### Background

Youth sport participation offers many benefits including the development of self-esteem, peer socialisation and general fitness. However, an emphasis on competitive success, often driven by goals of elite-level travel team selection, collegiate scholarships, Olympic and National team membership and even professional contracts, has seemingly become widespread. This has resulted in an increased pressure to begin high-intensity training at young ages. Such an excessive focus on early intensive training and competition at young ages rather than skill development can lead to overuse injury and burnout.

### Purpose

To provide a systematic, evidenced-based review that will (1) assist clinicians in recognising young athletes at risk for overuse injuries and burnout; (2)delineate the risk factors and injuries that are unique to the skeletally immature young athlete; (3) describe specific high-risk overuse injuries that present management challenges and/or can lead to long-term health consequences; (4) summarise the risk factors and symptoms associated with burnout in young athletes; (5)provide recommendations on overuse injury prevention.

### Methodology

Medical Subject Headings (MeSHs) and text words were searched on 26 March 2012 from MEDLINE, CINAHL and PsycINFO. The search yielded 953 unique articles. Additional articles were found using cross-referencing. The process was repeated on 10 July 2013 to review any new articles since the original search. Screening by the authors yielded a total of 208 relevant sources that were used for this article. Recommendations were classified using the Strength of Recommendation Taxonomy (SORT) grading system.

### Definition of overuse injury

Overuse injuries occur due to repetitive submaximal loading of the musculoskeletal system when rest is not adequate to allow for structural adaptation to take place. Injury can involve the muscle-tendon unit, bone, bursa, neurovascular structures and the physis. Overuse injuries unique to young athletes include apophyseal injuries and physeal stress injuries.

### Epidemiology

It is estimated that 27 million US youth between 6 and 18 years of age participate in …

https://bjsm.bmj.com/content/bjsports/48/4/287.full.pdf

Overuse Injuries and Burnout in Youth Sports: APositionStatementfromtheAmericanMedicalSocietyfor Sports Medicine

Division of Sports Medicine and Non-Operative Orthopaedics, Departments of Family Medicine and Orthopaedics, University of California, Los Angeles, California, USA Departments of Pediatrics and Orthopaedic Surgery, University of Chicago, Chicago, Illinois, USA Department of Pediatrics, Eastern Virginia School of Medicine, Norfolk, Virginia, USA Departments of Orthopedics and Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA Departments of Family Medicine and Orthopaedic Surgery and Rehabilitation, Stritch School of Medicine, Loyola University Chicago, Chicago, Illinois, USA Departments of Pediatrics and Orthopedics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA Departments of Orthopaedics and Family Medicine, University of California, San Francisco, California, USA

Overuse injuries and burnout in youth sports: a position statement from the American Medical Society for Sports Medicine.

Background Physical activity is important in both prevention and treatment of many common diseases, but sports injuries can pose serious problems.

Objective To determine whether physical activity exercises can reduce sports injuries and perform stratified analyses of strength training, stretching, proprioception and combinations of these, and provide separate acute and overuse injury estimates.

Material and methods PubMed, EMBASE, Web of Science and SPORTDiscus were searched and yielded 3462 results. Two independent authors selected relevant randomised, controlled trials and quality assessments were conducted by all authors of this paper using the Cochrane collaboration domain-based quality assessment tool. Twelve studies that neglected to account for clustering effects were adjusted. Quantitative analyses were performed in STATA V.12 and sensitivity analysed by intention-to-treat. Heterogeneity (I2) and publication bias (Harbord's small-study effects) were formally tested.

Results 25 trials, including 26 610 participants with 3464 injuries, were analysed. The overall effect estimate on injury prevention was heterogeneous. Stratified exposure analyses proved no beneficial effect for stretching (RR 0.963 (0.846–1.095)), whereas studies with multiple exposures (RR 0.655 (0.520–0.826)), proprioception training (RR 0.550 (0.347–0.869)), and strength training (RR 0.315 (0.207–0.480)) showed a tendency towards increasing effect. Both acute injuries (RR 0.647 (0.502–0.836)) and overuse injuries (RR 0.527 (0.373–0.746)) could be reduced by physical activity programmes. Intention-to-treat sensitivity analyses consistently revealed even more robust effect estimates.

Conclusions Despite a few outlying studies, consistently favourable estimates were obtained for all injury prevention measures except for stretching. Strength training reduced sports injuries to less than 1/3 and overuse injuries could be almost halved.

https://bjsm.bmj.com/content/bjsports/48/11/871.full.pdf

The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials

Youth have very high participation and injury rates in sport. Sport is the leading cause of injury in youth. Sport injury reduces future participation in physical activity which adversely affects future health. Sport injury may lead to overweight/obesity and post-traumatic osteoarthritis. The objective of the systematic review and meta-analysis was to evaluate the efficacy of injury prevention neuromuscular training strategies in youth sport. Three electronic databases were systematically searched up to September 2014. Studies selected met the following criteria: original data; analytic prospective design; investigated a neuromuscular training prevention strategy intervention(s) and included outcomes for injury sustained during sport participation. Two authors assessed the quality of evidence using Downs and Black (DB) criteria. Meta-analyses including randomised controlled trials only (RCTs) to ensure study design homogeneity were completed for lower extremity and knee injury outcomes. Of 2504 potentially relevant studies, 25 were included. Meta-analysis revealed a combined preventative effect of neuromuscular training in reducing the risk of lower extremity injury (incidence rate ratio: IRR=0.64 (95% CI 0.49 to 0.84)). Though not statistically significant, the point estimate suggests a protective effect of such programmes in reducing the risk of knee injury (IRR=0.74 (95% CI 0.51 to 1.07)). There is evidence for the effectiveness of neuromuscular training strategies in the reduction of injury in numerous team sports. Lack of uptake and ongoing maintenance of such programmes is an ongoing concern. A focus on implementation is critical to influence knowledge, behaviour change and sustainability of evidence informed injury prevention practice.

Neuromuscular training injury prevention strategies in youth sport: a systematic review and meta-analysis

The promotion of sport and physical activity (PA) for children is widely recommended to support a healthy lifestyle, but being engaged in sport bears the risk of sustaining injuries. Injuries, in turn, can lead to a reduction in current and future involvement in PA and, therefore, may negatively affect future health as well as quality of life. Thus, sports injury prevention is of particular importance in youth. The aim of this systematic review was to quantify the effectiveness of exercise-based injury prevention programs in child and adolescent sport in general, and with respect to different characteristics of the target group, injury prevention program, and outcome variables. An Internet-based literature search was conducted in six databases (CINAHL, Cochrane, EMBASE, ISI Web of Science, PubMed, SPORTDiscus) using the following search terms with Boolean conjunction: (sport injur* OR athletic injur* OR sport accident*) AND (prevent* OR prophylaxis OR avoidance) AND (child* OR adolescent OR youth). Randomized controlled trials and controlled intervention studies in organized sport, published in English in a peer-reviewed journal, analyzing the effects of an exercise-based injury prevention program in athletes younger than 19 years of age. Two reviewers evaluated eligibility and methodological quality. Main outcome extracted was the rate ratio (RR). Statistical analyses were conducted using the inverse-variance random effects model. Twenty-one trials, conducted on a total of 27,561 athletes (median age 16.7 years [range 10.7–17.8]), were included. The overall RR was 0.54 (95 % CI 0.45–0.67) [p < 0.001]. Girls profited more from injury prevention than boys (p = 0.05). Both prevention programs with a focus on specific injuries (RR 0.48 [95 % CI 0.37–0.63]) and those aiming at all injuries (RR 0.62 [95 % CI 0.48–0.81]) showed significant reduction effects. Pre-season and in-season interventions were similarly beneficial (p = 0.93). Studies on programs that include jumping/plyometric exercises showed a significant better (p = 0.002) injury preventive effect (RR 0.45 [95 % CI 0.35–0.57], Z = 6.35, p < 0.001) than studies without such exercises (RR 0.74 [95 % CI 0.61–0.90], Z = 3.03, p = 0.002). The results provide good evidence and clearly demonstrate beneficial effects of exercise-based injury prevention programs in youth sports as they can result in statistically significant and practically relevant injury reduction. In particular, multimodal programs including jumping/plyometric exercises can be recommended. However, there is a considerable lack of data for children (under 14 years of age) and for individual sports in general. Future research should include these groups and focus on the effect of specific exercises and compliance.

Exercise-Based Injury Prevention in Child and Adolescent Sport: A Systematic Review and Meta-Analysis

Lower limb injuries in sport are increasingly prevalent and responsible for large economic as well as personal burdens In this review we seek to determine which easily implemented functional neuromuscular warm-up strategies are effective in preventing lower limb injuries during sports participation and in which sporting groups they are effective Seven electronic databases were searched from inception to January 2012 for studies investigating neuromuscular warm-up strategies and injury prevention The quality of each included study was evaluated using a modified version of the van Tulder scale Data were extracted from each study and used to calculate the risk of injury following application of each evaluated strategy Nine studies were identified including six randomized controlled trials (RCT) and three controlled clinical trials (CCT) Heterogeneity in study design and warm-up strategies prevented pooling of results Two studies investigated male and female participants, while the remaining seven investigated women only Risk Ratio (RR) statistics indicated 'The 11+' prevention strategy significantly reduces overall (RR 067, confidence interval (CI) 054 to 084) and overuse (RR 045, CI 028 to 071) lower limb injuries as well as knee (RR 048, CI 032 to 072) injuries among young amateur female footballers The 'Knee Injury Prevention Program' (KIPP) significantly reduced the risk of noncontact lower limb (RR 05, CI 033 to 076) and overuse (RR 044, CI 022 to 086) injuries in young amateur female football and basketball players The 'Prevent Injury and Enhance Performance' (PEP) strategy reduces the incidence of anterior cruciate ligament (ACL) injuries (RR 018, CI 008 to 042) The 'HarmoKnee' programme reduces the risk of knee injuries (RR 022, CI 006 to 076) in teenage female footballers The 'Anterior Knee Pain Prevention Training Programme' (AKP PTP) significantly reduces the incidence of anterior knee pain (RR 027, CI 014 to 054) in military recruits Effective implementation of practical neuromuscular warm-up strategies can reduce lower extremity injury incidence in young, amateur, female athletes and male and female military recruits This is typically a warm-up strategy that includes stretching, strengthening, balance exercises, sports-specific agility drills and landing techniques applied consistently for longer than three consecutive months In order to optimize these strategies, the mechanisms for their effectiveness require further evaluation

https://link.springer.com/content/pdf/10.1186%2F1741-7015-10-75.pdf

The effectiveness of neuromuscular warm-up strategies, that require no additional equipment, for preventing lower limb injuries during sports participation: a systematic review

Wiskott–Aldrich Syndrome (WAS) is characterized by recurrent infections, thrombocytopenia, and eczema. Here, we show that WASp-deficient mice on a BALB/c background have dysregulated cutaneous immune homeostasis with increased leukocyte accumulation in the skin, 1 week after birth. Increased cutaneous inflammation was associated with epithelial abnormalities, namely, altered keratinization, abnormal epidermal tight junctional morphology and increased trans-epidermal water loss; consistent with epidermal barrier dysfunction. Immune and physical barrier disruption was accompanied by progressive skin dysbiosis, highlighting the functional significance of the disrupted cutaneous homeostasis. Interestingly, the dysregulated immunity in the skin preceded the systemic elevation in IgE and lymphocytic infiltration of the colonic lamina propria associated with WASp deficiency. Mechanistically, the enhanced immune cell accumulation in the skin was lymphocyte dependent. Elevated levels of both Type 2 (IL-4, IL-5) and Type 17 (IL-17, IL-22, IL-23) cytokines were present in the skin, as well as the ‘itch’ factor IL-31. Unexpectedly, the canonical WAS-associated cytokine IL-4 did not play a role in the immune dysfunction. Instead, IL-17 was critical for skin immune infiltration and elevation of both Type 2 and Type 17 cytokines. Our findings reveal a previously unrecognized IL-17-dependent breakdown in immune homeostasis and cutaneous barrier integrity in the absence of WASp, targeting of which may provide new therapeutic possibilities for the treatment of skin pathologies in WAS patients.

/pdf/il-17-dependent-dysregulated-cutaneous-immune-homeostasis-in-j74x6c0t.pdf

Katherine Herman

Papers

The effectiveness of neuromuscular warm-up strategies, that require no additional equipment, for preventing lower limb injuries during sports participation: a systematic review

IL-17-Dependent Dysregulated Cutaneous Immune Homeostasis in the Absence of the Wiskott–Aldrich Syndrome Protein