Soccer Season Research Articles

Impact of technical and physical performance on match outcome over five elite European soccer seasons.

The technical and physical performance, a key part of overall soccer performance, tend to evolve due to changes in game rules, playing styles, and training methodology. Nevertheless, little has been reported in the literature on how match performance has changed over time in elite championships and leagues. Thus, this study aimed to assess the impact of selected technical and physical team performance indicators on match outcome over five seasons in the Russian Premier League. Twenty-two technical and physical team performance variables, recorded with an optical tracking system, were examined in 1186 matches played in the Russian Premier League during the 2016-2017 to 2020-2021 seasons. For pooled data in all examined seasons, shots on target were higher in won vs. drawn and lost matches. Percentage of challenges won was higher in won vs. drawn and lost matches. Sprint distance, counterattacks, shots, interceptions, recoveries, crosses, and the percentage of successful tackles all showed small though significant differences between match outcomes. Slightly greater odds of a more favorable match outcome were involved by increases in all selected variables, except crosses, showing an opposite effect. In the 2020-2021 season, ball possession time reported a slightly higher impact on match outcome than in previous seasons. The present results show that some technical performance variables have a great effect on match outcome, while other technical indicators and physical metrics have a smaller though still potentially relevant impact. These effects do not substantially differ across the five examined seasons.

Blood sample profile helps to injury forecasting in elite soccer players

PurposeBy analyzing external workloads with machine learning models (ML), it is now possible to predict injuries, but with a moderate accuracy. The increment of the prediction ability is nowadays mandatory to reduce the high number of false positives. The aim of this study was to investigate if players’ blood sample profiles could increase the predictive ability of the models trained only on external training workloads.MethodEighteen elite soccer players competing in Italian league (Serie B) during the seasons 2017/2018 and 2018/2019 took part in this study. Players’ blood samples parameters (i.e., Hematocrit, Hemoglobin, number of red blood cells, ferritin, and sideremia) were recorded through the two soccer seasons to group them into two main groups using a non-supervised ML algorithm (k-means). Additionally to external workloads data recorded every training or match day using a GPS device (K-GPS 10 Hz, K-Sport International, Italy), this grouping was used as a predictor for injury risk. The goodness of ML models trained were tested to assess the influence of blood sample profile to injury prediction.ResultsHematocrit, Hemoglobin, number of red blood cells, testosterone, and ferritin were the most important features that allowed to profile players and to analyze the response to external workloads for each type of player profile. Players’ blood samples’ characteristics permitted to personalize the decision-making rules of the ML models based on external workloads reaching an accuracy of 63%. This approach increased the injury prediction ability of about 15% compared to models that take into consideration only training workloads’ features. The influence of each external workload varied in accordance with the players’ blood sample characteristics and the physiological demands of a specific period of the season.ConclusionField experts should hence not only monitor the external workloads to assess the status of the players, but additional information derived from individuals’ characteristics permits to have a more complete overview of the players well-being. In this way, coaches could better personalize the training program maximizing the training effect and minimizing the injury risk.

Relationship between Variations in the Accumulated Workload and the Change of Direction Ability in Elite Young Soccer Players

Background: The main aim of this study was to evaluate the relationships between training workload (WL) parameters with variations in the change of direction (COD) in under-16 soccer players. Methods: Twenty-seven under-16 elite soccer players were daily monitored for their WL across 15 weeks during the competitive soccer season. Additionally, players were assessed two times for anthropometric measures (weight, height, sitting height and leg length), COD performance (modified 505 test) and maturity offset measured using the peak height velocity (PHV). Results: A correlational analysis was performed to determine the relationship between the variation in COD performance and accumulated WL parameters. Moreover, a regression analysis was executed to explain the variations in the percentage of COD performance considering the accumulated WL parameters and PHV of the season (r = 0.93; p ≤ 0.01) and training monotony during the early-season (r = 0.53; p ≤ 0.05). There were associations between the acute workload during the start of the season and the COD during the end of the season (r = 0.47; p ≤ 0.05). The multiple linear regression analysis showed that 55% of the variation in COD performance between the early and end of season could be explained by the acute or chronic WL, training monotony or strain and the PHV. Conclusions: This information might be useful for practitioners and coaches aiming to improve the COD performance in youth soccer players during an entire competitive season.

Are acute:chronic workload ratios of perceived exertion and running based variables sensible to detect variations between player positions over the season? A soccer team study

BackgroundThe aim of this study was to describe and compare the in-season variations of acute: chronic workload ratio (ACWR) coupled, uncoupled, and exponentially weighted moving average (EWMA) through session rating of perceived exertion (s-RPE), total distance (TD), high-speed running distance (HSRD) and sprint distance (SPRINT) in three different periods of an elite soccer season according to player positions.MethodsTwenty male elite players (age: 29.4 ± 4.4) from an Asian First League team were daily monitored for twenty consecutive weeks during the 2017–2018 in-season. Forty-seven trainings and twenty matches were monitored using global positioning system units (GPS) to collect TD, HSRD and SPRINT. Through the collection of s-RPE, TD, HSRD, and SPRINT by ACWR and EWMA were calculated for each training session.ResultsThe results revealed that according to different periods of the season, workload measures observed in mid-season were meaningfully higher compared with early-season (g = ranging from 0.53 to 4.98) except for EWMASPRINT. In general, wingers and strikers tended to have greater scores in workload measures compared to the defenders and midfielders (g = ranging from 0.41 to 5.42).ConclusionsThese findings may provide detailed information for coaches and sports scientists regarding the variations of acute and chronic workload ratio and external loading in-season and between player positions in an elite soccer team.

In-Season Quantification and Relationship of External and Internal Intensity, Sleep Quality, and Psychological or Physical Stressors of Semi-Professional Soccer Players.

Simple SummaryIn this study, we analyse the relationship of the in-season variations of external, internal and well-being measures across different periods of a semi-professional soccer season (early-, mid- and end-season) and describe TM and TS for the entire period of the analysis. The main findings of our study revealed that increasing the training intensity affects the well-being of the players and consequently the training intensity management. Coaches and their staff should consider the results of this study, because despite the relationship between external and internal intensity, each has a unique effect on the perception of the player’s training intensity management.The purpose of this study was two-fold: (a) to describe and analyse the relationship of the in-season variations of external and internal intensity metrics as well as well-being measures across different periods of a semi-professional soccer season (early-, mid- and end-season); and (b) to describe training monotony (TM) and training strain (TS) for 20 weeks in a semi-professional soccer season. Eighteen semi-professional players (age: 29 ± 4.1) from the Asian First League team participated in this study. The players were monitored for 20 consecutive weeks during in-season for external training intensity, internal training intensity and well-being parameters. The in-season was organized into three periods: early-season (weeks 1–7); mid-season (weeks 8–13); and end-season (weeks 14–20). Total distance (TD), high-speed running distance (HSRD), sprint distance, rate of perceived exertion (RPE), session-RPE (s-RPE), TM, TS, heart rate average and maximum, as well as sleep quality, stress and muscle soreness were collected. Results revealed that TD, HSRD and sprint distance (total values) were meaningfully greater during end-season than in the early-season. RPE showed a significantly highest value during the end-season (4.27 AU) than in early- (3.68 AU) and mid-season (3.65 AU), p < 0.01. TS showed significant differences between early-season with mid-season (p = 0.011) and end-season (p < 0.01), and the highest value occurred in week 17 during end-season (6656.51 AU), while the lowest value occurred in week 4 during early-season (797.17 AU). The average TD periods showed a moderate to large correlation with RPE, sleep and s-RPE at early-, mid- and end-season. Increasing the training intensity without considering the well-being of the players affects the performance of the team. Examining processes of the relationship between training intensity and other psychological indicators among players will probably be effective in training planning. Sports coaches and fitness professionals should be wary of changes in TM and TS that affect players performance. Therefore, to better control the training, more consideration should be given by the coaches.

Acute and Chronic Workload Ratios of Perceived Exertion, Global Positioning System, and Running-Based Variables Between Starters and Non-starters: A Male Professional Team Study

The study aim was 2-fold (i) to describe and compare the in-season variations of acute: chronic workload ratio (ACWR) coupled, ACWR uncoupled, and exponentially weighted moving average (EWMA) through session-rated perceived exertion (s-RPE), total distance (TD), high-speed running distance (HSRD), and sprint distance across different periods of a professional soccer season (early, mid, and end-season) between starters and non-starters; (ii) to analyze the relationship the aforementioned measures across different periods of the season for starters and non-starters. Twenty elite soccer players (mean ± SD age, 29.4 ± 4.4 y; height, 1.8 ± 0.1 m; and body mass, 74.8 ± 2.3 kg). They were divided into starter and non-starter groups and were evaluated for 20 weeks. ACWR had general changes throughout the season. At the beginning and end of the mid-season, the highest ACWR was observed in three parameters: s-RPE, TD, and HSRD. ACWR and EWMA through sprint distance were higher at the beginning of the early-season than at any other time of the season.The ACWR coupled of s-RPE shows a significant higher value for non-starters than starters (p = 0.015; g = −1.01 [−1.98, −0.09]) and the ACWR coupled of TD shows a significant higher value for starters than non-starters in early-season (p < 0.01; g = 3.01 [1.78, 4.46]) and shows a significant higher value for non-starters than starters in mid-season (p < 0.01; g = −2.52 [−3.83, −1.39]), and end-season (p < 0.01; g = −2.57 [−3.89, −1.43]). While the EWMA of TD shows a significant higher value for starters than non-starters in early-season (p < 0.01; g = 2.25 [1.17, 3.49]) and mid-season (p < 0.01; g = 2.42 [1.31, 3.71]), and shows a significant higher value for non-starters than starters in end-season (p < 0.01; g = −2.23 [−3.47, −1.16]). Additionally, we found some correlations between external and internal load measures during three periods of the in-season. The study’s main finding was that the indexes of ACWR and EWMA were useful to detect differences between period and between playing status with the exception for the sprint variable. In addition, the necessary work for non-starter players’ improvement is not done during training, and these players lose their readiness as the season progresses. Consequently, these players perform poorly during the match. Therefore, coaches and their staff should consider devising new activities to keep non-starter players physically fit. This deficit must be accounted for in training because they compete in fewer matches and have less burden than starters.

Examining the Dynamic Nature of Anterior Cruciate Ligament Injury Risk Factors in Women's Collegiate Soccer.

Anterior cruciate ligament (ACL) injuries are a common and devastating injury in women's soccer. Several risk factors for ACL injury have been identified, but have not yet been examined as potentially dynamic risk factors, which may change throughout a collegiate soccer season. Prospective cohort study. Nine common clinical screening assessments for ACL injury risk, consisting of range of motion, movement quality, and power, were assessed in 29 Division I collegiate women's soccer players. Preseason and midseason values were compared for significant differences. Change scores for each risk factor were also correlated with cumulative training loads during the first 10weeks of a competitive soccer season. Hip external rotation range of motion and power had statistically significant and meaningful differences at midseason compared with preseason, indicating they are dynamic risk factors. There were no significant associations between the observed risk factor changes and cumulative training load. Hip external rotation range of motion and power are dynamic risk factors for ACL injury in women's collegiate soccer athletes. Serial screening of these risk factors may elucidate stronger associations with injury risk and improve prognostic accuracy of screening tools.

Prevalence of Heading in Middle School American Youth Club Soccer Players

Research Objectives To find out the frequency of heading event occurrence in the youth club soccer season. Design Observational study. Setting Community setting at the soccer match playground. Participants Player on an “Oceanside Breakers Competitive male soccer team” composed of 6th-grade middle school players and their opponents’ team. Interventions No interventions. Main Outcome Measures Number of heading occurrence in the participants and opposite team observer by the research team. Results The mean standardized assessment of concussion (SAC) score for the observed soccer team was 24.9±2.6 (out of 30). The number of heading occurrences in the consecutive 11 matches in both teams are 47, 34, 26, 23, 33, 29, 45, 31, 32, 40, 51. The average heading occurrence is 35.5 times/ match in a season. The observed team showed that the frequency of heading is more in the middle location 18.72±8.79 compared to the forward location (14.34±8.51) and the defense (10.34±7.1). However, there is no significant difference between the number of heading events at different locations of the play level (forward, middle, and defense) F2,10=1.097; p=.372. Conclusions Independent of the player's location, all players are susceptible to heading occurrence in the soccer game. With the high frequency of this occurrence, there is a need to address this problem at the level of the soccer federation and policymakers of the soccer game. The players, coaches, family members need to be educated to decrease the heading occurrence in the soccer game since the repetitive heading occurrence may have a negative influence on the developing brain. Author(s) Disclosures None of the authors have conflicts of interest. To find out the frequency of heading event occurrence in the youth club soccer season. Observational study. Community setting at the soccer match playground. Player on an “Oceanside Breakers Competitive male soccer team” composed of 6th-grade middle school players and their opponents’ team. No interventions. Number of heading occurrence in the participants and opposite team observer by the research team. The mean standardized assessment of concussion (SAC) score for the observed soccer team was 24.9±2.6 (out of 30). The number of heading occurrences in the consecutive 11 matches in both teams are 47, 34, 26, 23, 33, 29, 45, 31, 32, 40, 51. The average heading occurrence is 35.5 times/ match in a season. The observed team showed that the frequency of heading is more in the middle location 18.72±8.79 compared to the forward location (14.34±8.51) and the defense (10.34±7.1). However, there is no significant difference between the number of heading events at different locations of the play level (forward, middle, and defense) F2,10=1.097; p=.372. Independent of the player's location, all players are susceptible to heading occurrence in the soccer game. With the high frequency of this occurrence, there is a need to address this problem at the level of the soccer federation and policymakers of the soccer game. The players, coaches, family members need to be educated to decrease the heading occurrence in the soccer game since the repetitive heading occurrence may have a negative influence on the developing brain.

Does Sleep Quality between Back-to-Back Matches Influence Running Performance in Canadian Female University Soccer Players? A GPS-based Time-Series Analysis

Background: Soccer competitions performed with less than or equal to 24 hours of recuperation, including inadequate amounts of quality sleep, may adversely affect performance. Objective: The purpose of this research was to assess running performance between self-reported good and poor sleepers in female university sport soccer players (N = 12) in matches played with ≤ 24 hours of recovery. Methods: In this cross-sectional and observational study, twelve female university soccer players (mean age: 19.44 + 1.69 yr) were followed throughout one season of competition using a time-series analysis of running performance and comparing good (n = 7) versus poor (n = 5) sleepers. Global positioning systems (GPS) were used to evaluate jogging/sprinting performance throughout the 2016 soccer season. Good and poor sleepers were determined via the Pittsburgh Sleep Quality Index (PSQI). Results: There was a significant reduction (p .05) in running performance from the first to the second game in the entire cohort, while post hoc analysis indicated that good sleepers performed better on the relative speed performance parameter when comparing the first game to the second game; however, there was no change in this performance variable in the poor sleepers between the first and second game. Conclusions: Our study indicates that Canadian female university soccer players may need longer than 24 hours of recovery to perform optimally in subsequent matches. Generally, good and poor sleepers perform similarly except for GPS relative speed in back-to-back matches with 24 hours of recovery.

Influence of Tactical Formation on Average and Peak Demands of Elite Soccer Match-Play

Global Positioning Systems (GPS) have provided practitioners with information on the activity profiles of team-sport players. There is no available literature identifying the average or peak physical demands of elite soccer in the USA. This investigation aims to quantify the activity profiles and most demanding passages of elite soccer competition within different positions, periods, and tactical formations. Activity profiles were captured from 449 whole-period, and 661 peak-period data from 24 field players across a 31-game Major League Soccer season. Total distance covered (metres), average speed (m·min-1), and number of acceleration and deceleration (m·s-2) efforts were used to comprise whole-period profiles. Peak values for speed (m·min-1) were obtained by using a moving-average approach for durations lasting 1, 2, 3, 5, and 10 minutes. Across all positions the 4-2-3-1, 3-4-3, and 4-3-3 formations showed a decrease in average speed between the first and second halves. The 4-3-1-2 yielded greatest whole-period accelerations and decelerations for full backs, and overall distance covered and average speed for strikers. Most peak intensities were observed in the first half of match-play, with attacking midfielders and strikers demonstrating their greatest activity during the first half of a 4-3-1-2 formation. Altering tactical formations results in different physical outputs for all positional groups. Depending on the formation implemented, positional groups resulted in differences, with physical outputs, between halves during match-play.

Use of plastic geocellular modules as a replacement gravel layer for natural turf rootzones

AbstractA trial was conducted to assess the suitability of a novel plastic geocellular drainage layer (Permavoid) as a replacement for a conventional gravel layer in a high‐quality sports pitch. The trial was conducted during the 2014–2015 and 2015–2016 United Kingdom football (soccer) seasons. Perennial ryegrass (Lolium perenne L.) was grown under five different rootzone depth treatments (50, 100, 200, and 300 mm over Permavoid and 300 mm over gravel as a control representing current practices). These were repeated for two contrasting rootzone types. The trial area was subjected to artificial football‐style wear throughout each playing season, with irrigation and nutritional inputs as would be normal for a high‐quality football pitch. Infiltration rates, rootzone moisture content, turf cover and tractional strength for the 200‐ to 300‐mm rootzone over Permavoid and 300 mm over gravel were the same throughout the trial. The replacement of the gravel drainage layer with Permavoid had no negative effect on the rootzone's hydraulic characteristics or turfgrass growth over the 2‐yr study period. In addition, it may be possible to use shallower rootzone depths in some circumstances, reducing the volume of material needed for construction. Shallower rootzones (50–100 mm) experienced greater fluctuations in rootzone moisture content, which was likely to be directly related to rootzone depth. Rootzone type had a minor effect, with finer rootzones holding onto more moisture and allowing slightly stronger turf. Therefore, when managing shallower and/or coarser rootzones, maintenance programs need to reflect the moisture and nutrient retention characteristics of these growing media.

Are Off-Field Activities an Underestimated Risk for Hamstring Injuries in Dutch Male Amateur Soccer Players? An Exploratory Analysis of a Prospective Cohort Study

PurposeThe purpose of this study was to explore what extent male amateur soccer players participate in off-field activities and whether these off-field activities are associated with the development of hamstring injuries.MethodsAmateur soccer players (n = 399) from first-class selection teams (n = 32) filled out a baseline screening questionnaire concerning off-field activities (i.e., work and study type and hours, traveling time, sleep, energy costs, and time spent on other activities) and their history of hamstring injury as a part of a cluster-randomized controlled trial. Throughout one competition, the players reported weekly their hamstring injuries, which were verified by medical/technical staff. Multivariable Firth corrected logistic regression models were used to explore associations between off-field activities and hamstring injuries.ResultsSixty-five hamstring injuries were recorded. Previous injury was significantly associated with hamstring injuries (OR ranging from 1.94 [95% CI 1.45–2.61] to 2.02 [95% CI 1.49–2.73]), but off-field activities were not.ConclusionAlthough amateur soccer players spent a relatively large amount of time on off-field activities, we did not find off-field activities measured at baseline to be associated with hamstring injuries in the subsequent competitive soccer season. In contrast, previous hamstring injury was found to be strongly associated with (recurrent) hamstring injuries.

Variations of High-Intensity GPS Derived Measures between Playing Status during a Full Soccer Season in a Professional Male Team

Background: This study’s aim was twofold: (i) to compare starters and non-starters on a professional soccer team in terms of variations in training intensity indexes across a season, calculated through total distance, sprint distance, accelerations (Acc), and decelerations (Dec) and (ii) to analyse the relationship between the intensity indexes for each playing status. Methods: Nineteen players (age, 29.4 ± 4.4 years; height, 1.8 ± 0.1 m; body mass, 74.8 ± 2.3 kg) were divided into starters and non-starters and followed for 43 weeks using global positioning systems. Results: Training intensity measures (acute:chronic workload ratio [ACWR], coupled and uncoupled) were higher during the latter stage of the season. Total distance peaked during the mid-season, whereas the highest value for exponentially weighted moving average (EWMA) was recorded later in the season. Interestingly, the EMWA of total distance showed little variation during the season for players of both playing statuses. The EWMA of total distance showed a significant higher value for starters than non-starters (p = 0.036; g = 1.27 [0.31, 2.32]). The interruption in games between week 34 and week 35 due to COVID-19 moved some measures into the injury risk zone — namely, the ACWR coupled of sprint distance and Dec; the ACWR uncoupled of total distance, sprint distance, Acc, Dec; and the EWMA of sprint distance, Acc and Dec. Conclusions: The highest training intensity measures were reported late in the season and were similar between starters and non-starters. Across the season, only one difference between starters and non-starters occurred, revealing that training intensity was properly managed throughout the season regardless of the status of the players.

Comparison of Head Impact Exposure Across Common Activities in Youth Soccer

The objective of this study was to compare head impact exposure across common training activities in soccer. Soccer is a popular youth sport in the United States, but repetitive head impacts during training may result in neurocognitive deficits. Current research has identified factors associated with increased head impact exposure in soccer, but research has yet to contextualize head impact exposure across soccer activities. Modifying practice structure may be an avenue for reducing head impact exposure and concussion risk in soccer. Eight U15 soccer players participated in this study for 2 soccer seasons. Players wore a custom instrumented mouthpiece sensor during all practices and games. On-field activities were recorded with a time-synchronized camera. Research personnel recorded the duration of all practice (e.g., technical training, team interaction) and game activities performed by each player, and film review was performed to identify all head contact events during each session. Head impact exposure was quantified in terms of peak kinematics and impacts per player per hour. The amount of time an athlete was exposed to an activity was also evaluated. Mixed effects models were used to compare peak kinematics and generalized linear models were used to compare impact rates across activity types. Activity types were associated with peak kinematics and impact rate. Technical training activities were associated with higher impact rates and lower mean kinematics compared to other activity types. Team interaction activities and game play were associated with the highest rotational kinematics, but the lowest impact rates. A similar number of player-to-player contact events occurred within technical training, team interaction, and game play activities. Interventions designed to reduce head impact frequency in soccer may benefit from targeting technical training activities; whereas, interventions designed to reduce head impact magnitude may benefit from targeting team interaction and game activities.

Player Position Affects Relationship Between Internal and External Training Loads During Division I Collegiate Female Soccer Season.

Ishida, A, Travis, SK, Draper, G, White, JB, and Stone, MH. Player position affects relationship between internal and external training loads during Division I collegiate female soccer season. J Strength Cond Res 36(2): 513-517, 2022-The purpose of this study was to investigate how competition phase and player position affect the relationship between internal and external training loads (ITL and ETL, respectively) in collegiate female soccer. Seventeen players participated (21.8 ± 1.7 years; 165.1 ± 6.2 cm; and 63.7 ± 7.9 kg). Nineteen match-plays (10 nonconference and 9 conference) were completed during the 2019 competitive season, including 270 observations of 17 players (defenders = 5, midfielders = 9, and forwards = 3). Internal training load was assessed using session rating of perceived exertion (sRPE). External training load included total distance and high-speed running (HSR) distance. A linear mixed model was compiled with fixed effects of total distance, HSR, competition phase, and player position (defenders, midfielders, and forwards) and random effects of player. There were statistically significant main effects for total distance (p < 0.001), HSR (p = 0.047) and player position (p = 0.045) on the prediction model of sRPE. However, the main effect of competition phase did not statistically contribute to the prediction model of sRPE (p = 0.38). In the final model, total distance (p < 0.001) and player position for forwards (p = 0.008) were significant predictors of sRPE. However, there was no statistically significant fixed effect of HSR on sRPE (p = 0.15). The final model explained 60.6% of the variance in sRPE (R2 = 0.60), whereas the random effect also explained 6.1% of the variance (R2 = 0.06). Our findings indicated that total distance and player position were strong predictors of sRPE. The relationship between ITL and ETL should be monitored by player position in female soccer players.

The influence of sleep quality and quantity on soccer injuries in professional teams.

There is inconsistency in the relationship between sleeping measures and the occurrence of soccer injuries. Further, most studies investigated sleeping quantity and quality during soccer season but not during off-season. The purpose of this study was to determine the influence of sleeping off-season and during soccer season on the occurrence of injuries in professional soccer players. It was hypothesized that lower sleeping hours and players' thought of inadequate sleeping quantity and quality during off-season and soccer season would associate with the occurrence of soccer injuries. One-hundred and fifty-two professional soccer players (premier league and division I teams, age: 21.82±4.44, BMI: 22.21±2.74, sex: men [N.=91], women [N.=61]) answered questions related to their sleeping duration and whether that amount of sleep was enough prior to (off-season) and during soccer season. The sleep questions related to sleep quantity were derived from the Arabic Pittsburgh Sleep Quality Index. Players indicated also. Players indicated their injury profile, medical treatment, and time loss due to soccer injury. Sleeping measures were evaluated using univariate and multivariate logistic regression models to determine predictors of soccer injuries. Sixty-eight players (44.73%) were injured. Lower total sleeping time during off-season (OR:0.66, 95% CI:0.51-0.85, P=0.002), answering no on "did you regularly get enough sleep during off-season" (OR: 5.64, 95% CI: 2.58-12.27, P<0.001), and answering no on "do you think that your sleeping hours during off-season were enough" (OR:4.76, 95% CI: 1.98-11.46, P=0.001) associated significantly with soccer injuries (R2:38). Lower total sleeping time and not getting regularly enough sleeping time during off-season associated with more soccer injuries. This highlights the influence of sleeping quantity and quality off-season on the occurrence of soccer injuries among professional players.

Effects of Whole-Season Training and Match-Play on Hip Adductor and Abductor Muscle Strength in Soccer Players: A Pilot Study.

Previous investigations have associated weakness of hip muscles with a higher likelihood of developing hip groin injury. However, no previous investigation has examined the influence of soccer training and match-play during the season on maximal isometric hip adductor and abductor muscle strength. Maximal hip adductor and abductor muscle strength would increase after the preseason, maintaining relatively constant levels across the soccer season. Cross-sectional study. Level 3. A total of 26 semiprofessional male soccer players underwent measurements of maximal isometric hip adductor and abductor muscle strength at 3 time points of the soccer season: preseason, midseason, and end-season to investigate the longitudinal effect of soccer training and competition during a complete season on maximal isometric hip adductor and abductor muscle strength in the semiprofessional Spanish soccer player. Compared with preseason, hip abductor muscle strength increased in the midseason (14.2% and 17.1%, for dominant and nondominant limb, respectively; P < 0.001) and in the end-season (13.1%; P = 0.005, and 14.1%; P < 0.005). In contrast, hip adductor muscle strength remained unchanged across the season in both limbs. As a result, the adductor/abductor strength ratio in the nondominant limb was reduced at midseason and end-season time points (-14.6% and -18.4%, respectively; P < 0.001) with a corresponding tendency in the dominant limb (-9.3% and -15.0%, respectively; P > 0.05). While maximal hip abductor muscle strength increased throughout the season, hip adductor muscle strength remained stable across the season. This produced a substantial deficit in hip adductor/abductor strength ratio at midseason and end-season. The progressive imbalance in adductor/abductor strength across the soccer season may be an indicator of increased risk of groin injury and may reinforce the need for preventive rehabilitation activities focused on enhancing adductor muscle strength.

The simple, conventional markers of fatigue - variations in neuromuscular performance, creatine kinase and hydration status in elite soccer players over a season.

Background and Purpose: Fixture congestion, game-intensities and limited recovery negatively influence physical/physiological responses during a competitive soccer season. Therefore, the aim of the investigation was to examine weekly alterations in neuromuscular performance markers, creatine kinase and hydration in elite soccer players throughout a season. Study Design: Longitudinal Observational Study. Methods: Sixteen male professional soccer players competing in the English Football League Championship were assessed over the course of a season. All players provided a urine sample, a blood sample to assess creatine-kinase concentration and performed a countermovement jump test at the start of the season, in-season, pre-and post-match over 38 weeks. Results: Jump height was the most common marker of performance to be significantly reduced in-season compared to baseline (-5.4 to -11.3%, P&lt;0.05) with 45.2% of the time-points affected. Measures of FT:CT (-7.5 to -12.4%) and AP (-9.4 to -11.5%), also showed significant deteriorations throughout the season compared to baseline (P&lt;0.05) at several time-points. Max force (MF) significantly increased in-season (+5.1 to 7.0%) in 20% of the observed time-points compared to baseline. CK concentration significantly increased during 19% of the time-points (P&lt;0.05; 62 to 159%). Urine osmolality demonstrated significant differences in season compared to baseline, but none to levels of dehydration. Conclusion: Monitoring elite soccer players over the course of a competitive season shows alterations in neuromuscular performance and hydration status. These data suggest that assessing counter-movement jump performance may be a useful marker for monitoring responses to training/competition, while creatine-kinase and hydration status may be limited.

Spontaneous Knee Effusion in an Adolescent Soccer Player

A 13-year-old female recreational soccer player presented with spontaneous left knee effusion approximately 2 weeks after the start of soccer season. Radiographic imaging was negative, and a complete blood count identified an increase in inflammatory markers. Additional two-tier testing confirmed a Lyme disease diagnosis, which was unusual for an athlete residing in the southeast region of the United States. The presentation of knee effusion, and subsequently Lyme arthritis, is a common clinical manifestation of late-stage Lyme disease. Early recognition of this infection and prompt treatment by a variety of specialists reduce the severity or chronicity of symptoms.

Session Rating of Perceived Exertion (sRPE) Load and Training Impulse Are Strongly Correlated to GPS-Derived Measures of External Load in NCAA Division I Women's Soccer Athletes.

Purpose: The purpose of this study was to determine whether session rating of perceived exertion-derived training load (sRPE-TL) correlates with GPS-derived measures of external load in National Collegiate Athletics Association (NCAA) Division I female soccer athletes. Methods: Twenty-one NCAA Division 1 collegiate women’s soccer athletes (11 starters, 10 non-starters; 65.1 ± 7.2 kg, 168.4 ± 7.9 cm, 20.3 ± 1.5 yrs) volunteered to take part in this study. Data for this study were collected over the course of 16 weeks during the 2018 NCAA women’s soccer season. External load and heart rate (HR) data were collected during each training session and match during the season. At least 30 min after the end of an activity (e.g., match or practice), athletes were prompted to complete a questionnaire reporting their perceived exertion for the session. sRPE-TL was calculated at the end of the season by multiplying perceived exertion by the respective session duration. Results: sRPE-TL was very strongly correlated with total distance, distance covered in velocity zones 1–3, the number of accelerations in zones 4 and 5, total PlayerLoad™, and PlayerLoad™. For internal load, sRPE-TL correlated very strongly (0.70 ≤ |r| < 0.90) with Edward’s and Bannister’s TRIMP and strongly (0.50 ≤ |r| < 0.70) with duration spent in in heart rate zones 5 and 6 (80–90% and 90–100% max HR, respectively) while correlations with maximum HR (bpm), mean HR (bpm), and mean HR (%) and sRPE-TL were moderate (0.30 ≤ |r| < 0.50). Conclusions: In NCAA Division I women soccer, sRPE-TL is strongly associated with external measures of workload. These relationships were stronger during match play, with acceleration load and total distance exhibiting the strongest relationship with sRPE-TL.