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EXECUTIVE SUMMARY
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 team sports. The National Council of Youth Sports survey found that 60 million children aged 6–18 years participate in some form of organised athletics, with 44 million participating in more than one sport. There is very little research specifically on the incidence and prevalence of overuse injuries in children and adolescents. Overall estimates of overuse injuries versus acute injuries range from 45.9% to 54%. The prevalence of overuse injury varies by the specific sport, ranging from 37% (skiing and handball) to 68% (running). Overuse injuries are underestimated in the literature because most of the epidemiological studies define injury as requiring a time loss from participation.
Risk factors
Prior injury is a strong predictor of future overuse injury. Overuse injuries may be more likely to occur during the adolescent growth spurt. The physes, apophyses and articular surfaces in skeletally immature athletes in a rapid phase of growth are less resistant to tensile, shear and compressive forces than either mature bone or more immature prepubescent bone. A decrease in age-adjusted bone mineral density that occurs before peak height velocity may also play a role. Other factors that may contribute are a relative lack of lean tissue mass, an increase in joint hypermobility and imbalances in growth and strength. Physeal stress injuries appear to be more common during rapid growth, and may be related to a period of vulnerability of metaphyseal perfusion. There is little evidence to support a causal relationship between overuse injury and anatomic malalignment or flexibility. A history of amenorrhoea is a significant risk factor for stress fractures. Higher training volumes have consistently been shown to increase the risk of overuse injury in multiple sports. Other factors that may contribute to overuse injury, but lack clinical data include poor fitting equipment, particularly when not adjusted for changes in growth and overscheduling, such as multiple competitive events in the same day or over several consecutive days. This factor may be better considered as a marker for a high ratio of workload to recovery time.
Readiness for sports
Readiness for sports is related to the match between a child's level of growth, development (motor, sensory, cognitive, social/emotional) and the tasks/demands of the competitive sport. Chronological age is not a good indicator on which to base sport developmental models because motor, cognitive and social skills progress at different rates, independent of age. Coaches and parents may lack knowledge about normal development and signs of readiness for certain tasks, physically and psychosocially. This can result in unrealistic expectations that cause children and adolescents to feel as if they are not making progress in their sport. Consequently, children may lose self-esteem and withdraw from the sport.
Sport specialisation
Sport specialisation may be considered as an intensive, year-round training in a single sport at the exclusion of other sports. There is concern that early sport specialisation may increase the rates of overuse injury and sport burnout, but this relationship has yet to be demonstrated. Diversified sports training during early and middle adolescence may be more effective in developing elite-level skills in the primary sport due to skill transfer.
High risk overuse injuries
‘High-risk’ overuse injuries are those that can result in a significant loss of time from sport and/or threaten future sport participation. These include certain stress fractures, physeal stress injuries, osteochondritis dissecans, some apophyseal injuries and effort thrombosis. High-risk stress fractures include: the pars interarticularis of the spine, the tension side of the femoral neck, the patella, the anterior tibia (the ‘dreaded black line’), the medial malleolus, the talus, the tarsal navicular, the metaphyseal/diaphyseal junction of the fifth metatarsal (Jones’ fracture) and the sesamoids. A high index of suspicion should be maintained for athletes reporting pain at the sites of potential high-risk bone stress injuries including the central lumbar spine, anterior hip, groin or thigh, anterior knee, anterior leg, medial ankle, dorsal/medial midfoot, lateral foot and plantar aspect of the great toe. Physeal stress injuries can occur at the proximal humerus, distal radius, distal femur and the proximal tibia. Although most of the physeal stress injuries resolve with rest, some may result in growth disturbance and joint deformity. Effort thrombosis in athletes occurs as a consequence of thoracic outlet syndrome. A significant percentage of upper extremity effort thrombosis happens in adolescents as a result of overuse. First rib resection frequently results in a successful return to full activity. All cases should undergo evaluation for an underlying coagulopathy.
Burnout
Burnout is part of a spectrum of conditions that includes over-reaching and overtraining. It has been defined to occur as a result of chronic stress that causes a young athlete to cease participation in a previously enjoyable activity. Sport specialisation may be a factor. Data suggest that athletes who had early specialised training withdrew from their sport due to either an injury or a burnout from the sport. However, not all young athletes who drop out of sports are burned out. Most of the youths who discontinue a sport do so as a result of time conflicts and interest in other activities. Some may re-enter the same sport or participate in a different sport in the future. In children, there appears to be more of a psychological component related to burnout and attrition with adult supervised activities.
Prevention
Limiting weekly and yearly participation time, limits on sport-specific repetitive movements (eg, pitching limits) and scheduled rest periods are recommended (B). Such modifications need to be individualised based on the sport and the athlete's age, growth rate, readiness and injury history (C). Careful monitoring of training workload during the adolescent growth spurt is recommended, as injury risk seems to be greater during this phase (B). This apparent increased risk may be related to a number of factors including diminished size-adjusted bone mineral density, asynchronous growth patterns, relative weakness of growth cartilage and physeal vascular susceptibility. Preseason conditioning programmes can reduce injury rates in young athletes (B). Prepractice neuromuscular training can reduce lower extremity injuries (B). Given the altered biomechanics that may occur with ill-fitting equipment, proper sizing and resizing of equipment is recommended, although date are lacking that demonstrate a link to injury (C). To reduce the likelihood of burnout, an emphasis should be placed on skill development more than competition and winning (C).
Summary findings and recommendations
Overuse injuries are under-reported in the current literature because most of the injury definitions have focused on time loss from sport (B). Preparticipation examinations may identify prior injury patterns and provide an opportunity to assess sport readiness (C). A history of prior injury is an established risk factor for overuse injuries that should be noted as part of each injury assessment (A). Adolescent female athletes should be assessed for menstrual dysfunction as a predisposing factor to overuse injury (B). Parents and coaches should be educated regarding the concept of sport readiness (C). Variations in cognitive development, as well as motor skills, should be considered when setting goals and expectations. Early sport specialisation may not lead to a long-term success in sports, and may increase the risk for overuse injury and burnout (C). With the possible exception of early entry sports such as gymnastics, figure skating and swimming/diving, sport diversification should be encouraged at younger ages. When an overuse injury is diagnosed, it is essential to address the underlying cause(s) (C). The athlete, parents and coaches should be involved in reviewing all risk factors and developing a strategy to attempt to avoid recurrent injury. All overuse injuries are not inherently benign (A). Clinicians should be familiar with specific high-risk injuries, including stress fractures of the femoral neck, tarsal navicular, anterior tibial cortex and physis and effort thrombosis.
Footnotes
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▸ Due to space constraints only the Executive Summary is published in the print journal. To read the complete Consensus statement, please visit the journal online (http://dx.doi.org/10.1136/bjsports-2013-093299).