Overuse Injuries and Burnout in Youth Sports

Executive Summary BACKGROUND Youth sport participation offers many benefits including the development of self-esteem, peer socialization, 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 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: ∘ Assist clinicians in recognizing young athletes at risk for overuse injuries and burnout. ∘ Delineate the risk factors and injuries that are unique to the skeletally immature young athlete. ∘ Describe specific high-risk overuse injuries that present management challenges and/or can lead to long-term health consequences. ∘ Summarize the risk factors and symptoms associated with burnout in young athletes. ∘ Provide recommendations on overuse injury prevention. METHODOLOGY Medical Subject Headings (MeSHs) and text words were searched on March 26, 2012, for MEDLINE, CINAHL, and PsychINFO. Nine hundred fifty-three unique articles were initially identified. Additional articles were found using cross-referencing. The process was repeated July 10, 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 paper. 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 to 18 years of age participate in team sports. The National Council of Youth Sports survey found that 60 million children aged 6 to 18 years participate in some form of organized athletics, with 44 million participating in more than 1 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 epidemiologic studies define injury as requiring 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 amenorrhea 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. ∘ 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 and 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, both 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 SPECIALIZATION Sport specialization may be considered as intensive, year-round training in a single sport at the exclusion of other sports. There is concern that early sport specialization may increase 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 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 complaining of 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 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 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 overreaching 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 specialization may be a factor. ∘ Data suggest that athletes who had early specialized training withdrew from their sport either due to injury or burnout from the sport. However, not all young athletes who drop out of sports are burned out. ∘ Most youth who discontinue a sport do so as a result of time conflicts and interest in other activities. ∘ Some may reenter 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 individualized based upon 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 programs 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 data 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 underreported in the current literature because most injury definitions have focused on time loss from sport. (B) Preparticipation exams 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 specialization may not lead to long-term success in sports and may increase 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. BACKGROUND AND PURPOSE Participation in youth sports can be an enjoyable experience for children and adolescents with many potential benefits. It offers opportunities for peer socialization, the development of self-esteem and leadership qualities, and also promotes health and fitness. However, the increasing highly competitive nature of youth sports has fueled trends of extensive training, sport specialization, and participation in large numbers of competitive events at young ages. Consequently, overuse injuries and burnout have become common. This report will review what is currently known about the epidemiology and risk factors associated with overuse injuries and burnout in young athletes. It will highlight specific overuse injuries that may pose management challenges or lead to long-term consequences. Recommendations for prevention will also be presented. INTRODUCTION The number of participants in youth sports is difficult to determine. The National Federation of State High School Associations reported that 7 713 577 student athletes (4 490 854 male, 3 222 723 female) participated in 2012–2013.1 However, this represents only a fraction of all participants at any level. Estimates for younger athletes and/or those in nonscholastic sports may best be projected from data obtained by national sport organizations. One recent survey found that approximately 27 million children and adolescents between the age of 6 and 17 years participate regularly in team sports in the United States.2 Among specific youth sport organizations, an estimated 2.3 million children played Little League baseball, over 600 000 participate in the America Youth Soccer Organization and 365 000 play softball.3,4 The 2008 National Council of Youth Sports survey found that approximately 60 million children aged 6 to 18 years participate in some form of organized athletics.5 Of these, approximately 44 million participated in more than 1 sport.5 In addition, although there is a paucity of data describing the extent of youth sport participation, it is clear that large numbers of children do not limit their sports to a given “season” and are involved throughout the calendar year in organized athletics. An emphasis on competitive success has become widespread, resulting in increased pressure to begin high-intensity training at young ages. This may be driven by parental goals of having their child selected for high-level travel teams, collegiate scholarships, and even professional contracts. Alternatively, the initiative may originate with the child or be fostered by coaches or peers. In pursuit of athletic success, children and their parents may enlist the services of a personal sport coach and/or fitness instructor, and also register for camps and showcase events. Some parents or coaches may encourage a child to concentrate on a single sport in an attempt to improve his or her chances of elite team selection, and therefore exposure to the college recruiting process. Children may also play on more than 1 team or participate in more than 1 sport at a given time. It is also important to recognize that children's sports are a big business.6 Coaches, personal trainers, club team organizations, sporting goods manufactures, tournament directors, and others have a financial stake in youth sports participation. Given this trend toward early and multifaceted training, frequent competition, and single sport specialization, it is no surprise that overuse injuries and burnout are common. This paper will describe several issues related to the development of overuse injury and burnout. Particular attention will be placed on the unique factors surrounding growth and development that deserve special consideration in young athletes. By understanding these issues, clinicians will better be able to treat these injuries, educate parents, athletes and coaches, and provide recommendations for injury prevention. METHODOLOGY Data Sources Three electronic databases were searched on March 26, 2012, to identify potentially relevant articles: MEDLINE, CINAHL, and PsychINFO. A combination of Medical Subject Headings (MeSHs) and text words were used in this search (Table 1). A total of 953 unique articles were identified. Additional articles and related information were found using cross-referencing and the authors' personal libraries. The articles were screened by title and by abstract. Those felt to be relevant to this document were reviewed in full by the authors. The process was repeated July 10, 2013, to review any new articles since the initial search was performed. A total of 208 unique references were ultimately chosen for this paper.TABLE 1: Search MethodologyDefinition of Overuse Injury Although there is no clear consensus on the definition of overuse injury, it is generally recognized that 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.7–10 Such injury may involve the muscle-tendon unit, bone, articular cartilage, physis, bursa, and/or neurovascular structures. During sport participation, repetitive loading to these structures results in microtrauma. When recovery between loading exposures is sufficient, tissue adaptation occurs to accommodate the imposed stress. However, excessive stress and/or an inadequate recovery period can overwhelm the ability of the tissue to remodel, resulting in a weakened, damaged structure. This imbalance between training loads and recovery is a key factor, perhaps even more so in young athletes with an immature musculoskeletal system. Because of ongoing growth and development, the types of overuse injuries that occur in young athletes differ compared to adults.11,12 Specifically, growth-related conditions such as apophysitis and physeal stress injury are unique to young athletes.13–15 Apophyseal injuries typically occur in early adolescence. The most common sites involve the tibia tubercle of the knee (Osgood-Schlatter disease), the calcaneal apophyisis of the heel (Sever's disease), and the medial epicondylar apophysis of the elbow (often referred to as Little Leaguer's Elbow). Anterior knee pain is one of the most frequent complaints in the young athlete.16 In early adolescence this is usually due to Osgood-Schlatter disease, while in later adolescence the tibial tubercle apophysis matures, and patellofemoral pain syndrome (PFPS) becomes the more common cause of knee pain. Overuse injuries of the physis (eg, proximal humerus in throwers, distal radius in gymnasts) occur in early to mid-adolescence.14,17–19 As skeletal maturity is achieved, overuse injuries to bone begin to follow adult injury patterns (eg, stress reactions and stress fractures). EPIDEMIOLOGY OF OVERUSE INJURIES Overall, there is very little research specifically on the incidence and prevalence of overuse injuries in children and adolescents.20–24 Furthermore, studies of sports injuries in youth are limited by several issues including injury reporting methodology, injury classification, and standardization of outcomes. In particular, injury definitions that require time loss from sport underestimate the burden of overuse injuries.9,25 A recent study of 100 US high schools reported that the overall injury rate (acute and overuse) in 20 high school sports was 1.71/1000 athlete exposures (AEs) during the 2010–2011 school year.23 This database estimates 3.7 million injuries occurred that resulted in more than 1 day's time loss from sports. This estimate does not include injuries seen outside of the high school setting. Importantly, this study further underestimates injury rates since it does not account for injuries which did not result in time loss, as is the case in many overuse injuries.9 Another data source, the National SAFE KIDS Campaign, estimates that more than 3.5 million children are injured annually playing sports or participating in recreational activities.22 Estimates of the proportion of all sports injuries that are due to overuse range from 45.9% to 54%.7,24,26 Although evidence is sparse, there is concern that these injuries are increasing.27–29 The frequency and type of overuse injuries in elite young athletes varies by sport and by age.30 Sport-related training and conditioning are also factors (eg, resistance training as an adjunct to soccer training).30 Overuse, noncontact injuries in American football are 2.6 times more likely to occur at the college level than high school.31 In a recent 3-year study of 16 sports at 1 university, 29.3% of injuries were considered overuse injuries.9 Baxter-Jones et al studied 453 elite young athletes in 4 sports (231 boys, 22 girls; 8–16 years of age) and found that the prevalence of overuse injuries varied by sport: 63% for swimmers, 33% for gymnasts and tennis players, and 15% for soccer players.30 Other studies report the prevalence of overuse injury among different youth sports to range from 37% (skiing and handball) to 68% (running).32–34 RISK FACTORS FOR OVERUSE INJURIES A of factors have been to contribute to overuse injuries. are often either or factors (Table factors are defined as and factors to forces related to the sport the biomechanics of the and the sporting factors include in growth and development, anatomic muscle-tendon and a history of prior injury. factors include sport training and The of an or an factor to injury risk is on the athlete, the sport and the that occurs during Furthermore, it is important to recognize that many overuse injuries result from a of multiple risk factors in specific with an this concept is for the evaluation and of athletes with overuse of for Overuse is also relevant to that some risk factors are (eg, neuromuscular others are not (eg, age, in young of the developing musculoskeletal system are important to Although little data that a causal relationship between risk factors and overuse injury, recognizing these potential to injury is important in recurrent injury and in developing injury prevention Prior Injury injury is the predictor of future overuse injury may occur as a result of inadequate of the index injury and/or a to recognize and the factors that to the original injury. and Children undergo growth and development at an growth and are development is more the development of child's play can on the exposure to and play growth and cognitive development both successful participation in sports. Overall and height increase in the and adolescent to their peak height and at approximately age may experience age is a process that and component of occurs at an rate in an Although in the rates have been to increase injury data a link between and injury are Overuse injuries may be more common during the adolescent growth spurt. studies demonstrate that the growth present at 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 distal radius fractures peak during and before peak height fractures, distal physeal stress injuries, and pain also appear to occur with a greater prevalence during the adolescent growth studies are to further this A decrease in age-adjusted bone mineral density that occurs before peak height velocity may also play a A relationship to acute fractures has been but in overuse injury has not yet been In addition, is seen between bone and the of bone during the growth spurt resulting in diminished bone Other factors that may contribute are a relative lack of lean tissue mass, an increase in joint hypermobility, and imbalances in growth and growth of results in changes in mass, and stress forces on muscle-tendon growth cartilage, and that frequently occur These imbalances in growth and with repetitive appear related to increased injury although the relationship is not and is likely Overuse injuries of the physis may be due to diminished related to excessive of physeal stress injuries of the distal radius in young gymnasts an to injuries in which metaphyseal has been This injury is more likely to occur in gymnasts who are the age range of the adolescent growth such as patellofemoral elbow and excessive lumbar are some of the more risk factors for overuse has also been associated with injury in some of these including both and is difficult to in the setting. In addition, a cause and relationship between these and injury has been studies have not established Given the of sport-specific placed on the more information is to models anatomic may injury Overall, the of versus tissue in to injury is and likely sport can be altered of The of to particularly in is yet The of an can have both a and a long-term on lower extremity such as and loading rate, as well as knee However, the clinical of this with to on injury rates There is also the potential to increase injury risk on the of the altered on sport participation. A causal relationship between and injury risk has not been Early that the muscle-tendon during the adolescent growth spurt that may contribute to However, several recent studies have not shown any relationship between growth and in or the of on injury risk have shown that age, and specific sports are mass, and of during the adolescent growth and all can and This is likely due to the need for greater for extremity during a time when and are This may play a in the increased risk for injury seen during the growth or in extremity appear to increase These can as the for programs that in sport-specific In some it is not clear if changes in joint range of play a in overuse injury or a In a decrease in with greater in is typically seen relative to the One study in a including during or phase and during or recovery the in a to potentially cause and/or These studies suggest sport-specific deserve further to if such factors to overuse injury. Strength and of youth fitness include those related to bone and Among young general and fitness Children who have not some of general and motor skills may be at increased risk for injury, although little data at this time. Some potential risk factors that are include and lack of and A history of in sports that is a risk factor for bone stress injury. One study in collegiate female found a relationship between number of year and risk of stress with having the studies have that a history of amenorrhea is a significant risk factor for stress The inadequate with bone density, and increased The relationship between and the likelihood of stress is not well The studies generally focused on young and adolescents. There is little data regarding menstrual