Previous injury as a risk factor for injury in elite football: a prospective study over two consecutive seasons

The Value of the Patient History in the Periodic Health Evaluation: Patient Interviews Capture 4 Times More Injuries Than Electronic Questionnaires

OBJECTIVE

To assess the value of the patient interview and electronic questionnaire methods of health history data collection in elite athletes.

DESIGN

Cohort study.

METHODS

A retrospective chart review compared health history data collected by questionnaire and by interview in a cohort of 142 athletes who participated in a periodic health evaluation at the US Olympic & Paralympic Training Center sports medicine clinic. The main outcome measure was number of injuries reported by either interview or written questionnaire.

RESULTS

Six hundred twenty-six injuries were reported by interview and 157 by questionnaire. The mean ± SD number of injuries reported per participant was 4.4 ± 4.2 by interview and 1.1 ± 1.3 by questionnaire (difference, 3.3; P<.001). Capture rate by method was similar across sexes and for both Olympic and Paralympic athletes. More injuries were reported by interview than by questionnaire for all injury categories, except for concussions and surgeries.

CONCLUSION

Patient interviews capture 4 times as many past or current injuries than electronic questionnaires in athletes training for the Olympic and Paralympic Games. Questionnaires provide incomplete health history information in this patient population. J Orthop Sports Phys Ther 2021;51(1):46-51. Epub 11 Dec 2020. doi:10.2519/jospt.2021.9821.

Epidemiology of Concussions in High School Boys' Ice Hockey, 2008/09 to 2016/17 School Years

OBJECTIVE

This study examined the epidemiology of concussions in high school boys' ice hockey during the 2008/09 to 2016/17 school years.

DESIGN

Prospective cohort study. Athletic trainers from an average 33 high schools annually reported boys' ice hockey concussion and athlete-exposure (AE) data for the High School Reporting Information Online system.

SETTING

Convenience sample of high school boys' ice hockey programs during the 2008/09 to 2016/17 school years.

PATIENTS OR OTHER PARTICIPANTS

High school boys' ice hockey players (aged ∼14-18 years).

INDEPENDENT VARIABLES

Concussion data on event type, injury mechanism, symptom resolution time, and time loss were obtained.

MAIN OUTCOME MEASURES

Concussion rates with 95% confidence intervals (CIs) and distributions were calculated.

RESULTS

Overall, 348 concussions were reported in boys' ice hockey during the 2008/09 to 2016/17 academic years, leading to a concussion rate of 0.68/1000 AEs (95% CI, 0.61-0.75). Most occurred in competitions (85.6%), particularly after the first period (72.1% of all competition concussions). Among practice concussions, most occurred after the first hour of practice (60.0%). Most concussions were due to player contact (47.7%) and boards/glass contact (31.9%). Although 69.0% of concussed athletes had symptoms resolve in less than 7 days, only 14.1% returned to activity within a week.

CONCLUSIONS

Most concussions occurred within the second and third periods. Preventive strategies that counter an increased risk of concussion due to a greater intensity of gameplay coupled with increased fatigue may be warranted. Moreover, athletes may further benefit from prevention efforts that focus on anticipating impacts during gameplay.

Trunk endurance, posterior chain flexibility, and previous history of musculoskeletal pain predict overuse low back and lower extremity injury: a prospective cohort study of 545 Navy Cadets

OBJECTIVE

To investigate predictors of low back and lower extremity musculoskeletal injury in a cohort of Naval cadets.

DESIGN

Prospective Cohort Study METHODS: 545 Naval cadets (Males, n = 394, 72%) were followed-up over eight months. Nine variables were investigated as predictors: history of musculoskeletal symptoms in the last 12 months, ankle dorsiflexion range of motion, sit and reach test, isometric hip abduction and external rotation strength, alignment during the single leg squat test, single leg hop test for distance, prone plank and side plank tests. All injuries that required medical attention were registered. Predictive associations were examined using univariable and multivariable logistic regression analyses.

RESULTS

The incidence of all injuries was 7%. Cadets who failed the 60-second plank test (OR = 3.3; 95% CI, 1.2-8.8, P = 0.04), had ≤18 cm in the sit and reach test (OR = 4.0; 95% CI, 1.4-11.2, P = 0.01), or reported pain in the last 12 months in two or more body regions (OR = 2.7; 95% CI, 1.02-7.3, P = 0.04), had greater odds of sustaining an overuse injury. No predictors were identified for acute injuries.

CONCLUSION

Decreased trunk endurance on the prone plank test, reduced posterior chain flexibility on the sit and reach test, and a history of pain reported in two or more sites in the last 12 months were predictors of overuse injuries in Naval cadets. Assessment and intervention of these modifiable risk factors may be clinically relevant in injury screening and prevention.

Evaluation of Musculoskeletal Re-Injury Occurrence in Previously Concussed National Football League Athletes

Introduction

Increased risk of musculoskeletal (MSK) injury post-concussion has been reported in collegiate athletes, yet it is unknown if professional football athletes are at the same risk of secondary injury. The objective of this study was to determine if the risk of MSK injury in National Football League (NFL) athletes increases after concussion.

Methods

NFL injury reports from 2013 to 2017 were collected from public websites. Concussed athletes (n=91) were equally matched to a non-injured control and an athlete with an incident of musculoskeletal (MSK) injury.

Results

Following their return to sport, concussed athletes were 2.35 times more likely to have a subsequent MSK injury relative to non-injured controls (95% CI: 2.35 [1.25, 4.44], P = 0.01), but were no more likely than athletes with an incident MSK injury (P = 0.55). Likewise, athletes with an incident MSK injury were no more likely to have a subsequent MSK injury than controls (P = 0.08).

Discussion

Increased odds of MSK injury in the 12-week period following a concussion in professional football athletes warrants future research on the acute effects of concussion and the relationship to MSK injury risk.

Practicability of lower extremity functional performance tests and their measurement properties in elite athletes: protocol for a systematic review

INTRODUCTION

Lower extremity injury (LEI) is highly prevalent and its occurrence increases the risk of future injury in athletic populations. Identifying athletes at risk of injury is the key to target injury-prevention programmes. Functional performance tests (FPT) assess an athlete's ability to produce and accept forces during movement tasks reflective of those experienced in sport, and are used to identify deficits in physical qualities or neuromuscular control. This review aims to identify FPT which have potential to predict LEI and assess their measurement properties associated with reliability, validity, responsiveness and practicability (interpretability and feasibility).

METHODS/ANALYSIS

This protocol will be reported using the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol and the COnsensus-based Standards for the selection of health Measurement INstruments Methodology. The search strategy has two stages: stage 1 will identify lower limb FPT used in athletic populations; and stage 2 will assess the measurement properties of the identified FPT. A sensitive search strategy will use MEDLINE, EMBASE, CINHAL and SPORTdiscus databases; from inception to June 2020. Hand searching reference lists, key journals and grey literature will be completed. One reviewer will complete search 1 and data extraction. Two reviewers will complete the search, data extraction and risk-of-bias assessment for search 2. Evidence will be pooled or summarised by individual measurement property by each individual study and grouped by FPT. Meta-analysis using a random effects model with subgroup analysis will be performed where possible. Pooled or summarised results for each FPT in relation to each measurement property will be rated against the criteria for good measurement properties. Two reviewers will assess the overall body of evidence per measurement property per FPT using the modified Grading of Recommendations, Assessment, Development and Evaluation guidelines. This review will enable clinicians to make an informed choice when selecting FPT.

ETHICS AND DISSEMINATION

No ethical approval is required for this review and the results will be disseminated through peer-reviewed publications and submitted for conference presentation.

PROSPERO REGISTRATION NUMBER

CRD42020188932.

Recommendations for Hamstring Function Recovery After ACL Reconstruction

It is important to optimise the functional recovery process to enhance patient outcomes after major injury such as anterior cruciate ligament reconstruction (ACLR). This requires in part more high-quality original research, but also an approach to translate existing research into practice to overcome the research to implementation barriers. This includes research on ACLR athletes, but also research on other pathologies, which with some modification can be valuable to the ACLR patient. One important consideration after ACLR is the recovery of hamstring muscle function, particularly when using ipsilateral hamstring autograft. Deficits in knee flexor function after ACLR are associated with increased risk of knee osteoarthritis, altered gait and sport-type movement quality, and elevated risk of re-injury upon return to sport. After ACLR and the early post-operative period, there are often considerable deficits in hamstring function which need to be overcome as part of the functional recovery process. To achieve this requires consideration of many factors including the types of strength to recover (e.g., maximal and explosive, multiplanar not just uniplanar), specific programming principles (e.g., periodised resistance programme) and exercise selection. There is a need to know how to train the hamstrings, but also apply this to the ACLR athlete. In this paper, the authors discuss the deficits in hamstring function after ACLR, the considerations on how to restore these deficits and align this information to the ACLR functional recovery process, providing recommendation on how to recover hamstring function after ACLR.

Factors influencing optimum countermovement jump performance and movement strategy in Championship professional football players: implications for player profiling

Single leg countermovement jump (CMJ) is a common profiling test influenced by sport, age, sex and playing level. Controlling for these confounding variables, outfield players from an English Championship squad (n = 36) were retrospectively categorized as best (n = 10) or worst (n = 10), based on mean single leg CMJ height and flight time:contraction time ratio. Movement strategy was quantified as force-time history metrics differentiating eccentric and concentric phases. Jump height revealed that best performers elicited greater rate of force development in both phases (P ≤ 0.033), with concentric impulse the strongest predictor of performance. Time ratio also differentiated best performers as utilizing a shallower (P = 0.002) countermovement, with concentric rate of force development the strongest predictor of good performance. Successful jump height performance can mask ineffectual eccentric and stretch shortening cycle neuromuscular characteristics. Time ratio is therefore advocated as the key performance indicator, with movement strategy prioritized over gross outcome measures.

Recurrent and Subsequent Injuries in Professional and Elite Sport: a Systematic Review

BACKGROUND

Injury surveillance in professional sport categorises injuries as either "new" or "recurrent". In an attempt to make categorisation more specific, subsequent injury categorisation models have been developed, but it is not known how often these models are used. The aim was to assess how recurrent and subsequent injuries are reported within professional and elite sport.

METHODS

Online databases were searched using a search strategy. Studies needed to prospectively report injury rates within professional or elite sports that have published consensus statements for injury surveillance.

RESULTS

A total of 1322 titles and abstract were identified and screened. One hundred and ninety-nine studies were screened at full text resulting in 81 eligible studies. Thirty studies did not report recurrent injuries and were excluded from data extraction. Within the studies that reported recurrent injuries, 21 reported the number and percentage; 13 reported only the proportion within all injuries; three reported only the number; five reported the number, percentage and incidence; and two only reported the incidence. Seven studies used subsequent injury terminology, with three reporting subsequent injury following concussion, one using an amended subsequent injury model and three using specific subsequent injury categorisation models. The majority of subsequent injuries (ranging from 51 to 80%) were categorised as different and unrelated to the index injury. The proportion of recurrent injuries (exact same body area and nature related to index injury) ranged from 5 to 21%.

CONCLUSIONS

Reporting recurrent or subsequent injuries remains inconsistent, and few studies have utilised subsequent injury models. There is limited understanding of subsequent injury risk, which may affect the development of injury prevention strategies.

TRIAL REGISTRATION

CRD42019119264.

Influence of Lumbar Mobilizations During the Nordic Hamstring Exercise on Hamstring Measures of Knee Flexor Strength, Failure Point, and Muscle Activity: A Randomized Crossover Trial

OBJECTIVE

The aims of this study were to quantify the effects of spinal mobilization on force production, failure point, and muscle activity of the hamstrings during the Nordic hamstring exercise (NHE), and to explore individual differences in responses.

METHODS

In a replicated randomized crossover trial, 24 asymptomatic, recreationally active men (age [mean ± standard deviation]: 27 ± 6 years; body mass: 82 ± 17 kg; height: 181 ± 8 cm) completed 2 standardized intervention trials (L4/5 zygapophyseal mobilizations) and 2 control trials. The failure point of the NHE was determined with 3D motion capture. Peak force, knee flexor torque, and electromyography (EMG) of the biceps femoris were measured. Data analyses were undertaken to quantify mean intervention response and explore any individual response heterogeneity.

RESULTS

Mean (95% confidence interval) left-limb force was higher in intervention than in control trials by 18.7 (4.6-32) N. Similarly, right-limb force was higher by 22.0 (3.4-40.6) N, left peak torque by 0.14 (0.06-0.22) N • m, and right peak torque by 0.14 (0.05-0.23) N • m/kg. Downward force angle was decreased in intervention vs control trials by 4.1° (0.5°-7.6°) on the side of application. Both peak EMG activity (P = .002), and EMG at the downward force (right; P = .020) increased in the intervention condition by 16.8 (7.1-26.4) and 8.8 (1.5-16.1) mV, respectively. Mean downward acceleration angle changed by only 0.3° (-8.9° to 9.4°) in intervention vs control trials. A clear response heterogeneity was indicated only for right force (Participant × Intervention interaction: P = .044; response heterogeneity standard deviation = 34.5 [5.7-48.4] N). Individual response heterogeneity was small for all other outcomes.

CONCLUSION

After spinal mobilization, immediate changes in bilateral hamstring force production and peak torque occurred during the NHE. The effect on the NHE failure point was unclear. Electromyographic activity increased on the ipsilateral side. Response heterogeneity was generally similar to the random trial-to-trial variability inherent in the measurement of the outcomes.

Global Positioning System Analysis of Physical Demands in Small and Large-Sided Games with Floaters and Official Matches in the Process of Return to Play in High Level Soccer Players

The aim of this study was twofold: (i) to analyze the physical demands in the return to play (RTP) process of high-level soccer players in the role of floater in different soccer sided games (SGs) formats (i.e., 4vs4 + 2 and 8vs8 + 1); and (ii) to analyze the differences in physical demands encountered by regular and floater players among the SGs formats and official matches by means of global positioning system technology (GPS APEX pod, North Ireland) was used. Twenty-six highly trained, male soccer players (U16 years) participated in this investigation. Players were classified into two groups: 23 regular and 3 floater players, a total of eight SGs were analyzed, which involved the recording of 80 observations of regular and floater players. Match-play players showed most likely-probable differences in distance covered at high-intensity per minute (D > 14.4/min), at high-speed running per minute (D > 21/min), and peak velocity (Vpeak) in comparison to floaters in the 8vs8 + 1 LSG (large-side-games), and presented most likely differences in accelerations >2/min in comparison to match-play players. Therefore, the use of floaters during the last phase of the RTP (return to play) seems to be a useful strategy for progressive reintroduction into specific training (1) floater in the 4vs4 + 2 SSG; (2) floater in the 8vs8 + 1 LSG; (3) regular player in the 4vs4 + 2 SSG; and (4) regular player in the 8vs8 + 1 LSG before starting full trainings and returning to competition.

Hamstring muscle injury in the athlete: state of the art

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

Ultrasound-Guided Percutaneous Needle Electrolysis and Rehab and Reconditioning Program for Rectus Femoris Muscle Injuries: A Cohort Study with Professional Soccer Players and a 20-Week Follow-Up

Rectus femoris muscle strains are one of the most common injuries occurring in sports such as soccer. The purpose of this study was to describe the safety and feasibility of a combination of percutaneous needle electrolysis (PNE) and a specific rehab and reconditioning program (RRP) following an injury to the rectus femoris in professional soccer players. Thirteen professional soccer players received PNE treatment 48 h after a grade II rectus femoris muscle injury, followed by a the RRP 24 h later. Assessment of recovery from injury was done by registering the days taken to return to train (RTT), return to play (RTP), and structural and functional progress of the injured muscle was registered through ultrasound imaging and match-GPS parameters. Also, adverse events and reinjuries were recorded in the follow up period of twenty weeks. The RTT registered was 15.62 ± 1.80 days and RTP was 20.15 ± 2.79 days. After fourteen days, the ultrasound image showed optimal repair. Match-GPS parameters were similar before and after injury. There were no relapses nor were any serious adverse effects reported during the 20-week follow-up after the RTP. A combination of PNE and a specific RRP facilitated a faster RTP in previously injured professional soccer players enabling them to sustain performance and avoid reinjuries.

Lower limb MSK injuries among school-aged rugby and football players: a systematic review

OBJECTIVE

The objective of this systematic review was to explore the incidence of lower limb musculoskeletal (MSK) injuries sustained by rugby union, rugby league, soccer, Australian Rules and Gaelic football players under 18 years. The review sought to identify the mechanisms and types of injury sustained and to compare between sports.

DESIGN

This systematic review focused on the incidence of lower limb injury in adolescent team sports that involved running and kicking a ball. A literature search of studies published prior to January 2020 was conducted using SportDiscus, Medline and PubMed databases. The Standard Quality Assessment Criteria appraisal tool was used to assess the quality of each article included in the review. Two or more authors independently reviewed all papers.

RESULTS

Sixteen papers met the inclusion criteria; prospective cohort (N=14), retrospective (n=1) and longitudinal (n=1). These studies investigated injuries in rugby union and rugby league (n=10), football (soccer) (n=3), Australian Rules (n=2) and Gaelic football (n=1). There were a total of 55 882 participants, aged 7-19 years old, who reported 6525 injuries. The type, site and mechanisms of injury differed across sports.

SUMMARY

Lower limb injuries were common in adolescent rugby, soccer, Gaelic football and Australian Rules football players, however these studies may not fully reflect the true injury burden where recurrent and overuse injuries have not been considered. There were differences between sports in the mechanisms, types and severity of injury.

The mechanism of hamstring injuries - a systematic review

Background

Injuries to the hamstring muscles are among the most common in sports and account for significant time loss. Despite being so common, the injury mechanism of hamstring injuries remains to be determined.

Purpose

To investigate the hamstring injury mechanism by conducting a systematic review.

Study design

A systematic review following the PRISMA statement.

Methods

A systematic search was conducted using PubMed, EMBASE and the Cochrane Library. Studies 1) written in English and 2) deciding on the mechanism of hamstring injury were eligible for inclusion. Literature reviews, systematic reviews, meta-analyses, conference abstracts, book chapters and editorials were excluded, as well as studies where the full text could not be obtained.

Results

Twenty-six of 2372 screened original studies were included and stratified to the mechanism or methods used to determine hamstring injury: stretch-related injuries, kinematic analysis, electromyography-based kinematic analysis and strength-related injuries. All studies that reported the stretch-type injury mechanism concluded that injury occurs due to extensive hip flexion with a hyperextended knee. The vast majority of studies on injuries during running proposed that these injuries occur during the late swing phase of the running gait cycle.

Conclusion

A stretch-type injury to the hamstrings is caused by extensive hip flexion with an extended knee. Hamstring injuries during sprinting are most likely to occur due to excessive muscle strain caused by eccentric contraction during the late swing phase of the running gait cycle.

Level of evidence

Level IV

Can musculoskeletal screening test findings guide interventions for injury prevention and return from injury in field hockey?

OBJECTIVES

The aim of this study is to identify if intrinsic factors tested in the preseason screening (PSS) can identify an elevated risk of injury. This aim has two aspects; to assess whether previous injury is associated with ongoing deficits in performance, and to assess if the PSS can identify differences in intrinsic factors that profile risk of future injury.

DESIGN

A cohort of state level field hockey players were tested on a screening test battery including proprioception, postural stability, muscular strength and range of motion, to establish if these intrinsic factors were useful in identifying elevated risk of injury. Retrospective injury data was collated to determine association with previous injury and prospective injury data was collated to determine association with future injury.

PARTICIPANTS

A total of 130 field hockey players were included in this study, from state level squads (age ± SD = 20.96 (3.75); height = 176.09 cm). Groups for prescreening and post screening injury status (injured/not injured) were established for comparison to screening test results.

RESULTS

Right Active Movement Extent Discrimination Assessment (AMEDA), left AMEDA and right Y-balance test (YBT) anterior direction (Ant) were significantly associated (p < 0.05) with injury prior to screening. Right YBTAnt and right and left hip internal rotation (IR) were significantly associated (p < 0.05) with injury post screening. The YBTAnt and YBT posteromedial (PMed) reach directions and Hip IR are associated with previous hamstring injury and show a difference between post screening injured and non-injured groups.

CONCLUSIONS

AMEDA, R YBTAnt, Hip IR tests should be a focus for recovery after previous injury and during season preparation. Full recovery may improve readiness to return to play and reduce risk of primary injury or re-injury. YBTAnt and YBTPmed and Hip IR show a performance deficit link between previous injury and subsequent re-injury of hamstrings. Since these are the most common re-injury types in this cohort, these tests are clinically useful in informing return to play decisions for hockey players.

Prospective analysis of craniofacial soccer incidents during FIFA competitions: an observational study

The aim of this prospective epidemiological study was to evaluate the occurrence of incidents involving the craniofacial region of soccer players during three official FIFA competitions. The craniofacial incidents were identified by video analysis of all 144 matches of two FIFA World Cups (2014/2018) and the 2017 FIFA Confederations Cup. Data collection included incident type, incident severity, site affected, incident cause and referee decision. The multivariate Poisson regression model was performed to analyze the associations between covariates. A total of 238 incidents were observed in the craniofacial region (1.6 incidents/match), representing a rate of 48.5 incidents per 1000 hours. At least 80.6% of the matches presented at least one incident, and, in more than 60%, the referee's decision was no foul. According to severity, 26.8% of the incidents were classified as having mild or high severity. Incidents involving lacerations or fracture presented higher severity compared with hits (IRR 3.45[95%CI: 1.89-6.30]). Head-to-head impacts showed an incidence of severe incidents twice as high as those involving upper extremities (IRR 2.01[95%CI:1.07-3.76]). A high number of craniofacial incidents were observed in the last FIFA competitions. Head-to-head impacts and lacerations or fractures were associated with higher incident severity.

Utility of the anterior reach Y-BALANCE test as an injury risk screening tool in elite male youth soccer players

OBJECTIVES

Examine growth and maturation trends in dynamic balance using the anterior reach Y-Balance test, and its utility as an injury risk screening tool.

DESIGN

Cross sectional and prospective cohort.

SETTING

Elite male youth soccer players.

PARTICIPANTS

346 players grouped as pre, circa or post peak height velocity (PHV).

MAIN OUTCOME MEASURES

Pre-season anterior reach absolute and relative Y-Balance test scores and seasonal prospective lower extremity injury monitoring.

RESULTS

Absolute reach distances were greatest post-PHV (p < 0.05). Relative to leg length, pre-PHV achieved the highest scores and increased between-limb differences. Significant associations between injury and anterior reach scores were present in pre (OR: 0.94, CI: 0.91-0.98, p < 0.05) and circa-PHV (OR: 1.05, 95% CI: 1.05-1.10, p < 0.05). Increased age (OR: 1.49, 95% CI: 1.04-2.13, p < 0.05) and height (OR: 1.06, 95% CI: 0.99-1.13, p = 0.82) were risk factors post-PHV. No differences in injury occurrence were shown between players with absolute reach difference >4 cm in any group.

CONCLUSIONS

Anterior reach scores increased injury risk, but associations were small and inconsistent. The Y-Balance should be used with caution as a screening tool in this cohort.

Strength and Power Training in Rehabilitation: Underpinning Principles and Practical Strategies to Return Athletes to High Performance

Injuries have a detrimental impact on team and individual athletic performance. Deficits in maximal strength, rate of force development (RFD), and reactive strength are commonly reported following several musculoskeletal injuries. This article first examines the available literature to identify common deficits in fundamental physical qualities following injury, specifically strength, rate of force development and reactive strength. Secondly, evidence-based strategies to target a resolution of these residual deficits will be discussed to reduce the risk of future injury. Examples to enhance practical application and training programmes have also been provided to show how these can be addressed.

Breaking the myths of competition: a cross-sectional analysis of injuries among CrossFit trained participants

Objectives

The purpose of this study was to examine the injury rates of individuals engaged in CrossFit training and examine the risk of injury associated with competition.

Study design

Cross-sectional analysis.

Methods

Descriptive statistics, including injury incidence and rates, were examined for individuals reporting participation in a CrossFit sanctioned competition between 2013 and 2017. To examine the odds of being injured, we considered logistic regression models, where the primary independent measure was participation length—individual measures of interest included age, sex, body mass index, CrossFit affiliation and competition status.

Results

3049 individuals completed the survey (60% completion rate). All competitors, regardless of competition level, had similar incidence of injury (χ²=1.1, p=0.571). For those who reported competing, our calculated injury rate was 0.21–0.54 injuries per 1000 training hours, while for those not competing, the injury rate was calculated as 0.39–1.30 injuries per 1000 training hours. Logistic regression demonstrated short length of participation in CrossFit training as the main factor associated with the odds of being injured (OR=1.82; 95% CI: 1.15 to 2.92). Additionally, training at an official CrossFit affiliate appeared to have a protective effect from injury (OR=0.85; 95% CI: 0.65, 1.10).

Conclusion

Our findings provide evidence of the low risk of injury related to these events. Moreover, these findings support the notion that musculoskeletal injuries may be the result of poor progression plans, which may be minimised by participating in an official CrossFit affiliate.

Risk Factors in Elite, Adolescent Male Soccer Players: Prospective Study

Purpose. To find risk factors for soccer-related musculoskeletal injuries among elite, adolescent male soccer players. Methods. Prior to the season, various physical, clinical, and functional measurements were taken. One season was used as an injury surveillance period. Then, after the season, measures of potential risk factors were compared between (1) those players who sustained musculoskeletal injuries and (2) those who remained injury free. Results. Among 61 players, 37.7% (23/61) sustained soccer-related musculoskeletal injuries. After adjusting for covariates in a logistic regression model, presence of previous hip and low back injury (adjusted odds ratio [aOR] = 8.93, P = .046) and Functional Movement Screen (FMS) scores (aOR = 1.92, P = .022) were independently associated with musculoskeletal injures. Conclusion. Elite, adolescent male soccer players with a history of hip and back injury are at greater risk of sustaining a soccer-related musculoskeletal injury. In addition, our study indicated greater risk of sustaining a future soccer-related injury as FMS scores increase.

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

OBJECTIVE

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

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

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

Previous and current injury and not training and competition factors were associated with future injury prevalence across a season in adolescent elite athletes

INTRODUCTION

Understanding the factors associated with different injury prevalence profiles in young athletes is needed for the design of tailored injury prevention programs.

OBJECTIVES

To explore the factors associated with different levels of injury prevalence in adolescent elite athletes.

METHODS

A total of 389 adolescent elite athletes (age range 15-19 years), participating in 16 different sports, were monitored repeatedly over 52 weeks using the Oslo Sports Trauma Research Center Overuse Injury Questionnaire. The athletes were grouped in three injury categories: (1) "Low injury"; (2) "Medium injury"; and (3) "High injury," based on the proportion of times the athletes reported substantial injury over the season.

RESULTS

Logistic and multinomial regression identified substantial injury the first week (odds ratio (OR) 53.9, 95% confidence interval (CI) 7.1-407.7), and an interaction between sex and previous injury (OR 3.9, 95% CI 1.1-12.4) as significant factors that increased the odds of belonging in the High injury compared to the Low injury group. A female athlete with a previous injury the last 12 months had a higher probability of belonging in the High injury group compared to a male athlete.No significant (p > .05) difference in training, sleep, or competition exposure was found across the injury category.

CONCLUSION

Current substantial injury and previous injury were strongly associated with the most injured athletes. Coaches and medical team should consider limiting the injured athlete competition exposure.

The UEFA Heading Study: Heading incidence in children's and youth' football (soccer) in eight European countries

To assess the real-life magnitude of the heading incidence in children's and youth' football in eight European countries with different "football cultures," a cross-sectional observational design, in which one match per team in 480 different teams from eight European countries (2017/18-2018/19), was recorded by video. One training session was recorded in 312 teams. Clubs with Under-10, Under-12 (female/male/mixed), and Under-16 female and male teams were eligible to participate. Heading frequencies and types were analyzed. Results are presented as headers per match/training and per team. Incidence rates (IR) per 1000 match/training hours were calculated. Under-10 teams carried out the lowest average number of headers per match (8.8), followed by Under-16 female (17.7), Under-12 (18.4), and Under-16 male (35.5). Total number of headers per match and team varied between countries. 80% of the total number of headers were single intentional headers, 12% heading duels, 3% unintentional headers by getting hit, and 5% others (trends apparent in all age groups). Three head injuries occurred during match play corresponding to an IR of 0.70 (95% CI, 0.23-2.16). The lowest number of headers per training and team was found in Under-10 (21.3), followed by Under-16 females (34.1), Under-12 (35.8), and Under-16 males (45.0). In conclusion, this large-scale study presents novel data about the number and type of headers in youth' football throughout Europe. A more precise understanding of the heading incidence, specifically in young players, is mandatory for the debate of restrictions on heading in youth football.

Injury risk and injury incidence rates in CrossFit

INTRODUCTION

Despite completing complex movements under cardiovascular and muscular fatigued conditions, CrossFit suggested safety of participants is one of the most important factors to consider. Therefore, the aim of this brief review was to provide an overview of the injury incidence and incidence rates reported in the current literature as well as to assess the injury risks associated with CrossFit.

EVIDENCE ACQUISITION

Research papers were searched using the following databases: Scopus, SPORTDiscus, Web of Science, PubMed, and MEDLINE. The search identified 718 potential articles across all databases. After the application of inclusion criteria, a total of 14 articles were included in this review.

EVIDENCE SYNTHESIS

The shoulder, spine, and knee are the most commonly injured areas in CrossFit. Injury incidence of each study ranges from 12.8-73.5% and reported injury rates ranging from 0.27-3.3/1000 training hours.

CONCLUSIONS

Reported findings in the current literature would suggest CrossFit has a relatively low injury risk. The current review highlights three important factors associated with injury incidence and incidence rates in CrossFit: 1) training frequency; 2) duration of CrossFit experience; 3) individuals that compete in CrossFit competitions. Due to recall bias and selection bias further research is warranted over a longitudinal prospective study. Additionally, further research is needed to investigate mechanisms of injury and the relationship between training load and injury risk in CrossFit.

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

OBJECTIVE

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

DESIGN

Systematic review update.

DATA SOURCES

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

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

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

METHOD

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

RESULTS

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

SUMMARY/CONCLUSION

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

The Effects of a Mindfulness-Based Program on the Incidence of Injuries in Young Male Soccer Players

The authors tested the effectiveness of a mindfulness-based program in reducing sport-injury incidence. A total of 168 young male elite soccer players were randomly assigned to mindfulness and control groups. The mindfulness group consisted of seven sessions based on the mindfulness-acceptance-commitment approach, while the control group consisted of seven presentations on sport-injury psychology. Athlete exposure and injury data were recorded during one season. State and trait mindfulness, sport anxiety, stress, and attention control of participants were assessed. Number of injuries, average of injuries per team, and days lost to injury in the mindfulness group were significantly lower than those in the control group. Mindfulness and attention control were lower and sport anxiety and stress were higher in injured players than in noninjured players. Psychological variables were associated with injury. Mindfulness training may reduce the injury risk of young soccer players due to improved mindfulness and attention control and reduced sport anxiety.

Characteristics and associated factors of physical activity-related injuries among university students in southern China

This cross-sectional study aimed to describe the characteristics of physical activity-related injury (PARI) and to explore its associated factors among university students in Chaoshan district. Selected from the baseline survey in March and April, 434 students graded 1-3 from two universities were interviewed face-to-face in April and May 2017. Socio-demographics, physical activity (PA) participation, risk-taking behaviors, and PARI occurrences in the past 12 months were collected. Group Lasso logistic regression was applied to identify the risk factors of PARI. Totally, 317 PARI episodes were reported by 184 subjects with an overall injury risk of 0.73 injuries/student/year (males: 1.00, females: 0.63) and an injury incidence density of 0.81 injuries per 1000 PA exposure hours (males: 1.13, females: 0.69). Most injuries involved the lower extremities and were sprains and strains. Males, sports team members, and those with high-risk rebellious and anti-social behaviors were more likely to sustain PARI compared to their counterparts. Those who participated in vigorous-intensity PA with longer duration (particularly ≥ 150 min/week) were at a higher risk for PARI. This study indicates that PARI is a health concern among university students and great efforts should be taken to prevent them from PARI when promoting a physically active lifestyle.

Match Situations Leading to Head Injuries in Professional Male Football (Soccer)-A Video-Based Analysis Over 12 Years

OBJECTIVE

To identify risk situations promoting head injuries in professional male football (soccer) and to investigate the impact of a rule change in 2006 punishing elbow-head contacts.

DESIGN

Analysis of video sequences of head events leading to head injury.

PARTICIPANTS

Professional football players of the first male German Bundesliga.

MAIN OUTCOME MEASURES

Observational criteria of head impacts on video recordings (players' actions preceding head injuries, foul play-referee's decision and assessment of rater, ball possession, on-pitch medical treatment, and consequences of head impact).

RESULTS

Three hundred thirty-four head injuries were reported in kicker Sportmagazin corresponding to an incidence rate of 2.25 (95% confidence interval 2.01-2.51) per 1000 player match hours. The injured player predominantly jumped (60%), headed the ball (36%), or ran forwards (20%); the noninjured players mainly jumped (64%), headed the ball (27%), or raised the elbow to the head (23%). Free ball situations (2 players challenge for the ball) caused most of the head injuries (81%). The players' action "raising the elbow" during a head injury seemed to be lower after the rule change.

CONCLUSIONS

Jumping for the ball with the intention of heading is the predominant action associated with head injury risk. Head injuries occur most often when players challenge for the ball in a header duel. As head injuries bear the potential risk of long-term health sequelae, the identification of situational circumstances is essential to develop preventative means in the future.

A Longitudinal Investigation of Muscle Injuries in an Elite Spanish Male Academy Soccer Club: A Hamstring Injuries Approach

The aims of this study were to analyze the muscle injury incidence in an elite Spanish soccer academy during three consecutive seasons attending to different chronological age groups (i.e., U14, U16, U19 and senior) and to examine the hamstring injury incidence in this elite soccer academy. Elite male youth soccer players (227) participated in this study. A total of 207 time-loss injuries (i.e., injuries that involve at least one absence day) were observed during this study period. The overall incidence rate of muscle injury was 1.74 muscle injuries/1000 h. In addition, higher muscle injury incidence was observed during match play in comparison to training sessions (6.78 vs. 3.20 muscle injuries/1000 h, p < 0.05). The oldest age group presented the highest injury rate (2.73 muscle injuries/1000 h, p < 0.05), with the burden (i.e., number of absence days per 1000 h of exposure) peak values recorded in the U16 age group (26.45 absence days/1000 h). In addition, muscle tears accounted for the greatest percentage of muscle injuries (43.5%), and the most frequent anatomical site of injury was the hamstring (30.4%). Muscle tear was the most common type of hamstring injury (49.2%), with the biceps femoris the most commonly injured muscle of the hamstring complex (39.7%). Fullbacks (FB), wide midfielders (WM) and forwards (F) suffered a greater number of hamstring injuries. Hamstring injury incidence showed a seasonal variation, as indicated by peaks in August and October. Specifically, the highest injury incidence was observed in the final part of each period during match play. These results reinforce the necessity to implement individual preventive strategies according to each specific injury profile across the youth soccer development phase.

Improving predictor selection for injury modelling methods in male footballers

Objectives

This objective of this study was to evaluate whether combining existing methods of elastic net for zero-inflated Poisson and zero-inflated Poisson regression methods could improve real-life applicability of injury prediction models in football.

Methods

Predictor selection and model development was conducted on a pre-existing dataset of 24 male participants from a single English football team's 2015/2016 season.

Results

The elastic net for zero-inflated Poisson penalty method was successful in shrinking the total number of predictors in the presence of high levels of multicollinearity. It was additionally identified that easily measurable data, that is, mass and body fat content, training type, duration and surface, fitness levels, normalised period of 'no-play' and time in competition could contribute to the probability of acquiring a time-loss injury. Furthermore, prolonged series of match-play and increased in-season injury reduced the probability of not sustaining an injury.

Conclusion

For predictor selection, the elastic net for zero-inflated Poisson penalised method in combination with the use of ZIP regression modelling for predicting time-loss injuries have been identified appropriate methods for improving real-life applicability of injury prediction models. These methods are more appropriate for datasets subject to multicollinearity, smaller sample sizes and zero-inflation known to affect the performance of traditional statistical methods. Further validation work is now required.

Meniscal Injuries in the Olympic and Elite Athletes

INTRODUCTION

Elite and Olympian athletes are often stretching the upper limits of normal physiology and biomechanics of the musculoskeletal system in their efforts to excel in their sport. For them to get back to their sport at the same level after injury, the management, repair techniques, and rehabilitation protocols should be robust to permit healing of tissues to allow supra-normal loading and performance. The knee and the meniscus are commonly injured in these sports. Yet, the incidence, mechanisms, types of injuries to the meniscus, and their management are not known across different sports in the Olympics.

METHODS

We set out to look into the incidence and the trends of publications on meniscal injuries of the knee in Olympic games. A search of the PubMed and Scopus for these injuries using a search strategy gave 79 and 116 articles, respectively.

RESULTS

There were very few publications giving the incidence of meniscal injuries in the Olympics. Football is the sport with the highest rate of meniscal injuries. Different sports are popular in different countries, and depending on the popularity and the country reporting these injuries, incidences differed. There was data available from India and Brazil for Elite athlete from diverse sports, whereas most data from other countries were for football and soccer. Knee was found to be the second most commonly injured part of the body in both Winter and Summer Olympics as well as the Youth Winter Olympics. Data were not available from the Youth Summer Olympics to make any conclusions. The number of publications on this topic is low. We presented the timeline of publications and citations of articles on this topic. The top country, language, journal, university, and author were USA, English, American Journal of Sports Medicine, Hospital of Special Surgery in New York and Brophy RH, respectively. The data on the risk factors for meniscal injuries were analyzed, discussed, and presented for football, as this was the most extensively studied sport.

CONCLUSIONS

Even though the knee is one of the commonly injured anatomical locations in elite athletes, there is a lack of literature on meniscal injuries in this subset of population. We looked at possible reasons and made recommendations to improve data collection on these injuries.

Injury epidemiology in Australian male professional soccer

OBJECTIVES

To describe the injury epidemiology of the Australian male professional soccer league (A-League) over 6 consecutive seasons.

DESIGN

Prospective observational cohort study.

METHODS

Match-loss injury data was collected from each A-League club (n=10) for each competition match (n=27/season) over 6 seasons (2012/13-2017/18). Injuries were collected weekly through a standardised protocol and were classified by setting, mechanism, severity, the type and location on the body. Generalised Linear Models were used to estimate the injury incidences (injury/round/season), whilst rate ratios were reported for total injuries and within abovementioned injury classifications.

RESULTS

Overall injury incidence was not significantly different ranging from 4.8 (95%CI:4.1-5.8) to 6.7 (95%CI:5.8-7.8) between seasons 2012/13 to 2017/18 (p>0.05). Match injuries remained stable whilst training injuries decreased across the 6 seasons (exp(β) 0.59[95%CI:0.36-1.0]; p=0.04). Respectively, contact and non-contact injuries were not significantly different across the 6 seasons, although non-contact injuries were more common than contact injuries (p>0.05). Mild severity injuries decreased (exp(β) 0.64 [95%CI:0.4-0.9];p=0.02), whilst moderate severity injuries increased (exp(β) 1.7 [95%CI:1.0-2.8];p=0.04) in season 2017/18 compared to 2012/13. The most common injuries were at thigh (23-36%), of which the majority were hamstring injuries (54%-65%) of muscle/tendon type (50-60% of total injuries/season). Injuries remained stable across the seasons by type and location (p>0.05 and p>0.05, respectively).

CONCLUSIONS

Injury rates, mechanisms, locations and types have remained relatively stable over recent seasons of the A-League. Current Australian professional soccer league medical practices may have contributed to the stability of injury rates.

Effectiveness of an Unexpected Disturbance Program in the Early Stage of Rehabilitation in Athletes With Unilateral Knee Ligament Injury

CONTEXT

Sensorimotor, proprioceptive, and neuromuscular programs are critical for the successful rehabilitation of injured athletes, and these decrease reinjury rates.

OBJECTIVE

To investigate the effects of an unexpected disturbance program (UDP) on balance and unilateral strength metrics in athletes with unilateral knee ligament injury.

DESIGN

A 3-week parallel-group experimental design consisting of 9 rehabilitation sessions.

SETTING

National Sports Institute.

PARTICIPANTS

Twenty-one national-level athletes (age 21.4 [4.4] y, body mass 63.9 [10.8] kg, height 169.0 [10.2] cm) who had sustained a unilateral knee ligament injury.

INTERVENTION

An UDP program designed to evoke rapid sensorimotor responses was compared with traditional training and a nonexercise control group.

MAIN OUTCOME MEASURES

Unilateral total, anteroposterior, and mediolateral sway with eyes open and closed and unilateral isometric strength.

RESULTS

Traditional exercises tended to outperform the UDP when unilateral balance testing was performed with eyes open; however, balance improvement following UDP tended to be greater in the eyes-closed condition. Significant strength gains in both the injured and uninjured legs were only observed following the UDP. This increase in unilateral isometric strength was 23.4 and 35.1 kg greater than the strength improvements seen in the traditional rehabilitation and control groups (P < .05).

CONCLUSIONS

UDP could improve neural aspects of rehabilitation to improve rehabilitation outcomes by improving strength, sensorimotor function, and proprioception. Given the complementary adaptations, an UDP could provide an effective adjunct to traditional rehabilitation protocols and improve return-to-play outcomes.

Prevention of severe knee injuries in men's elite football by implementing specific training modules

PURPOSE

Injury prevention of knee injuries by means of training and warm-up exercises has been investigated in several studies in amateur football. However, the number of investigations in elite football is limited despite the currently higher injury incidence of severe knee injuries. Therefore, the purpose of this study was to investigate whether specifically adapted preventive training modules may reduce severe knee injuries in elite football.

METHODS

In a prospective controlled cohort study of elite football players in Germany, an injury prevention programme with 5 modules was implemented in the season of 2015-2016. The training modules were specifically adapted to this skill level and based on scientific evidence, team coach preferences, and the specific environment of this playing level. Of the 62 teams taking part in this study, 26 used the new trainings modules and 36 continued their standard programme as a control group. Success of the programme was documented by means of an injury report over one season. The primary outcome was reduction in severe knee injuries.

RESULTS

A pre-seasonal investigation had identified five modules to be implemented in the training routine. Postural stability, mobilisation of lower extremity joints, leg and trunk stabilisation, jumping, and landing exercises as well as agility movements were incorporated into the programme to prevent severe knee injuries in elite football. Over the season, the study group (529 players) with the adapted training modules had sustained 52 severe knee injuries (incidence: 0.38 per 1000 h football exposure; prevalence: 9.8%) compared to 108 severe knee injuries in the control group (601 players) using the standard programme (incidence: 0.68 per 1000 h football exposure; prevalence: 18.0%; p < 0.05). The overall injury incidence for any other type of injury was comparable between the two groups (3.3 vs. 3.4 in h 1000 football, n.s.).

CONCLUSION

Appropriate preventive training modules reduce severe knee injuries in elite football significantly. The key for the sustainability of preventive training measures are programmes specifically adapted to the demands of the playing level and to the preferences of the coaches LEVEL OF EVIDENCE: II.

Rapid hamstrings to quadriceps ratio at long muscle lengths in professional football players with previous hamstring strain injury

Hamstring strain injuries (HSI) are the most common injury in male professional football and are potentially a primary risk factor to re-injury. Although the isokinetic strength ratios have often been used to identify strength imbalances that can augment the risk of injury in football players, the rate of torque development hamstring to quadriceps ratio (RTD H/Q) has rarely been considered in previous reports. Furthermore, little consideration has been given to selective hamstring lengths (30° of knee flexion) and its influence on torque production. The aim of this study was to investigate the RTD H/Q at long hamstring lengths, conventional (concentric/concentric) and functional (eccentric/concentric) H/Q ratios in football players with and without previous HSI. Twenty-four professional male football players (12 and 12 without previous HSI) performed maximal voluntary isometric contractions at long hamstring lengths (knee and hip flexed at 30° and 85°, respectively) and isokinetic concentric and eccentric contractions at 180°.s^-1 and 60°.s^-1. Conventional and functional H/Q ratios based on peak torque throughout the entire isokinetic range of motion and at long hamstring lengths were calculated. The RTD H/Q was extracted at long hamstring lengths in incrementing time periods of 50 milliseconds (ms) from the onset of contraction (50-250 ms). No significant differences were found between groups in any H/Q ratios studied. However, small effects (d = 0.4) were found in previously injured hamstrings to lower RTD H/Q at 50 ms and flexor eccentric torque. Previous HSI group showed small to moderate (0.4 > d < 0.6) higher RTD H/Q in late time intervals (>100 ms).

Epidemiology of hip and groin injuries in Swedish male first football league

PURPOSE

This study aimed to investigate the incidence, pattern, and burden of hip/groin injuries in Swedish professional male football players over five consecutive seasons.

METHODS

Injury history from 16 football teams in the Swedish male first football league was evaluated during five consecutive seasons. The team's medical staff recorded team exposure and time-loss injuries prospectively between 2012 and 2016.

RESULTS

In total, 467 time-loss injuries located in the hip/groin area were recorded among 1,687 professional male football players, with an overall incidence and burden of 0.82/1,000 h and 15.6/1,000 h, respectively. There appeared to be an increased risk of hip/groin injuries during the last two seasons (2015-2016); however, the difference was not statistically significant (n.s). Recurrent injury rate was relatively low (14%), and overuse injuries accounted for the majority of injuries and absence days. Muscle injuries were the main injury type, while kicking and sprinting/running were the primary causes of injury. Goalkeepers had the lowest percentage of injuries and absence days.

CONCLUSION

Hip/groin injuries are a substantial problem in football, but does not seem to be an increasing phenomenon in the Swedish male first football league. Index and overuse injuries accounted for the majority of injuries and absence days. Thus, the focus should be on preventing hip/groin injuries to lower the injury rate. These new findings should be taken into consideration when designing and implementing preventive training interventions.

LEVEL OF EVIDENCE

II.

Artificial intelligence for team sports: a survey

The sports domain presents a number of significant computational challenges for artificial intelligence (AI) and machine learning (ML). In this paper, we explore the techniques that have been applied to the challenges within team sports thus far. We focus on a number of different areas, namely match outcome prediction, tactical decision making, player investments, fantasy sports, and injury prediction. By assessing the work in these areas, we explore how AI is used to predict match outcomes and to help sports teams improve their strategic and tactical decision making. In particular, we describe the main directions in which research efforts have been focused to date. This highlights not only a number of strengths but also weaknesses of the models and techniques that have been employed. Finally, we discuss the research questions that exist in order to further the use of AI and ML in team sports.

PREVALENCE OF HAMSTRING INJURIES IN SUMMER LEAGUE BASEBALL PLAYERS

BACKGROUND AND PURPOSE

Hamstring injuries (HSI) occur more commonly in baseball than are often appreciated and can impact the potential career of a player. Little is known about the historical incidence of these injuries in summer league players preparing for their upcoming collegiate season or being drafted by major league team(s). Summer league baseball players have a high historical incidence of HSI which are often unknown at the start of their summer league play. The purpose of this study was to administer a validated questionnaire to assess various factors regarding the prevalence of prior hamstring injuries, current symptoms of posterior thigh pain or hamstring injuries in amateur summer league baseball players, and to provide details on the injury history, time lost from injury, injury reocurrence, position, individual player physical characteristics and physical activities that might be associated with those injuries.

STUDY DESIGN

Cross-sectional Observational Study.

METHOD

A self-reported, validated questionnaire regarding the history, prevalence, reoccurrence and functional impact of HSI and posterior thigh pain was administered to and completed by 201 out of 251 summer league baseball players associated with the Cape Cod League and the Northwoods League at the start of the 2013-2015 seasons. The questionnaire was administered by certified athletic trainers associated with each team. Participation was voluntary and informed consent was obtained from all players.

RESULTS

Forty seven out of 201 players surveyed reported a HSI history. Sixty-six percent of these players (N = 31) reported unilateral injuries and 34% (N = 16) reported bilateral injuries. Reoccurrence rate was 27.7% across all players. Approximately 1/3rd of all position players (catchers 33.3%, infielders 32.6% and outfielders 31.6%) reported a HSI history compared to 12.9% of all pitchers. Significant differences (p<.05) existed between the HSI and Non-HSI groups for self-reported symptoms, soreness, and pain, as well as function and quality of life. Within the HSI history group, players who batted left and threw right reported the most injuries.

CONCLUSION

A large number of position players and pitchers who report for summer league baseball have a history of posterior thigh pain and HSI. Those with prior injuries have a high reoccurrence rate. Position players have a higher incidence of injury than do pitchers.

LEVEL OF EVIDENCE

3.

Exercise interventions to prevent hamstring injuries in athletes: A systematic review and meta-analysis

The aim of this meta-analysis was to assess the effectiveness of exercise-based interventions for prevention of hamstring injuries in sport. PubMed, Cochrane Central Register of Controlled Trials, Web of Science, ResearchGate, CINAHL, PEDro, ScienceDirect and Google Scholar databases were searched for randomized controlled trials and prospective cohort studies exploring the effects of exercise interventions on hamstring injury incidence. Subgroup analyses were performed to determine effects of several independent variables related to the interventions. Altogether, 17 studies were included. Exercise interventions decreased hamstring injury risk (RR = 0.49; 95%CI = 0.40-0.59; p < 0.001). There were similar effects found for interventions performed ≤2 times per week (RR = 0.35; 95%CI = 0.15-0.82) and the interventions performed >2 times per week (RR = 0.44; 95%CI = 0.31-0.61). Similarly, there were similar effects found for the interventions with progressive increase in load (RR = 0.53; 95%CI = 0.37-0.74) and the interventions with constant loads (RR = 0.46; 95%CI = 0.36-0.58). Other subgroup analyses (intervention supervision, sport type, inclusion of Nordic hamstring exercise and type of the trial) also showed no indications on specific characteristics of the interventions, that increase the preventive effects. Our findings showed that hamstring injury incidence can be decreased with exercise-based interventions, and that weekly frequency and load progression are not among the most important variables to consider in prevention programmes design.

Janitor ergonomics and injuries in the safe workload ergonomic exposure project (SWEEP) study

INTRODUCTION

A Minnesota union identified to researchers at the University of Minnesota a concern relevant to a possible relation between their daily workload and outcome of occupational injuries among a population of janitors.

OBJECTIVE

To assess if the ergonomic workload is related to injuries among janitors.

METHODS

Following an initial group discussion among janitors, which identified common and hazardous tasks potentially leading to occupational injuries, a questionnaire was developed, pre-tested, and distributed to the janitors. Questions addressed various exposures, including workload, and comprehensive information regarding injury occurrence over two six-month sequential periods (May 2016-October 2016, November 2016-April 2017). Quantitative ergonomic analyses were performed on a sub-group of janitors (n = 30); these included data collection to identify Borg Perceived Exertion (Borg) and Rapid Entire Body Assessment (REBA) scores. Descriptive, multivariable with bias adjustment analyses were conducted on the resulting data.

RESULTS

Eight tasks were found to be common for janitors. All average REBA scores for the tasks were identified in the high-risk category. The task of repeatedly emptying small trash cans (<25lb) was significantly related to injuries. Average Borg scores fell between the very light perceived exertion and somewhat difficult perceived exertion categories. Multivariable regression analyses indicated that age-sex-standardized ergonomic workload, measured by task frequencies and REBA or Borg scores, was positively related to injury occurrence.

CONCLUSIONS

Standardized ergonomic workload was positively related to injury occurrence. This information serves as a basis for further research and potential intervention efforts.

Prevalence and Factors Associated With Injuries in Elite Spanish Volleyball

CONTEXT

Prevalence studies have been carried out widely on elite volleyball players. However, the extent to which specific prevention strategies are used and the influence of the sport equipment on the occurrence of injuries have been sparsely investigated.

OBJECTIVE

To describe the prevalence of injuries sustained during 1 season in elite Spanish volleyball leagues and to investigate the association of injuries with factors such as player court position, injury mechanism, type of shoes used when playing, or participation in prevention activities.

DESIGN

Descriptive cross-sectional epidemiology study: observational study.

SETTING

European elite professional volleyball.

PARTICIPANTS

Professional volleyball players from the elite Spanish volleyball league.

MAIN OUTCOME MEASURES

A self-report questionnaire assessed the presence of injury during a volleyball season. Questions included the type of injury, its anatomic location, participation in prevention strategies, shoe type, the injury mechanism, the season period, the period of leave, and the treatment received.

RESULTS

In total, 490 players (71.2% response rate) completed and returned the questionnaire. The injury prevalence was 66.9%, and the average of injuries per player was 0.94 (0.85) (range: 0-4). Most Spanish elite volleyball players participated in prevention programs during the season (90.3%) and played volleyball with low-top shoes (83.6%), but these factors were not associated with the prevalence of injuries (P > .05). The anatomic regions with the most injuries were the ankle, knee, and shoulder; the most common types of injury were sprains, tendinopathies, and strains, usually occurring during blocking and attack actions during the in-season period.

CONCLUSIONS

Despite most elite volleyball players participating in prevention programs, the results reveal a high injury prevalence. Further prospective research on the effectiveness of prevention strategies in elite volleyball is needed.

Comprehensive movement system screening tool (MSST) for athletes: Development and measurement properties

OBJECTIVES

Non-traumatic extremity injuries are particularly common in sports, representing a significant economic, academic, and psychosocial burden on athletes. Proposed musculoskeletal risk factors for increased injury and decreased performance in athletes include movement pattern inefficiency, decreased regional stability, decreased mobility, and asymmetrical movement. The Movement System Screening Tool (MSST) is a comprehensive screening tool designed to assess these factors. Thus, the purpose of this study was to describe the development and determine the content and construct validity and inter-rater reliability of the MSST.

METHODS

A modified Delphi panel of experts determined content validity. 80 athletes (40 with and 40 without a current non-traumatic shoulder injury) completed 21 clinical tests, with exploratory factor analysis and known group analysis performed to determine construct validity. Two independent raters were used to establish individual item and composite score inter-rater reliability.

RESULTS

Exploratory factor analysis identified three of the four apriori constructs over 7 factors (14 tests), representing 63% of the variance. Known group analysis revealed a significantly lower composite score in athletes with vs. without a current non-traumatic shoulder injury (56.9±5.8 vs. 62.7±4.5, respectively). A preliminary cut score of 62 was chosen with sensitivity of 85% and specificity of 44%. Composite score inter-rater reliability was excellent ICC _(2,1)=0.94, 95% CI (0.91, 0.96) and item reliability ranged from κ=.57 to 1.00.

CONCLUSIONS

The MSST possesses constructs representative of injury risk and measurement properties acceptable for use in clinical settings. Comprehensive screens with construct validity and known measurement error are needed not only to identify athletes at risk of injury, but also provide an instrument that can be used in studies that seek to validate training approaches proposed to change movement impairment and injury risk in athletes.

Prevalence of Sports-Related Injuries and Illnesses in Paralympic Athletes

BACKGROUND

With increased participation in Paralympic sports, the burden of sports-related injuries and illnesses may increase. However, there is limited knowledge about the epidemiology of sports-related injuries and illnesses in Paralympic sports (SRIIPS).

OBJECTIVE

To describe among Swedish Paralympic athletes the 1-year retrospective period prevalence of severe SRIIPS and the point prevalence of all SRIIPS and to examine differences in prevalence proportions between athletes with different impairments, behaviors, and sport characteristics.

DESIGN

Cross-sectional study.

SETTING

Swedish Paralympic Programme.

PARTICIPANTS

One hundred and four Paralympic athletes with visual, physical, and intellectual impairment.

METHODS

An eHealth application adapted to Paralympic athletes was used to collect self-report data on existing and previous SRIIPS, as well as impairment, behavior, and sport characteristics.

MAIN OUTCOME MEASUREMENTS

One-year retrospective period prevalence and point prevalence.

RESULTS

The period prevalence of severe injuries was 31% (95% CI 23-40) and the point prevalence 32% (95% CI 24-41). The period prevalence of severe illnesses was 14% (95% CI 9-23), and 13% of the athletes (95% CI 8-22) reported a current illness. More severe injuries (P <.05) were reported by athletes aged 18 to 25 years, not using assistive device, having pain during sport, using analgesics, continuing training injured, and feeling guilt when missing exercise. Athletes who reported a previous severe injury, having pain in daily life and during sport, using analgesics, and being upset when unable to exercise had a higher prevalence of current injuries (P <.05). Being female, reporting previous severe illness, using prescribed medication, and feeling anxious/depressed were features associated with ongoing illnesses (P <.05).

CONCLUSION

Paralympic athletes report a high prevalence of SRIIPS. Behavioral and psychological aspects as well as pain and use of medication appear to be associated with the occurrence of SRIIPS. The results imply that factors leading to SRIIPS are complex and call for a broad biopsychosocial approach when developing preventive measures.

LEVEL OF EVIDENCE

III.

Hamstring muscles' function deficit during overground sprinting in track and field athletes with a history of strain injury

In this study, we aimed to clarify the characteristics of neuromuscular function, kinetics, and kinematics of the lower extremity during sprinting in track and field athletes with a history of strain injury. Ten male college sprinters with a history of unilateral hamstring injury performed maximum effort sprint on an athletic track. The electromyographic (EMG) activity of the long head of the biceps femoris (BFlh) and gluteus maximus (Gmax) muscles and three-dimensional kinematic data were recorded. Bilateral comparisons were performed for the EMG activities, pelvic anterior tilt angle, hip and knee joint angles and torques, and the musculotendon length of BFlh. The activity of BFlh in the previously injured limb was significantly lower than that in the uninjured limb during the late-swing phase of sprinting (p < 0.05). However, the EMG activity of Gmax was not significantly different between the previously injured and uninjured limbs. Furthermore, during the late-swing phase, a significantly more flexed knee angle (p < 0.05) and a decrease in BFlh muscle length (p < 0.05) were noted in the injured limb. It was concluded that previously injured hamstring muscles demonstrate functional deficits during the late swing phase of sprinting in comparison with the uninjured contralateral muscles.

Epidemiology of physical activity-related injuries in Chinese university students

Knowledge gaps of the physical activity-related injury (PARI) problem among general undergraduates exist. We conducted a study in four universities, where 1421 students graded 1-3 were interviewed face-to-face during April and May after their completion of the baseline survey in March and April 2017, aiming to describe the incidence and characteristics of PARI. PARI experience and physical activity (PA) participation in the past 12 months were collected. Injury incidence density (IID) and risk, and injury characteristics were evaluated for the overall sample and by gender. Pearson chi-square or Fisher's exact tests and independent-sample t tests were used to test between-group differences. We found that 486 PARIs were reported totally by 289 participants, with an overall IID of 0.57 per 1000 hours of exposure (males: 1.07, females: 0.45) and an injury risk of 0.34 injuries/student/y (males: 0.52; females: 0.28). Higher IIDs were found in roller skating, football, and basketball. The majority of injuries occurred outdoors and involved the lower extremities, with sprain and strain being the primary injury types. Moreover, most injuries were new, acute, and happened in non-contact situations. Of all injuries, 52.1% required medical attention and 64.6% resulted in inactivity of one or more days. Some significant differences were observed between males and females. Our study indicates that PARI is a public health concern among Chinese university students, which can provide direction for targeted prophylactic interventions to underpin the sex-specific injury mechanism to reduce PARI.