Double-Leg and Single-Leg Jump Test Reference Values for Athletes With and Without Anterior Cruciate Ligament Reconstruction Who Play Popular Pivoting Sports, Including Soccer and Basketball: A Scoping Review.

OBJECTIVE: To synthesize and present reference values for double-leg and single-leg jump tests in healthy athletes who play pivoting sports, and athletes with anterior cruciate ligament reconstruction (ACLR) who play pivoting sports. DESIGN: Scoping review. LITERATURE SEARCH: We searched PubMed, the Cochrane Library, MEDLINE, Embase, and Web of Science until April 7, 2023. STUDY SELECTION CRITERIA: We included reference values in 2 different categories: (1) double-leg and/or single-leg jump test outcomes in pivoting-sport athletes with ACLR at a specific time point during rehabilitation, and (2) double-leg and/or single-leg jump test outcomes in healthy pivoting-sport athletes. DATA SYNTHESIS: We performed data synthesis for reference values from double-leg jump tests (squat jump and countermovement jump) and single-leg jump tests (vertical hop, single hop for distance, triple hop for distance, crossover hop for distance, medial triple hop for distance, lateral triple hop for distance, 6-m timed hop, side hop, drop jump, and 10-second repeated hop) that were performed according to a standardized test description. We summarized the data for type of sport, sex, sport participation level, and age group. RESULTS: Of the 27 included studies, nine reported reference values from healthy soccer players, six from healthy basketball players, and eleven from other healthy pivoting-sport athletes. LSI dominant/nondominant (LSI-D/ND) ranged between 97% and 106% for healthy soccer players, and between 99% and 120% for healthy basketball players. Four studies reported reference values from pivoting-sport athletes with ACLR from 7 to 10 months postsurgery. CONCLUSION: This scoping review summarizes double-leg and single-leg jump test reference values for athletes who play common pivoting sports, including soccer and basketball. J Orthop Sports Phys Ther 2024;54(6):1-14. Epub 20 March 2024. doi:10.2519/jospt.2024.12374.

Growth-related sports injuries among young male professional football players in the Netherlands: a prospective cohort study concerning injury incidence, severity and burden.

OBJECTIVES: To investigate the incidence, type and location of growth-related sports injuries (GRSI) in youth professional football in the Netherlands. Secondary, to gain more knowledge on the injury severity and burden of GRSI. METHODS: In this prospective, longitudinal cohort study, 813 players aged 10-18 are included. Data collection is performed by instructing the medical staff of six professional football club academies to register GRSI by means of standardized forms. Training and match exposure are registered individually on a weekly basis. Injury incidence was calculated as number of GRSI per 1000 hours, injury severity as the median number of days lost in categories and injury burden as the number of days lost per 1000 hours. RESULTS: A total of 62 GRSI were documented in the football season 2021-2022. The total incidence of GRSI was 0.62/1000 hours football exposure. Morbus Osgood Schlatter and Morbus Sever were most common types of GRSI, both with incidence rates of 0.22/1000 hours exposure. About 58.3% of the documented GRSI were classified as major (>28 days lost). Within this group, the mean severity was 55 days time-loss to football. CONCLUSIONS: GRSI are relatively common in youth professional football. The most common types are Morbus Sever and Morbus Osgood Schlatter. Morbus Osgood Schlatter has the highest injury severity and burden compared to other types of GRSI.

Findings: GRSI incidence is significant in youth professional football, with M. Osgood Schlatter and M. Sever as the most common types of GRSI. More than half of GRSI are classified as major injuries. The mean injury severity is 55 days-lost due to injury, showing significant injury burden for GRSI. About 20.6% of the GRSI concerns a recurrent injury. GRSI incidence is highest in U13 and U14 players compared to other age groups. GRSI occur more frequently during matches compared to training.Implications: The results of this study provide insight into GRSI incidence and severity for youth professional football during a player's developmental years. The results from this study can be used in practice to recognize and acknowledge GRSI in young professional football players. These data will provide clinicians with prognostic information about expected length of the absence following specific types of GRSI.Caution: The results can most likely be extrapolated to other youth professional football academies. External validity towards other populations such as female professional or amateur youth football requires further validation through prospective studies.

Study on Hamstring Re-injury Prevention (SHARP): protocol for an international multicentre, randomised controlled trial.

INTRODUCTION: Previous studies showed that the Nordic hamstring exercise (NHE) effectively prevents primary hamstring injury. However, no study investigated the secondary preventing effect of the NHE on hamstring reinjury. The primary purpose of this study is to investigate the effectiveness of the NHE for preventing hamstring reinjury after return to play (RTP) following a hamstring injury in football players. The secondary purpose is to determine the effect of the NHE on sprint and jump performance. METHODS AND ANALYSIS: This is an international multicentre, prospective, parallel-group randomised controlled trial study. Subjects include male or female football players aged 18-40 years and within 1 week of RTP following a hamstring injury will be randomised into Nordics or a control group. Subjects in both groups continue their regular football training, but the Nordics group will perform an additional NHE programme. An online questionnaire will be sent to the subjects in both groups once per week within the first 10 weeks, then continued at months 6, 9 and 12. In a (performance) substudy, we will evaluate the effect of the NHE on sprint and vertical jump performance at three time points (at the beginning of the study, after 10 weeks and 12 months of follow-up).The primary outcomes are the incidence of hamstring reinjury within 2 and 12 months. The secondary outcomes are sprint and jump performance, adherence to the programme, duration of reinjury and reinjury burden. ETHICS AND DISSEMINATION: This study is approved by the medical ethics committee of Amsterdam University Medical Center (UMC) in the Netherlands (METC 2021_117), Faculty of Medicine Universitas Gadjah Mada in Indonesia (KE/FK/1248/EC/2021), Norwegian School of Sport Sciences in Norway (number 216-2 70 122) and Denmark (ethical submission in process). The study's findings will be disseminated in scientific peer-reviewed journals and presented at international conferences. TRIAL REGISTRATION NUMBER: NL9711.

Quadriceps and Hamstrings Strength Reference Values for Athletes With and Without Anterior Cruciate Ligament Reconstruction Who Play Popular Pivoting Sports, Including Soccer, Basketball, and Handball: A Scoping Review.

OBJECTIVE: To synthesize and present reference values for quadriceps and hamstrings strength tests in healthy athletes who play pivoting sports and in athletes with anterior cruciate ligament reconstruction (ACLR) who play pivoting sports. DESIGN: Scoping review. LITERATURE SEARCH: We searched PubMed, the Cochrane Library, MEDLINE, Embase, and Web of Science up to January 26, 2021. STUDY SELECTION CRITERIA: We included reference values in 2 different categories: (1) quadriceps and hamstrings strength test outcomes in healthy pivoting-sport athletes, and (2) quadriceps and hamstrings strength test outcomes in pivoting-sport athletes with ACLR at a specific time point during rehabilitation. DATA SYNTHESIS: We performed a qualitative synthesis for reference values from isokinetic (at 60°/s, 180°/s, and 300°/s) and isometric quadriceps and hamstrings strength tests. We summarized the data for type of sport, sex, sport participation level, and age group. RESULTS: Of the 42 included studies, 26 reported reference values from healthy soccer players, 4 from healthy basketball players, 4 from healthy handball players, and 11 from other healthy pivoting-sport athletes. The limb symmetry index dominant/nondominant limb (LSI-D/ND) ranged from 98% to 114% for healthy athletes. Six studies reported reference values in pivoting-sport athletes with ACLR at a specific time point during rehabilitation. After 7 months, strength values for athletes with ACLR were comparable to those of healthy pivoting-sport athletes. CONCLUSION: This scoping review summarizes quadriceps and hamstrings strength reference values for athletes who play the most common pivoting sports, including soccer, basketball, and handball. J Orthop Sports Phys Ther 2022;52(3):142-155. Epub 31 Dec 2021. doi:10.2519/jospt.2022.10693.

Isokinetic hamstring and quadriceps strength interpretation guideline for football (soccer) players with ACL reconstruction: a Delphi consensus study in the Netherlands.

Strength testing is a key part of rehabilitation and return to sport (RTS) decision making for football players after anterior cruciate ligament reconstruction (ACLR). Isokinetic testing has been the gold standard for strength measurement for decades, but a uniform protocol and clinical implications of test results are lacking. Therefore, this study aimed to 1) develop a uniform protocol for football players based on knowledge and experience from experts in the field of ACL rehabilitation and 2) clarify the clinical interpretation of different isokinetic test outcomes. In a structured Delphi consensus procedure 42 experts (98% full response rate) fulfilled three rounds that involved a survey, content analysis and anonymised feedback report for each round. Surveys addressed the isokinetic protocol, evaluation report and torque-angle curve of the isokinetic test for strength evaluation in football players after ACLR. The final protocol consisted of concentric knee flexion and extension isokinetic testing with 5 repetitions at 60°/sec, 20 repetitions at 180°/sec and 15 repetitions at 300°/sec and 60 seconds rest between sets. All parameters were deemed valuable, with Peak Torque, Max Rep Total Work, Total Work, Range of Motion and Agonist to Antagonist ratio being considered key for clinical interpretation. For qualitative assessment, it was advised to assess the shape, course, volume, potential dips, peak, and build-up to the peak of the parabola. This Delphi consensus study provided a guideline for data collection and clinical interpretation of isokinetic strength testing in football players after ACLR.

Effective But Not Adhered to: How Can We Improve Adherence to Evidence-Based Hamstring Injury Prevention in Amateur Football?

OBJECTIVES: To investigate adherence to a Nordic hamstring exercise (NHE) program in a real-world context of male amateur football, and the perceptions of end users (players) and intervention deliverers (coaches and medical staff) about adherence to this proven effective program. DESIGN: Retrospective cohort study. SETTING: Dutch amateur football. PARTICIPANTS: Two hundred sixty-four players, 23 coaches, and 29 medical staff from Dutch amateur football teams that participated in a national randomized controlled trial 2 years earlier. INDEPENDENT VARIABLES: Nordic hamstring exercise program. MAIN OUTCOME MEASURES: Nordic hamstring exercise program adherence during 2014 and 2015. Intervention or control group allocation during the trial, transfers, and personal perception about adherence to the program were also examined. RESULTS: Of all players, 69% reported never, 16% sometimes, 6% frequently, 5% often, and 4% always performing exercises of the NHE program. Adherence to the NHE program was higher among players who had been in the NHE arm of the previous trial and among players who had not been transferred to another club compared with players who had been transferred. Key factors in stimulating players to adhere to the NHE program were knowledge of the NHE and personal motivation. Coaches and medical staff members also mentioned personal motivation and consensus with team staff as key factors to encourage NHE adherence. CONCLUSIONS: Among high-level male amateur football players, adherence to an evidence-based hamstring injury-prevention program was very low. It is essential to recognize factors that stimulate or limit adherence to injury-prevention programs for effective programs to actually lead to a reduction in hamstring injuries in a real-world context.

Exercise-Based Strategies to Prevent Muscle Injury in Male Elite Footballers: An Expert-Led Delphi Survey of 21 Practitioners Belonging to 18 Teams from the Big-5 European Leagues.

PURPOSE: To define based on expert opinion and practical experience using a systematic and scientific approach, (1) the perceived most effective exercise-based strategies to prevent muscle injury in elite footballers; and, (2) when and how these exercise programs are prescribed based on the number of days between games i.e. implementation strategy. METHODS: A Delphi survey obtained opinions and assessed for agreement. Delphi respondents consisted of 21 experienced sports practitioners (12 ± 5.3 years in elite football and with an academic background) belonging to 18 teams from the Big-5 European football leagues; England, France, Germany, Italy, Spain. Three teams were represented collaboratively by two experts. The Delphi process involves sequential rounds each evolving based on the responses from the previous. The number of rounds is not pre-defined and continues until an agreement is either achieved or it is clear that no agreement will be reached. Frequency of responses was recorded where the agreement was sought (i.e. in closed questions) and an agreement was achieved if ≥ 13/18 (70%) respondents agreed. For open-ended questions, a qualitative content analysis was performed to identify recurring themes and when themes were specified by ≥ 13 (70%), these were also considered as reaching an agreement. Practitioners had the opportunity to raise concerns if they disagreed with the 'agreement from recurrent themes'. RESULTS: There were four Delphi rounds (100% response for each round). Sprinting and High-Speed Running (HSR) focused exercises were agreed as most effective (perceived) to prevent muscle injuries. Eccentric exercise was perceived as the next most effective. It was agreed that sprinting and HSR be integrated into coaches training, and target 100% of players worst-case match scenario (e.g. volume, intensity) based on individual maximum speeds. Eccentric exercise was recommended to be implemented according to the context of the main football session and planned/actual sprinting and HSR content. It was agreed that eccentrics can be performed before or after training, context dependent. The day to perform specific sprinting and HSR or eccentric exercises depended on the proximity of previous and upcoming matches. Other exercises reaching agreement as 'somewhat effective' included concentric and isometric, horizontal and vertical plyometrics, coordination, core and dynamic flexibility in addition to core stability. No agreement was reached for multi-joint, resisted sprinting, kicking or agility exercises nor simultaneous single-leg strength and stability. Finally, no agreement was reached regarding programming variables e.g. sets, repetitions as deemed too contextual. CONCLUSION: Regarding exercise-based strategies, particular importance agreed by the Delphi expert group was to focus on sprinting, HSR and eccentric exercises, integrated with a variety of other exercise modes which also carry some level of effectiveness in a multidimensional programme. Context was agreed to be key and decision-making about when to undertake/ how to prescribe exercise strategies to be made according to the content of normal football training and the proximity of matches.

Return to play after hamstring injuries in football (soccer): a worldwide Delphi procedure regarding definition, medical criteria and decision-making.

There are three major questions about return to play (RTP) after hamstring injuries: How should RTP be defined? Which medical criteria should support the RTP decision? And who should make the RTP decision? The study aimed to provide a clear RTP definition and medical criteria for RTP and to clarify RTP consultation and responsibilities after hamstring injury. The study used the Delphi procedure. The results of a systematic review were used as a starting point for the Delphi procedure. Fifty-eight experts in the field of hamstring injury management selected by 28 FIFA Medical Centres of Excellence worldwide participated. Each Delphi round consisted of a questionnaire, an analysis and an anonymised feedback report. After four Delphi rounds, with more than 83% response for each round, consensus was achieved that RTP should be defined as 'the moment a player has received criteria-based medical clearance and is mentally ready for full availability for match selection and/or full training'. The experts reached consensus on the following criteria to support the RTP decision: medical staff clearance, absence of pain on palpation, absence of pain during strength and flexibility testing, absence of pain during/after functional testing, similar hamstring flexibility, performance on field testing, and psychological readiness. It was also agreed that RTP decisions should be based on shared decision-making, primarily via consultation with the athlete, sports physician, physiotherapist, fitness trainer and team coach. The consensus regarding aspects of RTP should provide clarity and facilitate the assessment of when RTP is appropriate after hamstring injury, so as to avoid or reduce the risk of injury recurrence because of a premature RTP.

Hamstring-and-Lower-Back Flexibility in Male Amateur Soccer Players.

OBJECTIVE: This study investigated the hamstring-and-lower-back flexibility (HLBF) of male adult amateur soccer players, using the sit-and-reach test (SRT), with a view to obtaining population-based reference values and to determining whether SRT scores are associated with player characteristics. DESIGN: Cross-sectional cohort study. SETTING: Teams from high-level Dutch amateur soccer competitions were recruited for participation. PARTICIPANTS: Dutch male high-level amateur field soccer players (n = 449) of age 18 to 40 years. Players with a hamstring injury at the moment of SRT-measurement or any other injury that prevented them from following the SRT protocol were excluded. MAIN OUTCOME MEASURES: Sit-and-reach test scores were measured and then population-based reference values were calculated as follows: >2SD below mean (defining "very low" HLBF), 1SD-2SD below mean ("low" HLBF), 1SD below mean to 1SD above mean ("normal" HLBF), 1SD-2SD above mean ("high" HLBF), and >2SD above mean ("very high" HLBF). Whether SRT scores were correlated with player characteristics was determined using a Pearson correlation coefficient or Spearman rho. RESULTS: Sit-and-reach test scores ranged from 0 to 43.5 cm (mean 22.0 cm, SD 9.2). The cutoff points for population-based reference values were <3.5 cm for "very low", 3.5 to 13.0 cm for "low", 13.0 to 31.0 cm for "normal", 31.0 to 40.5 cm for "high", and >40.5 cm for "very high". Sit-and-reach test scores were significantly associated with players' height (ρ = -0.132, P = 0.005), body mass index (r = 0.114, P = 0.016), and history of anterior cruciate ligament surgery (P < 0.001). CONCLUSIONS: This study is the first to describe the HLBF of amateur soccer players. The SRT reference values with cutoff points may facilitate evidence-based decision making regarding HLBF, and the SRT might be a useful tool to assess injury risk, performance, or for diagnostic purposes.

No Relationship Between Hamstring Flexibility and Hamstring Injuries in Male Amateur Soccer Players: A Prospective Study.

BACKGROUND: In soccer, although hamstring flexibility is thought to play a major role in preventing hamstring injuries, the relationship between hamstring flexibility and hamstring injuries remains unclear. PURPOSE: To investigate the relationship between hamstring flexibility and hamstring injuries in male amateur soccer players. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: This study included 450 male first-class amateur soccer players (mean age, 24.5 years). Hamstring flexibility was measured by performing the sit-and-reach test (SRT). The relationship between hamstring flexibility and the occurrence of hamstring injuries in the following year, while adjusting for the possible confounding effects of age and previous hamstring injuries, was determined with a multivariate logistic regression analysis. RESULTS: Of the 450 soccer players, 21.8% reported a hamstring injury in the previous year. The mean (±SD) baseline score for the SRT was 21.2 ± 9.2 cm. During the 1-year follow-up period, 23 participants (5.1%) suffered a hamstring injury. In the multivariate analysis, while adjusting for age and previous injuries, no significant relationship was found between hamstring flexibility and hamstring injuries ( P = .493). CONCLUSION: In this group of soccer players, hamstring flexibility (measured with the SRT) was not related to hamstring injuries. Age and previous hamstring injuries as possible confounders did not appear to influence this relationship. Other etiological factors need to be examined to further elucidate the mechanism of hamstring injuries.

Return to Play After Hamstring Injuries: A Qualitative Systematic Review of Definitions and Criteria.

BACKGROUND: More than half of the recurrent hamstring injuries occur within the first month after return-to-play (RTP). Although there are numerous studies on RTP, comparisons are hampered by the numerous definitions of RTP used. Moreover, there is no consensus on the criteria used to determine when a person can start playing again. These criteria need to be critically evaluated, in an attempt to reduce recurrence rates and optimize RTP. OBJECTIVE: To carry out a systematic review of the literature on (1) definitions of RTP used in hamstring research and (2) criteria for RTP after hamstring injuries. STUDY DESIGN: Systematic review. METHODS: Seven databases (PubMed, EMBASE/MEDLINE, CINAHL, PEDro, Cochrane, SPORTDiscus, Scopus) were searched for articles that provided a definition of, or criteria for, RTP after hamstring injury. There were no limitations on the methodological design or quality of articles. Content analysis was used to record and analyze definitions and criteria for RTP after hamstring injury. RESULTS: Twenty-five papers fulfilled inclusion criteria, of which 13 provided a definition of RTP and 23 described criteria to support the RTP decision. "Reaching the athlete's pre-injury level" and "being able to perform full sport activities" were the primary content categories used to define RTP. "Absence of pain", "similar strength", "similar flexibility", "medical staff clearance", and "functional performance" were core themes to describe criteria to support the RTP decision after hamstring injury. CONCLUSION: Only half of the included studies provided some definition of RTP after hamstring injury, of which reaching the athlete's pre-injury level and being able to perform full sport activities were the most important. A wide variety of criteria are used to support the RTP decision, none of which have been validated. More research is needed to reach a consensus on the definition of RTP and to provide validated RTP criteria to facilitate hamstring injury management and reduce hamstring injury recurrence. PROSPERO systematic review registration number: CRD42015016510.

The preventive effect of the nordic hamstring exercise on hamstring injuries in amateur soccer players: a randomized controlled trial.

BACKGROUND: Hamstring injuries are the most common muscle injuries in soccer, and they have a high rate of recurrence. Eccentric hamstrings strength is recognized as an important modifiable risk factor. This led to the development of prevention exercises such as the nordic hamstring exercise (NHE). The effectiveness of the NHE on hamstring injury prevention has never been investigated in amateur soccer. PURPOSE: To investigate the preventive effect of the NHE on the incidence and severity of hamstring injuries in male amateur soccer players. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Male amateur soccer players (age, mean ± SD, 24.5 ± 3.8 years) from 40 teams were randomly allocated to an intervention (n = 20 teams, 292 players) or control group (n = 20 teams, 287 players). The intervention group was instructed to perform 25 sessions of NHE in a 13-week period. Both the intervention and control groups performed regular soccer training and were followed for hamstring injury incidence and severity during the 2013 calendar year. At baseline, personal characteristics (eg, age, injury history, field position) were gathered from all participants via a questionnaire. Primary outcome was injury incidence. Secondary outcomes were injury severity and compliance with the intervention protocol. RESULTS: A total of 38 hamstring injuries were recorded, affecting 36 of 579 players (6.2%). The overall injury incidence rate was 0.7 (95% CI, 0.6-0.8) per 1000 player hours, 0.33 (95% CI, 0.25-0.46) in training, and 1.2 (95% CI, 0.82-1.94) in matches. Injury incidence rates were significantly different between the intervention (0.25; 95% CI, 0.19-0.35) and control groups (0.8; 95% CI, 0.61-1.15), χ(2)(1, n = 579) = 7.865; P = .005. The risk for hamstring injuries was reduced in the intervention group compared with the control group (odds ratio, 0.282; 95% CI, 0.110-0.721) and was statistically significant (P = .005). No statistically significant differences were identified between the intervention and control groups regarding injury severity. Compliance with the intervention protocol was 91%. CONCLUSION: Incorporating the NHE protocol in regular amateur training significantly reduces hamstring injury incidence, but it does not reduce hamstring injury severity. Compliance with the intervention was excellent.

The preventive effect of the Nordic hamstring exercise on hamstring injuries in amateur soccer players: study protocol for a randomised controlled trial.

BACKGROUND: Hamstring injuries are the most common muscle injury in male amateur soccer players and have a high rate of recurrence, often despite extensive treatment and long rehabilitation periods. Eccentric strength and flexibility are recognised as important modifiable risk factors, which have led to the development of eccentric hamstring exercises, such as the Nordic hamstring exercise. As the effectiveness of the Nordic hamstring exercise in reducing hamstring injuries has never been investigated in amateur soccer players, the aim of this study is to investigate the effect of this exercise on the incidence and severity of hamstring injuries in male amateur soccer players. An additional aim is to determine whether flexibility is associated with hamstring injuries. STUDY DESIGN: Cluster-randomised controlled trial with soccer teams as the unit of cluster. METHODS: Dutch male amateur soccer players, aged 18-40 years, were allocated to an intervention or control group. Both study groups continued regular soccer training during 2013, but the intervention group additionally performed the Nordic hamstring exercise (25 sessions over 13 weeks). Primary outcomes are the incidence of initial and recurrent hamstring injury and injury severity. Secondary outcomes are hamstring-and-lower-back flexibility and compliance. Compliance to the intervention protocol was also monitored. DISCUSSION: Eccentric hamstring strength exercises are hypothesised to reduce the incidence of hamstring injury among male amateur soccer players by 70%. The prevention of such injuries will be beneficial to soccer players, clubs, football associations, health insurance companies and society. TRIAL REGISTRATION: NTR3664.

How effective are exercise-based injury prevention programmes for soccer players? : A systematic review.

BACKGROUND: The incidence of soccer (football) injuries is among the highest in sports. Despite this high rate, insufficient evidence is available on the efficacy of preventive training programmes on injury incidence. OBJECTIVE: To systematically study the evidence on preventive exercise-based training programmes to reduce the incidence of injuries in soccer. DATA SOURCES: The databases EMBASE/MEDLINE, PubMed, CINAHL, Cochrane Central Register of controlled trials, PEDro and SPORTDiscus™ were searched for relevant articles, from inception until 20 December 2011. The methodological quality of the included studies was assessed using the PEDro scale. STUDY SELECTION: The inclusion criteria for this review were (1) randomized controlled trials or controlled clinical trials; (2) primary outcome of the study is the number of soccer injuries and/or injury incidence; (3) intervention focusing on a preventive training programme, including a set of exercises aimed at improving strength, coordination, flexibility or agility; and (4) study sample of soccer players (no restrictions as to level of play, age or sex). The exclusion criteria were: (1) the article was not available as full text; (2) the article was not published in English, German or Dutch; and (3) the trial and/or training programme relates only to specific injuries and/or specific joints. To compare the effects of the different interventions, we calculated the incidence risk ratio (IRR) for each study. RESULTS: Six studies involving a total of 6,099 participants met the inclusion criteria. The results of the included studies were contradictory. Two of the six studies (one of high and one of moderate quality) reported a statistical significant reduction in terms of their primary outcome, i.e. injuries overall. Four of the six studies described an overall preventive effect (IRR<1), although the effect of one study was not statistically significant. The three studies that described a significant preventive effect were of high, moderate and low quality. CONCLUSIONS: Conflicting evidence has been found for the effectiveness of exercise-based programmes to prevent soccer injuries. Some reasons for the contradictory findings could be different study samples (in terms of sex and soccer type) in the included studies, differences between the intervention programmes implemented (in terms of content, training frequency and duration) and compliance with the programme. High-quality studies investigating the best type and intensity of exercises in a generic training programme are needed to reduce the incidence of injuries in soccer effectively.

Iliotibial band syndrome in runners: a systematic review.

BACKGROUND: The popularity of running is still growing and, as participation increases, the incidence of running-related injuries will also rise. Iliotibial band syndrome (ITBS) is the most common injury of the lateral side of the knee in runners, with an incidence estimated to be between 5% and 14%. In order to facilitate the evidence-based management of ITBS in runners, more needs to be learned about the aetiology, diagnosis and treatment of this injury. OBJECTIVE: This article provides a systematic review of the literature on the aetiology, diagnosis and treatment of ITBS in runners. SEARCH STRATEGY: The Cochrane Library, MEDLINE, EMBASE, CINAHL, Web of Science, and reference lists were searched for relevant articles. SELECTION CRITERIA: Systematic reviews, clinical trials or observational studies involving adult runners (>18 years) that focused on the aetiology, diagnosis and/or treatment of ITBS were included and articles not written in English, French, German or Dutch were excluded. DATA COLLECTION AND ANALYSIS: Two reviewers independently screened search results, assessed methodological quality and extracted data. The sum of all positive ratings divided by the maximum score was the percentage quality score (QS). Only studies with a QS higher than 60% were included in the analysis. The following data were extracted: study design; number and characteristics of participants; diagnostic criteria for ITBS; exposure/treatment characteristics; analyses/outcome variables of the study; and setting and theoretical perspective on ITBS. MAIN RESULTS: The studies of the aetiology of ITBS in runners provide limited or conflicting evidence and it is not clear whether hip abductor weakness has a major role in ITBS. The kinetics and kinematics of the hip, knee and/or ankle/foot appear to be considerably different in runners with ITBS to those without. The biomechanical studies involved small samples, and data seem to have been influenced by sex, height and weight of participants. Although most studies monitored the management of ITBS using clinical tests, these tests have not been validated for this patient group. While the articles were inconsistent regarding the treatment of ITBS, hip/knee coordination and running style appear to be key factors in the treatment of ITBS. Runners might also benefit from mobilization, exercises to strengthen the hip, and advice about running shoes and running surface. CONCLUSION: The methodological quality of research into the management of ITBS in runners is poor and the results are highly conflicting. Therefore, the study designs should be improved to prevent selection bias and to increase the generalizability of findings.