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

The inclusion of vibration therapy in rehabilitating a gastrocnemius tear: a case study in master athlete

[Purpose] The aim of this case study was to determine if VT could be included into a rehabilitation programme by monitoring the progress of muscle pain, range of motion and muscle strength. [Participant and Methods] An international male master hockey player sustained a medial gastrocnemius 5 cm tear prior to the World Cup. VT was applied early in the rehabilitation programme where 9 sessions of VT were performed during the first 16 days. Other conventional rehabilitative exercises were included. [Results] Twenty-eight days post-injury the athlete returned to full playing. Calf pain had subsided by day 8 with a change of 12° in ankle dorsi flexion range of motion. Grade 5 calf strength was attained by day 16, which was equivalent to the unaffected limb’s strength. There were no residual side effects of including VT into the rehabilitation programme and it did not compromise the athlete’s recovery. [Conclusion] To ensure optimal loading of VT, 9 sessions were implemented and progressively increased; consequently, there was no detrimental effect on the rehabilitative process. The athlete reported no side effects of using VT and its ease and time efficient application has a role to complementing soft tissue injury rehabilitation.

Prospective Evaluation of Injuries occurred during the Brazilian Soccer Championship in 2016

Objective  To identify the incidence, the prevalence, the characteristics, and the possible risk factors for injuries occurring during the matches of the Brazilian Soccer Championship.

Methods  A prospective study was carried out to collect data on the injuries that occurred during the 2016 Brazilian Soccer Championship. Lesions were recorded by the physician responsible for each team through an online software.

Results  Among the 864 athletes included in the study, 231 (26.7%) of the players presented some injury during the tournament. In total, 312 injuries were recorded during the Brazilian Soccer Championship, with an average of 0.82 injuries per game. The incidence of injuries was 24.9 injuries per 1,000 match hours. Midfielders and forwards presented, respectively, an injury risk 3.6 and 2.4 times higher than goalkeepers.

Conclusion  The prevalence and incidence of lesions were, respectively, 26.7% and 24.9 injuries per 1,000 match hours. The most frequently affected body segment was the lower limbs (76.3%), and the athletes acting in midfield and forward positions were the most affected. Moreover, the greater prevalence of injuries occurred in the first part of the championship.

Circulating, Cell-Free DNA for Monitoring Player Load in Professional Football

Purpose: Player monitoring in elite sport settings is becoming increasingly important. Questionnaire-based methods and biomarkers such as circulating, cell-free DNA (cfDNA) are suggested for load monitoring. cfDNA concentrations were shown to increase depending on total distance covered in football and were associated with overtraining in weight lifters. Thus, the objective of this study was to examine whether cfDNA is feasible as a monitoring tool in elite football players. Methods: Capillary blood samples from 22 male elite football players were collected over 4 mo of a regular season. Sampling was conducted the day before, 1 day after, or several days after regular-season games and/or training. In addition, each player filled in a visual analogue scale (VAS) questionnaire including the items "general perceived exertion," "muscular fatigue," and "mental fatigue." Performance during training and games was tracked by the Catapult system and with the OPTA system, respectively. Results: cfDNA values were significantly elevated in players the day after regular-season games (1.4-fold; P = .0004) in line with the scores of the VAS. Both parameters showed significantly higher values during midweek-game weeks. cfDNA concentrations correlated with training data, and VAS was correlated with the tracking of the season games. However, cfDNA and VAS did not correlate with each other. Conclusions: cfDNA concentrations at rest and VAS scores are influenced by previous load in professional football players. Future studies will reveal whether cfDNA might serve as a practically applicable marker for player load in football players.

A comparison of the isometric force fatigue-recovery profile in two posterior chain lower limb tests following simulated soccer competition

Aim

To evaluate the reliability of isometric peak force (IPF) in a novel “long-length” 90°Hip:20°Knee (90:20) strength test and to compare the simulated soccer match induced fatigue-recovery profile of IPF in this test with that of an isometric 90°Hip:90°Knee (90:90) position test.

Methods

Twenty semi-professional soccer players volunteered for the study of which 14 participated in the first part of the study which assessed 90:20 reliability (age = 21.3 ± 2.5 years, height = 1.79 ± 0.07 m, body mass = 73.2 ± 8.8 kg), while 17 completed the second part of the study evaluating fatigue-recovery (age 21.2±2.4 yrs., height = 180 ± 0.09 m, body mass 73.8 ± 8.9 kg). We evaluated the inter-session reliability of IPF in two 90:20 test protocols (hands on the wall (HW); and hands on chest (HC)) both performed on two occasions, 7 days apart. We then assessed 90:20 (HC) and 90:90 IPF immediately before (PRE) and after (POST) after a simulated soccer match protocol (BEAST90mod) and 48 (+48 h) and 72 hours (+72 h) later.

Results

Part one: the 90:20 showed moderate to high overall reliability (CV’s of 7.3% to 11.0%) across test positions and limbs. CV’s were lower in the HW than HC in the dominant (7.3% vs 11.0%) but the opposite happened in the non-dominant limb where CV’s were higher in the HW than HC (9.7% vs 7.3%). Based on these results, the HC position was used in part two of the study. Part two: 90:20 and 90:90 IPF was significantly lower POST compared to PRE BEAST90mod across all testing positions (p<0.001). IPF was significantly lower at +48 h compared to PRE in the 90:20 in both limbs (Dominant: p<0.01,Non-dominant: p≤0.05), but not in the 90:90. At +72 h, IPF was not significantly different from PRE in either test.

Conclusions

Simple to implement posterior IPF tests can help to define recovery from competition and training load in football and, potentially, in other multiple sprint athletes. Testing posterior chain IPF in a more knee extended 90:20 position may provide greater sensitivity to fatigue at 48 h post simulated competition than testing in the 90:90 position, but also may require greater degree of familiarization due to more functional testing position.

Australian Football League Injury Characteristics Differ Between Matches and Training: A Longitudinal Analysis of Changes in the Setting, Site, and Time Span From 1997 to 2016

Background:

Injury surveillance has been used to quantify the scope of the injury burden in Australian football. However, deeper statistical analyses are required to identify major factors that contribute to the injury risk and to understand how these injury patterns change over time.

Purpose:

To compare Australian Football League (AFL) injury incidence, severity, prevalence, and recurrence by setting, site, and time span from 1997 to 2016.

Study Design:

Descriptive epidemiology study.

Methods:

A total of 15,911 injuries and medical illnesses recorded by team medical staff at each club were obtained from the AFL’s injury surveillance system and analyzed using linear mixed models with 3 fixed effects (setting, time span, site) and 1 random effect (club). All types of injuries and medical illnesses were included for analysis, provided that they caused the player to miss at least 1 match during the regular season or finals. Five-season time spans (1997-2001, 2002-2006, 2007-2011, and 2012-2016) were used for comparisons. Incidence rates were expressed at the player level. Recurrences were recoded to quantify recurrent injuries across multiple seasons.

Results:

Compared with training injuries, match injuries had a 2.8 times higher incidence per season per club per player (matches: 0.070 ± 0.093; training: 0.025 ± 0.043; P < .001). Match injuries resulted in 1.9 times more missed matches per club per season (matches: 17.2 ± 17.0; training: 9.1 ± 10.5; P < .001). and were more likely to be recurrences (matches: 11.6% ± 20.0%; training: 8.6% ± 21.8%; P < .001). From the 1997-2001 to 2007-2011 time spans, overall injury severity increased from a mean of 3.2 to 3.7 missed matches (P ≤ .01). For the most recent 2012-2016 time span, injuries resulted in 3.6 missed matches, on average. Hip/groin/thigh injuries had the highest incidence (0.125 ± 0.120) and prevalence (19.2 ± 16.4) rates, and recurrences (29.3% ± 27.9%) were 15% more likely at this site than any other injury site.

Conclusion:

The risks of match injuries are significantly higher than those of training injuries in the AFL. Compared with the 1997-2001 time span, injuries became more severe during the 2007-2011 time span.

Injury incidence in semi-professional football claims for increased need of injury prevention in elite junior football

PURPOSE

Injuries are a common occurrence in football. Sufficient epidemiological data are available in professional football but not in salaried semi-professional football. This study investigates the injury incidence at different levels of semi-professional football with focus on junior football.

METHODS

The data were based on injury reports provided by players and medical staff over the 2015-2016 season, which corresponded to the consensus statement for data samples in football. This study investigated the injury incidence and prevalence of five skill levels of semi-professional football (the fourth to the seventh league and elite junior football).

RESULTS

1130 players had sustained 2630 injuries over the 2015-2016 season. The overall injury incidence was 9.7 per 1000 h football exposure; prevalence with at least one injury was 79%. The highest overall injury incidence in elite junior football was 10.4 in 1000 h football exposure. The fifth league had the lowest incidence with 9.0 in 1000 h football (p < 0.05). Traumatic injuries most often occurred in the fourth league (3.9 in 1000 h football). The body areas most affected by traumatic injury were knees, ankles and thighs. Elite junior players had a significantly higher incidence of overuse complaints (7.4 in 1000 h football) than the fourth league (5.4, p = 0.005). The body areas most affected by overuse complaints were the lower back, thigh and groin. No differences were found between the different positions on field.

CONCLUSIONS

Salaried semi-professional football involves a high overall injury incidence. The highest incidence, particularly of overuse injuries, was seen in elite junior football. These findings should be incorporated in specific injury prevention training or screenings beginning in junior football. Level of evidence II.

Monitoring of Post-match Fatigue in Professional Soccer: Welcome to the Real World

Participation in soccer match-play leads to acute and transient subjective, biochemical, metabolic and physical disturbances in players over subsequent hours and days. Inadequate time for rest and regeneration between matches can expose players to the risk of training and competing whilst not entirely recovered. In professional soccer, contemporary competitive schedules can require teams to compete in excess of 60 matches over the course of the season with periods of fixture congestion occurring, prompting much attention from researchers and practitioners to the monitoring of fatigue and readiness to play. A comprehensive body of research has investigated post-match acute and residual fatigue responses. Yet the relevance of the research for professional soccer contexts is debatable, notably in relation to the study populations and designs employed. Monitoring can indeed be invasive, expensive, time inefficient, and difficult to perform routinely and simultaneously in a large squad of regularly competing players. Uncertainty also exists regarding the meaningfulness and interpretation of changes in fatigue response values and their functional relevance, and practical applicability in the field. The real-world need and cost-benefit of monitoring must be carefully weighed up. In relation to professional soccer contexts, this opinion paper intends to (1) debate the need for post-match fatigue monitoring; (2) critique the real-world relevance of the current research literature; (3) discuss the practical burden relating to measurement tools and protocols, and the collection, interpretation and application of data in the field; and (4) propose future research perspectives.

Injury prevalence and risk factors in a Greek team's professional football (soccer) players: a three consecutive seasons survey

This study investigated the prevalence and risk factors of injuries on a cohort of 123 Greek team's professional football players during three consecutive seasons, 2015/16-to-2017/18. Injuries were assessed and regression analysis was used to evaluate the potential risk factors. Three-quarters of the players were recorded as injured with 2.3 injuries/injured player, and the injury incidence was 55 injuries/1,000 match-playing-exposure-hours. The mean rehabilitation days were 29.3/injured player (95%CI 22.4-36.8) and 13.0/injury (95%CI 8.6-17.4). The majority of injured players has been found to have moderate-to-major/severe injuries and most of the injuries were traumatic than overuse (p < 0.05). The number of injuries were related to the recurrence of injury (beta = 0.646, p < 0.001) and the rehabilitations days (beta = 0.271, p < 0.001). High prevalence of injuries was found as the recurrence of injury and rehabilitation days were their main predictive risk factors. In order to reduce the risk of injuries, continuous effort is required in the rehabilitation of players.

Acute and Residual Soccer Match-Related Fatigue: A Systematic Review and Meta-analysis

BACKGROUND

Understanding soccer players' match-related fatigue and recovery profiles likely helps with developing conditioning programs that increase team performance and reduce injuries and illnesses. In order to improve match recovery (the return-to-play process and ergogenic interventions) it is also pivotal to determine if match simulation protocols and actual match-play lead to similar responses.

OBJECTIVES

(1) To thoroughly describe the development of fatigue during actual soccer match play and its recovery time course in terms of physiological, neuromuscular, technical, biochemical and perceptual responses, and (2) to determine similarities of recovery responses between actual competition (11 vs. 11) and match simulations.

METHODS

A first screening phase consisted of a systematic search on PubMed (MEDLINE) and SportDiscus databases until March 2016. Inclusion criteria were: longitudinal study with soccer players; match or validated protocol; duration > 45 min; and published in English.

RESULTS

A total of 77 eligible studies (n = 1105) were used to compute 1196 effect sizes (ES). Half-time assessments revealed small to large alterations in immunological parameters (e.g. leukocytes, ES = 1.9), a moderate decrement in insulin concentration (ES = - 0.9) and a small to moderate impairment in lower-limb muscle function (ES = - 0.5 to - 0.7) and physical performance measures (e.g. linear sprint, ES = - 0.3 to - 1.0). All the systematically analyzed fatigue-related markers were substantially altered at post-match. Hamstrings force production capacity (ES = - 0.7), physical performance (2-4%, ES = 0.3-0.5), creatine kinase (CK, ES = 0.4), well-being (ES = 0.2-0.4) and delayed onset muscle soreness (DOMS, ES = 0.6-1.3) remained substantially impaired at G + 72 h. Compared to simulation protocols, 11 vs. 11 match format (CK, ES = 1.8) induced a greater magnitude of change in muscle damage (i.e. CK, ES = 1.8 vs. 0.7), inflammatory (IL-6, ES = 2.6 vs. 1.1) and immunological markers and DOMS (ES = 1.5 vs. 0.7) than simulation protocols at post-assessments. Neuromuscular performances at post-match did not differ between protocols.

CONCLUSION

While some parameters are fully recovered (e.g. hormonal and technical), our systematic review shows that a period of 72 h post-match play is not long enough to completely restore homeostatic balance (e.g. muscle damage, physical and well-being status). The extent of the recovery period post-soccer game cannot consist of a 'one size fits all approach'. Additionally, the 'real match' (11 vs. 11 format) likely induces greater magnitudes of perceptual (DOMS) and biochemical alterations (e.g. muscle damage), while neuromuscular alterations were essentially similar. Overall, coaches must adjust the structure and content of the training sessions during the 72-h post-match intervention to effectively manage the training load within this time-frame.

Epidemiology of injuries among Italian footballers: the role of the playing field

Background

Football has a higher injury rate compared with other team sports such as rugby, in terms of two main categories: intrinsic (individual) and extrinsic (environmental) factors. The playing field is an extrinsic risk factor which has been poorly investigated in the literature.

Purpose

The aim of our study was to define the incidence and risk factors of injuries in a cohort of footballers comparing the role of three different types of playing field (hard court, natural grass or synthetic grass).

Study design

This was a cross sectional prevalence study.

Methods

The population comprised footballers recruited by a convenience sample; the instrument used for the survey was an anonymous self-administered questionnaire.

Results

267 football players were enrolled (average age 23.4±4.8 years), of whom 33.7% (n=90/267) played on hard court, 33.0% (n=88/267) on natural grass and 33.3% (n=89/267) on synthetic grass. The overall incidence of injury was 40.1 (95% CI 34.1 to 46.8) ×1000 person-years of training, with higher values for ankle and knee injuries. Ankle injuries (aOR 0.4; P=0.021) were associated with playing on natural grass as a protective factor, while playing on natural grass seemed to be a risk factor for muscular injuries (aOR 2.3; P=0.026).

Conclusion

Our study showed a high lifetime prevalence of injury among footballers (57%), in particular among athletes who play and train on a hard court. We have studied a topic poorly investigated previously and provide the opportunity to understand interventions to increase the capacity of stakeholders in preventing injuries.

Injury incidence in elite youth field hockey players at the 2016 European Championships

Despite being an essential consideration when deciding rule changes, injury prevention strategies, and athlete development models, there is little epidemiological data of U18 field hockey player injuries-something explicitly referred to in the 2015 International Olympic Committee's Consensus Statement on Youth Athlete Development. The aim of this study was to quantify incidence and characteristics of injuries in elite youth field hockey players during a major international tournament. Standardized reporting forms detailing time, location on pitch, mechanism and anatomical location of injury were completed for new musculoskeletal conditions resulting in a time stoppage by the umpire and where a player was noticeably affected by an injury for up to 20 s regardless of time stoppage. Injury incidence was 1.35 and 2.20 injuries/match or 53 and 86 injuries per 1000 player match hours for boys (B) and girls (G) respectively; girls were over three times more likely to have a minor injury. Most injuries were contusions due to being hit by the ball or stick (B: 12, G: 27), with high numbers of injuries to the torso (B: 8) and head/face (G: 7). Injuries during the penalty corner (B: 3, G: 4) were to the lower limb and hand, and boys were less likely to wear facial protection (B: 65.9%, G: 86.4%). Results form an essential initial dataset of injuries in U18 field hockey players. Current reporting protocols under-report injuries and must be addressed by the international governing body. The high number of head/face injuries, particularly in females, requires further investigation.

Training Load and Fatigue Marker Associations with Injury and Illness: A Systematic Review of Longitudinal Studies

Background

Coaches, sport scientists, clinicians and medical personnel face a constant challenge to prescribe sufficient training load to produce training adaption while minimising fatigue, performance inhibition and risk of injury/illness.

Objective

The aim of this review was to investigate the relationship between injury and illness and longitudinal training load and fatigue markers in sporting populations.

Methods

Systematic searches of the Web of Science and PubMed online databases to August 2015 were conducted for articles reporting relationships between training load/fatigue measures and injury/illness in athlete populations.

Results

From the initial 5943 articles identified, 2863 duplicates were removed, followed by a further 2833 articles from title and abstract selection. Manual searching of the reference lists of the remaining 247 articles, together with use of the Google Scholar ‘cited by’ tool, yielded 205 extra articles deemed worthy of assessment. Sixty-eight studies were subsequently selected for inclusion in this study, of which 45 investigated injury only, 17 investigated illness only, and 6 investigated both injury and illness. This systematic review highlighted a number of key findings, including disparity within the literature regarding the use of various terminologies such as training load, fatigue, injury and illness. Athletes are at an increased risk of injury/illness at key stages in their training and competition, including periods of training load intensification and periods of accumulated training loads.

Conclusions

Further investigation of individual athlete characteristics is required due to their impact on internal training load and, therefore, susceptibility to injury/illness.

Relationships Between Training Load Indicators and Training Outcomes in Professional Soccer

BACKGROUND

In professional senior soccer, training load monitoring is used to ensure an optimal workload to maximize physical fitness and prevent injury or illness. However, to date, different training load indicators are used without a clear link to training outcomes.

OBJECTIVE

The aim of this systematic review was to identify the state of knowledge with respect to the relationship between training load indicators and training outcomes in terms of physical fitness, injury, and illness.

METHODS

A systematic search was conducted in four electronic databases (CINAHL, PubMed, SPORTDiscus, and Web of Science). Training load was defined as the amount of stress over a minimum of two training sessions or matches, quantified in either external (e.g., duration, distance covered) or internal load (e.g., heart rate [HR]), to obtain a training outcome over time.

RESULTS

A total of 6492 records were retrieved, of which 3304 were duplicates. After screening the titles, abstracts and full texts, we identified 12 full-text articles that matched our inclusion criteria. One of these articles was identified through additional sources. All of these articles used correlations to examine the relationship between load indicators and training outcomes. For pre-season, training time spent at high intensity (i.e., >90 % of maximal HR) was linked to positive changes in aerobic fitness. Exposure time in terms of accumulated training, match or combined training, and match time showed both positive and negative relationships with changes in fitness over a season. Muscular perceived exertion may indicate negative changes in physical fitness. Additionally, it appeared that training at high intensity may involve a higher injury risk. Detailed external load indicators, using electronic performance and tracking systems, are relatively unexamined. In addition, most research focused on the relationship between training load indicators and changes in physical fitness, but less on injury and illness.

CONCLUSION

HR indicators showed relationships with positive changes in physical fitness during pre-season. In addition, exposure time appeared to be related to positive and negative changes in physical fitness. Despite the availability of more detailed training load indicators nowadays, the evidence about the usefulness in relation to training outcomes is rare. Future research should implement continuous monitoring of training load, combined with the individual characteristics, to further examine their relationship with physical fitness, injury, and illness.

A review advocating caution with Major League Soccer expansion and investment in more rehabilitation professionals

BACKGROUND AND PURPOSE

Major League Soccer (MLS) has aggressively expanded from 10 teams to 23 teams. With the addition of more teams, the league will have to dictate a schedule that maximizes the league's popularity, while also maintaining the health of the players. A longer season and congested game schedule could increase the risk of injury for players. The purpose of this commentary is to make recommendations for the prevention of injuries among MLS players with respect to proposed league expansion.

DESCRIPTION OF TOPIC

MLS has lengthened the regular season with each expansion in teams. An increase in season length was seen in conjunction with the MLS expansion from 14 to 19 teams during the 2008 through 2013 seasons. Data from the inaugural MLS season found injury rates were higher in games compared to practices and more injuries occurred later in the season. With the expansion of MLS, anterior cruciate ligament tears appeared to have increased each year.

DISCUSSION

Current evidence suggests the implementation of a proper preseason in addition to the once-per-week game frequency would best promote player health and well-being. Players may benefit from in-season injury prevention training and weekly load monitoring.

Physical performance tests - a relationship of risk factors for muscle injuries in elite level male football players

The purpose of the present study was to investigate whether there is a relationship between the outcome of preseason physical performance tests and the risk of sustaining lower extremity muscle injuries within the same season, in male football players at elite level. This is a cohort study of a male football team (63 players) from the first league in Swe-den. The football players are prospectively followed, in terms of muscle injuries of the lower extremity during five seasons between 2010 and 2014. All muscle injuries were evaluated and diagnosed with ultraso-nography. The following physical performance tests were included: squats, chin-ups, YoYo intermittent recovery level 2, counter movement jump, squat jump, standing long jump, sprint, one leg squat test, and a functional movement screen. A total of 86 muscle injuries occurred during the study period. No significant correlation was found between the results of the physical performance tests and muscle injuries of the lower extremity. None of the evaluated tests predicted the risk of sus-taining muscle injuries of the lower extremity. We conclude that muscle injury risk factors are more complex than solely related to the results of the preseason physical performance tests.

Professional football players at risk for non-acute groin injuries during the first half of the season: A prospective cohort study in The Netherlands

OBJECTIVES

To study the incidence, diagnostics, treatment, anatomical region and return to play of non-acute groin injuries among professional footballers in the Netherlands.

DESIGN

Prospective cohort study.

METHODS

Medical staff members of all Dutch professional football clubs, recording prospectively injury occurrence of all professional footballers in their clubs, were asked to fill in an injury form about time-loss (⩾ 8 days) non-acute groin injury over the 2012-2013 season.

RESULTS

A cohort of 410 players from 12 professional football clubs were included (response rate = 44%). The season incidence of non-acute groin injuries was nearly 7% (29 non-acute groin injuries). In 82% of all cases, the player suffered from non-acute groin injury in the first half of the season. The average time to return to play was 35 days, ranging from 8 to 84 days. The adductors were the most affected anatomical regions (82%), with the most frequent diagnosis being overuse of the adductors (36%), followed by adductor tendinopathy (18%). In addition to medical history and physical examination, ultrasound (50%) and MRI (32%) were the diagnostic methods most frequently mentioned. As well as physical therapy, treatment consisted mostly of manual therapy (96%) and dry needling (61%).

CONCLUSIONS

A professional club with a squad of 25 players can expect on average two non-acute groin injuries per season with an average time-loss of 35 days. Players are more at risk in the first half of the season. In Dutch professional football, ultrasound is commonly used to diagnose non-acute groin injury, while manual therapy is the most commonly applied treatment.

Muscle injury rate in professional football is higher in matches played within 5 days since the previous match: a 14-year prospective study with more than 130 000 match observations

Background

The association between match congestion and injury rates in professional football has yielded conflicting results.

Aim

To analyse associations between match congestion on an individual player level and injury rates during professional football matches.

Methods

Data from a prospective cohort study of professional football with 133 170 match observations were analysed with Poisson regressions. Associations between short-term match congestion, defined as number of days between two match exposures (≤3, 4, 5, 6 and 7–10 days) and injury rates were analysed. To analyse the influence of long-term match congestion, defined as individual match exposure hours in the 30 days preceding a match, observations were categorised into three groups (low, ≤4.5; medium, >4.5 to ≤7.5; and high, >7.5 hours).

Results

No differences in total match injury rates were found between the reference category (≤3 days) and the other categories of short-term congestion. Muscle injury rates were significantly lower in matches preceded by 6 (rate ratio (RR) 0.79; 95% CI 0.65 to 0.95) or 7–10 days (RR 0.81; 95% CI 0.71 to 0.93) compared with ≤3 days since the last match exposure. No differences in total and muscle injury rates between the three long-term match congestion groups were found.

Conclusions

In this study of male professional football players, there were no match congestion-related differences in total match injury rates, but muscle injury rates during matches were lower when players were given at least 6 days between their match exposures.

Prognostic factors for specific lower extremity and spinal musculoskeletal injuries identified through medical screening and training load monitoring in professional football (soccer): a systematic review

Background

Medical screening and load monitoring procedures are commonly used in professional football to assess factors perceived to be associated with injury.

Objectives

To identify prognostic factors (PFs) and models for lower extremity and spinal musculoskeletal injuries in professional/elite football players from medical screening and training load monitoring processes.

Methods

The MEDLINE, AMED, EMBASE, CINAHL Plus, SPORTDiscus and PubMed electronic bibliographic databases were searched (from inception to January 2017). Prospective and retrospective cohort studies of lower extremity and spinal musculoskeletal injury incidence in professional/elite football players aged between 16 and 40 years were included. The Quality in Prognostic Studies appraisal tool and the modified Grading of Recommendations Assessment, Development and Evaluation synthesis approach was used to assess the quality of the evidence.

Results

Fourteen studies were included. 16 specific lower extremity injury outcomes were identified. No spinal injury outcomes were identified. Meta-analysis was not possible due to heterogeneity and study quality. All evidence related to PFs and specific lower extremity injury outcomes was of very low to low quality. On the few occasions where multiple studies could be used to compare PFs and outcomes, only two factors demonstrated consensus. A history of previous hamstring injuries (HSI) and increasing age may be prognostic for future HSI in male players.

Conclusions

The assumed ability of medical screening tests to predict specific musculoskeletal injuries is not supported by the current evidence. Screening procedures should currently be considered as benchmarks of function or performance only. The prognostic value of load monitoring modalities is unknown.

Monitoring the effect of football match congestion on hamstring strength and lower limb flexibility: Potential for secondary injury prevention?

OBJECTIVES

To investigate the effect of competitive football match congestion on hamstring strength and lower limb flexibility.

DESIGN

Repeated measures.

SETTING

Elite male youth football.

PARTICIPANTS

Fifteen male elite youth football players from the national football association centre of excellence were included (age = 15.81 ±0.65 years, height = 171.95 ±6.89 cm, weight = 65.93 ±7.53 kg).

MAIN OUTCOME MEASURES

Hamstring strength and pain, ankle dorsiflexion, hip extension, knee extension and flexion range of motion.

RESULTS

Hamstring strength was highest at baseline and significantly reduced at 24 (p = 0.001, mean difference -0.19 Nm/Kg, CI₉₅ -0.28, -0.1) and 48 h post-match 1 (p = 0.002, mean difference -0.16 Nm/Kg, CI₉₅ -0.25, -0.07). Strength recovered by match day 2 before significantly reducing again 24 h post-match 2 (p = 0.012, mean difference -0.17 Nm/Kg, CI₉₅ -0.29, -0.04). Pain was lowest at baseline and increased in the post-match periods (p < 0.05) with standardised effect sizes ranging from 0.07 to 0.42. Passive knee flexion range decreased post-match (p < 0.01) with mean differences of 1.5°-2.7°. The other flexibility measures remained unaffected by match play.

CONCLUSION

Isometric hamstring strength and pain can be considered for inclusion in-season to monitor player's post-match hamstring recovery characteristics during congested match fixtures.

A 12-Month Prospective Cohort Study of Symptoms of Common Mental Disorders Among European Professional Footballers

OBJECTIVE

To determine the 12-month incidence and comorbidity of symptoms of common mental disorders (CMD) among European professional footballers and to explore the association of potential stressors with the health conditions under study among those European professional footballers.

DESIGN

Observational prospective cohort study with a follow-up period of 12 months.

PARTICIPANTS

Male professional footballers from 5 European countries (n = 384 at baseline).

ASSESSMENT OF RISK FACTORS

Adverse life events, conflicts with trainer/coach, and career dissatisfaction were explored by using validated questionnaires.

MAIN OUTCOME MEASURES

Symptoms of distress, anxiety/depression, sleep disturbance, and adverse alcohol use were assessed using validated questionnaires.

RESULTS

A total of 384 players (mean age of 27 years old; mean career duration of 8 years) were enrolled, of which 262 completed the follow-up period. The incidence of symptoms of CMD were 12% for distress, 37% for anxiety/depression, 19% for sleep disturbance, and 14% for adverse alcohol use. Over the follow-up period of 12 months, approximately 13% of the participants reported 2 symptoms, 5% three symptoms, and 3% four symptoms. Professional footballers reporting recent adverse life events, a conflict with trainer/coach, or career dissatisfaction were more likely to report symptoms of CMD, but statistically significant associations were not found.

CONCLUSIONS

The 12-month incidence of symptoms of CMD among European professional footballers ranged from 12% for symptoms of distress to 37% for symptoms of anxiety/depression. A professional football team typically drawn from a squad of 25 players can expect symptoms of CMD to occur among at least 3 players in one season.

Strategies for injury prevention in Brazilian football: Perceptions of physiotherapists and practices of premier league teams

OBJECTIVES

To describe the physiotherapists perceptions and the current practices for injury prevention in elite football (soccer) clubs in Brazil.

DESIGN

Cross-sectional study.

SETTING

Group of Science in Sports & Exercise, Federal University of Healthy Sciences of Porto Alegre (Brazil).

PARTICIPANTS

16 of the 20 football clubs involved in the Brazilian premier league 2015.

MAIN OUTCOME MEASURES

Physiotherapists answered a structured questionnaire.

RESULTS

Most physiotherapists (∼88%) were active in design, testing and application of prevention programs. Previous injury, muscle imbalance, fatigue, hydration, fitness, diet, sleep/rest and age were considered "very important" or "important" injury risk factors by all respondents. The methods most commonly used to detect athletes' injury risk were: monitoring of biochemical markers (100% of teams), isokinetic dynamometry (81%), questionnaires (75%), functional movement screen (56%), fleximetry (56%) and horizontal jump tests (50%). All clubs used strength training, functional training, core exercises and balance/proprioception exercises in their injury prevention program; and Nordic hamstring exercise and other eccentric exercises were used by 94% of clubs. "FIFA 11+" prevention program was adapted by 88% of clubs.

CONCLUSION

Physiotherapists perceptions and current practices of injury prevention within Brazilian elite football clubs were similar to those employed in developed countries. There remains a gap between clinical practice and scientific evidence in high performance football.

Calf muscle strain injuries in sport: a systematic review of risk factors for injury

OBJECTIVE

To systematically review the literature to identify risk factors for calf strain injury, and to direct future research into calf muscle injuries.

DESIGN

Systematic review DATA SOURCES: Database searches conducted for Medline, CINAHL, EMBASE, AMED, AUSPORT, SportDiscus, PEDro and Cochrane Library. Manual reference checks, ahead of press searches, citation tracking. From inception to June 2016.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies evaluating and presenting data related to intrinsic or extrinsic risk factors for sustaining future calf injury.

RESULTS

Ten studies were obtained for review. Subjects across football, Australian football, rugby union, basketball and triathlon were reported on, representing 5397 athletes and 518 calf/ lower leg muscle injuries. Best evidence synthesis highlights chronological age and previous history of calf strain are the strongest risk factors for future calf muscle injury. Previous lower limb injuries (hamstring, quadriceps, adductor, knee) show some limited evidence for an association. Numerous factors lack evidence of an association, including height, weight, gender and side dominance.

SUMMARY/CONCLUSION

Increasing age and previous calf strain injury are the most predictive of future calf injury. The overall paucity of evidence and the trend for studies of a high risk of bias show that further research needs to be undertaken.

Selected Physiological, Perceptual, and Physical Performance Changes During Two Bouts of Prolonged High-Intensity Intermittent Running Separated by 72 Hours

Dobbin, N, Lamb, KL, and Twist, C. Selected physiological, perceptual, and physical performance changes during two bouts of prolonged high-intensity intermittent running separated by 72 hours. J Strength Cond Res 31(12): 3474-3481, 2017-This study investigated the effects of performing a second 90-minute intermittent running protocol 72 hours after an initial trial on selected physiological, perceptual, and sprint running measures. Eight subelite soccer players provided measures of isokinetic muscle function, countermovement jump (CMJ), 10-m sprinting, and muscle soreness before, and at 0, 24, 48, and 72 hours after a 90-minute intermittent high-intensity running bout (IHIR-1). A second 90-minute IHIR bout (IHIR-2) was performed 72 hours after the first. Heart rates, ratings of perceived exertion (RPE), blood lactate concentration [Bla], and 10-m sprint times were recorded periodically during both IHIR. Analysis of effects revealed that in the 72-hour period after IHIR-1, there were most likely increases in muscle soreness and likely to very likely deteriorations in CMJ, 10-m sprint, and isokinetic muscle function. During IHIR-2, heart rates (possibly to likely) and [Bla] (possibly to very likely) were lower than IHIR-1, whereas RPE remained unchanged. Sprint times during IHIR-2 were also likely to very likely higher than in IHIR-1. It was evident that these team sport players exposed to repeat bouts of prolonged high-intensity running within 72 hours downregulated their sprint performances in the second bout despite no change in perceived effort. These findings have implications for managing training and match loads during periods of intense scheduling.

Hamstring injuries in elite Gaelic football: an 8-year investigation to identify injury rates, time-loss patterns and players at increased risk

Background

Hamstring injuries occur frequently in field sports, yet longitudinal information to guide prevention programmes is missing.

Aim

Investigate longitudinal hamstring injury rates and associated time loss in elite Gaelic football, while identifying subgroups of players at increased risk.

Methods

38 data sets from 15 elite male Gaelic football teams were received by the National Gaelic Athletic Association (GAA) Injury Surveillance Database between 2008 and 2015. Injury and exposure data were provided by the team's medical staff via an online platform.

Results

391 hamstring injuries were sustained accounting for 21% (95% CI 20.0% to 21.7%) of all injuries. Prevalence was 21% (95% CI 19.2% to 23.4%). Incidences were 2.2 (95% CI 1.9 to 2.4) per 1000 exposure hours, and 7.0 (95% CI 6.5 to 7.1) times greater in match play than in training. Typically each team sustained 9.0 (95% CI 7.0 to 11.0) hamstring injuries per season affecting the: bicep femoris belly (44%; 95% CI 39.4% to 48.7%); proximal musculotendinous junction (13%; 95% CI 9.8% to 16.3%); distal musculotendinous junction (12%; 95% CI 8.6% to 14.9%) and semimembranosis/semitendinosis belly (9%; 95% CI 6.3% to 11.7%). ∼36% (95% CI 31.5% to 41.0%) were recurrent injuries. Mean time loss was 26.0 (95% CI 21.1 to 33.0) days, which varied with age, injury type and seasonal cycle. Hamstring injuries accounted for 31% (95% CI 25.8% to 38.2%) of injury-related time loss. Previously injured players (rate ratio (RR)=3.3), players aged 18–20 years (IRR=2.3) or >30 years (RR=2.3), as well as defensive (IRR=2.0) and midfield players (RR=1.5), were most at risk of sustaining a hamstring injury. Comparisons of 2008–2011 with 2012–2015 seasons revealed a 2-fold increase in hamstring injury incidences. Between 2008 and 2015 training incidence increased 2.3-fold and match-play incidences increased 1.3-fold.

Conclusions

Hamstring injuries are the most frequent injury in elite Gaelic football, with incidences increasing from 2008–2011 to 2012–2015. Tailoring risk management strategies to injury history, age and playing position may reduce the burden of hamstring injuries.

Sports Injury Surveillance Systems: A Review of Methods and Data Quality

BACKGROUND AND AIMS

Data from sports injury surveillance systems are a prerequisite to the development and evaluation of injury prevention strategies. This review aimed to identify ongoing sports injury surveillance systems and determine whether there are gaps in our understanding of injuries in certain sport settings. A secondary aim was to determine which of the included surveillance systems have evaluated the quality of their data, a key factor in determining their usefulness.

METHODS

A systematic search was carried out to identify (1) publications presenting methodological details of sports injury surveillance systems within clubs and organisations; and (2) publications describing quality evaluations and the quality of data from these systems. Data extracted included methodological details of the surveillance systems, methods used to evaluate data quality, and results of these evaluations.

RESULTS

Following literature search and review, a total of 15 sports injury surveillance systems were identified. Data relevant to each aim were summarised descriptively. Most systems were found to exist within professional and elite sports. Publications concerning data quality were identified for seven (47%) systems. Validation of system data through comparison with alternate sources has been undertaken for only four systems (27%).

CONCLUSIONS

This review identified a shortage of ongoing injury surveillance data from amateur and community sport settings and limited information about the quality of data in professional and elite settings. More surveillance systems are needed across a range of sport settings, as are standards for data quality reporting. These efforts will enable better monitoring of sports injury trends and the development of sports safety strategies.

How much is too much? (Part 1) International Olympic Committee consensus statement on load in sport and risk of injury

Athletes participating in elite sports are exposed to high training loads and increasingly saturated competition calendars. Emerging evidence indicates that poor load management is a major risk factor for injury. The International Olympic Committee convened an expert group to review the scientific evidence for the relationship of load (defined broadly to include rapid changes in training and competition load, competition calendar congestion, psychological load and travel) and health outcomes in sport. We summarise the results linking load to risk of injury in athletes, and provide athletes, coaches and support staff with practical guidelines to manage load in sport. This consensus statement includes guidelines for (1) prescription of training and competition load, as well as for (2) monitoring of training, competition and psychological load, athlete well-being and injury. In the process, we identified research priorities.

Practitioners' Perceptions of the Soccer Extra-Time Period: Implications for Future Research

Qualitative research investigating soccer practitioners’ perceptions can allow researchers to create practical research investigations. The extra-time period of soccer is understudied compared to other areas of soccer research. Using an open-ended online survey containing eleven main and nine sub questions, we gathered the perceptions of extra-time from 46 soccer practitioners, all working for different professional soccer clubs. Questions related to current practices, views on extra-time regulations, and ideas for future research. Using inductive content analysis, the following general dimensions were identified: ‘importance of extra-time’, ‘rule changes’, ‘efficacy of extra-time hydro-nutritional provision’, ‘nutritional timing’, ‘future research directions’, ‘preparatory modulations’ and ‘recovery’. The majority of practitioners (63%) either agreed or strongly agreed that extra-time is an important period for determining success in knockout football match-play. When asked if a fourth substitution should be permitted in extra-time, 67% agreed. The use of hydro-nutritional strategies prior to extra-time was predominately considered important or very important. However; only 41% of practitioners felt that it was the most important time point for the use of nutritional products. A similar number of practitioners account (50%) and do not (50%) account for the potential of extra-time when training and preparing players and 89% of practitioners stated that extra-time influences recovery practices following matches. In the five minute break prior to extra-time, the following practices (in order of priority) were advocated to players: hydration, energy provision, massage, and tactical preparations. Additionally, 87% of practitioners advocate a particular nutritional supplementation strategy prior to extra-time. In order of importance, practitioners see the following as future research areas: nutritional interventions, fatigue responses, acute injury risk, recovery modalities, training paradigms, injury epidemiology, and environmental considerations. This study presents novel insight into the practitioner perceptions of extra-time and provides information to readers about current applied practices and potential future research opportunities.

Sports-related workload and injury risk: simply knowing the risks will not prevent injuries: Narrative review

Training loads contribute to sports injury risk but their mitigation has rarely been considered in a sports injury prevention framework. A key concept behind monitoring training loads for injury prevention is to screen for those at increased risk of injury so that workloads can be adjusted to minimise these risks. This review describes how advances in management of workload can be applied as a preventive measure. Primary prevention involves screening for preparticipation load risk factors, such as low training loads, prior to a training period or competition. Secondary prevention involves screening for workloads that are known to precede an injury developing so that modification can be undertaken to mitigate this risk. Tertiary prevention involves rehabilitation practices that include a graded return to training programme to reduce the risk of sustaining a subsequent injury. The association of training loads with injury incidence is now established. Prevention measures such as rule changes that affect the workload of an athlete are universal whereas those that address risk factors of an asymptomatic subgroup are more selective. Prevention measures, when implemented for asymptomatic individuals exhibiting possible injury risk factors, are indicated for an athlete at risk of developing a sports injury. Seven key indicated risks and associated prevention measures are proposed.

Injury prevention strategies at the FIFA 2014 World Cup: perceptions and practices of the physicians from the 32 participating national teams

Purpose

The available scientific research regarding injury prevention practices in international football is sparse. The purpose of this study was to quantify current practice with regard to (1) injury prevention of top-level footballers competing in an international tournament, and (2) determine the main challenges and issues faced by practitioners in these national teams.

Methods

A survey was administered to physicians of the 32 competing national teams at the FIFA 2014 World Cup. The survey included 4 sections regarding perceptions and practices concerning non-contact injuries: (1) risk factors, (2) screening tests and monitoring tools, (3) preventative strategies and (4) reflection on their experience at the World Cup.

Results

Following responses from all teams (100%), the present study revealed the most important intrinsic (previous injury, accumulated fatigue, agonist:antagonist muscle imbalance) and extrinsic (reduced recovery time, training load prior to and during World Cup, congested fixtures) risk factors during the FIFA 2014 World Cup. The 5 most commonly used tests for risk factors were: flexibility, fitness, joint mobility, balance and strength; monitoring tools commonly used were: medical screen, minutes/matches played, subjective and objective wellness, heart rate and biochemical markers. The 5 most important preventative exercises were: flexibility, core, combined contractions, balance and eccentric.

Conclusions

The present study showed that many of the National football (soccer) teams’ injury prevention perceptions and practices follow a coherent approach. There remains, however, a lack of consistent research findings to support some of these perceptions and practices.

Efficacy of the FIFA 11+ Injury Prevention Program in the Collegiate Male Soccer Player

BACKGROUND

The Fédération Internationale de Football Association (FIFA) 11+ program has been shown to be an effective injury prevention program in the female soccer cohort, but there is a paucity of research to demonstrate its efficacy in the male population.

HYPOTHESIS

To examine the efficacy of the FIFA 11+ program in men's collegiate United States National Collegiate Athletic Association (NCAA) Division I and Division II soccer.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Before the commencement of the fall 2012 season, every NCAA Division I and Division II men's collegiate soccer team (N = 396) was solicited to participate in this research study. Human ethics review board approval was obtained through Quorum Review IRB. Sixty-five teams were randomized: 34 to the control group (CG; 850 players) and 31 to the intervention group (IG; 675 players). Four teams in the IG did not complete the study, reducing the number for analysis to 61. The FIFA 11+ injury prevention program served as the intervention and was utilized weekly. Athlete-exposures (AEs), compliance, and injury data were recorded using a secure Internet-based system.

RESULTS

In the CG, 665 injuries (mean ± SD, 19.56 ± 11.01) were reported for 34 teams, which corresponded to an incidence rate (IR) of 15.04 injuries per 1000 AEs. In the IG, 285 injuries (mean ± SD, 10.56 ± 3.64) were reported for 27 teams, which corresponded to an IR of 8.09 injuries per 1000 AEs. Total days missed because of injury were significantly higher for the CG (mean ± SD, 13.20 ± 26.6 days) than for the IG (mean ± SD, 10.08 ± 14.68 days) (P = .007). There was no difference for time loss due to injury based on field type (P = .341).

CONCLUSION

The FIFA 11+ significantly reduced injury rates by 46.1% and decreased time loss to injury by 28.6% in the competitive male collegiate soccer player (rate ratio, 0.54 [95% CI, 0.49-0.59]; P < .0001) (number needed to treat = 2.64).

What is the extent of exposure to periods of match congestion in professional soccer players?

This study investigated exposure to periods of match congestion in regular starter players in a professional soccer team across 4 competitive seasons (2009-2013). Players were divided into 2 groups: club players (club match exposure only, n = 41) and national team players (club and national team exposure, n = 22). The frequency of congested periods that players were potentially exposed to per season was initially determined: 2-match cycles - potential exposure to 2 successive matches separated by a ≤ 3-day interval calculated immediately from the end of play in match 1 to the start of play in match 2 occurred on 12.5 ± 5.1 and 16.0 ± 4.7 occasions for club and national team players, respectively. Multiple-match cycles: potential exposure to 3-, 4-, 5- or 6-matches played successively within a ≤ 4-day period commencing from the day after each match occurred on 8.5 ± 2.1, 4.3 ± 1.7, 3.0 ± 0.8 and 1.8 ± 0.5 occasions for club and 11.5 ± 2.4, 6.5 ± 0.6, 4.5 ± 1.9 and 3.0 ± 1.4 occasions for national team players, respectively. With regard to actual exposure in club and national team players, respectively, participation in both matches in 2-match cycles attained 61.2% and 59.3% while 90-min play in both matches was only completed on 38.2% and 40.5% of occasions and ≥75-min play on 47.6% and 50.0% of occasions, despite availability to play in both groups being >86%. While availability to play in all players was frequently >70% for multiple-match cycles, a trend was observed for a sharp decline in participation as the number of matches in the cycles increased. Therefore, the present players were not extensively exposed to periods of fixture congestion.

Perceptions of well-being and physical performance in English elite youth footballers across a season

The 2011 English Elite Player Performance Plan (EPPP) stipulates training volumes that could put elite youth players at high risk of non-functional overreaching. The aim of the study was to assess player perceptions of well-being and physical performance to these high training loads. Fourteen academy football players (mean ± SD: age 17 ± 1 years; stature 179 ± 6 cm; body mass 70.8 ± 8.6 kg, at pre-season) completed a perception of well-being questionnaire 1-4 times per week throughout each training block (pre-season, in-season 1, 2, 3). Physical performance tests were carried out at the end of each training block. Increases in training exposure (P < 0.05; [Formula: see text] = 0.52) and moderate to large deteriorations in perceptions of well-being (motivation, sleep quality, recovery, appetite, fatigue, stress, muscle soreness P < 0.05; [Formula: see text] = 0.30-0.53) were evident as the season progressed. A moderate decrease in 30 m sprint performance (P < 0.05; [Formula: see text] = 0.48), a large improvement in Yo-Yo intermittent recovery test performance (P < 0.05; [Formula: see text] = 0.93) and small decreases in countermovement jump (P > 0.05; [Formula: see text] = 0.18) and arrowhead agility (P < 0.05; [Formula: see text] = 0.24) performance were evident as the season progressed. The present findings show an imbalance between stress and recovery in English elite youth players even when players experience lower training exposure than stipulated by the EPPP.

Recovery-stress balance and injury risk in professional football players: a prospective study

Professional football is a contact sport with a high risk of injury. This study was designed to examine the contribution of stress and recovery variables as assessed with the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) to the risk of injury in professional football players. In a prospective, non-experimental cohort design, 22 professional football players in the highest German football league were observed over the course of 16 months. From January 2010 until April 2011, the players completed the RESTQ-Sport a total of 222 times in monthly intervals. In addition, injury data were assessed by the medical staff of the club. Overall, 34 traumatic injuries and 10 overuse injuries occurred. Most of the injuries were located in the lower limb (79.5%), and muscle and tendon injuries (43.2%) were the most frequently occurring injury type. In a generalised linear model, the stress-related scales Fatigue (OR 1.70, P = 0.007), Disturbed Breaks (OR 1.84, P = 0.047) and Injury (OR 1.77, P < 0.001) and the recovery-related scale Sleep Quality (OR 0.53, P = 0.010) significantly predicted injuries in the month after the assessment. These results support the importance of frequent monitoring of recovery and stress parameters to lower the risk of injuries in professional football.