Complex systems approach for sports injuries: moving from risk factor identification to injury pattern recognition-narrative review and new concept.

Injury prediction is one of the most challenging issues in sports and a key component for injury prevention. Sports injuries aetiology investigations have assumed a reductionist view in which a phenomenon has been simplified into units and analysed as the sum of its basic parts and causality has been seen in a linear and unidirectional way. This reductionist approach relies on correlation and regression analyses and, despite the vast effort to predict sports injuries, it has been limited in its ability to successfully identify predictive factors. The majority of human health conditions are complex. In this sense, the multifactorial complex nature of sports injuries arises not from the linear interaction between isolated and predictive factors, but from the complex interaction among a web of determinants. Thus, the aim of this conceptual paper was to propose a complex system model for sports injuries and to demonstrate how the implementation of complex system thinking may allow us to better address the complex nature of the sports injuries aetiology. According to this model, we should identify features that are hallmarks of complex systems, such as the pattern of relationships (interactions) among determinants, the regularities (profiles) that simultaneously characterise and constrain the phenomenon and the emerging pattern that arises from the complex web of determinants. In sports practice, this emerging pattern may be related to injury occurrence or adaptation. This novel view of preventive intervention relies on the identification of regularities or risk profile, moving from risk factors to risk pattern recognition.

Examining the effect of the injury definition on risk factor analysis in circus artists.

A secondary data analysis of a prospective cohort study was conducted to explore how different definitions of injury affect the results of risk factor analyses. Modern circus artists (n=1281) were followed for 828,547 performances over a period of 49 months (2004-2008). A univariate risk factor analysis (age, sex, nationality, artist role) estimating incidence rate ratios (IRR) with 95% confidence intervals (95% CI) was conducted using three injury definitions: (1) medical attention injuries, (2) time-loss injuries resulting in ≥1 missed performances (TL-1) and (3) time-loss injuries resulting in >15 missed performances (TL-15). Results of the risk factor analysis were dependent on the injury definition. Sex (females to male; IRR=1.13, 95% CI; 1.02-1.25) and age over 30 (<20 years to >30 years; IRR=1.37, 95% CI; 1.07-1.79) were risk factors for medical attention injuries only. Risk of injury for Europeans compared with North Americans was higher for TL-1 and TL-15 injuries compared with medical attention injuries. Finally, non-sudden load artists (low-impact acts) were less likely than sudden load artists (high-impact acts) to have TL-1 injuries, but the risk of medical attention injuries was similar. The choice of injury definition can have effects on the magnitude and direction of risk factor analyses.

Proceedings from the Ice Hockey Summit on concussion: a call to action.

The objective of this proceedings is to integrate the concussion in sport literature and sport science research on safety in ice hockey to develop an action plan to reduce the risk, incidence, severity, and consequences of concussion in ice hockey. A rationale paper outlining a collaborative action plan to address concussions in hockey was posted for review two months prior to the Ice Hockey Summit: Action on Concussion. Focused presentations devoted specifically to concussion in ice hockey were presented during the Summit and breakout sessions were used to develop strategies to reduce concussion in the sport. This proceedings and a detailed scientific review (a matrix of solutions) were written to disseminate the evidence-based information and resulting concussion reduction strategies. The manuscripts were reviewed by the authors, advisors and contributors to ensure that the opinions and recommendations reflect the current level of knowledge on concussion in hockey. Six components of a potential solution were articulated in the Rationale paper and became the topics for breakout groups that followed the professional, scientific lectures. Topics that formed the core of the action plan were: metrics and databases; recognizing, managing and return to play; hockey equipment and ice arenas; prevention and education; rules and regulations; and expedient communication of the outcomes. The attendees in breakout sessions identified action items for each section. The most highly ranked action items were brought to a vote in the open assembly, using an Audience Response System (ARS). The strategic planning process was conducted to assess: Where are we at?; Where must we get to?; and What strategies are necessary to make progress on the prioritized action items? Three prioritized action items for each component of the solution and the percentage of the votes received are listed in the body of this proceedings.

The effectiveness of a neuromuscular prevention strategy to reduce injuries in youth soccer: a cluster-randomised controlled trial.

BACKGROUND: Soccer is a leading sport for participation and injury in youth. OBJECTIVE: To examine the effectiveness of a neuromuscular prevention strategy in reducing injury in youth soccer players. DESIGN: Cluster-randomised controlled trial. SETTING: Calgary soccer clubs (male or female, U13-U18, tier 1-2, indoor soccer). PARTICIPANTS: Eighty-two soccer teams were approached for recruitment. Players from 60 teams completed the study (32 training (n=380), 28 control (n=364)). INTERVENTION: The training programme was a soccer-specific neuromuscular training programme including dynamic stretching, eccentric strength, agility, jumping and balance (including a home-based balance training programme using a wobble board). The control programme was a standardised warm-up (static and dynamic stretching and aerobic components) and a home-based stretching programme. MAIN OUTCOME MEASURES: Previously validated injury surveillance included injury assessment by a study therapist. The injury definition was soccer injury resulting in medical attention and/or removal from a session and/or time loss. RESULTS: The injury rate in the training group was 2.08 injuries/1000 player-hours, and in the control group 3.35 injuries/1000 player-hours. Based on Poisson regression analysis, adjusted for clustering by team and covariates, the incidence rate ratios (IRR) for all injuries and acute onset injury were 0.62 (95% CI 0.39 to 0.99) and 0.57 (95% CI 0.35 to 0.91). Point estimates also suggest protection of lower extremity, ankle and knee sprain injuries (IRR=0.68 (95% CI 0.42 to 1.11), IRR=0.5 (95% CI 0.24 to 1.04) and IRR=0.38 (95% CI 0.08 to 1.75)). CONCLUSIONS: A neuromuscular training programme is protective of all injuries and acute onset injury in youth soccer players.

Is protective equipment useful in preventing concussion? A systematic review of the literature.

OBJECTIVE: To determine if there is evidence that equipment use reduces sport concussion risk and/or severity. DATA SOURCES: 12 electronic databases were searched using a combination of Medical Subject Headings and text words to identify relevant articles. REVIEW METHODS: Specific inclusion and exclusion criteria were used to select studies for review. Data extracted included design, study population, exposure/outcome measures and results. The quality of evidence was assessed based on epidemiologic criteria regarding internal and external validity (ie, strength of design, sample size/power calculation, selection bias, misclassification bias, control of potential confounding and effect modification). RESULTS: In total, 51 studies were selected for review. A comparison between studies was difficult due to the variability in research designs, definition of concussion, mouthguard/helmet/headgear/face shield types, measurements used to assess exposure and outcomes, and variety of sports assessed. The majority of studies were observational, with 23 analytical epidemiologic designs related to the subject area. Selection bias was a concern in the reviewed studies, as was the lack of measurement and control for potentially confounding variables. CONCLUSIONS: There is evidence that helmet use reduces head injury risk in skiing, snowboarding and bicycling, but the effect on concussion risk is inconclusive. No strong evidence exists for the use of mouthguards or face shields to reduce concussion risk. Evidence is provided to suggest that full facial protection in ice hockey may reduce concussion severity, as measured by time loss from competition.

Sport concussion assessment tool: baseline values for varsity collision sport athletes.

OBJECTIVE: To determine baseline symptom and neurocognitive norms for non-concussed and previously concussed varsity athletes using the sport concussion assessment tool (SCAT). STUDY DESIGN: Descriptive cohort study. SETTING: University of Calgary. SUBJECTS: 260 male and female university football, ice hockey and wrestling athletes over three seasons (2005-7). METHODS: A baseline SCAT was completed during preseason medical evaluation. Subjects were grouped as follows: all participants, men, women, never concussed (NC) and previously concussed (PC). MAIN RESULTS: The mean age of participants was 20.5 years (range 17-32). In total, 41.2% of all athletes had a total post-concussion symptom scale (PCSS) score of 0. The mean baseline PCSS scores were as follows: all participants 4.29; men 3.52; women 6.39; NC 3.75 and PC 5.25. The five most frequently reported symptoms for all athletes were fatigue/low energy (37% of subjects), drowsiness (23%), neck pain (20%), difficulty concentrating (18%) and difficulty remembering (18%). The median immediate recall score was 5/5 for all groups. Women scored a median of 5/5 on delayed recall, whereas all remaining groups scored a median of 4/5. Months in reverse order were successfully completed by 91.6% of subjects. All participants, women and PC scored a median of 6 on reverse digits, whereas men and NC scored a median of 5. CONCLUSIONS: The mean SCAT baseline PCSS score was approximately 5, although just under half of the athletes scored 0. Female athletes scored better on tests of neurocognitive function. PC athletes scored better than NC athletes on all neurocognitive tests except delayed five-word recall.

Consensus statement on injury definitions and data collection procedures for studies of injuries in rugby union.

Wide variations in the definitions and methodologies used for studies of injuries in rugby union have created inconsistencies in reported data and made interstudy comparisons of results difficult. The International Rugby Board established a Rugby Injury Consensus Group (RICG) to agree on appropriate definitions and methodologies to standardize the recording of injuries and reporting of studies in rugby union. The RICG reviewed the consensus definitions and methodologies previously published for football (soccer) at a meeting in Dublin to assess their suitability for and application to rugby union. Following this meeting, iterative draft statements were prepared and circulated to members of the RICG for comment; a follow-up meeting was arranged in Dublin at which time all definitions and procedures were finalized. At this stage, all authors confirmed their agreement with the consensus statement. The agreed-on document was presented to and approved by the International Rugby Board Council. Agreement was reached on definitions for injury, recurrent injury, nonfatal catastrophic injury, and training and match exposures together with criteria for classifying injuries in terms of severity, location, type, diagnosis, and causation. The definitions and methodology presented in this consensus statement for rugby union are similar to those proposed for football. Adoption of the proposals presented in this consensus statement should ensure that more consistent and comparable results will be obtained from studies of injuries within rugby union.

Overview of concussion consensus statements since 2000.

More refereed publications on sports-related concussion have appeared since 2000 than in all previous years combined. Three international consensus statements, documents from the National Athletic Trainers' Association (NATA) and the American College of Sports Medicine (ACSM), and entire issues of the Clinical Journal of Sport Medicine and the Journal of Athletic Training have been devoted to this subject. The object of this article is to critique the consensus statements and NATA and ACSM documents, pointing out areas of controversy.

Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries.

Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football injuries; this has made inter-study comparisons difficult. An Injury Consensus Group was established under the auspices of FIFA Medical Assessment and Research Centre. Using a nominal group consensus model approach, a working document that identified the key issues related to definitions, methodology and implementation was discussed by members of the group during a 2-day meeting. Following this meeting, iterative draft statements were prepared and circulated to members of the group for comment before the final consensus statement was produced. Definitions of injury, recurrent injury, severity and training and match exposures in football together with criteria for classifying injuries in terms of location, type, diagnosis and causation are proposed. Proforma for recording players' baseline information, injuries and training and match exposures are presented. Recommendations are made on how the incidence of match and training injuries should be reported and a checklist of issues and information that should be included in published reports of studies of football injuries is presented. The definitions and methodology proposed in the consensus statement will ensure that consistent and comparable results will be obtained from studies of football injuries.

Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries.

Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football (soccer) injuries, making interstudy comparisons difficult. Therefore an Injury Consensus Group was established under the auspices of Fédération Internationale de Football Association Medical Assessment and Research Centre. A nominal group consensus model approach was used. A working document on definitions, methodology, and implementation was discussed by the group. Iterative draft statements were prepared and circulated to members of the group for comment before the final consensus statement was produced. Definitions of injury, recurrent injury, severity, and training and match exposures in football together with criteria for classifying injuries in terms of location, type, diagnosis, and causation are proposed. Proforma for recording players' baseline information, injuries, and training and match exposures are presented. Recommendations are made on how the incidence of match and training injuries should be reported and a checklist of issues and information that should be included in published reports of studies of football injuries is presented.

Summary and agreement statement of the 2nd International Conference on Concussion in Sport, Prague 2004.

In November 2001, the 1st International Symposium on Concussion in Sport was held in Vienna, Austria to provide recommendations for the improvement of safety and health of athletes who suffer concussive injuries in ice hockey, football (soccer), and other sports. The 2nd International Symposium on Concussion in Sport was organised by the same group and held in Prague, Czech Republic in November 2004. It resulted in a revision and update of the Vienna consensus recommendations, which are presented here.

Relation between running injury and static lower limb alignment in recreational runners.

OBJECTIVES: To determine if measurements of static lower limb alignment are related to lower limb injury in recreational runners. METHODS: Static lower limb alignment was prospectively measured in 87 recreational runners. They were observed for the following six months for any running related musculoskeletal injuries of the lower limb. Injuries were defined according to six types: R1, R2, and R3 injuries caused a reduction in running mileage for one day, two to seven days, or more than seven days respectively; S1, S2, and S3 injuries caused stoppage of running for one day, two to seven days, or more than seven days respectively. RESULTS: At least one lower limb injury was suffered by 79% of the runners during the observation period. When the data for all runners were pooled, 95% confidence intervals calculated for the differences in the measurements of lower limb alignment between the injured and non-injured runners suggested that there were no differences. However, when only runners diagnosed with patellofemoral pain syndrome (n = 6) were compared with non-injured runners, differences were found in right ankle dorsiflexion (0.3 to 6.1), right knee genu varum (-0.9 to -0.3), and left forefoot varus (-0.5 to -0.4). CONCLUSIONS: In recreational runners, there is no evidence that static biomechanical alignment measurements of the lower limbs are related to lower limb injury except patellofemoral pain syndrome. However, the effect of static lower limb alignment may be injury specific.

Exercise counselling by family physicians in Canada.

BACKGROUND: Exercise counselling is not frequently conducted by family physicians in several countries. Little is known about the exercise counselling practices of family physicians in Canada. The objective of this study was to assess physician confidence, current versus desired practice, and barriers related to the counselling of exercise by family physicians in Canada. METHODS: The study was a cross-sectional survey that included a random selection of family physicians in six provinces. A total of 330 family physicians completed the questionnaire, resulting in a response rate of 61.1%. A family physician was defined as a physician who practices family medicine at least 75% of their practice time. RESULTS: A total of 58.2% believed only 0-25% of their patients would respond to their counselling and 42.4% felt "moderately knowledgeable" to exercise counsel. Only 11.8% counselled 76-100% of their patients about exercise, but 43.3% thought they should be counselling 76-100% of their patients. Barriers to exercise counselling that rated most important included lack of time (65.7%) and lack of exercise education in medical school (64.8%). CONCLUSIONS: Family physicians indicated their current level of exercise counselling is suboptimal and confidence levels in exercise counselling were not high. Future educational opportunities for physicians may assist in improving exercise counselling.

The impact of face shield use on concussions in ice hockey: a multivariate analysis.

OBJECTIVE: To identify specific risk factors for concussion severity among ice hockey players wearing full face shields compared with half face shields (visors). METHODS: A prospective cohort study was conducted during one varsity hockey season (1997-1998) with 642 male ice hockey players (median age 22 years) from 22 teams participating in the Canadian Inter-University Athletics Union. Half of the teams wore full face shields, and half wore half shields (visors) for every practice and game throughout the season. Team therapists and doctors recorded on structured forms daily injury, participation, and information on face shield use for each athlete. The main outcome measure was any traumatic brain injury requiring assessment or treatment by a team therapist or doctor, categorised by time lost from subsequent participation and compared by type of face shield worn. RESULTS: Players who wore half face shields missed significantly more practices and games per concussion (2.4 times) than players who wore full face shields (4.07 sessions (95% confidence interval (CI) 3.48 to 4.74) v 1.71 sessions (95% CI 1.32 to 2.18) respectively). Significantly more playing time was lost by players wearing half shields during practices and games, and did not depend on whether the athletes were forwards or defence, rookies or veterans, or whether the concussions were new or recurrent. In addition, players who wore half face shields and no mouthguards at the time of concussion missed significantly more playing time (5.57 sessions per concussion; 95% CI 4.40 to 6.95) than players who wore half shields and mouthguards (2.76 sessions per concussion; 95% CI 2.14 to 3.55). Players who wore full face shields and mouthguards at the time of concussion lost no playing time compared with 1.80 sessions lost per concussion (95% CI 1.38 to 2.34) for players wearing full face shields and no mouthguards. CONCLUSIONS: The use of a full face shield compared with half face shield by intercollegiate ice hockey players significantly reduced the playing time lost because of concussion, suggesting that concussion severity may be reduced by the use of a full face shield.

Risk factors for groin injuries in hockey.

PURPOSE: The objective of this cohort study was to determine the level of off-season sport specific activity, peak isometric adductor torque, and hip abduction flexibility that are predictive of groin or abdominal strain injury in the National Hockey League (NHL). METHODS: The subjects were 1292 consenting NHL players. Estimated relative risks of injury are reported using the following exposures: 1) level of sport specific training in the off-season, 2) peak isometric adductor torque, 3) total hip abduction flexibility, 4) previous injury, 5) years of NHL experience, and 6) skate blade hollow measurement. Estimates of probability of injury are predicted for various levels of exposures on the basis of logistic regression analysis. RESULTS: During training camp, players who reported less than 18 sessions sport specific training in the off-season were at greater than three times the risk of injury than those who did not (relative risk (RR); 3.38 95% confidence interval (CI), 1.45-7.92). Players who reported previous history of this injury were at more than two times the risk of injury than those who did not (RR, 2.88; 95% CI, 1.33-6.26). Veterans were at greater than five times the risk of injury than rookies (RR, 5.69; 95% CI, 2.05-15.85). Peak isometric adductor torque, total abduction flexibility, and skate blade hollow measurement were not predictive of injury. There is evidence of a dose-response gradient as predicted probability of injury decreases with increasing levels of sport specific training. In the regular season, sport specific training was not as strong a risk factor (RR, 2.32; 95% CI, 1.0-5.39). CONCLUSION: Low levels of off-season sport specific training and previous injury are clearly risks for groin injury at an elite level of hockey. Future research is required to investigate prevention strategies for this injury in hockey.

Evidence-based review of sport-related concussion: basic science.

The evidence base for sport-related concussive brain injury is reviewed in this paper. In the past, pathophysiological understanding of this common condition has been extrapolated from studies of severe brain trauma. More recent scientific study demonstrates that this approach is unsatisfactory, and the clinical features of concussion represent a predominantly functional brain injury rather than manifest by structural or neuropathological damage. Such understanding of this condition remains incomplete at this stage.