GPS watches for measuring distances covered by team sports players.

Monitoring locomotor demands in team sports becomes popular in professional and recreational daily activities. Precise measurements are main of importance in training routine. The aim of this study is three-fold: (i) analyze the validity of Polar M400 Global Positioning System (GPS) watches for measuring distances covered in team sports simulation cycle; (ii) testing inter-unit reliability of two devices attached during testing; and (iii) testing inter-session reliability for the same simulation cycle. Methods: Twenty-one team athletes (age: 24.5 ± 5.2 years; body mass: 71.8 ± 5.7 kg; height: 176.5 ± 4.3 cm) were tested in the team sport simulation cycle (TSSC). Two Polar M400 sport watches were used by each player on their wrists at the same time. The data obtained from Polar M400 were compared to the reference fixed distance of the TSSC to determine the watch validity. Inter-session reliability was also tested using the two watches in two different sessions. Results: No significant differences between the reference value and the watches (F = 1.086; p = 0.368; ηp2 ≤0.042) were found. The %CV (0.03-0.05%) and SEM (0.05-0.09) values found for all considered groups confirmed good levels of reliability of the Polar M400 to measure total distance. Conclusions: The Polar M400 is a valid and reliable watch for measuring the distances covered by team sport athletes. Both coaches and athletes can monitor the distances covered with accuracy and precision, through the use of the Polar M400 sport watch.

Comparison of the neuromuscular response to three different Turkish, semi-professional football training sessions typically used within the tactical periodization training model.

This study examined the neuromuscular responses to three typical football (soccer) training sessions and the reliability of peak speed (PS) measured during a submaximal running test (SRT) for identifying neuromuscular fatigue (NMF) status. Jump height (CMJH) and peak velocity (CMJPV) were collected from a CMJ test, while peak speed (PS) was collected during an SRT before and after each training session. Large effect size (ES) decreases were observed in each variable post-training (ES; - 1.42 to - 2.32). Significant differences (> 0.001) were detected between each football session's external load variables. Coefficients of variations were small (< 10%) with moderate (CMJPV; 0.53, PS; 0.44) and strong (CMJH; 0.72) intraclass correlation coefficients between pre-test measures. The demands of each football session aligned with the principles of tactical periodization and were sufficient to produce the fatigue necessary to elicit physiological adaptations. PS was also shown to be a viable measure of monitoring NMF status.

Relationships of Final Velocity at 30-15 Intermittent Fitness Test and Anaerobic Speed Reserve with Body Composition, Sprinting, Change-of-Direction and Vertical Jumping Performances: A Cross-Sectional Study in Youth Soccer Players.

This study aimed to determine the relationships of locomotor profile (combination of a player's maximal oxygen uptake and running economy)-measured by the final velocity attained at 30-15 Intermittent Fitness Test (VIFT) and the anaerobic speed reserve (ASR)-with the body composition, countermovement jump (CMJ), sprinting performances, and change-of-direction (COD) ability of youth soccer players. A cross-sectional study design was implemented. A total of 124 youth soccer players from different age groups (15, 16, 17, 18, and 19 years old) were voluntarily recruited. ASR was determined based on the difference between maximal sprint speed (MSS) and VIFT. Players were tested for the following measures: (i) body composition (body mass and body fat percentage); (ii) CMJ (height of jump); (iii) sprinting time measured at 5, 10, 15, 20, 25, and 30 m; (iv) MSS measured in the best split time (5 m) over the 30 m test; (v) COD ability (time, asymmetry index); and (vi) final velocity at 30-15 IFT (VIFT). A Pearson product-moment correlation test was used to examine the relationships. Height and body mass exhibited large correlations with VIFT (r = 0.835 and r = 0.699, respectively) and small correlations with ASR (r = 0.177 and r = 0.256, respectively). The CMJ was largely correlated with VIFT (r = 0.631 to r = 0.650) while presenting small correlations with ASR (r = 0.227 to r = 0.232). Both VIFT and ASR had moderate (r = 0.3 to r = 0.5) correlations with sprinting time at different distances and very large correlations with MSS (r = 0.797 to r = 0.866). The COD time was largely correlated with VIFT (r = 0.765 and r = 0.775) while exhibiting small-to-moderate correlations with ASR (r = -0.279 and r = -0.301). In conclusion, it was found that locomotor performance at 30-15 VIFT presents high levels of correlation with anthropometry and physical fitness; ASR also presents correlations with these variables, but they are smaller. This suggest that ASR is an independent variable that should be considered for inclusion in information for characterizing players' capacities.

Load-Velocity Relationship Variables to Assess the Maximal Neuromuscular Capacities During the Back-Squat Exercise.

BACKGROUND: The relationship between the external load lifted and movement velocity can be modeled by a simple linear regression, and the variables derived from the load-velocity (L-V) relationship were recently used to estimate the maximal neuromuscular capacities during 2 variants of the back-squat exercise. HYPOTHESIS: The L-V relationship variables will be highly reliable and will be highly associated with the traditional tests commonly used to evaluate the maximal force and power. STUDY DESIGN: Twenty-four male wrestlers performed 5 testing sessions (a 1-repetition maximum [1RM] session, and 4 experimental sessions [2 with the concentric-only back-squat and 2 with the eccentric-concentric back-squat]). Each experimental session consisted of performing 3 repetitions against 5 loads (45%-55%-65%-75%-85% of the 1RM), followed by single 1RM attempts. LEVEL OF EVIDENCE: Level 3. METHODS: Individual L-V relationships were modeled from the mean velocity collected under all loading conditions from which the following 3 variables were calculated: load-axis intercept (L0), velocity-axis intercept (v0), and area under the line (Aline = L0·v0/2). The back-squat 1RM strength and the maximum power determined as the apex of the power-velocity relationship (Pmax) were also determined as traditional measures of maximal force and power capacities, respectively. RESULTS: The between-session reliability was high for the Aline (coefficient of variation [CV] range = 2.58%-4.37%; intraclass correlation coefficient [ICC] range = 0.98-0.99) and generally acceptable for L0 and v0 (CV range = 5.08%-9.01%; ICC range = 0.45-0.96). Regarding the concurrent validity, the correlations were very large between L0 and the 1RM strength (rrange = 0.87-0.88) and nearly perfect between Aline and Pmax (r = 0.98-0.99). CONCLUSION: The load-velocity relationship variables can be obtained with a high reliability (L0, v0, and Aline) and validity (L0 and Aline) during the back-squat exercise. CLINICAL RELEVANCE: The load-velocity relationship modeling represents a quick and simple procedure to estimate the maximal neuromuscular capacities of lower-body muscles.

Variations of the Locomotor Profile, Sprinting, Change-of-Direction, and Jumping Performances in Youth Soccer Players: Interactions between Playing Positions and Age-Groups.

The purpose of this study was two-fold: (i) analyze the variations of locomotor profile, sprinting, change-of-direction (COD) and jumping performances between different youth age-groups; and (ii) test the interaction effect of athletic performance with playing positions. A cross-sectional study design was followed. A total of 124 youth soccer players from five age-groups were analyzed once in a time. Players were classified based on their typical playing position. The following measures were obtained: (i) body composition (fat mass); (ii) jump height (measured in the countermovement jump; CMJ); (iii) sprinting time at 5-, 10-, 15-, 20-, 25- and 30-m; (iv) maximal sprint speed (measured in the best split time; MSS); (v) COD asymmetry index percentage); (vi) final velocity at 30-15 Intermittent Fitness Test (VIFT); and (vii) anaerobic speed reserve (ASR = MSS - VIFT). A two-way ANOVA was used for establishing the interactions between age-groups and playing positions. Significant differences were found between age-groups in CMJ (p < 0.001), 5-m (p < 0.001), 10-m (p < 0.001), 15-m (p < 0.001), 20-m (p < 0.001), 25-m (p < 0.001), 30-m (p < 0.001), VIFT (p < 0.001), ASR (p = 0.003), MSS (p < 0.001), COD (p < 0.001). Regarding variations between playing positions no significant differences were found. In conclusion, it was found that the main factor influencing changes in physical fitness was the age group while playing positions had no influence on the variations in the assessed parameters. In particular, as older the age group, as better was in jumping, sprinting, COD, and locomotor profile.

Monitoring the post-match neuromuscular fatigue of young Turkish football players.

Neuromuscular fatigue tests have been used in previous studies to organize post-match training programs and to minimize injuries. The aim of this study is to describe the neuromuscular fatigue that occurs after a football match and to examine the relationship between internal and external load values in the match and fatigue parameters obtained at different time intervals. Twenty male U19 academy league soccer players (age: 19; height: 181.3 ± 4.3; weight: 73.4 ± 6.7) participated in the study. The countermovement jump (CMJ) test was applied to the players 24 h before, as well as 24, 48, 72, 96, and 120 h after a football match. During the CMJ tests, the maximum velocity of each player during the jump was recorded by using the GymAware linear position transducer. The CMJ maximum velocity values 24 h before and 24 h after the match, as well as the CMJ height values (Cohen's d: 1.210; p < 0.001), were statistically different from the values recorded 24 h before and 24 and 48 h after the match (Cohen's d: 1.578; p < 0.001; Cohen's d: 0,922; p < 0.009). The correlation values were not statistically significant. The results suggest, CMJ height and CMJ maximum velocity values, which determine neuromuscular fatigue after a football match, can be used by practitioners to display post-match neuromuscular fatigue measurements.