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Background: Several studies have revealed the positive healthy impacts of branched-chain fatty acids (BCFAs). However, most of these studies evaluated the serum BCFAs in humans, or treatment with exogenous BCFAs in animal or in-vitro models and the health impacts of dietary BCFAs have not yet been studied. Due to positive effects of BCFAs in sport, in the current study, we aimed to investigate the association between dietary BCFAs and metabolic and inflammatory parameters among elite and subelite soccer players. Methods: A cross-sectional study was carried out among 335 elite and subelite soccer players (196 male), aged between 20 and 45 years old. Soccer players were enrolled from 32 teams under the directive of The Chinese Football Association. Demographic, anthropometric, and dietary assessments were performed and laboratory measurement including serum lipids, glycemic markers, and high-sensitivity C-reactive protein was measured. Results: Those with the highest dietary BCFAs consumption had higher appetite (p =.009). Also, high consumption of dietary BCFAs was associated with lower diastolic blood pressure (odds ratio: 0.958; confidence interval: 0.918–0.999; p =.046) and low high-sensitivity C-reactive protein concentrations in the third tertile of dietary BCFAs (odds ratio: 0.431; confidence interval: 0.300–0.618; p <.001). No other association between biochemical variables and dietary BCFAs was found. Conclusion: As shown in the current study, higher dietary BCFAs consumption was associated with lower diastolic blood pressure and inflammation. Due to very limited number of studies, further studies are needed to have a better perspective of these associations and their underlying mechanisms. [ABSTRACT FROM AUTHOR]

This study investigated the effect of oral and topical sodium bicarbonate (SB) on soccer-specific performance during simulated soccer exercise. In a block randomized, double-blind, crossover design, 10 collegiate male soccer players (stature: 181.7 ± 3.2 cm, body mass: 81.7 ± 10.5 kg) performed soccer-specific performance tests (countermovement jumps, Illinois agility, 8 × 25 m repeated sprints) throughout a 90-min soccer-specific aerobic field test (SAFT90) following 0.3 g/kg body mass SB in capsules (SB-ORAL), 0.9036 g/kg body mass PR Lotion (SB-LOTION), or placebo capsules and lotion (PLA). Soccer-specific performance tests were conducted pre-SAFT90, during half-time and post-SAFT90. Blood samples were analyzed for acid–base balance (pH; bicarbonate, HCO 3 − ) and strong ions (sodium, Na+; potassium, K+). Average sprint times were quicker for SB-ORAL than PLA during half-time (3.7%; p =.049; g =.57) and post-SAFT90 (4.9%; p =.041; g =.66). SB-ORAL increased pH and HCO 3 − prewarm-up and during half-time (p <.05), and lowered K+ during half-time (p =.035) compared with PLA. SB-LOTION increased pH (p =.019) and lowered K+ (p =.012) during half-time compared with PLA. SB-LOTION increased Na+ postexercise compared with PLA (p =.008). Repeated sprint times during simulated soccer exercise improved for SB-ORAL, which might have been mechanistically underpinned by elevated blood buffering capacity and greater regulation of strong ion concentration. Consuming SB in capsules is a more effective strategy than topical SB application for improving blood buffering capacity and repeated sprint performance throughout competitive soccer matches. [ABSTRACT FROM AUTHOR]

Objectives: Dietary strategies to improve arachidonic acid:eicosapentaenoic acid (AA:EPA) ratios are of interest due to potential reductions in inflammation and oxidative stress following exercise. The aim of this study was to investigate the impact of a novel dietary intervention, that is, the ingestion of 30 g of dark chocolate, on blood lipid profiles and gut microbiota composition in elite male soccer players. Methods: Professional male soccer players were randomly assigned to the experimental group (DC) provided with 30 g of dark chocolate or to the control group (WC), provided with 30 g of white chocolate, for 30 days. Before and after intervention, blood, fecal sample, and anthropometry data were collected. For each outcome, two-way repeated-measure analysis of variance was used to identify differences between baseline and endpoint (Week 4), considering treatment (dark chocolate, white chocolate) as intersubjects' factors. Metagenomic analysis was performed following the general guidelines, which relies on the bioBakery computational environment. Results: DC group showed increased plasma polyphenols (from 154.7 ± 18.6 μg gallic acid equivalents/ml to 185.11 ± 57.6 μg gallic acid equivalents/ml, Δ pre vs. post = +30.41 ± 21.50) and significant improvements in lipid profiles: total cholesterol (Δ −32.47 ± 17.18 mg/dl DC vs. Δ −2.84 ± 6.25 mg/dl WC, Time × Treatment interaction p <.001), triglycerides (Δ −6.32 ± 4.96 mg/dl DC vs. Δ −0.42 ± 6.47 mg/dl WC, Time × Treatment interaction p <.001), low-density lipoprotein (Δ −18.42 ± 17.13 mg/dl vs. Δ −2.05 ± 5.19 mg/dl WC, Time × Treatment interaction p <.001), AA/EPA ratio (Δ −5.26 ± 2.35; −54.1% DC vs. Δ −0.47 ± 0.73, −6.41% WC, Time × Treatment interaction p <.001) compared with WC group. In addition, 4 weeks of intervention showed a significant increase in high-density lipoprotein concentration in DC group (Δ + 3.26 ± 4.49 mg/dl DC vs. Δ −0.79 ± 5.12 mg/dl WC). Microbial communities in the DC group maintained a slightly higher microbial stability over time (exhibiting lower within-subject community dissimilarity). Conclusion: Ingesting 30 g of dark chocolate over 4 weeks positively improved AA:EPA ratio and maintained gut microbial stability. Dark chocolate ingestion represents an effective nutritional strategy to improve blood lipid profiles in professional soccer players. What Are the Findings? Ingesting 30 g of dark chocolate for 4 weeks positively influences blood lipid AA: EPA ratio while maintaining gut microbial stability. What This Study Adds? Dietary intake of specific foods such as dark chocolate represents an alternative strategy to support the health and recovery of elite soccer players. WhatImpact Might This Have on Clinical Practice in the Future? From a clinical and translational perspective, dark chocolate ingestion positively modulates favorable blood lipid profiles and polyunsaturated fatty acid metabolism while maintaining gut microbial stability. Dark chocolate ingestion may be considered as an effective nutritional strategy in elite sport environments during periods of high-intensity training and congested competitions. Further research is required to determine functional outcomes associated with the observed improvements in blood lipid profiles. [ABSTRACT FROM AUTHOR]

Purpose: To determine the acute response of lactate supplementation on athletic performance. Method: Fifteen athletes under the age of 15 performed the following 4 sessions in a nonrandomized order: (1) familiarization, (2) control, (3) participants ingested calcium lactate (21.5 mg·kg−1 body mass), and (4) participants ingested a placebo (PLA, calcium carbonate, 21.5 mg·kg−1 body mass). The capsules were randomly offered and consumed 60 minutes before the physical tests. To assess the physical performance, the athletes executed squat jump, countermovement squat jump, 20-m linear sprint, change of direction test, and running anaerobic sprint test. Results: There were no significant differences between conditions for squat jump, countermovement jump, change of direction, and minimum power obtained in the running anaerobic sprint test (P >.05). Conversely, we observed a worse performance (P <.05) in the 20-m linear sprint test in the PLA and lactate conditions compared with control (P <.05). The lactate condition worsened performance during running anaerobic sprint test for peak power, mean power, and fatigue index compared with control and PLA (P <.05). Conclusions: Calcium lactate supplementation worsened repetitive running sprint ability and 20-m sprint performance. However, lactate supplementation does not affect jump or agility capacity. Therefore, calcium lactate supplementation seems to be an ineffective strategy to improve anaerobic and neuromuscular performance in soccer players 15 years of age or less. [ABSTRACT FROM AUTHOR]

This study critically examines the suitability of using a single drop height to assess the reaction strength index in trained and active participants, a key component of athletic performance. Using a cross-sectional design, 377 trained (n = 163) and active (n = 214) participants aged 14–18 years performing drop jumps from 4 different heights (24, 32, 40, and 48 cm) were studied. The primary aim was to explore the individual differences in reaction strength index at these heights and to assess whether a single height can reliably represent stretch-shortening cycle capabilities. While the repeated measures analysis of variance did not reveal any significant differences, the Bland–Altmann analysis revealed significant individual discrepancies between the performance of the drop heights, resulting in a mean absolute error of 32.1 and a mean absolute percentage error of 20.6%. These results strongly suggest that a single drop height is not sufficient to determine performance in the stretch-shortening cycle. This has important practical implications as it can lead to underestimates of performance trends. The study advocates the inclusion of a range of drop heights in routine testing to accurately measure reactive power and thus improve the effectiveness of individualized training programs for young athletes/active youth. [ABSTRACT FROM AUTHOR]

Purpose: To compute reference centiles for 5- and 30-m sprint times relative to chronological and skeletal age in youth soccer players. Subsequently, to compare individual's sprint performance scores derived from the chronological and skeletal age reference centiles. Methods: Sprint times were collected for a sample of male U11 to U19 soccer players (n = 1745 data points). Skeletal age data were available for a subsample (n = 776 data points). Reference centiles were fitted using generalized additive models for location, scale, and shape. Individual z scores relative to chronological and skeletal age reference centiles were computed and compared for each maturity group (late, on-time, early, and very early) using standardized mean differences (SMD). Results: Reference centiles for chronological age increased more rapidly between 10.5 and 15.5 years, while reference centiles for skeletal age increased more rapidly between 13.0 and 16.5 years. Differences in chronological and skeletal z scores for very early (SMD: −0.73 to −0.43) and late (SMD: 0.58 to 1.29) maturing players were small to large, while differences for early (SMD: −0.30 to −0.19) and on-time (SMD: 0.16 to 0.28) were trivial to small. Conclusion: Reference centiles provide a valuable tool to assist the evaluation of sprint performance in relation to chronological and skeletal age for talent identification purposes in youth soccer players. [ABSTRACT FROM AUTHOR]

Purpose: This study compared the physiological profiles and energy-system contributions of trained football players engaged in regular-passing and third-man-passing small-sided games (SSGs) that included 4 versus 4 and a goalkeeper. Methods: Ten male trained football players participated in this crossover study. All participants were randomly assigned to either regular-passing SSG or third-man-passing SSG (4 vs 4 with a goalkeeper, 35-m × 17-m pitch size, and 6-min match duration). During these SSGs, physiological parameters including peak and mean heart rate, oxygen uptake ( V ˙ O 2 peak and V ˙ O 2 mean), metabolic equivalents in V ˙ O 2 peak and V ˙ O 2 mean , and blood lactate concentrations (peak La− and delta La− [Δ La−]), were measured. Energy contributions (oxidative [WOxi], glycolytic [WGly], and phosphagen [WPCr] systems) and Global Positioning System (GPS) variables (total distance, total acceleration counts, mean speed, and maximum speed) were also analyzed. Results: No significant differences in physiological parameters and GPS variables were found between regular- and third-man-passing SSGs. WOxi in kilojoules and percentages was significantly higher during both SSGs than WPCr and WGly (P <.0001, respectively). WPCr and WPCr + WGly values during third-man-passing SSGs were significantly higher than those during regular-passing SSGs (P <.05). Additionally, low to moderate positive correlations were observed between WOxi, WGly in kilojoules, V ˙ O 2 peak , V ˙ O 2 mean , peak La−, Δ La−, total acceleration counts, and mean speed (r =.39–.64). Conclusions: Third-man-passing SSGs may be useful for increasing anaerobic capacity. More third-man-passing SSG sessions in preparation for football games may support high metabolic power and repeated powerful anaerobic performances in trained football players. [ABSTRACT FROM AUTHOR]

Maximum running speed is a performance determinant in para-athletics and cerebral palsy football. Sixty international para-athletes with brain impairments completed five activity-limitation tests (standing broad jump, four bounds for distance, split jumps, 10-m speed skip, and running in place) and two criterion tests (40-m sprint and modified agility test). The same three tests (standing broad jump, four bounds for distance, and 10-m speed skip) that correlated with running performance in nondisabled runners (.67 < r < −.82; p <.05; 75% of variance) also correlated in para-athletes with brain impairments (.41 < r < −.62; p <.01; 55% of variance). Standing broad jump, four bounds for distance, split jumps, and running in place also correlated with change-of-direction speed (.43 < r < −.63; p <.01; 58% of variance). Results indicate that methods of classification for para-athletics with nondisabled runners are also valid with para-athletes with brain impairments, and new sport-specific relationships were found for assessing the performance of rapid and short sprints toward different directions, specific of a team para-sport like cerebral palsy football. [ABSTRACT FROM AUTHOR]

Purpose: Agility in young soccer players has long been associated with physical attributes like strength, speed, and power. The aims of this study were to investigate the relationship between cognitive factors and agility performance in this unique population. Methods: 39 young soccer players age 13.56 (SD 0.58) years were assessed for leg-muscle function (jump tests) and maturation status (peak height velocity). The Y-Agility Test, which included decision making in players, was used to measure performance. Cognitive factors such as perceptual skills and decision making were evaluated with the Y-Agility Test. Results: The linear regression showed an absence of significance between the Y-Agility Test and drop-jump contact (P =.283), Y-Agility Test and drop-jump flight (P =.185), Y-Agility Test and squat jump (P =.868), and Y-Agility Test and countermovement jump (P =.310). The linear mixed-model analyses suggested a difference between early-average maturers (P =.009) and early-late maturers (P =.005) but did not show a difference between average-late subjects (P = 1.000). Drop-jump flight did not show a difference in maturation (early-average P = 1.000; early-late P = 1.000; average P = 1.000). Squat-jump performance did not demonstrate any significance (early-average P =.618; early-late P = 1.000; P = 1.000). Countermovement-jump performance did not show any significance (early-average P = 1.000; early-late P = 1.000; average-late P =.492). Finally, agility performance does not show any significance between maturation levels (early-average maturer P =.450; early-late P = 1.000; average-late P =.830). Conclusion: Agility in young soccer players appears to follow a nonlinear trajectory, with cognitive factors possibly playing a more significant role than previously thought. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to quantify training and match-day (MD) load during 3-, 4-, and 5-day microcycles in professional adult football, as well as to analyze the effect of the microcycle length on training load produced the day after the match (MD + 1) and the day before the match (MD − 1). Methods: The study involved 20 male professional football players whose external and internal loads were monitored for a whole season. The training exposure, total distance covered, high-speed-running distance, sprint distance (SD), individual SD above 80% of the individual maximum velocity (D > 80%), and the number of accelerations and decelerations were quantified, as well as rating of perceived exertion and session rating of perceived exertion training load. Results: Microcycle length affected most of the variables of interest: high-speed-running distance (F = 9.04, P <.01), SD (F = 13.90, P <.01), D > 80% (F = 20.25, P <.01), accelerations (F = 10.12, P <.01), and decelerations (F = 6.01, P <.01). There was an interaction effect between the training day and microcycle type for SD (F = 5.46, P <.01), D > 80% (F = 4.51, P <.01), accelerations (F = 2.24, P =.06), and decelerations (F = 3.91, P <.01). Conclusions: Coaches seem to be influenced by shorter microcycles in their training proposal, preferring sessions with a reduced muscle impact during shorter microcycles. Independent of the length of the congested fixture microcycle, the daily load seems to decrease when MD approaches. [ABSTRACT FROM AUTHOR]

Purpose: Prediction of athlete wellness is difficult—or, many sports-medicine practitioners and scientists would argue, impossible. Instead, one settles for correlational relationships of variables gathered at fixed moments in time. The issue may be an inherent mismatch between usual methods of data collection and analysis and the complex nature of the variables governing athlete wellness. Variables such as external load, stress, muscle soreness, and sleep quality may affect each other and wellness in a dynamic, nonlinear, way over time. In such an environment, traditional data-collection methods and statistics will fail to capture causal effects. If we are to move this area of sport science forward, a different approach is required. Methods: We analyzed data from 2 different soccer teams that showed no significance between player load and wellness or among individual measures of wellness. Our analysis used methods of attractor reconstruction to examine possible causal relationships between GPS/accelerometer-measured external training load and wellness variables. Results: Our analysis showed that player self-rated stress, a component of wellness, seems a fundamental driving variable. The influence of stress is so great that stress can predict other components of athlete wellness, and, in turn, self-rated stress can be predicted by observing a player's load data. Conclusion: We demonstrate the ability of nonlinear methods to identify interactions between and among variables to predict future athlete stress. These relationships are indicative of the causal relationships playing out in athlete wellness over the course of a soccer season. [ABSTRACT FROM AUTHOR]

Context: We designed this study to investigate the effects of 2 myofascial release techniques, Instrument-Assisted Soft Tissue Mobilization (IASTM) and Foam Roller (FR), on pain, joint range of motion, and muscle strength in athletes suffering from iliotibial band (ITB) tightness. Design: A total of 39 male soccer players were enrolled in this randomized controlled trial, aged between 18 and 23 years who were divided into 3 groups: Only Exercise, IASTM, and FR. Methods: All participants performed daily strengthening and stretching exercises, while 1 group added IASTM, and the other added FR to the exercise program. We evaluated ITB tightness with the Ober test and an inclinometer, pressure pain threshold, using an algometer, and we evaluated muscle strength with the Cybex Norm Isokinetic device. Results: We found that all 3 groups exhibited an increase in the Ober inclination angle after the interventions (P =.001), but the increase was greater for participants in the IASTM and FR groups, compared with exercise alone. Additionally, both the IASTM and FR groups displayed an increased pressure pain threshold (P =.001), whereas there was no change in the control group. Moreover, while all 3 groups experienced an increase in hip muscle strength (P =.001), the IASTM and FR groups exhibited a greater increase compared with exercise alone (P =.001). Conclusions: Based on these findings, exercise improves pain, range of motion, and muscle strength in athletes with ITB tightness, and IASTM, and FR techniques enhanced exercise effects but did not differ from one another. While our study demonstrated that both IASTM and FR techniques significantly enhance the benefits of exercise for athletes with ITB tightness, further research could delve into the long-term effects of these interventions. [ABSTRACT FROM AUTHOR]

This study aimed to determine whether caffeine gum influenced perceptual-cognitive and physical performance during the extra-time period of simulated soccer match-play. Semiprofessional male soccer players (n = 12, age: 22 ± 3 years, stature: 1.78 ± 0.06 m, mass: 75 ± 9 kg) performed 120-min soccer-specific exercise on two occasions. In a triple-blind, randomized, crossover design, players chewed caffeinated (200 mg; caffeine) or control (0 mg; placebo) gum for 5 min following 90 min of soccer-specific exercise. Perceptual-cognitive skills (i.e., passing accuracy, reaction time, composure, and adaptability) were assessed using a soccer-specific virtual reality simulator, collected pre- and posttrial. Neuromuscular performance (reactive-strength index, vertical jump height, absolute and relative peak power output, and negative vertical displacement) and sprint performance (15 and 30 m) were measured at pretrial, half-time, 90 min, and posttrial. Caffeine gum attenuated declines in reaction time (pre: 90.8 ± 0.8 AU to post: 90.7 ± 0.8 AU) by a further 4.2% than placebo (pre: 92.1 ± 0.8 AU to post: 88.2 ± 0.8 AU; p <.01). Caffeine gum reduced composure by 4.7% (pre: 69.1 ± 0.8 AU to post: 65.9 ± 0.8 AU) versus placebo (pre: 68.8 ± 0.8 AU to post: 68.3 ± 0.8 AU; p <.01). Caffeine gum did not influence any other variables (p >.05). Where caffeine gum is consumed by players prior to extra-time, reaction time increases but composure may be compromised, and neuromuscular and sprint performance remain unchanged. Future work should assess caffeine gum mixes with substances like L-theanine that promote a relaxed state under stressful conditions. [ABSTRACT FROM AUTHOR]

Purpose: To explore how the change-point method can be used to analyze complex longitudinal data and detect when meaningful changes (change points) have occurred during rehabilitation. Method: This design is a prospective single-case observational study of a football player in a professional club who sustained an acute lower-limb muscle injury during high-speed running in training. The rehabilitation program was entirely completed in the football club under the supervision of the club's medical team. Four wellness metrics and 5 running-performance metrics were collected before the injury and until the player returned to play. Results: Data were collected over 130 days. In the univariate analysis, the change points for stress, sleep, mood, and soreness were located on days 30, 47, 50, and 50, respectively. The change points for total distance, acceleration, maximum speed, deceleration, and high-speed running were located on days 32, 34, 37, 41, and 41, respectively. The multivariate analysis resulted in a single change point for the wellness metrics and running-performance metrics, on days 50 and 67, respectively. Conclusions: The univariate approach provided information regarding the sequence and time point of the change points. The multivariate approach provided a common change point for multiple metrics, information that would benefit clinicians to have a broad overview of the changes in the rehabilitation process. Clinicians may consider the change-point method to integrate and visualize data from multiple sources to evaluate athletes' progression along the return-to-sport continuum. [ABSTRACT FROM AUTHOR]

Purpose: There are multiple postexercise recovery technologies available in the market based on the assumption of blood-flow enhancement. Lower-limb intermittent pneumatic compression (IPC) has been widely used, but the available scientific evidence supporting its effectiveness remains scarce, requiring a deeper investigation into its underlying mechanisms. The aim of this study was to assess the hemodynamic effects caused by the use of IPC at rest. Methods: Twenty-two soccer and track and field athletes underwent two 15-minute IPC protocols (moderate- [80 mm Hg] and high-pressure [200 mm Hg]) in a randomized order. Systolic peak velocity, end-diastolic peak velocity, arterial diameter, and heart rate were measured before, during (at the eighth minute), and 2 minutes after each IPC protocol. Results: Significant effects were observed between before and during (eighth minute) the IPC protocol for measures of systolic (P <.001) and end-diastolic peak velocities (P <.001), with the greater effects observed during the high-pressure protocol. Moreover, 2 minutes after each IPC protocol, hemodynamic variables returned to values close to baseline. Arterial diameter presented significant differences between pressures during the IPC protocols (P <.05), while heart rate remained unaltered. Conclusion: IPC effectively enhances transitory blood flow of athletes, particularly when applying high-pressure protocols. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether menstrual-cycle symptoms are associated with sleep in elite female athletes. Methods: Sleep was assessed for a minimum of 25 nights (range = 25–31) using activity monitoring and sleep diaries. Menstrual-cycle symptoms were collected over the same duration in 12 elite female professional soccer players. Generalized estimating equations were used to examine the relationship between the day of the menstrual cycle (from day 1) and total menstrual-cycle symptoms on sleep characteristics. Results: There was a significant relationship between sleep duration and the day of the menstrual cycle (P =.042) and total symptoms reported that day (P <.001), with sleep duration increasing by 21 minutes for every symptom reported. There was a negative day × symptom interaction on sleep duration (P =.004), indicating that with increased symptoms, the day of the menstrual cycle had a smaller relationship with sleep duration. Sleep efficiency (P =.950), wake after sleep onset (P =.217), and subjective sleep quality (P =.080) were not related to the day of the menstrual cycle. The total symptoms reported had no relationship with sleep efficiency (P =.220), subjective sleep quality (P =.502), or sleep latency (P =.740) but did significantly relate to wake after sleep onset (P <.001), with a significant day × symptom interaction (P <.001). Conclusions: Sleep duration increased from day 1 of the menstrual cycle and was associated with the number of menstrual-cycle symptoms reported. All other sleep metrics remained unchanged; however, total symptoms reported were related to wake after sleep onset. Monitoring and managing menstrual-cycle symptoms should be encouraged due to a potential relationship with sleep characteristics. [ABSTRACT FROM AUTHOR]

Purpose: The relationship between external load and creatine-kinase (CK) response at the team/position or individual level using Global Positioning Systems (GPS) has been studied. This study aimed to compare GPS-derived and Football Movement Profile (FMP) –derived CK-prediction models for national-team soccer players. The second aim was to compare the performance of general and individualized CK prediction models. Methods: Four hundred forty-four national-team soccer players (under 15 [U15] to senior) were monitored during training sessions and matches using GPS. CK was measured every morning from whole blood. The players had 19.3 (18.1) individual GPS-CK pairs, resulting in a total of 8570 data points. Machine learning models were built using (1) GPS-derived or (2) FMP-based parameters or (3) the combination of the 2 to predict the following days' CK value. The performance of general and individual-specific prediction models was compared. The performance of the models was described by R2 and the root-mean-square error (RMSE, in units per liter for CK values). Results: The FMP model (R2 =.60, RMSE = 144.6 U/L) performed similarly to the GPS-based model (R2 =.62, RMSE = 141.2 U/L) and the combination of the 2 (R2 =.62, RMSE = 140.3 U/L). The prediction power of the general model was better on average (R2 =.57 vs R2 =.37) and for 73% of the players than the individualized model. Conclusions: The results suggest that FMP-based CK-prediction models perform similarly to those based on GPS-derived metrics. General machine learning models' prediction power was higher than those of the individual-specific models. These findings can be used to monitor postmatch recovery strategies and to optimize weekly training periodization. [ABSTRACT FROM AUTHOR]

Among all the innovative applications of immersive technologies in the sport industry, augmented reality (AR) has demanded more scholarly attention. Particularly, using AR face filters that layer computer-generated visual effects over the physical world on mobile devices became a valued marketing tactic that brands employed to attract fans. Yet, limited empirical evidence has explored the effect of AR on sport fans' digital fandom. Through an online quasi-experiment (N = 250) following a 2022 FIFA World Cup match between the U.S. and U.K. soccer (e.g., association football) teams, data suggest an important role of BIRGing (basking in reflected glory) in influencing fans' AR filter use. Specifically, fans with a stronger tendency to bask in reflected glory elicited a higher perception of affiliation and enjoyment, which tended to be more likely to use AR. These effects were heightened when fans' team identification was higher and they believed their team performed better. Theoretical and practical implications were addressed accordingly. [ABSTRACT FROM AUTHOR]

We compared the declarative tactical knowledge (DTK) of 196 male and female players (16.9 ± 2.4 years) belonging to the academy of a Spanish professional football club with their participation (minutes played), football competence (coaching staff assessment), and future potential (technical direction prediction). The DTK had no correlation with the minutes played (%) by the participants during the 2021–22 season (r = −.162, p =.045). Student's t test for independent samples compared the football competence of the participants with high DTK (n = 74) and low DTK (n = 76), proving a small impact (p =.021, d = 0.39) in favor of the first group. Although the high-DTK group showed a better average of potentiality, the technical direction identified more potential players for the first team in the low-DTK group. In conclusion, no solid evidence was found to justify that participants with higher DTK in each team were those who played more minutes and showed greater football competence and potentiality. [ABSTRACT FROM AUTHOR]

Context: The hip adductor and abductor muscles play vital roles as stabilizers in the lower-extremity. Their activation during soccer-specific actions is essential, but local muscular fatigue can hinder athletic performance and increase the risk of injury. Design: This study aimed to observe the variations in frontal plane hip strength in female college soccer players before and after a high-workload soccer-specific training session. Furthermore, the study sought to compare the relative changes in hip strength with the internal and external load measures obtained during that session. Methods: Twenty female college soccer players participated in a retrospective observational study. Isometric hip adductor and abductor strength were measured before and after a training session in the college spring season. Measurements were taken with a handheld dynamometer (MicroFET 2) while the players were supine. Global positioning system sensors (Catapult Vector S7), commonly worn by players during training sessions and competitive matches, were used to measure external and internal loads. Statistical analyses were performed using paired samples t test to assess hip adductor and abductor strength changes before and after the training session. Spearman rank was used to identify correlation coefficients between global positioning system data and isometric hip strength. Results: The findings revealed significant decreases in the strength of the right hip adduction (P =.012, −7% relative change), right abduction (P =.009, −7.6% relative change), and left abduction (P =.016, −4.9% relative change) after the training session. Furthermore, relative decreases in hip isometric adduction and abduction strength are related to the distance covered at high speeds. Conclusion: The results of this study highlight that hip isometric adduction and abduction strength tend to decrease after exposure to high workloads during soccer-specific training. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to enhance the understanding of soccer match peak demands by describing worst-case scenario (WCS) and time spent above 80% and 90% of the WCS for total distance (TD) and high-speed running (HSR). The investigation considered playing level (first team vs under-19 [U19] team) and playing position (center backs, fullbacks, midfielders, and forwards) to assess how WCS and the time spent above specific thresholds vary across different populations. Methods: Data from 31 players in a professional Italian soccer club were collected during the 2022–23 season. Microtechnology devices tracked physical activity during matches. Players were categorized by position, and WCS was determined using rolling averages over a 1-minute period. Time spent above 80% and 90% of WCS for TD and HSR was calculated. Results: The U19 team exhibited higher HSR WCS compared with the first team (∼63 m·min−1 vs ∼56 m·min−1). Midfielders recorded the highest TD WCS (∼208 m·min−1), and forwards exhibited the highest HSR WCS (∼70 m·min−1). The first team spent significantly more time above 80% (∼6 min) and 90% (∼1 min) of TD WCS. Midfielders spent significantly more time above the 80% (∼7 min) of TD WCS, while forwards above the 80% (∼2 min) of HSR WCS. Conclusions: The study emphasizes that WCS used alone may not sufficiently capture real match intensity. Considering the time spent above specific thresholds provides additional insights (ie, between-levels differences and position). Practitioners should consider both WCS and time spent above thresholds for individualized training prescriptions, reflecting differences in playing roles. [ABSTRACT FROM AUTHOR]

Purpose: Global navigation satellite system device–derived metrics are commonly represented by discrete zones with intensity often measured by standardizing volume to per-minute of activity duration. This approach is sensitive to imprecision in duration measurement and can lead to highly variable outcomes—transforming data from zones to a gradient may overcome this problem. The purpose of this study was to critically evaluate this approach for measuring team-sport activity demands. Methods: Data were collected from 129 first-team and 73 academy matches from a Scottish Premiership football club. Gradients were calculated for velocity, acceleration, and deceleration zones, along with per-minute values for several commonly used metrics. Means and 95% CIs were calculated for playing level, as well as first-team positional groups. Within-subject coefficients of variation were also calculated for match level, position, and individual groups. Results: The gradient approach showed consistency with per-minute metrics when measuring playing level and position groups. With coefficients of variation of 10.8% to 26.9%, the gradients demonstrated lower variability than most per-minute variables, which ranged from 10.7% to 84.5%. Conclusions: Gradients are a potentially useful way of describing intensity in team sports and compare favorably to existing intensity variables in their ability to distinguish between match types and position groups, providing evidence that gradient variables can be used to monitor match and training intensity in team sports. [ABSTRACT FROM AUTHOR]

Context: Sport-related dystonia is a rare form of activity-specific dystonia that can severely impair an athlete's ability to perform. Due to a lack of data on the condition, it is difficult to diagnose and often overlooked, and no gold standard treatment has yet been defined. Case Presentation: We present a rare and challenging case of sport-related dystonia that affected a 24-year-old male professional soccer player. The patient presented with severe rigidity and dystonia of the right lower-extremity, particularly the ankle and foot. The symptoms set on >1 year prior to the presentation to our outpatient clinic. He began to complain of stiffness and difficulty moving his lower limbs, especially his right leg, initially when playing soccer, but then also when walking normally. On presentation, he was unable to run and walked with difficulty, supporting his body weight only on the outside of his right foot. He also reported a motor trick and reverse motor trick involving the oral musculature in order to move his lower limb more freely. Management and Outcomes: An integrated rehabilitation approach based on postural rehabilitation, neuromuscular rehabilitation, and dental intervention was used to successfully treat this condition. The approach included: (1) postural rehabilitation with the Mézières-Bertelè method to reduce muscular stiffness, (2) neuromuscular re-education with Tai Chi exercises and electromyography-guided biofeedback, and (3) dental intervention and swallowing rehabilitation to limit impaired oral habits (due to the relationship between his impaired lower limb movements and motor tricks of the oral musculature). After 7 months of integrated rehabilitation, the patient returned to professional soccer. Conclusions: This case report highlights the potential efficacy of an integrative rehabilitation approach for sports dystonia, particularly in cases where traditional treatments may not be effective. Such an approach could be considered a valuable option in the management of this rare, but debilitating, condition in athletes. Further research is needed to assess the effectiveness of this approach in larger populations. [ABSTRACT FROM AUTHOR]

Purpose: To (1) examine within-individual player dose–response associations between selected training-load measures and changes in aerobic fitness level via submaximal exercise heart rate (HRex%) and (2) measure the relationships between these dose–response associations with basal HRex% (to study the influence of fitness level on dose–response relationship). Methods: During an in-season phase, selected training-load measures including total minutes, total distance, mechanical work (the sum number of accelerations and decelerations > 3 m2), high metabolic load distance, and Edwards' training impulse were collected via Global Positioning System and heart-rate sensors for analyzing accumulated load. A submaximal warm-up test was used repeatedly before and after 9 phases to elicit HRex% and track fitness changes at an individual level. Results: Negative to positive extensive ranges of within-individual associations were found among players for different metrics (r = −.84 to.89). The relationship between pooled HRex% (basal fitness) and dose–response correlations showed inverse very large (r = −.71) and large (r = −.65) values for accumulated weekly minutes and distance. However, moderate values were found for all other measures (r = −.35 to −.42). Conclusions: Individual players show extensive different ranges of dose–response associations with training measures. The dose–response association is influenced by players' fitness level, and players with lower fitness levels show stronger inverse relationships with accumulated minutes and total distance. [ABSTRACT FROM AUTHOR]

Purpose: Injury prevention is a crucial aspect of sports, particularly in high-performance settings such as elite female football. This study aimed to develop an injury prediction model that incorporates clinical, Global-Positioning-System (GPS), and multiomics (genomics and metabolomics) data to better understand the factors associated with injury in elite female football players. Methods: We designed a prospective cohort study over 2 seasons (2019–20 and 2021–22) of noncontact injuries in 24 elite female players in the Spanish Premiership competition. We used GPS data to determine external workload, genomic data to capture genetic susceptibility, and metabolomic data to measure internal workload. Results: Forty noncontact injuries were recorded, the most frequent of which were muscle (63%) and ligament (20%) injuries. The baseline risk model included fat mass and the random effect of the player. Six genetic polymorphisms located at the DCN, ADAMTS5, ESRRB, VEGFA, and MMP1 genes were associated with injuries after adjusting for player load (P <.05). The genetic score created with these 6 variants determined groups of players with different profile risks (P = 3.1 × 10−4). Three metabolites (alanine, serotonin, and 5-hydroxy-tryptophan) correlated with injuries. The model comprising baseline variables, genetic score, and player load showed the best prediction capacity (C-index:.74). Conclusions: Our model could allow efficient, personalized interventions based on an athlete's vulnerability. However, we emphasize the necessity for further research in female athletes with an emphasis on validation studies involving other teams and individuals. By expanding the scope of our research and incorporating diverse populations, we can bolster the generalizability and robustness of our proposed model. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to compare the maximum and rapid force production of Spanish football players and explore the differences between age group and level of competition. Methods: A cross-sectional study was developed to evaluate the peak force (PF), relative PF, and rate of force development over 250 ms (RFD0−250) during the isometric midthigh pull between groups of football players based on age group (senior vs junior) and level of competition (national vs regional). Using a portable isometric rig, 111 football players performed 2 isometric midthigh-pull trials on a force plate. Two-way analysis of variance with Bonferroni post hoc correction was applied, and statistical significance was set at P ≤.05. The PF, relative PF, and RFD0−250 0, 25, 50, 75, and 100 percentiles were also calculated and descriptively reported, separated by age group and level of competition. Results: The analysis of variance revealed a significant main effect of the level of competition for the PF (P <.001), relative PF (P =.003), and RFD0−250 (P <.001). There was a significant main effect of age group for the PF (P <.001). There was a significant interaction effect of the age group × level of competition for relative PF (P =.014). National players were stronger than regional players on the PF and RFD0−250 (P <.001). Senior players were stronger than junior players for the PF (P <.001). Conclusions: Maximum and rapid force production are crucial for Spanish football players as they progress in both level of competition and age group. Practitioners should encourage young football players to prioritize strength development to improve their athletic performance. [ABSTRACT FROM AUTHOR]

Although referees who officiate in the amateur football leagues are exposed to various stressors that can negatively affect their mental health (MH), little is known about their MH symptoms. The purpose of the study was to evaluate MH symptoms of referees who officiate in the Turkish amateur football leagues. An online survey was sent to all referees in the Turkish amateur football leagues (n = 4,900) incorporating standardized scales assessing depression, anxiety, and stress. A total of 1,279 referees participated in the study. Female referees reported higher depression (p <.01) and anxiety (p =.02) scores than males. Younger referees (23–27 years) reported higher depression (p =.01) and anxiety (p <.01) scores than older (>38 years) referees. Results showed that symptoms of depression, anxiety, and stress scores were associated with marital status (being single), lower incomes, severe sports injury history, and inadequate social support. In light of these results, MH assessments should be undertaken to detect which referees are at greater risk of MH problems and facilitate appropriate and timely MH interventions. Further study is needed to inform MH risk reduction strategies and/or programming. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was 2-fold: (1) to examine the relationships between psychophysiological responses and locomotor demands with variations in technical performance during 2v2 and 4v4 conditioned games and (2) to compare psychophysiological and locomotor responses among players exhibiting higher and lower technical performance levels during the conditioned games. Methods: Twenty-four male youth soccer players (16.3 ± 0.8 y old) participating at the trained/developmental level underwent monitoring for psychophysiological responses (including heart rate, rating of perceived exertion, and visual analog scale), locomotor demands (such as distance covered), and technical performance variables (including successful and unsuccessful passes and shots, as well as lost balls) across 2v2 and 4v4 formats. These formats were applied 4 times within a single session and were replicated twice over 2 weeks. Results: Large correlations between the number of lost balls per minute and mean heart rate were found in both the 2v2 and 4v4 games (r =.586 and r =.665, respectively). Successful shots were inversely and largely correlated with mean heart rate (r = −.518) in 4v4 games. The number of interceptions per minute was inversely and significantly correlated with the visual analog scale in 2v2 and 4v4 games (r = −.455 and r = −.710, respectively). The frequency of lost balls was significantly higher among players who attained a higher mean heart rate (2v2: +42.9%, P =.031, d = −0.965; 4v4: +57.1%, P <.001, d = −2.072). Conclusions: Coaches should be aware that highly psychophysiologically demanding scenarios may significantly impair technical performance. Therefore, prioritizing technical performance by deliberately adjusting the intensity should be considered. [ABSTRACT FROM AUTHOR]

Purpose: The study had 3 purposes: (1) to develop an index using machine-learning techniques to predict the fitness status of soccer players, (2) to explore the index's validity and its relationship with a submaximal run test (SMFT), and (3) to analyze the impact of weekly training load on the index and SMFT outcomes. Methods: The study involved 50 players from an Italian professional soccer club. External and internal loads were collected during training sessions. Various machine-learning algorithms were assessed for their ability to predict heart-rate responses during the training drills based on external load data. The fitness index, calculated as the difference between actual and predicted heart rates, was correlated with SMFT outcomes. Results: Random forest regression (mean absolute error = 3.8 [0.05]) outperformed the other machine-learning algorithms (extreme gradient boosting and linear regression). Average speed, minutes from the start of the training session, and the work:rest ratio were identified as the most important features. The fitness index displayed a very large correlation (r =.70) with SMFT outcomes, with the highest result observed during possession games and physical conditioning exercises. The study revealed that heart-rate responses from SMFT and the fitness index could diverge throughout the season, suggesting different aspects of fitness. Conclusions: This study introduces an "invisible monitoring" approach to assess soccer player fitness in the training environment. The developed fitness index, in conjunction with traditional fitness tests, provides a comprehensive understanding of player readiness. This research paves the way for practical applications in soccer, enabling personalized training adjustments and injury prevention. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of repeated-sprint training with voluntary hypoventilation at low (RSH-VHL) and high (RS-VHH) lung volume on repeated-sprint ability (RSA) in female athletes. Methods: Over a 6-week period, 24 female soccer players completed 12 sessions of repeated 30-m running sprints with end-expiratory breath holding (RSH-VHL, n = 8), end-inspiratory breath holding (RS-VHH, n = 8), or unrestricted breathing (RS-URB, n = 8). Before and after training, a running RSA test consisting of performing 30-m all-out sprints until exhaustion was implemented. Results: From before to after training, the number of sprints completed during the RSA test was increased in both RSH-VHL (19.3 [0.9] vs 22.6 [0.9]; P <.01) and RS-VHH (19.3 [1.5] vs 20.5 [1.7]; P <.01) but not in RS-URB (19.4 [1.3] vs 19.5 [1.7]; P =.67). The mean velocity and the percentage decrement score calculated over sprints 1 to 17 were, respectively, higher (82.2% [1.8%] vs 84.6% [2.1%] of maximal velocity) and lower (23.7% [3.1%] vs 19.4% [3.2%]) in RSH-VHL (P <.01), whereas they remained unchanged in RS-VHH and RS-URB. The mean arterial oxygen saturation recorded during training at the end of the sprints was lower in RSH-VHL (92.1% [0.4%]) than in RS-VHH (97.3% [0.1%]) and RS-URB (97.8% [0.1%]). Conclusions: This study shows that female athletes can benefit from the RSH-VHL intervention to improve RSA. The performance gains may have been limited by the short sprinting distance with end-expiratory breath holding, which provoked only moderate hypoxemia. The increase in the number of sprints in RS-VHH seems to show that factors other than hypoxia may have played a role in RSA improvement. [ABSTRACT FROM AUTHOR]

Purpose: The monitoring of training loads and quantification of physical performance are common practices in youth soccer academies to support coaches in prescribing and programming training for individuals. The interaction between training load and physical performance is unknown during a preseason period in youth soccer players. The current study assessed changes in training load and physical assessments across a 4-week preseason period. The relationship between physical performance and match playing time in youth male soccer players was also investigated. Methods: The training loads of 25 professional youth academy male soccer players were monitored throughout a 4-week preseason period. Assessments of power, agility, speed, and aerobic capacity were undertaken in the first training session. Session ratings of perceived exertion (sRPE) and well-being questionnaires were collected during all training sessions and preseason matches. Playing time during subsequent competitive matches was recorded. Results: T test and 30-m-sprint assessments, conducted on the first day of preseason, were predictors of sRPE throughout preseason (t test χ2/df = 2.895, poor adjustment; 30-m sprint χ2/df = 1.608, good adjustment). YoYo Test performance was related with changes in perceived fatigue (χ2/df = 0.534, very good adjustment). Faster players reported higher values of sRPE, and players with higher aerobic capacity reported higher levels of fatigue across preseason. Well-being, perceived fatigue and soreness, and sRPE decreased across preseason. Greater match durations were related to higher levels of fatigue during preseason (P <.05). Conclusion: The current study highlights the relationship between training load, physical assessments, and playing time. Coaches and practitioners can use physical test data at the start of preseason as an indication of players that report higher sRPE, perceived fatigue, and reduced well-being across preseason, supporting decisions around individualized training prescriptions. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this study were to examine the variability of selected external load metrics within 15-minute intervals during soccer match play and examine their relationship with players' high-intensity intermittent fitness. Methods: A total of 18 male soccer players were monitored for their external load metrics during 26 matches, which included total distance, high-metabolic-load distance, and mechanical work (defined as the sum of accelerations and decelerations >3 m2). Additionally, players completed the 30-15 Intermittent Fitness Test. Results: Total distance had lower coefficients of variation than high-metabolic-load distance and mechanical work (effect size [ES]: 5.2 to 6.4; very large). Within-player Δ-15min showed moderate to large decreases (ES: −0.7 to −1.6) and increases (ES: 0.9 to 1.8) in absolute and coefficient-of-variation values, respectively. Large relationships (r =.55 to.61) were observed between the Intermittent Fitness Test and 15-minmean and 15-minbest in all selected external load metrics. However, small to moderate (0.27 to 0.41) associations were observed between the Intermittent Fitness Test and Δ-15min in selected external load metrics. Conclusions: These findings suggest that players with relatively lower intermittent running capacity might show lower variability during matches, as evidenced by smaller reductions in high-intensity actions during the final 15 minutes. We attribute these observations to players' possessing better pacing strategies. [ABSTRACT FROM AUTHOR]

Purpose: This preliminary study examined the influence of estimated menstrual-cycle (MC) phase on responses to soccer matches and training sessions in preparation for and during the FIFA (Fédération internationale de football association) Women's World Cup 2019. Methods: Twenty outfield players representing a national team were tracked over a 45-day period. External (10-Hz global positioning system; total and distance covered at high-metabolic power [≥20 W·kg−1]) and internal load measures (minutes ≥80% heart-rate maximum, sessional ratings of perceived exertion) were collected during all training and matches, with single-item wellness measures (fatigue, soreness, sleep quality, and sleep duration) collected each morning prior to activity. MC phase was estimated individually via an algorithm, informed from pretournament survey responses and ongoing symptom reporting (FitrWoman). Model comparison statistics were used to determine the impact of estimated MC phase in nonhormonal contraceptive users (n = 16). Results: Sessional rating of perceived exertion responses to total distances ≥5 km were higher during the luteal phase (+0.6–1.0 au; P ≤.0178) versus menstruation (phase 1), but no other observable dose–response trends were observed. Sleep, fatigue, and soreness ratings were not typically associated with MC phase, with the exception of exacerbated fatigue ratings in luteal versus follicular phase 48 hours postmatch (−0.73 au, P =.0275). Conclusions: Preliminary findings suggest that estimated MC phase may contribute to the understanding of the dose–response to soccer training and matches. [ABSTRACT FROM AUTHOR]

In sport, there is extensive evidence that supports the benefits associated with a mastery climate. However, limited studies have explored how physical tools could be used to promote mastery climates in youth sport contexts. Using an action research approach, we sought to understand the benefits and drawbacks of applying tools grounded in goal setting to promote a mastery environment: (a) an "arm sleeve" to be worn by athletes during training and matches and (b) a "reflection sheet" for use pre- and posttraining/-matches. These tools were implemented for a 3-week period with a U13 academy team (18 players and two coaches). Based on observation notes, focus groups, and one-on-one interviews, the analysis showed that the arm sleeves were helpful reminders for process goals, whereas the coaches had abandoned the use of reflection sheets due to lack of time. The benefits and drawbacks of the tools are discussed while pedagogical and practical implications are considered. [ABSTRACT FROM AUTHOR]

Context: Wheelchair Power Soccer (WPS) is the only team sport that allows the participation of people with severe physical disabilities who require the daily use of motorized wheelchairs. These individuals may live with chronic pain due to the characteristics of the disabilities and treatments, interfering with their health and limiting their participation in sports. Objectives: To investigate the prevalence of musculoskeletal pain and its relationship with mood in WPS players and to analyze the incidence of traumatic injuries during a championship. Methods: A prospective, longitudinal study was carried out on 30 WPS athletes (93.33% male) with a mean (SD) (range) age of 22.37 (9.79) (47) years. Data collection was performed during a South American WPS Championship lasting 3 days, with: investigation of the presence of musculoskeletal pain and mood through a questionnaire; investigation of the occurrence of traumatic injuries through match observation; and confirmation of the occurrence of traumatic injuries through access to medical department records. Results: About 30% (n = 9/30) of the sample presented some pain on the day of evaluation, with an intensity of 5.67 (3.35) (10) points on the visual analog scale. The most common regions of pain were the lower back (13.3%, n = 4/30), thoracic (10%; n = 3/30), and cervical (10%; n = 3/30) areas of the spine. A total of 46.7% (n = 14/30) reported pain in the month before data collection but of less intensity (2.56 [4] [10] points), the most common regions being the lower limbs (20%; n = 6/30) and cervical spine (20%; n = 6/30). Among the between-group comparisons (ie, participants with pain vs without pain), no relationship was observed between mood state and pain. No traumatic injuries were identified during the competition. Conclusion: The presence of musculoskeletal pain was common in WPS players, but it was not related to mood. As no traumatic injuries were observed during the championship, this modality seems to be safe for people with physical disabilities in general. [ABSTRACT FROM AUTHOR]

Over the past 25 years, a hermeneutic struggle has unfolded in English football between those spectators who wish to stand at matches and the risks associated with this practice in all-seated stadia. Amid this tension, fans have had to negotiate a neoliberal and authoritarian regime. However, the struggles of supporters against social control in football are characterized by the building of a long-term social movement against all-seating. In seeking to break down the state's disciplinary power and its marketization of football, this movement, "Safe Standing," has achieved several recent policy-based victories in the United Kingdom and Europe and is now firmly embedded within sports stadia developments and the demands of fans in North America and Australasia. Although these different contexts are temporally and culturally sensitive, they are interdependently linked through relational time frames and discursive practices that make up the modern consumption of football. This research applies relational sociology to analyze the fan networks that successfully built this movement across the U.K. fan activist scene, characterized by relational collective action, which complicates the individual and collective dimensions of activism. [ABSTRACT FROM AUTHOR]

Although professional women's football has benefitted from recent surges in popularity, challenges to progress and distinguish the sport persist. The gender-schema theory explains the tendency for individuals to hold female sports to male standards, a phenomenon that leads to negative outcomes in areas such as media representation and consumer perception. One area in which schemas have a more discreet effect is player and team performance, where the assumption that technical metrics developed in men's football are transferable to women's football remains unfounded. Using expected goals, a metric synonymous with the probability of a shot being scored, we highlight how variables important to shot quality and shot execution differ across gender, and how attempts to evaluate female footballers with models built on men's data increase estimation errors. These results have theoretical and practical implications for the role they play in reframing schemas and improving the methods used to evaluate performance in women's sports. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effects of unilateral flywheel training (FT), using a rotational conical pulley, including multidirectional movements with either preplanned or random unanticipated/unexpected executions on functional performance in football players. Methods: A total of 32 young male football players were randomly assigned to an FT program including preplanned unilateral multidirectional movements (PTG, n = 11), an FT executing the same unilateral movements through random (ie, right or left leg) unanticipated (ie, verbal or visual cue) or unexpected (ie, moment where the cue was provided) situations (UTG, n = 11), or a control group (n = 10) that followed their football training routine. FT consisted of 1 set × 5–12 repetitions of 4 exercises performed once a week for 10 weeks. Intermittent endurance performance, repeated unilateral and bilateral jumping ability, change-of-direction (COD) ability, linear sprint velocity, preplanned repeated-sprint ability (RSA), and uncertainty RSA (RSA-RANDOM) were assessed preintervention and postintervention. Results: Significant improvements were found in RSA-RANDOM performance (P <.05, effect size [ES] range: UTG [1.83–2.16], PTG [0.69–0.73]) and COD (P <.05, ES: UTG = 1.34, PTG = 0.98]) in both training groups. Furthermore, significant improvements were also found in intermittent endurance performance (P =.016, ES = 0.37) and sprinting (P =.006, ES = 0.45) in UTG. No changes in any variable were found in the control group. No significant between-groups differences (P >.05) were reported between UTG and PTG, while differences were observed to the control group in unilateral jumping ability, COD, and RSA-RANDOM for UTG, and in RSA-RANDOM for PTG. Conclusions: A 10-week unilateral FT improved RSA-RANDOM and COD ability in youth football players, so both preplanned and unexpected situations should be included on strength training. [ABSTRACT FROM AUTHOR]

Purpose: Monitoring player readiness to train and perform is an important practical concept in football. Despite an abundance of research in this area in the male game, to date, research is limited in female football. The aims of this study were, first, to summarize the current literature on the monitoring of readiness in female football; second, to summarize the current evidence regarding the monitoring of the menstrual cycle and its potential impact on physical preparation and performance in female footballers; and third, to offer practical recommendations based on the current evidence for practitioners working with female football players. Conclusions: Practitioners should include both objective (eg, heart rate and countermovement jump) and subjective measures (eg, athlete-reported outcome measures) in their monitoring practices. This would allow them to have a better picture of female players' readiness. Practitioners should assess the reliability of their monitoring (objective and subjective) tools before adopting them with their players. The use of athlete-reported outcome measures could play a key role in contexts where technology is not available (eg, in semiprofessional and amateur clubs); however, practitioners need to be aware that many single-item athlete-reported outcome measures instruments have not been properly validated. Finally, tracking the menstrual cycle can identify menstrual dysfunction (eg, infrequent or irregular menstruation) that can indicate a state of low energy availability or an underlying gynecological issue, both of which warrant further investigation by medical practitioners. [ABSTRACT FROM AUTHOR]

Context: The aim of this study was to analyze the muscle activity of the hamstring muscles and the lateral gastrocnemius during different variants of the single-leg bridge (SLB) in futsal players. Design: Cross-sectional study. Methods: Twenty-two futsal players (age = 24.8 [3.9] y) volunteered to participate in this study. The participants performed 3 variations of the SLB with the knee flexed at 45°. The first position was performed with the ankle in plantar position with flat support, the second with the ankle in dorsiflexion (DF) with heel support, and the third with the ankle in DF and external rotation (ER) with heel support. The Wilcoxon rank-sum test assessed the difference between variables for samples with the rank-biserial correlation effect size. Spearman correlation coefficients were used to examine the associations of the percentage maximal voluntary isometric contraction for each muscle with peak force and rate of force development with 3 different variances of the SLB. Results: The variation of ankle DF and ER with heel support generated higher muscle activity in BF in concentric (P<.01, effect size [ES] = -0.613); isometric (P<.042, ES = -0.494); and eccentric (P<.005, ES = -0.668) contraction than ankle DF with heel support. In contrast, the variation of ankle DF and ER with heel support generated fewer muscle activity in lateral gastrocnemius in concentric (P < .001, ES = 0.779); isometric (P < .003, ES = 0.708); and eccentric (P < .014, ES = 0.589) contraction than ankle DF with heel support. Conclusions: The position of DF and ER was the best position in SLB to train the BF. It could be convenient to start rehabilitation of the BF with flat foot postition or ankle in DF with heel support and progress with the position of the ankle in DF and ER with heel support. [ABSTRACT FROM AUTHOR]

Background: Submaximal fitness test (SMFT) outcome measures are frequently collected with a wide array of technologies and methodological approaches. Purpose: To examine the test–retest reliability of various SMFT outcome measures derived from different protocols and analytical techniques. Methods: Twenty-six semiprofessional adult soccer players performed 3 SMFT protocols, including 2 continuous (3 min, 11 and 12.8 km·h−1) and 1 intermittent (4 × 50 m, 18 km·h−1) twice, each separated by 7 days. Heart-rate (HR) indices (exercise HR, HR recovery) and scapula-mounted (PlayerLoad vector magnitude) and foot-mounted (flight time and contact time, stride length) microelectrical mechanical system–derived variables were collected using different time frames and analytical approaches adopted in the literature and practice. Absolute reliability was quantified as the group mean difference, typical error of measurement, also expressed as the coefficient of variation (where appropriate) and standardized units (ie, d). Intraclass correlation coefficient was used to quantify relative reliability. Results: The highest degrees of reliability were evident for exercise HR (typical error: 1.0%–1.6% points), the vertical component of PlayerLoad (expressed in arbitrary units; coefficient of variation: 5.5%–7.0%), and contact time (coefficient of variation: 1.5%–3.0%). These estimates were not influenced by SMFT protocol or analytical approach. All other measures displayed poorer reliability and/or were different between protocols and analytical methods. Conclusions: SMFT protocols impact the test–retest reliability of various outcome measures; however, exercise HR, vertical PlayerLoad, and contact time (derived from foot-mounted micro-electrical mechanical systems) appear to have stable measurement properties to assist the assessment of aerobic capacity and lower-limb neuromuscular status, respectively. [ABSTRACT FROM AUTHOR]

Objectives: To analyze the positional distances covered above generic and individualized speed thresholds within the most demanding phases of match play. Categorized by position, 17 English Premier League players' match data were analyzed over 2 consecutive seasons (2019–20 and 2020–21). The most demanding phases of play were determined using a rolling average across 4 periods of 1, 3, 5, and 10 minutes. Distance covered in the time above the standard speed of 5.5 m/s was analyzed, with individualized metrics based on the maximal aerobic speed (MAS) test data. Results: Central defenders displayed lower values for high-intensity periods when compared with fullbacks, midfielders, and wide midfielders for both generic and individualized metrics. MAS during 1-minute periods was significantly higher for forwards when compared with central defenders (82.9 [18.9] vs 67.5 [14.8] for maximum high-speed running [HSR] and 96.0 [15.9] vs 75.7 [13.8] HSR for maximum MAS activity). The maximum effect size differences between the central midfielders, wide midfielders, and fullbacks for HSR and MAS measures under the maximum HSR criterion was 0.28 and 0.18 for the 1-minute period, 0.36 and 0.19 for the 3-minute period, 0.46 and 0.31 for the 5-minute period, and 0.49 and 0.315 for the 10-minute period. Conclusions: Individualized speed metrics may provide a more precise and comparable measure than generic values. Data appear to be consistent across playing positions except for central defenders. This information may allow practitioners to directly compare individualized physical outputs of non–central defenders during the most demanding phases of play regardless of the players' positional group. This may provide coaches with important information regarding session design, training load, and fatigue monitoring. [ABSTRACT FROM AUTHOR]

Prior studies have explored the relationship between knee valgus and musculoskeletal variables to formulate injury prevention programs, primarily for females. Nonetheless, there is insufficient evidence pertaining to professional male soccer players. Here, the aim was to test the correlation of lateral trunk inclination, hip adduction, hip internal rotation, ankle dorsiflexion range of motion, and hip isometric strength with knee valgus during the single-leg vertical jump test. Twenty-four professional male soccer players performed a single-leg vertical hop test, hip strength assessments, and an ankle dorsiflexion range of motion test. A motion analysis system was employed for kinematic analysis. Maximal isometric hip strength and ankle dorsiflexion range of motion were tested using a handheld dynamometer and a digital inclinometer, respectively. The correlation of peak knee valgus with peak lateral trunk inclination was.43 during the landing phase (P =.04) and with peak hip internal rotation was −.68 (P <.001). For knee valgus angular displacement, only peak lateral trunk inclination presented a moderate positive correlation (r =.40, P =.05). This study showed that trunk and hip kinematics are associated with knee valgus, which could consequently lead to increased knee overload in male professional soccer players following a unilateral vertical landing test. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was (1) to test the effect of movement restriction of the free leg during unilateral vertical jump on performance and power output comparing 2 different jump techniques: flexed (Classic technique) and straight (FC Luzern technique) free leg, and (2) to test the correlation between performance and power output obtained using these 2 techniques. Twenty elite soccer players performed squat (SJ) and countermovement (CMJ) jumps on each leg. The jump height and peak power output were compared between the 2 techniques for both legs. The jump height and peak power were significantly higher for the classic test for SJ and CMJ (P <.001) with no side effects or interactions. The angular range of motion of the free leg was higher for the Classic test than for the FC Lucerne test (P <.001), with no difference in the angular range of motion of the trunk. A moderate correlation was found between the 2 techniques on peak power (SJ: r =.626; CMJ: r =.649) and jump height (SJ: r =.742; CMJ: r =.891). Consequently, FC Lucerne technique, limiting the contribution of the free leg, is more appropriate to assess lower limb strength capacities during unilateral jump test. [ABSTRACT FROM AUTHOR]

Most people with intellectual disabilities have comorbid health conditions, which will impact optimization of sporting performance. Classification is used in Paralympic events to ensure that those with similar levels of functional ability compete fairly against each other. An evidence-based approach needs to be developed for athletes with intellectual disabilities to be classified in relation to their overall functional capacity into competition groups of similar ability. This research builds on previous work using the taxonomy of The International Classification of Functioning, Disability and Health (ICF) to group athletes with intellectual disabilities into comparable competition groups as an approach to Paralympic classification. Three groups of athletes—Virtus, Special Olympics, and Down syndrome—are compared using the ICF questionnaire indicating functional health status in relation to sporting performance. The questionnaire was found to discriminate between athletes with Down syndrome and other athletes, and an approach to using a cutoff score to develop competition classes is explored. [ABSTRACT FROM AUTHOR]

The aim of this study was to identify contextual factors that negatively affect activity and participation among powerchair football (PF) players. Thirty-seven semistructured interviews were conducted with PF players (Mage = 27.9 ± 8.2 years) in France (n = 18) and the United States (n = 19). Participants reported acute back and neck pain as the primary morbidities resulting from PF participation, with sustained atypical posture in the sport chair as the primary cause. Competition-related physical and mental stress were also identified as participation outcomes. Accompanying the many benefits of PF, participants recognized negative impacts of discomfort, physical fatigue, and mental fatigue. Interventions such as seating modifications, thermotherapy to combat pain, napping to combat acute physical stress, and mental preparation to manage state anxiety were all identified as prospective interventions. [ABSTRACT FROM AUTHOR]

Clinical Scenario: Injuries that affect the groin region are among the most common in football players. To prevent this condition, studies have focused on strengthening the adductors, hip flexors, or abdominal muscles. Recent investigations have used an eccentric-biased exercise (Copenhagen Adduction Exercise [CAE]) that promotes functional and architectural adaptations in the muscle tissue, though its effect on injury risk reduction is unknown. Clinical Question: Can the Copenhagen Adduction Exercise prevent groin injuries in soccer players? Summary of Key Findings: The literature was searched for studies investigating the potential groin injury risk reduction effect of the CAE. (1) Three studies met the inclusion criteria and were used for this appraisal; (2) one study observed a significantly lower injury rate ratio favoring the group that used the CAE program; and (3) 2 studies found similar or higher injury rates in the intervention groups, not supporting the inclusion of the CAE as a preventative tool. Clinical Bottom Line: There is conflicting evidence that usage of the CAE is superior to not performing adductor strengthening exercises in mitigating the risk of sustaining groin injuries. Given the evidence supporting these findings, it is advisable to exercise caution when contemplating the incorporation of the CAE into training regimens aimed at preventing groin injuries. Strength of Recommendation: There is Grade B evidence to suggest that inclusion of the CAE may not be associated with reduced injury rates. [ABSTRACT FROM AUTHOR]

Context: Nordic hamstring strength (NH strength) and single leg bridge test (SLBT) scores are used to predict the risk of hamstring strain injury. Although NH strength and SLBT scores may be related, the relationship between NH strength and SLBT score remains unknown. Objectives: This study investigated the relationship between NH strength and SLBT scores in university soccer players. Design: Cross-sectional study. Setting: Research laboratory. Participants: 38 male university soccer players. Main Outcome Measures: NH strength and SLBT scores. Interventions: A participant was instructed to lean forward gradually at the slowest possible speed from a kneeling posture with the knee joint flexed 90° for the NH strength measurement. Participants in the SLBT crossed their arms over their chests, pushed down from their heels, and lifted their hips off the ground as many times as they could until they failed. We investigated the relationship between NH strength and SLBT scores in the left and right sides using Spearman rank correlation coefficient. Additionally, we calculated the percentage of left–right asymmetry in NH strength and SLBT scores and investigated the relationship between these variables using Pearson correlation coefficient. Results: There were no significant correlations between NH strength and SLBT scores in the right (rs =.239, P =.16) and left (rs =.311, P =.065) legs. Furthermore, there was no significant relationship between NH strength and SLBT between-limb asymmetry (r =.073, P =.671). Conclusions: NH strength and SLBT scores could be different indexes, indicating either maximal muscle strength or muscle endurance. Thus, the findings suggested that when assessing risk factors for hamstring strain injury, both NH strength and SLBT scores should be measured. [ABSTRACT FROM AUTHOR]

Purpose: To determine the minimum number of events (training or matches) for producing valid acceleration–speed (AS) profiles from global navigation satellite system (GNSS) data. Methods: Nine elite female soccer players participated in a 4-week training camp consisting of 19 events. AS profile metrics calculated from different combinations of athlete events were compared to force–velocity (FV) profile metrics from 2 × 40-m stand-alone sprint effort trials, using the same GNSS 10-Hz technology. Force–velocity profiles were calculated, from which AS profiles were obtained. AS profiles from training and matches were generated by plotting acceleration and speed points and performing a regression through the maximal points to obtain the AS metrics (theoretical maximal speed, x-intercept [in meters per second], theoretical maximal acceleration, y-intercept [in meters per second squared], and the slope per second). A linear mixed model was performed with the AS metrics as the outcome variables, the number of events as a fixed effect, and the participant identifier as a mixed effect. Dunnett post hoc multiple comparisons were used to compare the means of each number of event grouping (1–19 events) to those estimated from the dedicated sprint test. Results: Theoretical maximal speed and theoretical maximal acceleration means were no longer significantly different from the isolated sprint reference with 9 to 19 (small to trivial differences = −0.31 to −0.04 m·s−1, P =.12–.99) and 6 to 19 (small differences = −0.4 to −0.28 m·s−2, P =.06–.79) events, and the slopes were no longer different with 1 to 19 events (trivial differences = 0.06–0.03 s−1, P =.35–.99). Conclusions: AS profiles can be estimated from a minimum of 9 days of tracking data. Future research should investigate methodology resulting in AS profiles estimated from fewer events. [ABSTRACT FROM AUTHOR]

The goal of this study was to extend the contemporary athlete activism literature by (a) exploring athlete activism beyond a strictly North American context and (b) examining how athlete activism at an organizational/institutional level (i.e., sport organization) may be framed differently than activist efforts at an individual level (i.e., athlete). By examining two examples of activism in German soccer, we show that the framing of both athlete-enacted and organization-enacted examples of activism highlighted the importance of speaking up when human rights are violated, called for the display of solidarity, and discussed the broader political implications for such protests. Additionally, framing of both examples of activism included voices of criticism regarding the sport organizations governing global sport. As calls for accountability of sport organizations suppressing athlete expression are becoming increasingly common in global sport, this study adds to a shifting focus of activism research targeting the sport institutions that often perpetuate the various injustices individual athletes call attention to. [ABSTRACT FROM AUTHOR]