Muscle injury rates in professional football increase with fixture congestion: an 11-year follow-up of the UEFA Champions League injury study

LaLiga Lockdown: Conditioning Strategy and Adaptation to In-Game Regulations during COVID-19 Pandemic Prevented an Increase in Injury Incidence

The first division of Spanish professional football (LaLiga) was suspended for 12 weeks as part of the policies enforced by health authorities during the first wave of COVID-19. During this period, players were confined to home for 8 weeks, followed by a club-based retraining period of 4 weeks. Afterwards, LaLiga’s teams completed 11 matches, with approximately 3 days of recovery between matches, to finish the competition. The aim of this investigation was to determine whether there is a difference in mean injury incidence in LaLiga players between the pre-lockdown period and post-lockdown period. A total of 277 players belonging to 11 teams competing in LaLiga were monitored during the 2019–2020 season. Injury incidence in the 27 matchdays completed before the lockdown was compared to the last 11 matchdays completed after the resumption of the competition. In comparison to the period before the suspension, the resumption of the championship did not significantly affect the injury incidence (4.2 vs. 5.4 injuries per 1000 h of exposure, p = 0.338). Injury incidence before suspension and after resumption of the competition was similar for muscle (2.6 vs. 3.4 injuries per 1000 h of exposure, p = 0.152) and ligament injuries (0.8 vs. 0.4 injuries per 1000 h of exposure, p = 0.062). The resumption of the competition also did not modify the distribution of injury according to body location (p = 0.948), injury type (p = 0.766), mode of onset (p = 0.614), severity (p = 0.065), or player position (p = 0.295). In summary, mean injury incidence in LaLiga players was similar before and after the lockdown. It is probable that the conditioning strategy adopted by clubs before the resumption of LaLiga and the adaptation of some in-game regulations helped to avoid an increased injury rate after the lockdown.

Prolonged restricted training, fixture congestion and player rotation: what the COVID-19 pandemic taught us about injury risk in professional collision sport

Objectives

The COVID19-induced suspension of the 2019-20 professional England rugby union season resulted in players being exposed to an extended restricted training period, coupled with a congested match schedule once competition resumed. We assessed the impact of these changes on match and training injuries in the final 20-weeks of the season following competition resumption.

Design

Epidemiological study.

Methods

The 2019-20 season was compared to the previous three seasons (2016-19).

Results

There was no significant difference in the mean incidence, severity and burden of training and match injuries in 2019-20 compared to 2016-19 period mean. The 2019-20 post-suspension mean match injury rate [77/1000 h (95%CIs [confidence intervals]: 67-89)] was comparable to the 2019-20 pre-suspension [93/1000 h (95%CIs: 85-101)] and significantly lower than the 2016-19 equivalent post-suspension period [97/1000 h (95CIs: 90-104) IRR [incidence rate ratio] 0.8 p=0.002]. In the 2019-20 season, there was a significantly higher rate of training injury post-suspension in comparison to pre-suspension [3.8/1000 h (95CIs: 3.3-4.4) vs 2.7/1000 h (95% CIs: 2.5-3.1) IRR 1.4 p=0.005]. There was no significant difference in the overall incidence, severity or burden of injuries sustained in fixtures with shorter (<6 days) turnarounds but there was a significantly higher burden of soft tissue injuries.

Conclusions

This is the first study to assess the effect of restricted training on injury risk in collision sports. Players were at an increased risk of training injury when returning from the suspension, but 10-weeks of preparatory training meant the incidence of match injury was not higher when competition resumed.

Calf Strain in Athletes

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Calf strain is a common condition. In high-performance athletes, calf strain contributes to a substantial absence from competition.

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Player age and history of a calf strain or other leg injury are the strongest risk factors for calf strain injury and reinjury.

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Although the diagnosis is often clinical, magnetic resonance imaging and ultrasound are valuable to confirm the location of the strain and the grade of injury.

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Nonoperative treatment is effective for most calf strain injuries. Operative management, although rarely indicated, may be appropriate for severe cases with grade-III rupture or complications.

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Further investigation is necessary to elucidate the benefits of blood flow restriction therapy, deep water running, lower-body positive pressure therapy, platelet-rich plasma, and stem cell therapy for calf strain rehabilitation.

Epidemiology of injuries in elite male and female futsal: a systematic review and meta-analysis

The main purpose of this study was to conduct a systematic review and meta-analysis quantifying the incidence of injuries in futsal players. A systematic search was conducted using MEDLINE, PubMed, Web of Science and Scopus databases and subsequently, six studies (14 cohorts) were selected. Separate meta-analyses for male and female players were conducted using a Poisson random-effect regression model approach. The overall and match incidence rates in elite male futsal players were 6.8 (95% CI = 0.0-15.2) and 44.9 (95% CI = 17.2-72.6) injuries/1000 hours of exposure. Pooled training injury rate in male players was not calculated due to the lack of studies reporting training injuries in this cohort. For females, an overall, training and match incidence rates of 5.3 (95% CI = 3.5-7), 5.1 (95% CI = 2.7-7.6) and 10.3 (95% CI = 0.6-20.1) injuries/1000 hours of exposure were reported. In males, match incidence rate in International tournaments was 8.5 times higher than in national leagues (77.2 [95% CI = 60.0-94.5] vs 9.1 [95% CI = 0.0-19.3] for international tournaments and national leagues, respectively). Elite male and female futsal players are exposed to a substantial risk of sustaining injuries, especially during matches.

Preseason Injury Characteristics in Spanish Professional Futsal Players: The LNFS Project

ABSTRACT

López-Segovia, M, Vivo Fernández, I, Herrero Carrasco, R, and Pareja Blanco, F. Preseason injury characteristics in Spanish professional futsal players: the National Futsal League (LFNS) project. J Strength Cond Res 36(1): 232-237, 2022-This study aimed to examine the incidence of injuries and their characteristics among professional Spanish futsal players during the preseason period and to compare injury-related variables in the context of both competition and training. Eleven futsal teams belonging to the First and Second Spanish Division and 161 players participated in the study. Characteristics of injuries, including type, location, cause and time of injury, injury recurrence, and duration of absence, were recorded. A total of 62 injuries were reported; injury rates of 9.9 (95% confidence interval [CI]: 7.0-12.5) injuries/1,000 training hours and 61.1 (95% CI: 25.7-96.5) injuries/1,000 match hours were collected. These data indicate a mean of 5.64 ± 2.66 injuries per team during the preseason period. Of these injuries, 92.1% involved the lower limbs. When data from training and competition were analyzed together, the highest incidence of injuries affected the ankle (21%), followed by the hip/groin and knee (19.4% each). The most common type of injury was muscle rupture/tear/strain (29.0%). During training, the highest percentage of injuries were located in the knee (23.9%), followed by the ankle and hip/groin (21.7% in each case), while during matches, the thigh (35.7%) followed by the ankle (21.4%) was the regions most affected. A significant relationship (p = 0.008) was observed between injury cause (without contact, with other player, with the ball, and others) and injury context (training, match). To conclude, the results of this study suggest the need for injury prevention protocols focuses on the ankle and the knee joints and muscle strain prevention.

ACL injury prevention: Where have we come from and where are we going?

Anterior cruciate ligament (ACL) injuries are one of the most common and severe knee injuries across sports. As such, ACL injury prevention has been a focus of research and sports medicine practice for the past three-plus decades. Examining the current research and identifying both clinical strategies and research gaps, the aim of this review is to empower clinicians and researchers with knowledge of where the ACL injury prevention literature is currently and where it is going in the future. This paper examines the mechanism of ACL injury prevention, screening, implementation, compliance, adherence, coronavirus, and areas of future research. Clinical significance: The time lag between research and practical implementation in general healthcare settings can be as long as 17 years; however, athletes playing sports today are unable to wait that long. With effective programs already established, implementation and adherence to these programs is essential. Strategies such as coaching education, increasing awareness of free programs, identifying barriers, and overcoming implementation obstacles through creative collaboration are just a few ways that could help improve both ACL injury prevention implementation and adherence.

Detrimental effects on executive function and mood following consecutive days of repeated high-intensity sprint interval exercise in trained male sports players

Intensified periods of competition are common in many team sports, potentially leading to increased fatigue and reduced performance. The purpose of this study was to investigate the effect of repeated high-intensity sprint interval exercise on cognitive function, mood and perceptions of energy and fatigue. Twenty-four trained rugby players completed multiple bouts of repeated sprints across two consecutive days. Prior to and following each set of maximal effort sprints or equivalent control duration, a battery of cognitive tasks assessing simple and choice reaction time, visuo-spatial working memory and inhibition were completed as well as visual analogue scales that assessed mood, energy, and fatigue. Accuracy of incongruent Stroop responses was significantly lower across day 2 compared to day 1 and the control condition. Four-choice reaction time was slower across day 2 whilst feelings of alertness, contentedness, and physical and mental energy were reduced while ratings of physical and mental fatigue increased. These findings suggest that intensified periods of high-intensity sprint interval exercise have detrimental effects on executive function, mood and perceptions of physical and mental energy, and fatigue. These deleterious effects have the potential to impact performance and may increase the propensity for injury/accidents in certain sporting and non-sporting contexts.

Variation in Physical Performance of Futsal Players During Congested Fixtures

PURPOSE

To investigate the match-to-match variation of physical performance during official congested fixtures in elite futsal players.

METHODS

Physical performance was measured by external and internal load metrics in 12 elite male futsal players. Two periods with 3 matches within 4 days were analyzed. The variation in physical performance of the players during matches was analyzed using the latent growth curve modeling that estimated interindividual and intraindividual growth paths.

RESULTS

Playing time had a significant effect on physical performance growth with significant paths of interindividual and intraindividual variability. Players who competed for more time revealed lower initial levels (ie, first match) of total distance covered (β = -0.62), high-speed running (β = -0.18), accelerations (β = -0.31), decelerations (β = -0.44), and session rate of perceived exertion (β = 0.81) than players who competed for less time (P < .05). In addition, players who competed for more time revealed higher increases in total distance covered (β = 0.47), high-speed running (β = 0.16), and session rate of perceived exertion (β = 0.66) and lower increases in accelerations (β = -0.21) and decelerations (β = -0.58) than players who competed for less time from the first to the third match (P < .05).

CONCLUSIONS

Congested fixtures did not affect physical performance in elite futsal players. Playing time showed to be a key performance factor. There was a considerable heterogeneity in the responsiveness to physical performance over congested fixtures, suggesting an analysis of individual variability to evaluate real changes in match performance, training intensity, and workload.

Increased Lower Extremity Injury Risk Associated With Player Load and Distance in Collegiate Women's Soccer

BACKGROUND

There is limited research regarding the impact of workload on injury risk specific to women's soccer. Wearable global positioning system (GPS) units can track workload metrics such as total distance traveled and player load during games and training sessions. These metrics can be useful in predicting injury risk.

PURPOSE

To examine the relationship between injury risk and player workload as collected from wearable GPS units in National Collegiate Athletic Association (NCAA) Division I women's soccer players.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Lower extremity injury incidence and GPS workload data (player load, total distance, and high-speed distance) for 65 NCAA Division I women's soccer players were collected over 3 seasons. Accumulated 1-, 2-, 3-, and 4-week loads and acute-to-chronic workload ratios (ACWR) were classified into discrete ranges by z-scores. ACWR was calculated using rolling averages and exponentially weighted moving averages (EWMA) models. Binary logistic regression models were used to compare the 7:28 rolling average and EWMA ACWRs between injured and noninjured players for all GPS/accelerometer variables. The prior 1-, 2-, 3-, and 4-week accumulated loads for all GPS/accelerometer variables were compared between the injured and uninjured cohorts using 2-sample t tests.

RESULTS

There were a total of 53 lower extremity injuries that resulted in lost time recorded (5.76/1000 hours "on-legs" exposure time; 34 noncontact and 19 contact injuries). The prior 2-week (7242 vs 6613 m/s2; P = .02), 3-week (10,533 vs 9718 m/s2; P = .02), and 4-week (13,819 vs 12,892 m/s2; P = .04) accumulated player loads and 2-week (62.40 vs 57.25 km; P = .04), 3-week (90.97 vs 84.10 km; P = .03), and 4-week (119.31 vs 111.38 km; P = .05) accumulated total distances were significantly higher for injured players compared with noninjured players during the same time frames. There were no significant differences in player load, total distance, or high-speed distance ACWR between injured and noninjured players for both the rolling averages and EWMA calculations.

CONCLUSION

Higher accumulated player load and total distance, but not ACWR, were associated with injury in women's soccer players.

The Effect of High-Intensity Accelerations and Decelerations on Match Outcome of an Elite English League Two Football Team

Objectives: Previous research has highlighted the frequency of high-intensity accelerations and decelerations in elite football. The influence of these actions on match performance outcomes has not been established. The aim of the present study was to identify the influence of high-intensity accelerations and decelerations on match performance outcomes (i.e., win, draw, lost). Comparisons were also made between team and positional high-intensity accelerations and decelerations recorded within the games. Methods: 26 elite outfield footballers from an elite English Football League (EFL) Two team completed the present study. Global Positioning System (GPS) technology was utilised to quantify high-intensity accelerations and decelerations during 45 games in a competitive season. Magnitude analysis and the effects of results, positions and fixture periods were observed. Results: Significant effects of results, periods and positions were observed (p ≤ 0.05), with the highest outputs observed in games won. Positionally, fullbacks and centre forwards in a 4–3–3 formation exhibited the greatest frequency of high-intensity accelerations and decelerations. Very large differences were observed between the frequency of high-intensity decelerations compared to accelerations in games won (g = 2.37), drawn (g = 2.99) and lost (g = 3.59). The highest team frequencies of high-intensity accelerations (n = 3330) and decelerations (n = 6482) were completed in games won. Conclusions: The frequency of high-intensity accelerations and decelerations has a significant impact on match performance outcomes in an elite English League Two football team. Consideration needs to be given to specific conditioning and recovery strategies to optimise high-intensity acceleration and deceleration performance in games. Caution should be taken as these findings are representative of one team within the EFL.

The Interval Between Matches Significantly Influences Injury Risk in Field Hockey

Fixture congestion increases injury risk in football, but how it impacts other sports is unclear. The aim of this study was to identify associations between match density and injury incidence in field hockey players. Injury data from a prospective cohort study of professional and youth players was analysed in two ways. Inter-match intervals were clustered into<2424-hours, 3–7-days, and 13 + days, and injury rate ratios (IRR) were calculated to identify differences between clusters in match injuries. Separately, a Lasso-penalised Poisson regression model was used to determine the association between match load across the previous 24-hours, 3-days, 7-days and 14-days, and match and training injuries. Injury rates in matches within 24-hours of the previous match were mostly significantly higher when compared to matches after 3–7-days (IRRs: 3.78; 6.77, P = 0.003; 0.005). While a higher match exposure in the preceding 24-hour and 3-day periods was associated with higher combined match and training injury rates (β̂ = 0.0001; 0.0018), a higher match exposure in the previous 7-and 14-day periods was associated with a reduced injury rate (β̂ = –0.0001; –0.0005). Due to the increased injury risk in matches 3-days and especially 24-hours following the previous fixture, match distribution should be cautiously planned.

Factors Associated With Noncontact Injury in Collegiate Soccer: A 12-Team Prospective Study of NCAA Division I Men's and Women's Soccer

BACKGROUND

Multiteam, multi-institution prospective studies of both women's and men's sports are essential for collectively investigating injury and primary to the generalization and individualization of injury prevention strategies.

HYPOTHESIS

Characteristics of workload, sleep, and contextual factors will be associated with injury risk in collegiate soccer athletes.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Injuries, workload, and sleep characteristics were recorded daily throughout a complete season for 256 athletes from 12 separate National Collegiate Athletic Association Division I men's and women's soccer teams. Workload and contextual factors were assessed via multilevel Poisson regression to capture differences in injury incidence rate ratio (IRR). Paired t test and multilevel logistic regressions were used to assess the relationship between sleep behavior and injury.

RESULTS

Collegiate soccer athletes had lower rates of noncontact injury in the in-season (IRR, 0.42) and postseason (IRR, 0.48) compared with preseason, lower rates of injury in training (IRR, 0.64) compared with matches, and higher injury rates with only 1 day of rest in the previous week (IRR, 1.58) compared with >1 day. Injury rates peaked when training occurred 4 days before a match (IRR, 2.24) compared with a match. Injury rate increased exponentially with increases in the number of noncontact injuries incurred throughout the season (IRR, 2.23). Lower chronic loading, higher training monotony, and acute spikes and lulls in workload were associated with higher noncontact injury rates. Alterations in previous week sleep quality were associated with injury, while chronic sleep behavior and acute alterations (<7 days) in sleep behavior were not (P > .05).

CONCLUSION

Athlete and schedule-specific contextual factors, combined with characteristics of workload and weekly sleep behavior, are significantly associated with injury in collegiate soccer. Multiteam prospective cohort studies involving objective and subjective monitoring allow for the identification of multiple injury risk factors in sports, which can be used to guide injury prevention strategies. Maintaining higher chronic workloads, lowering training monotony, minimizing acute spikes or lulls in workloads, managing workloads during preseason and for athletes with previous injury, integrating more rest and recovery during congested periods, and optimizing sleep quality are all practical considerations for reducing injury risk in collegiate soccer.

Acute Effects of Tecar Therapy on Skin Temperature, Ankle Mobility and Hyperalgesia in Myofascial Pain Syndrome in Professional Basketball Players: A Pilot Study

(1) Background: Myofascial pain syndrome (MPS) is a clinical condition characterized by localized non-inflammatory musculoskeletal pain caused by myofascial trigger points. Diathermy or Tecar therapy (TT) is a form of noninvasive electro-thermal therapy classified as deep thermotherapy based on the application of electric currents. This technique is characterized by immediate effects, and its being used by high performance athletes. (2) Methods: A total of thirty-two participants were included in the study who were professional basketball players. There was a 15-person Control Group and a 17-person Intervention Group. TT was applied in the Intervention Group, while TT with the device switched off (SHAM) was applied in the Control Group. The effects were evaluated through the Lunge test, infrared thermography, and pressure threshold algometry at baseline, 15, and 30 min after the intervention. (3) Results: the Intervention Group exhibited a greater increase in absolute temperature (F_[1,62] = 4.60, p = 0.040, η²_p = 0.13) compared to the Control Group. There were no differences between the groups in the Lunge Test (F_[1.68,53.64] = 2.91, p = 0.072, η²_p = 0.08) or in pressure algometry (visual analog scale, VAS) (F_[3.90] = 0.73, p = 0.539, η²_p = 0.02). No significant short-term significant differences were found in the rest of the variables. (4) Conclusions: Diathermy can induce changes in the absolute temperature of the medial gastrocnemius muscle.

Effectiveness and safety of massage for athletic injuries: A protocol for systematic review and meta-analysis

BACKGROUND

Athletic injuries have been a major area of interest in the field of sports and clinical medicine. Implemented on people's skin, muscles, and joints as an important part of complementary and alternative medicine (CAM), massage therapy has a positive effect on athletic injuries. This protocol is to provide the methods used to evaluate the effectiveness and safety of massage therapy for patients with athletic injuries.

METHODS

A systematic search will be performed in the following electronic databases for randomized controlled trials (RCTs) to evaluate the effectiveness and safety of massage therapy in treating athletic injuries: PubMed, the Cochrane Library, EMBASE and four Chinese databases (CNKI, Wan Fang, CBMdisc and VIP). Each database will be searched from inception to July 2021. The entire process will include study selection, data extraction, risk of bias assessment and meta-analysis.

RESULTS

A high-quality synthesis of current evidence of massage therapy for patients with athletic injuries will be provided.

CONCLUSIONS

This systematic review will provide evidence for assessing the credibility of massage therapy for patients with athletic injuries.

DISSEMINATION AND ETHICS

The results of this review will be disseminated through peer-reviewed publication. This review does not require ethical approval because all the data used in this systematic review and meta-analysis have already been published. Furthermore, all of these data will be analyzed anonymously during the review process.

INPLASY REGISTRATION NUMBER

INPLASY202170066.

Coaches' attitudes to injury and injury prevention: a qualitative study of Irish field hockey coaches

Translating injury prevention research into practice has been challenging, which may be due to a poor understanding of the contextual factors influencing the occurrence of injury. Coaches are key figure in sporting environments and hold pivotal roles in preventing injury. Therefore, the aim of this study was to investigate the attitudes of field hockey coaches to injury and injury prevention. Thirteen field hockey coaches from the amateur Irish Hockey League were interviewed. Reflexive thematic analysis led to three general dimensions comprised five higher-order themes, categorised from 16 lower-order themes. Coaches had positive beliefs regarding the benefits of injury prevention over injury management. However, they lacked the necessary knowledge and skills to successfully implement injury prevention strategies with players. Coaches recognised the importance of empowering players to self-manage training loads to promote injury prevention but acknowledged the need to protect younger players from increased loads. Many barriers to injury prevention were not controllable by coaches including fixture congestion and poor structuring of the sport's domestic calendar. While coaches can play a key role in the implementation of injury prevention strategies, there is also a requirement to examine how system level barriers to injury prevention can be reduced.

Muscle Damage Biomarkers in Congestion Weeks in English Premier League Soccer Players: A Prospective Study for Two Consecutive Seasons

The current study was conducted to compare muscle damage biomarkers in single- vs. multi-match weeks in elite soccer players for two consecutive seasons. A secondary objective was to analyze the influence of playing position and exposure time on muscle damage in single- vs. multi-match weeks. This is a prospective cohort study performed in a professional elite soccer club in the English Premier League during the 2018-2019 and 2019-2020 seasons up until the lockdown due to the COVID-19 pandemic. Data were collected in the Medical Department Room of an English Premier League Club before and after the soccer game from a total of 29 elite soccer players (mean ± S.D.; age = 27.59 ± 3.83 years; height = 1.83 ± 0.05 m; body mass = 80.16 ± 7.45 kg) who were enrolled in the club during both seasons. The main outcome measurements were creatine kinase (CK), weight, lean mass, % fat DEXA, high speed running, total distance, density of total distance and high-speed running and wellbeing questionnaires. Significance was set at p < 0.05. Players who completed more than 60 min in the previous game had significantly increased pregame CK levels and fatigue in multi-match weeks. Midfielders had both significantly increased pregame CK and muscle soreness in multi-match weeks. Midfielders and players with an exposure time of at least 60 min showed higher pregame CK values that should play a key role for deciding substitutions.

Compression Stockings Used During Two Soccer Matches Improve Perceived Muscle Soreness and High-Intensity Performance

ABSTRACT

Gimenes, SV, Marocolo, M, Pavin, LN, Pagoto Spigolon, LM, Neto, OB, Côrrea da Silva, BV, Duffield, R, and Ribeiro da Mota, G. Compression stockings used during two soccer matches improve perceived muscle soreness and high-intensity performance. J Strength Cond Res 35(7): 2010-2017, 2021-Evidence on the use of compression stockings (CS) during soccer matches is limited. Thus, we evaluated the acute effects of CS on match-based physical performance indicators and perceptual responses during 2 consecutive soccer matches with 72-hour recovery. Twenty outfield players were randomly allocated to the CS group (20-30 mm Hg) or control group (non-CS) and performed 2 matches (5 players using CS or regular socks per team/match). Match loads {rating of perceived exertion × minutes; CS ∼830 vs. control 843 (arbitrary units [AU])} and heart rate (HR) responses (both CS and control ∼86% HRpeak) did not differ (p > 0.05) between CS and control groups. Although total distance covered did not differ (p > 0.05) between groups, CS increased distances (effect size [ES] = 0.9-1.32) in higher-speed zones (>19 km·h-1 CS ∼550 m vs. control ∼373 m) alongside an increased number of accelerations (-50.0 to -3.0 m·s-2) than control (CS: 33.7 ± 11.2 vs. control: 23.8 ± 7.9; p = 0.003; ES = 1.04). Perceived recovery did not differ (p > 0.05) between groups for either match but was worse in the second match for both groups. Perceived muscle soreness increased in control after match 2 (from 3.1 ± 1.9 to 6.3 ± 1.6 AU; p < 0.0010) but did not in CS (from 2.8 ± 1.4 to 4.1 ± 1.9 AU; p = 0.6275; ES = 1.24 CS vs. control after match). Accordingly, CS use during 2 soccer matches with 72-hour recovery reduces perceived muscle soreness in the second match and increases higher-speed match running performance.

Running Patterns in LaLiga Before and After Suspension of the Competition Due to COVID-19

In the first wave of the COVID-19 outbreak (spring 2020), the first division of professional soccer in Spain (LaLiga) was suspended for 12 weeks as part of the lockdown imposed by the Spanish health authorities. Professional soccer players were confined to home for 8 weeks and then a retraining period of 4 weeks was set before the first competitive match. When competition was resumed, professional soccer teams competed in a congested calendar (11 matchdays in 39 days) while some in-game regulations were altered (up to 5 substitutions, refreshment pauses). The current research presents an analysis of running patterns before suspension and after resumption of LaLiga to determine how the lockdown affected players’ physical performance. To aid in this purpose, a pairwise comparison was performed of running patterns of the 2019–2020 vs. 2018–2019 season (i.e., control season). Using a two-way ANOVA (season x matchday), it was found that there was no main effect of the season on total running distance per match (P = 0.288) nor in the distances covered < 14.0 km/h (P = 0.294), at 21.0–23.9 km/h (P = 0.266), and at ≥ 24.0 km/h (P = 0.112). Only the distance at 14.0–20.9 km/h was affected by the season (P = 0.019) with a lower running distance on matchday 34 in the 2019–2020 vs. 2018–2019 season. The number of substitutions (from 2.9 to 4.5 substitutions per game; P < 0.001) and match duration (96 vs. 100 min; P < 0.001) significantly increased after resumption respect to the previous season. These data suggest that high-intensity running performance of professional soccer teams was maintained after the resumption of the competition while the alterations likely aided in the in-game regulations facilitated the maintenance of soccer physical performance.

Accumulative Competitive Season Training Stress Affects Neuromuscular Function and Increases Injury Risk in Uninjured D1 Female Athletes

Previous research has shown that acute competition training stress negatively affects neuromuscular function which can perpetuate a predisposition to injury. This study's aim was to investigate the effect of accumulated competition training stress effect on neuromuscular function and incidence of increased injury risk in uninjured female D1 soccer players. Neuromuscular function was evaluated in fifteen female division I soccer athletes who played >85% of competitive season competitions who were tested for mobility/stability, leg length symmetry, and vertical power at three different points across the competitive season (pre, mid, and post time blocks). Leg length symmetry was measured from the anterior superior iliac spine to the lateral malleolus prior to Y-balance testing. The Y-balance testing measures unilateral anterior, posteromedial, and posterolateral reach achieved in single leg stance using metrics that include L/R normalized composite reach (NCOMP), L/R normalized antiorior reach (NANT), and L/R NCOMP/NANT segmental differences across time. Injury risk was evaluated using validated objective criteria that included: (NCOMP total reach <94% of limb length^*3), (NANT reach distance <84% leg length) along with NCOMP and NANT asymmetries >4.0. Maximal vertical power (MVP) was measured via vertical jump. Multiple repeated measures ANOVAs evaluated NCOMP, NANT, MVP, and leg length symmetry across time with LSD post hoc testing when relevant (X ± SD). A significant main effect was found [F_{(1, 14)} = 62.92, p < 0.001; η² =0.82] with training stress and neuromuscular function without affecting maximal vertical power. Eighty percent of subject's bilateral NCOMP scores fell below the YBT reach standard at midseason (ES = 0.95, p = 0.02) while all subjects NANT reach distance remained below the reach threshold (ES = 0.74, p = 0.003) indicating a 6.5× and 2.5× greater injury risk, respectively. Competition stress affected neuromuscular function without affecting maximal power, which negatively impacted stability and increased injury risk.

The Effect of Fixture Congestion on Performance During Professional Male Soccer Match-Play: A Systematic Critical Review with Meta-Analysis

BACKGROUND

Fixture congestion (defined as a minimum of two successive bouts of match-play, with an inter-match recovery period of < 96 h) is a frequent and contemporary issue in professional soccer due to increased commercialisation of the sport and a rise in the number of domestic and international cup competitions. To date, there is no published systematic review or meta-analysis on the impact of fixture congestion on performance during soccer match play.

OBJECTIVE

We sought to conduct a systematic review and meta-analysis of the literature related to the effects of fixture congestion on physical, technical, and tactical performance in professional soccer match-play.

METHODS

Adhering to PRISMA guidelines and following pre-registration with the Open Science Framework ( https://osf.io/fqbuj ), a comprehensive and systematic search of three research databases was conducted to identify articles related to soccer fixture congestion. For inclusion in the systematic review and meta-analysis, studies had to include male professional soccer players, a congestion period that contained two matches ≤ 96 h, and have outcome measures related to physical, technical or tactical performance. Exclusion criteria comprised non-male and/or youth players, data that only assessed impact of congestion on injury, used simulated protocols, or were grey literature, such as theses or dissertations.

RESULTS

Out of sixteen articles included in the systematic review, only five were eligible for the meta-analysis, and the only variable that was measured consistently across studies was total distance covered. Fixture congestion had no impact on total distance covered [p = 0.134; pooled standardized mean difference; Hedge's G = 0.12 (- 0.04, 0.28)]. Between-study variance, heterogeneity, and inconsistency across studies were moderate [Cochrane's Q = 6.7, p = 0.150, I2 = 40.7% (CI 0.00, 93.34)]. Data from articles included in the systematic review suggest fixture congestion has equivocal effects on physical performance, with variation between studies and low quality of research design in some instances. Tactical performance may be negatively impacted by fixture congestion; however, only one article was identified that measured this element. Technical performance is unchanged during fixture congestion; however, again, research design and the sensitivity and relevance of methods and variables require improvement.

CONCLUSION

Total distance covered is not impacted by fixture congestion. However, some studies observed a negative effect of fixture congestion on variables such as low- and moderate-intensity distance covered, perhaps suggesting that players employ pacing strategies to maintain high-intensity actions. There is a lack of data on changes in tactical performance during fixture congestion. With ever increasing numbers of competitive matches scheduled, more research needs to be conducted using consistent measures of performance (e.g., movement thresholds) with an integration of physical, technical and tactical aspects.

Injury Profile in Women's Football: A Systematic Review and Meta-Analysis

BACKGROUND

Football is the most popular sport among women; however, little is known about the injury profile in this population. This information would help design tailored injury risk mitigation strategies that may make football safer for women.

OBJECTIVE

The aim of this study was to perform a systematic review and meta-analysis of epidemiological data of injuries in women´s football.

METHODS

A systematic review following PRISMA guidelines was performed up to January 2020 in PubMed, Web of Science, Sportdiscus and the Cochrane Library databases. Twenty-two studies reporting the incidence of injuries in women football were analysed. Two reviewers independently extracted data (intraclass correlation coefficient [ICC] for inter-reviewer reliability = 0.87) and assessed study quality using the STROBE statement, GRADE approach, Newcastle Ottawa Scale and Downs and Black assessment tools. Studies were combined in pooled analyses (injury incidence and injury proportion) using a Poisson random effects regression model.

RESULTS

The overall incidence of injuries in female football players was 6.1 injuries/1000 h of exposure. Match injury incidence (19.2 injuries/1000 h of exposure) was almost six times higher than training injury incidence rate (3.5 injuries/1000 h of exposure). Lower extremity injuries had the highest incidence rates (4.8 injuries/1000 h of exposure). The most common types of injuries were muscle/tendon (1.8 injuries/1000 h of exposure) and joint (non-bone) and ligament (1.5 injuries/1000 h of exposure), which were frequently associated with traumatic incidents. Slight/minimal injuries (1-3 days of time loss) were the most common. The incidence rate of injuries during matches in the top five world ranking leagues was higher than the rest of the leagues (19.3 vs 10.7 injuries/1000 h of exposure, respectively). The weighted injury proportion was 1.1 (95% confidence interval = 0.6-1.7) whereby on average players sustained more than one injury per season.

CONCLUSIONS

Female football players are exposed to a substantial risk of sustaining injuries, especially during matches that require the highest level of performance. To markedly reduce overall injury burden, efforts should focus on introducing and evaluating preventative measures that target match specific dynamics to make football players more capable of responding to the challenges that they have to deal with during match play.

REGISTRATION

This systematic review was registered in the PROSPERO international prospective register of systematic reviews (ID = CRD42019118152).

'As easy as riding a bike': a systematic review of injuries and illness in road cycling

OBJECTIVES

To allow the implementation of effective injury and illness prevention programmes for road cyclists, we wanted to first identify the injury/illness burden to this group of athletes. We, therefore, undertook a systematic review of all reported injuries/illness in road cycling.

DESIGN

Systematic review.

DATA SOURCES

Identification of articles was achieved through a comprehensive search of: MEDLINE, Embase, PsycINFO, Web of Science and Cochrane Library from inception until January 2020.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies reporting injuries/illness in adults participating in road cycling. Cycling commuter studies were excluded from the analysis.

METHOD

Two review authors independently screened titles and abstracts for eligibility and trial quality. Initial search criteria returned 52 titles and abstracts to be reviewed, with 12 studies included after reviewing the full text articles.

RESULTS

The most common injuries sustained were abrasions, lacerations and haematomas accounting for 40-60% of the total injuries recorded. Fractures (6-15%) were the second most frequent type of injury. Head injuries (including concussions) accounted for 5-15% of injuries with musculotendinous injuries accounting for 2-17.5%. The upper limb was more frequently affected by injuries than the lower limb, with amateurs appearing to be at higher risk of injury/illness than professionals. Clavicle was the prevalent fracture, with patellofemoral syndrome the number one overuse diagnosis. No meta-analysis of the results was undertaken due to the inconsistent methods of reporting.

CONCLUSION

This is the first systematic review of road cycling injuries. Injuries most often affected the upper limb, with clavicle being the most prevalent fracture and the most common overuse injury being patellofemoral syndrome.

Utility of Kinetic and Kinematic Jumping and Landing Variables as Predictors of Injury Risk: A Systematic Review

Purpose

Jump-landing assessments provide a means to quantify an individual’s ability to attenuate ground reaction forces, generate lower limb explosive power and maintain joint alignment. In order to identify risk factors that can be targeted through appropriate training interventions, it is necessary to establish which (scalar) objective kinetic, kinematic, and performance measures are most associated with lower-extremity injury.

Methods

Online searches of MEDLINE, SCOPUS, EBSCOHost, SPORTDiscus and PubMed databases were completed for all articles published before March 2020 in accordance with PRISMA guidelines.

Results

40 articles investigating nine jump-landing assessments were included in this review. The 79% of studies using drop jump (n = 14) observed an association with future injury, while only 8% of countermovement jump studies (n = 13) observed an association with injury risk. The 57% of studies using unilateral assessments found associations with risk of injury (n = 14). Studies using performance measures (jump height/distance) as outcome measure were only associated with injury risk in 30% of cases. However, those using kinetic and/or kinematic analyses (knee abduction moment, knee valgus angle, knee separation distance, peak ground reaction force) found associations with injury in 89% of studies.

Conclusion

The landing element of jump-landing assessments appears to be superior for identifying individuals at greater risk of injury; likely due to a closer representation of the injury mechanism. Consequently, jump-landing assessments that involve attenuation of impact forces such as the drop jump appear most suited for this purpose but should involve assessment of frontal plane knee motion and ground reaction forces.

Hamstring muscle injury in the athlete: state of the art

Hamstring injuries (HSI) are the source of significant impairment and disability for both professional and recreational athletes. The incidence and prevalence of HSIs has been well documented in the literature, as they are among the most common soft tissue injuries reported. The significant time loss due to injury and the inherent risk of reinjury pose a significant issue to the athlete, their career longevity and the success of their respective team. This review will deal predominantly with describing the prevalence and incidence of HSI in athletes, discuss risk factors and the mechanisms of injury for HSI, how to properly diagnose, image and prognosticate appropriate return to sport (RTS) for individuals who have sustained an HSI, prescribe treatment and prevention strategies and to discuss relevant options to decrease overall risk of primary and secondary recurrence of HSI.Current treatments of acute HSI necessitate a thorough understanding of the mechanism of injury, identifying muscle imbalances and/or weakness, inclusion of eccentric and concentric hamstring (HS) and hip extension (HE) exercises, evaluation of pathokinematic movement patterns and use non-surgical methods to promote healing and RTS. This methodology can be used prospectively to mitigate the overall risk of HSI. Injection therapies for HSI, including ultrasound-guided platelet-rich plasma and corticosteroids, may impart some short-term benefit, but the existing literature is largely inconclusive with respect to long-term functional outcomes. Future directions should prioritise injury prevention, early diagnosis and targeted interventions that combine both non-surgical and minimally invasive orthobiological approaches and identifying biomechanical risk factors prospectively to mitigate risk.

UEFA expert group statement on nutrition in elite football. Current evidence to inform practical recommendations and guide future research

Football is a global game which is constantly evolving, showing substantial increases in physical and technical demands. Nutrition plays a valuable integrated role in optimising performance of elite players during training and match-play, and maintaining their overall health throughout the season. An evidence-based approach to nutrition emphasising, a 'food first' philosophy (ie, food over supplements), is fundamental to ensure effective player support. This requires relevant scientific evidence to be applied according to the constraints of what is practical and feasible in the football setting. The science underpinning sports nutrition is evolving fast, and practitioners must be alert to new developments. In response to these developments, the Union of European Football Associations (UEFA) has gathered experts in applied sports nutrition research as well as practitioners working with elite football clubs and national associations/federations to issue an expert statement on a range of topics relevant to elite football nutrition: (1) match day nutrition, (2) training day nutrition, (3) body composition, (4) stressful environments and travel, (5) cultural diversity and dietary considerations, (6) dietary supplements, (7) rehabilitation, (8) referees and (9) junior high-level players. The expert group provide a narrative synthesis of the scientific background relating to these topics based on their knowledge and experience of the scientific research literature, as well as practical experience of applying knowledge within an elite sports setting. Our intention is to provide readers with content to help drive their own practical recommendations. In addition, to provide guidance to applied researchers where to focus future efforts.

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

Aims

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

Methods

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

Results

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

Conclusion

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

Is It High Time to Increase Elite Soccer Substitutions Permanently?

Rules determine how team sport matches occur. Match-induced fatigue is specific to each sport, and may be associated with injury incidence. For example, the injury rate in soccer is distinctly higher during matches than in training sessions. Understanding the differences between team sports rules might be useful for enhancing rules (e.g., safer sport). Therefore, this study aimed to evaluate the impact of the rule-induced physical demands between soccer, futsal, basketball, and handball, focusing on substitution rules. Data from the elite team sports' rules (e.g., absolute and relative court dimensions; the number of players, substitutions allowed, total game time, time-outs) were collected, including the changes due to the coronavirus disease (COVID-19) pandemic in soccer substitutions, and comparisons were performed. The data showed that soccer has higher rule-induced physical demands: e.g., substantially lower substitution rate, higher dimensions in absolute (eight to fifteen times), and relative (four to eight times) values. Simulations also showed that soccer has extremely large differences, even considering COVID-19 substitution changes (from three to up to five). We conclude that elite soccer has remarkably higher overall rule-induced physical demands than elite futsal, basketball and handball, and increasing soccer substitutions permanently (e.g., unlimited) might mitigate overall soccer demands.

TEAM to Defeat COVID-19: A Management Strategy Plan to Address Return to Play in Sports Medicine

A new viral disease named COVID-19 spread rapidly into a pandemic in early 2020. Most countries have active community transmission and imposed measures such as social distancing and travel restrictions to mitigate its effect. Many sporting events all over the globe were canceled or postponed. In this article, we briefly discuss some important topics regarding the COVID-19 pandemic and propose a strategy to manage return to play in professional athletes. We searched the PubMed and Google Scholar databases to identify articles published through May 12, 2020, using the following keywords: "coronavirus," "COVID-19," "SARS-CoV-2," "athlete," and "return to play." Although athletes have a lower risk of severe disease, preventive measures are still very important for minimizing time away from training, avoiding potential complications, slowing the pandemic spread, and ultimately protecting the health of those with a higher risk of complications and death. Athletes may present with mild disease, but complications such as pulmonary fibrosis and myocardial injuries have to be considered. Although still controversial, athletes should be evaluated before return to play and monitored accordingly afterward via proper clinical assessments and testing.

Fifteen-week window for recurrent muscle strains in football: a prospective cohort of 3600 muscle strains over 23 years in professional Australian rules football

OBJECTIVES

To determine the rates of muscle strain injury recurrence over time after return to play in Australian football and to quantify risk factors.

METHODS

We analysed Australian Football League player data from 1992 to 2014 for rates of the four major muscle strain injury types (hamstring, quadriceps, calf and groin) diagnosed by team health professionals. Covariates for analysis were: recent history (≤8 weeks) of each of the four muscle strains; non-recent history (>8 weeks) of each; history of hip, knee anterior cruciate ligament, knee cartilage, ankle sprain, concussion or lumbar injury; age; indigenous race; match level and whether a substitute rule was in place.

RESULTS

3647 (1932 hamstring, 418 quadriceps, 458 calf and 839 groin) muscle strain injuries occurred in 272 759 player matches. For all muscle strains combined, the risk of injury recurrence gradually reduced, with recurrence risks of 9% (hamstring), 5% (quadriceps), 2% (calf) and 6% (groin) in the first match back and remaining elevated for 15 weeks after return to play. The strongest risk factor for each muscle injury type was a recent history of the same injury (hamstring: adjusted OR 13.1, 95% CI 11.5 to 14.9; calf OR 13.3, 95% CI 9.6 to 18.4; quadriceps: OR 25.2, 95% CI 18.8 to 33.8; groin OR 20.6, 95% CI 17.0 to 25.0), followed by non-recent history of the same injury (hamstring: adjusted OR 3.5, 95% CI 3.2 to 3.9; calf OR 4.4, 95% CI 3.6 to 5.4; quadriceps OR 5.2, 95% CI 4.2 to 6.4; groin OR 3.5, 95% CI 3.0 to 4.0). Age was an independent risk factor for calf muscle strains (adjusted OR 1.6, 95% CI 1.3 to 2.0). Recent hamstring injury increased the risk of subsequent quadriceps (adjusted OR 1.8, 95% CI 1.2 to 2.7) and calf strains (OR 1.8, 95% CI 1.2 to 2.6). During the 'substitute rule' era (2011-2014), hamstring (adjusted OR 0.76, 95% CI 0.67 to 0.86), groin (OR 0.78, 95% CI 0.65 to 0.93) and quadriceps (OR 0.70, 95% CI 0.53 to 0.92) strains were less likely than outside of that era but calf (OR 1.6, 95% CI 1.3 to 1.9) strains were more likely than before the substitute rule era.

CONCLUSION

Recent injury is the greatest risk factor for the four major muscle strains, with increased risk persisting for 15 weeks after return to play.

Evaluation of Muscle Injuries in Professional Football Players: Does Coach Replacement Affect the Injury Rate?

OBJECTIVES

To assess the incidence and characteristics of muscle injuries in professional football players and to assess if coach dismissal may be related with muscle injuries within 1-month period from the dismissal.

DESIGN

Prospective cohort study during 3 consecutive seasons.

SETTING

Turkish Super League football teams.

PARTICIPANTS

One hundred eighteen male football players.

MAIN OUTCOME MEASURES

Data on time-loss muscle injuries confirmed using magnetic resonance imaging were recorded, including type, body part, duration, and lay-off time, and training session and match exposure times. The muscle injury rate was evaluated at 2 weeks and 30 days after coach dismissal.

RESULTS

In total, 124 muscle injuries were recorded, with injury incidences of 2.3 muscle injuries per 1000 hours of exposure overall, 1.2 in training sessions, and 13.6 in matches. Injury time loss ranged from 3 to 67 days (median, 13 days). Eighteen percent of the injuries (n = 23) were recurrent; no association was found between recurrence rate and the player's age or position (P = 0.15, P = 0.27, respectively). Recurrent injuries caused more severe injuries (26.1%, P = 0.02) and longer median lay-off time (P = 0.01). During the study, teams A and B replaced 7 and 3 coaches, respectively. The injury incidence increased to 5.3 per 1000 hours of exposure in the 2 weeks after the coach dismissal, and decreased to 4.5 within 1 month of coach dismissal.

CONCLUSION

Given the link between coach dismissal and increased rates of muscle strain injuries, increased attentiveness to preventing muscle injuries during coaching transitions and to the impact of new training regimens is required by trainers and medical teams.

The Effect of Thursday Night Games on In-Game Injury Rates in the National Football League

BACKGROUND

Although claims of increased injury rates with Thursday night National Football League (NFL) games exist, a paucity of data exist substantiating these claims.

PURPOSE

To evaluate the effect of rest between games on in-game injury rates as it pertains to overall injury incidence, location, and player position.

STUDY DESIGN

Descriptive epidemiologic study.

METHODS

Data were obtained from official NFL game books for regular season games from all 32 teams for the 2013-2016 seasons. All in-game injuries recorded in official game books were included. Rest periods between games were classified as short (4 days), regular (6-8 days), or long (≥10 days). Overall observed injury rates per team-game were analyzed in relation to different rest periods using negative binomial regression. For results with significant overall findings, pairwise comparisons were tested using the Wald chi-square test. Exploratory secondary analyses were performed in a similar fashion to assess differences in injury rates for the different rest periods when stratified by anatomic location and player position.

RESULTS

A total of 2846 injuries were identified throughout the 4 seasons. There was an overall significant difference in injuries per team-game between short, regular, and long rest (P = .01). With short rest, an observed mean of 1.26 injuries per game (95% CI, 1.06-1.49) was significantly different from the 1.53 observed injuries per game with regular rest (95% CI, 1.46-1.60; P = .03), but not compared with the 1.34 observed injuries per game with long rest (P = .56). For player position, only the tight end, linebacker, and fullback group demonstrated significant differences between the injury rates for different rest categories. Quarterback was the only position with more injuries during games played on Thursday compared with both regular and long rest. This specific analysis was underpowered and the difference was not significant (P = .08). No differences were found regarding injury rates in correlation with differences in rest periods with different injury locations.

CONCLUSION

A short rest period between games is not associated with increased rates of observed injuries reported in NFL game books; rather, our data suggest there are significantly fewer injuries for Thursday night games compared with games played on regular rest. Future research correlating rest and quarterback injury rates is warranted.

Epidemiology of injuries in professional football: a systematic review and meta-analysis

OBJECTIVE

We performed a systematic review and meta-analysis of epidemiological data of injuries in professional male football.

METHOD

Forty-four studies have reported the incidence of injuries in football. Two reviewers independently extracted data and assessed trial quality using the Strengthening the Reporting of Observational Studies in Epidemiology statement and Newcastle Ottawa Scale. Studies were combined in a pooled analysis using a Poisson random effects regression model.

RESULTS

The overall incidence of injuries in professional male football players was 8.1 injuries/1000 hours of exposure. Match injury incidence (36 injuries/1000 hours of exposure) was almost 10 times higher than training injury incidence rate (3.7 injuries/1000 hours of exposure). Lower extremity injuries had the highest incidence rates (6.8 injuries/1000 hours of exposure). The most common types of injuries were muscle/tendon (4.6 injuries/1000 hours of exposure), which were frequently associated with traumatic incidents. Minor injuries (1-3 days of time loss) were the most common. The incidence rate of injuries in the top 5 European professional leagues was not different to that of the professional leagues in other countries (6.8 vs 7.6 injuries/1000 hours of exposure, respectively).

CONCLUSIONS

Professional male football players have a substantial risk of sustaining injuries, especially during matches.

Hamstring Injuries Prevention in Soccer: A Narrative Review of Current Literature

Hamstring injuries and reinjuries are one of the most important sport lesions in several sport activities including soccer, Australian football, track and field, rugby, and in general in all sport activities requiring sprinting and acceleration. However, it is important to distinguish between the lesions of the biceps femoris and semitendinosus and semimembranosus. Indeed, three muscles representing the hamstring complex have a very different injury etiology and consequently require different prevention strategies. This fact may explain, at least in part, the high incidence of reinjuries. In soccer, hamstring injuries cause an important rate of time loss (i.e., in average 15–21 matches missed per club per season). The hamstring injury risk factors may be subdivided in three categories: “primary injury risk factors” (i.e., the risk factors mainly causing a first lesion), “recurrent injury risk factors” (i.e., the risk that can cause a reinjury), and bivalent injury risk factors” (i.e., the risk factors that can cause both primary injuries and reinjuries). The high incidence of hamstring lesions caused consequently an important increase in hamstring injury research. However, although the prevention has increased paradoxically, epidemiological data do not show a loss in injuries and/or reinjuries but, on the contrary, they show an increase in hamstring injuries. This apparent paradox highlights the importance both of the improvement in the prevention programs quality and the criteria for return to play after hamstring injury.

Recalibrating the risk of hamstring strain injury (HSI): A 2020 systematic review and meta-analysis of risk factors for index and recurrent hamstring strain injury in sport

OBJECTIVE

To systematically review risk factors for hamstring strain injury (HSI).

DESIGN

Systematic review update.

DATA SOURCES

Database searches: (1) inception to 2011 (original), and (2) 2011 to December 2018 (update). Citation tracking, manual reference and ahead of press searches.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies presenting prospective data evaluating factors associated with the risk of index and/or recurrent HSI.

METHOD

Search result screening and risk of bias assessment. A best evidence synthesis for each factor and meta-analysis, where possible, to determine the association with risk of HSI.

RESULTS

The 78 studies captured 8,319 total HSIs, including 967 recurrences, in 71,324 athletes. Older age (standardised mean difference=1.6, p=0.002), any history of HSI (risk ratio (RR)=2.7, p<0.001), a recent HSI (RR=4.8, p<0.001), previous anterior cruciate ligament (ACL) injury (RR=1.7, p=0.002) and previous calf strain injury (RR=1.5, p<0.001) were significant risk factors for HSI. From the best evidence synthesis, factors relating to sports performance and match play, running and hamstring strength were most consistently associated with HSI risk. The risk of recurrent HSI is best evaluated using clinical data and not the MRI characteristics of the index injury.

SUMMARY/CONCLUSION

Older age and a history of HSI are the strongest risk factors for HSI. Future research may be directed towards exploring the interaction of risk factors and how these relationships fluctuate over time given the occurrence of index and recurrent HSI in sport is multifactorial.

Understanding the presence of mental fatigue in English academy soccer players

Research has demonstrated that induced mental fatigue impairs soccer-specific technical, tactical and physical performance in soccer players. The findings are limited by the lack of elite players and low ecological validity of the tasks used to induce mental fatigue, which do not resemble the cognitive demands of soccer. The current study collected survey data from English academy soccer players (n = 256; age groups - U14 - U23), with questions comprising of five themes (descriptors of physical and mental fatigue, travel, education, match-play and fixture congestion). The survey consisted of multiple choice responses, checkboxes and blinded/unblinded (for duration based questions) 0-100 arbitrary unit (AU) slider scales. Listening to music (81.6% of players), using social media (58.3%) and watching videos (34.3%) were the most common pre-match activities. Pre-match subjective mental fatigue was low (18.7±18.8 AU), and most frequently reported at the end of a match (47±26 AU) and remained elevated 24-hours post-match (36±27 AU). Travel (29±24 AU), fixture congestion (44±25 AU) and education (30±26 AU) demonstrated a low to moderate presence of subjective mental fatigue. These findings provide an overview of activities performed by English academy soccer players pre-match, and demonstrate that mental fatigue is experienced as a result of match-play.

Are Elite Soccer Teams' Preseason Training Sessions Associated With Fewer In-Season Injuries? A 15-Year Analysis From the Union of European Football Associations (UEFA) Elite Club Injury Study

BACKGROUND

Preseason training develops players' physical capacities and prepares them for the demands of the competitive season. In rugby, Australian football, and American football, preseason training may protect elite players against in-season injury. However, no study has evaluated this relationship at the team level in elite soccer.

PURPOSE/HYPOTHESIS

The aim of this study was to investigate whether the number of preseason training sessions completed by elite soccer teams was associated with team injury rates and player availability during the competitive season. It was hypothesized that elite soccer teams who participate in more preseason training will sustain fewer injuries during the competitive season.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

We used the Union of European Football Associations (UEFA) injury dataset to analyze 44 teams for up to 15 seasons (total, 244 team-seasons). Separate linear regression models examined the association between the number of team preseason training sessions and 5 in-season injury measures. Injury-related problems per team were quantified by totals of the following: (1) injury burden, (2) severe injury incidence, (3) training attendance, (4) match availability, and (5) injury incidence.

RESULTS

Teams averaged 30 preseason training sessions (range, 10-51). A greater number of preseason training sessions was associated with less injury load during the competitive season in 4 out of 5 injury-related measures. Our linear regression models revealed that for every 10 additional preseason training sessions that the team performed, the in-season injury burden was 22 layoff days lower per 1000 hours (P = .002), the severe injury incidence was 0.18 severe injuries lower per 1000 hours (P = .015), the training attendance was 1.4 percentage points greater (P = .014), and the match availability was 1.0 percentage points greater (P = .042). As model fits were relatively low (adjusted R² = 1.3%-3.2%), several factors that contribute to in-season injury outcomes were unaccounted for.

CONCLUSION

Teams that performed a greater number of preseason training sessions had "healthier" in-season periods. Many other factors also contribute to in-season injury rates. Understanding the benefit of preseason training on in-season injury patterns may inform sport teams' planning and preparation.

Thermal and non-thermal effects off capacitive-resistive electric transfer application on the Achilles tendon and musculotendinous junction of the gastrocnemius muscle: a cadaveric study

Background

Calf muscle strain and Achilles tendon injuries are common in many sports. For the treatment of muscular and tendinous injuries, one of the newer approaches in sports medicine is capacitive-resistive electric transfer therapy. Our objective was to analyze this in vitro, using invasive temperature measurements in cadaveric specimens.

Methods

A cross-sectional study designed with five fresh frozen cadavers (10 legs) were included in this study. Four interventions (capacitive and resistive modes; low- and high-power) was performed for 5 min each by a diathermy “T-Plus” device. Achilles tendon, musculotendinous junction and superficial temperatures were recorded at 1-min intervals and 5 min after treatment.

Results

With the low-power capacitive protocol, at 5 min, there was a 25.21% increase in superficial temperature, a 17.50% increase in Achilles tendon temperature and an 11.27% increase in musculotendinous junction temperature, with a current flow of 0.039 A ± 0.02.

With the low-power resistive protocol, there was a 1.14% increase in superficial temperature, a 28.13% increase in Achilles tendon temperature and an 11.67% increase in musculotendinous junction temperature at 5 min, with a current flow of 0.063 A ± 0.02. With the high-power capacitive protocol there was an 88.52% increase in superficial temperature, a 53.35% increase in Achilles tendon temperature and a 39.30% increase in musculotendinous junction temperature at 5 min, with a current flow of 0.095 A ± 0.03. With the high-power resistive protocol, there was a 21.34% increase in superficial temperature, a 109.70% increase in Achilles tendon temperature and an 81.49% increase in musculotendinous junction temperature at 5 min, with a current flow of 0.120 A ± 0.03.

Conclusion

The low-power protocols resulted in only a very slight thermal effect at the Achilles tendon and musculotendinous junction, but current flow was observed. The high-power protocols resulted in a greater temperature increase at the Achilles tendon and musculotendinous junction and a greater current flow than the low-power protocols. The high-power resistive protocol gave the greatest increase in Achilles tendon and musculotendinous junction temperature. Capacitive treatments (low- and high-power) achieved a greater increase in superficial temperature.

Effects of phonophoresis with diclofenac linked gold nanoparticles in model of traumatic muscle injury

The use of nanotechnology for administering drugs is a recent development that presents promising results. Therapeutic Pulsed Ultrasound (TPU) is one such therapeutic option and is widely used for treating soft tissue lesions. Thus, the objective of this study was to investigate the therapeutic effect of phonophoresis using diclofenac (DC) linked to gold nanoparticles (GNPs) in the skeletal muscle of rats used as a model of traumatic muscular injury. Wistar rats were divided into eight groups (N = 10): Sham, Muscle injury (MI), MI + TPU, MI + DC, MI + GNPs, MI + TPU + DC, MI + TPU + GNPs, and MI + TPU + DC-GNPs. The traumatic injury was performed in the gastrocnemius with a single direct traumatic impact via an injuring press. The animals received daily treatment for 5 consecutive days with TPU and gel with DC and/or GNPs. Two hours after the last treatment session, animals were euthanized and the gastrocnemius muscle surgically removed for histological and biochemical analysis. The groups exposed to some therapies (MI + TPU + DC, MI + TPU + GNPs and MI + TPU + DC-GNPs) showed reduced levels of pro-inflammatory cytokines, whereas an increase in anti-inflammatory cytokine levels was observed in the group exposed to all therapies combined (MI + TPU + DC-GNPs). Reactive species production and protein damage resulting from oxidative damage was lower for the group exposed to all tested therapies had lower production. Lower protein damage was also observed in the TPU + GNPs group. The group that underwent all tested therapies combined showed a significant increase in antioxidants compared to the MI group. During histological analysis, the MI group showed large amounts of cell infiltration and centralized nuclei, whereas the MI + TPU + DC-GNPs group showed structural improvements. Pain levels in the MI + TPU + DC-GNPs group were lower than those of the MI group. We believe that the association of TPU with DC linked to GNPs decreases the inflammation caused by traumatic muscle injury and accelerates tissue repair.

A prospective study of health problems at the 2018 17/U and 19/U Australian National Netball Championships with comparison of surveillance methodology

OBJECTIVE

To investigate the incidence, site, nature and cause of injuries sustained during and four weeks following the 2018 Australian National Netball Championships (ANNC's) using medical attention and self-report surveillance tools.

DESIGN

Prospective cohort study.

METHOD

Injuries were recorded prospectively using medical attention and self-report data collection methods. One hundred and ninety-two athletes competed at the 2018 ANNC's with 96 athletes in each age group (17/U & 19/U).

RESULTS

There were 103 medical attention injuries sustained by 80 athletes resulting in an incidence rate of 89.4 per 1000 player hours. The most frequently recorded medical attention injury diagnoses across both age groups were lateral ankle ligament sprain (n=14, 13.6%), foot blisters (n=11, 10.7%), and lumbar pain (n=10, 9.7%). Ankle sprains (n=4), anterior cruciate ligament (ACL) ruptures (n=3) and concussion (n=3) recorded as the highest sports incapacity injuries. The self-report data collection revealed that 46 (27.2%) athletes arrived at the tournament with an existing self-reported injury/illness and 57 (39.3%) athletes had a self-reported injury/illness at the conclusion of the ANNC (RR 1.44 95%CI 1.05-1.99, p=0.030).

CONCLUSION

There are no recent studies reporting injury rates specifically in pre-elite netball players. This study found an incidence rate of 89.4 per 1000 player hours. Ankle sprains are the highest medical attention and sports-incapacity injury in pre-elite netball athletes. Foot blisters and low back pain also feature in the highest medical attention injuries and ACL rupture and concussion were high sports incapacity injuries at the ANNC's. Finally, combining both the medical attention and self-report injury/illness data collection methods identified more injuries/illnesses than the use of one method alone.

Italian consensus statement (2020) on return to play after lower limb muscle injury in football (soccer)

Return to play (RTP) decisions in football are currently based on expert opinion. No consensus guideline has been published to demonstrate an evidence-based decision-making process in football (soccer). Our aim was to provide a framework for evidence-based decision-making in RTP following lower limb muscle injuries sustained in football. A 1-day consensus meeting was held in Milan, on 31 August 2018, involving 66 national and international experts from various academic backgrounds. A narrative review of the current evidence for RTP decision-making in football was provided to delegates. Assembled experts came to a consensus on the best practice for managing RTP following lower limb muscle injuries via the Delphi process. Consensus was reached on (1) the definitions of 'return to training' and 'return to play' in football. We agreed on 'return to training' and RTP in football, the appropriate use of clinical and imaging assessments, and laboratory and field tests for return to training following lower limb muscle injury, and identified objective criteria for RTP based on global positioning system technology. Level of evidence IV, grade of recommendation D.

Quantifying Collective Performance in Rugby Union

Objectives: The aim of this study was to quantify collective experience based on cumulative shared selections of players and to assess its impact on team performance in international rugby union. We assume that the greater the experience, the better the group will perform. Methods: Scoresheets of all games involving at least one of all 10 nations participating at the Rugby Championship and the Six Nations Championship were collected from the end of the 1999 Rugby World Cup (RWC) up to the 2015 RWC. A single indicator quantifying the cumulative shared selections (CSS, the number of selections that each player has shared with the other ones) was computed for each match as a key collective experience indicator. The World Rugby Ranking points of each nation and the percentage of victories were used to estimate team performance. The study period was divided into sequences of 4 years corresponding to the period between two consecutive RWCs. For each sequence and nation, slopes and intercept of CSS trends were computed along with victory percentage and mean ranking points. Multiple linear regression analysis was used to establish the associations between team performance and experience. Results: In regards to the CSS trends, both intra- and inter-nation variability appears to exist. Positive and negative slopes can be observed for the same team from one 4-year cycle to the next. Still, CSS slope is found to be significantly associated with both ranking points (p value = 0.042, R ² = 0.13) and victory percentage (p value = 0.001, R ² = 0.42). Conclusion: The evolution of the CSS that quantifies the collective experience of a team is linked to its performance. Such an indicator could be helpful in the decision-making process of national coaching staff.

Effect of poor cooperation between coaching and medical staff on muscle re-injury in professional football over 15 seasons

Background

Muscle injury is the most common type of injury in football. Previous research has focused on traditional risk factors (eg, age, injury history, muscle imbalance/inflexibility) contributing to muscle re-injury. The effect of poor cooperation between the coaching and medical teams on the risk of re-injury remains unexplored in the sports medicine football literature.

Purpose

Examine the effect of poor cooperation between coaching and medical teams on muscle re-injury in professional football.

Methods

Retrospective review of the medical files of 97 footballers of a professional team in Dubai over 15 consecutive seasons (2002–2017). Medical team recorded all injuries in each player’s file. Data on the perceived level of cooperation between coaching and medical teams were available in the daily meeting notes from the head of the medical team. The level of perceived cooperation was ranked on a three-point Likert scale by the head of the medical team and depended on whether the coaching team accepted the player injury (excellent cooperation), brought some suggestion after discussion with the medical team (normal cooperation) or rejected it (poor cooperation).

Results

In total, 338 indirect muscle injuries (21 re-injuries) were recorded during 15 consecutive seasons., There was a significant increase in the mean number of total injuries (mean ± SE, 95% CI; 16±2, 12–21; P<0.0001), mean number of indirect muscle injuries (12±1, 95% CI 10–14; P<0.0001), and indirect muscle re-injuries (4±1, 95% CI 3–5; P<0.0001) during seasons with a poor perceived level of cooperation compared to seasons with a normal/excellent perceived level of cooperation.

Conclusion

Findings suggest that poor cooperation between coaching and medical teams may increase the risk of muscle re-injury in professional football. Future studies conducted in different clubs, leagues, countries, and even sports are required to further explore the effect of cooperation between coaching and medical teams on the risk of re-injury.