Version July 2025
INTRODUCTION —
Over the past few decades, an increasing number of child and young adolescent athletes have limited their participation in athletics to a single sport. While the goal of early specialization is to optimize performance and ultimate achievement, the approach may cause significant harm in some youth. As millions of children are involved, early sport specialization may be considered a worldwide public health issue.
The terminology, epidemiology, causes, and effects of early specialization in sport by children are discussed here along with guidelines for families and clinicians. Overtraining and specific injuries that may result from early specialization are reviewed separately in multiple UpToDate topics, including the following. (See "Overtraining syndrome in athletes" and "Throwing injuries of the upper extremity: Clinical presentation and diagnostic approach" and "Anterior cruciate ligament injury" and "Approach to chronic knee pain or injury in children or skeletally immature adolescents".)
TERMINOLOGY, BACKGROUND, AND KEY CONCEPTS
Definitions — The Jayanthi specialization scale developed by the author and his colleagues is likely the most common tool used to assess the degree of sport specialization and associated injury risk [1]. The scale consists of three questions:
●Have you chosen a main sport?
●Did you quit other sports to focus on your main sport (or only ever played one sport)?
●Do you train more than eight months per year in your main sport?
A "yes" answer to a question receives one point. A total score of zero to one is classified as low specialization, two as moderate specialization, and three as high specialization [1,2].
Other definitions for early specialization in sport have been used, including:
●"Intentional and focused participation in a single sport for a majority of the year that restricts opportunities for engagement in other sports and activities" [3].
●Exclusive participation in a single sport [4].
Inconsistency among definitions can create difficulties when interpreting and comparing results among studies.
Background and history — In 1993, Anders Ericsson and two of his colleagues published "The role of deliberate practice in the acquisition of expert performance," which introduced the concept of "deliberate practice." This study described how the accumulation of many hours of a particular type of practice enabled the development of expert performance among violinists at the Berlin Academy of Music. While the elements of deliberate practice (eg, appropriate level of challenge, regular feedback) were often neglected, the time required to achieve expert performance became widely known and served as the foundation for the "10,000-hour rule" popularized in Malcolm Gladwell's book Outliers.
Among other ideas, Ericsson theorized that without an early start it would be extremely difficult to reach expert status. This concept was not applied to athletics initially but over time was adopted by a growing number of coaches and parents. Advocates began working with athletes at younger ages with a goal of accumulating the "10,000 hours" needed to achieve expert performance.
Soon thereafter, some researchers began to question whether early specialization was a sound approach to athletic development. Jean Cote and others concluded there were multiple paths to athletic success [5,6]. Cote defined three phases of development in youth athletes, to be distinguished from an early specialization approach:
●Sport sampling years, when children try multiple sports and experience a mix of play and practice within each. This typically occurs between the ages of 6 and 13 years.
●Sport specialization years, when children select one or a few sports in which they have greater interest and more time is spent in structured practice. This occurs approximately from the age of 13 to 15 years.
●Sport investment years, when athletes focus on developing a high level of skill in one sport. This generally begins around the age of 16.
Cote went on to report that structured training perceived to be less fun by children may contribute to their quitting sport [7]. Others then began to theorize that early sport specialization might make young athletes more susceptible to burnout, social isolation, musculoskeletal injury, compromised growth and maturation, and manipulation by adults [5]. (See 'Outcomes' below.)
Developmental considerations in youth athletes
Overview and general guidance — Older children and adolescents progress through three main stages of physical development:
●Pre-adolescent (or pre-peak height velocity [pre-PHV]) – Usually, girls younger than 11 years and boys younger than 13. (See "Normal growth patterns in infants and prepubertal children".)
●Adolescent growth spurt (or circa-PHV) – Usually occurs around 11 years for girls and 13 years for boys but can vary widely among individual children. (See "Normal puberty".)
●Post-adolescent (or post-PHV)
Each stage involves different physiologic stresses and vulnerabilities. It remains unclear which stage carries the greatest overall risk for musculoskeletal injury and psychological burnout in youth athletes.
When evaluating youth athletes for possible sports-related overuse injuries, the distal-to-proximal scheme can be a useful tool. This scheme reflects the location of common overuse injuries as children progress through the developmental stages above. As examples, Sever disease occurs in the heel and is most common in pre-adolescents, Osgood-Schlatter disease occurs in the knee and is most common during the adolescent growth spurt, and conditions of the hip (eg, femoroacetabular impingement) or spine (eg, spondylolysis) are more common among post-adolescent athletes.
Pre-adolescence — Child athletes in the pre-PHV stage typically have open physes and apophyses (site of tendon attachment). These are a relatively common site of injury, often in the lower extremity. Apophyses in particular are susceptible to overuse injuries from sport, although these are not common. In part, such injuries occur because of the relative strength of ligaments compared with incomplete bony structures at this stage of development. Calcaneal apophysitis (ie, Sever disease) is an example of such injury. (See "Heel pain in the active child or skeletally immature adolescent: Overview of causes".)
Bone mineral density increases through physical activity at this stage of development, but this process is not complete. Thus, pre-adolescents are at increased risk of fractures involving the physis and adjacent metaphyseal and diaphyseal bones. Most injuries sustained at this stage heal well without complication.
Adolescence — As a child enters the circa-PHV stage, growth rates (particularly of the long bones) accelerate, and height may increase rapidly (eg, >6 cm/year). Body mass also increase. There is a relative shortening and stiffening of muscle-tendon units. Neuromuscular development is ongoing, and movement patterns are often suboptimal during this stage.
Injuries tend to occur in areas of greatest relative weakness at any particular time during this stage. Due to the rapid growth and increasing stiffness of myotendinous units, young athletes remain at risk for apophyseal injuries, including avulsions.
Depending upon activities and the child, physical stresses from sport may exceed the capacities of the epiphyses or apophyses, thereby causing injury. Tibial apophysitis (Osgood-Schlatter disease), proximal humeral epiphyseolysis (Little League shoulder), and distal radial physeal stress reaction are examples of such injury. (See "Osgood-Schlatter disease (tibial tuberosity avulsion)" and "Throwing injuries of the upper extremity: Clinical presentation and diagnostic approach", section on 'Proximal humeral epiphysiolysis (Little League shoulder)' and "Overview: Causes of chronic wrist pain in children and adolescents", section on 'Distal radius physeal stress reaction'.)
The lumbar spine, pelvis, and hips remain relatively immature, and youth athletes exposed to high volume and specialized training may develop stress injuries of the spine or apophyseal injuries of the hip. (See "Spondylolysis and spondylolisthesis in child and adolescent athletes: Clinical presentation, imaging, and diagnosis".)
Due to suboptimal movement patterns, the lower extremities are susceptible to injury such as patellofemoral pain, patellar instability, and (as they approach late PHV) ligament injury.
Post-adolescence — Once adolescents are skeletally mature and growth rates have slowed or ceased, the physes and apophyses of most bones have closed, and young athletes become more susceptible to muscle and ligament injuries as well as injuries to the axial spine. Such injuries are due in part to the greater volume and intensity of training and competitive sport in which older adolescents participate combined with the relative immaturity of the musculoskeletal system. In addition, ligaments and tendons become tighter during this stage of development, and resulting imbalances in strength and flexibility can contribute to injury risk. Athletes have greater muscle mass and strength but may not have developed proper neuromuscular control and sound movement patterns.
Despite closure or near closure of the physes, there remain bony regions that are not fully mature and remain susceptible to injury (eg, medial epicondyle of elbow, proximal humerus, hip apophyses). In light of the increased volume and intensity of athletic training that often occurs at this stage, injuries such as stress fractures due to relative energy deficiency in sport (REDS) may occur.
EPIDEMIOLOGY —
In a foundational, prospective study from 1993 of 456 elite youth athletes (tennis, gymnastics, soccer, swimming) in the United Kingdom, weekly training loads were approximately 10 hours per week, injury rates were low, and children generally reported positive experiences with sport [8]. While rates vary by sport, region, and certain demographic characteristics, the current rate of early specialization in sport has increased substantially since this early study, as have injury rates [9,10]. More children are specializing across a wider range of sports and are doing so at younger ages. This phenomenon has been described in the United States, Canada, Japan, New Zealand, and across Europe [9,11-14].
In a 2019 systematic review of 22 studies of outcomes related to early sport specialization, the authors found that non-elite or semi-elite athletes often specialized before reaching 13 years, while elite athletes typically had delayed specialization until the ages of 14 to 15 [15].
Trends by sport — Rates of early specialization vary widely by sport. In general, individual sports such as tennis have higher rates of early specialization than team sports [16]. Among individual sports where peak performance is achieved at a young age (eg, girls' gymnastics), early specialization is a long-standing phenomenon. However, specialization rates have also risen among participants in individual sports where peak performance occurs later and in many team sports.
Early specialization occurs in a range of individual sports, including tennis [16,17], gymnastics [10,16], figure skating [18], swimming [10], dance [16], and climbing [19]. In a study of over 500 elite junior tennis players, specialization occurred at an average age of 10.4 years [17]. In a large survey study, gymnasts reported an average age of specialization of 8.9 years [16].
Rates of early specialization have increased for many team sports. Sports with higher rates include football (soccer) [20,21], basketball, and volleyball [22]. In a study of 1544 high school athletes in Wisconsin, soccer had the highest percentage of athletes who were highly specialized (21.5 percent) and American football the lowest (0 percent) [23].
A study of 1190 injured youth athletes participating in 10 sports found that soccer had the highest percentage of specialized athletes, followed by basketball and volleyball [16]. Among the patients in this study participating in individual sports, tennis had the highest rate of specialization, followed by gymnastics and dance. The team sport with the youngest age of early specialization was soccer (10.9±2.4), while those with the oldest age were basketball (12.7±2.6), American football (13.0±1.6), and baseball/softball (13.2±2.6).
Trends by sex — Many studies performed in the United States have reported that females are more likely to specialize in sport at an early age than males [24,25], or to identify as a single-sport rather than multisport athlete [26]. One explanation for this difference is that females are more likely to participate in individual sports where early specialization is the historical norm, such as gymnastics and figure skating [16,27].
Among team sport athletes, rates of early specialization may not differ between boys and girls. In a survey study of former United States collegiate athletes, females (n = 544) were more likely to play a single sport before the age of 15 (23.4 versus 15.2 percent), but when comparison was limited to team sports (eg, soccer, baseball/softball), no significant differences were noted [10]. As another example, in a study of over 700 youth soccer players, no statistically significant difference in the rate of early specialization was noted between boys and girls, although boys were more likely to play soccer more than eight months of the year [21]. Other studies have noted higher early specialization rates among boys in team sports [28]
Trends by socioeconomic status — Socioeconomic status (SES) may influence the likelihood of early sport specialization among youth, as well as related injury patterns. In a study of nearly 1200 youth athletes in the United States, those with public insurance (ie, lower SES) had lower rates of early specialization and serious overuse injury than those with private health insurance (ie, higher SES) [29]. In another study of families in the Midwestern United States, those with household incomes above $100,000 were more likely to have children who specialized in their sport at younger ages [30]. In a questionnaire study, high school athletes from wealthier suburban areas reported higher rates of early specialization and overuse injury than those from rural areas [31]. Whether this trend extends to regions outside the United States is not well studied.
Trends by population density — Demographics may influence the likelihood of specialization, in part because fewer private youth sports clubs are available in sparsely populated areas. In a questionnaire study of 354 high school athletes from four high schools (two suburban and two rural) in the Midwestern United States, those living in suburban areas were significantly more likely to specialize early compared with their rural counterparts [31].
Trends in different nations and regions — The patterns and effects of early sport specialization vary by country and population.
●United States – Of the estimated 60 million children who play organized sports in the United States, as many as one-third are highly specialized in one sport according to some studies. Highly specialized athletes tend to be from larger schools and wealthier, suburban areas. Findings from studies of early sport specialization in the United States include:
•Females are more likely than males to specialize [24,25].
•Athletes at larger high schools are more likely to be highly specialized than those at smaller high schools [26].
•Athletes at suburban high schools are more likely to be highly specialized than those at rural high schools [31].
•Youth athletes from neighborhoods or households with higher income or education are more likely to be highly specialized [29,30].
●Canada – Sport specialization among Canadian youth is more prevalent during high school, when rates are like those in the United States, than during junior high school. In a study of 238 junior high school students (age 11 to 16), 18 percent were highly specialized (according to the Jayanthi scale), 34 percent were moderately specialized, and 48 were minimally specialized [11]. A study of 1504 high school students (age 14 to 19) reported that 31 percent were highly specialized, 37 percent were moderately specialized, and 32 percent were minimally specialized [12].
●Japan – According to a survey study of 570 university students, most of those who had participated in organized sports prior to university (85 percent) played a single sport [13]. This was true of 70 percent of students during upper elementary, 90 percent during junior high, and 99 percent during high school. This is likely due to the Japanese extracurricular activity system, which makes a range of sports and cultural clubs available to students but encourages students to join a single club [32].
●New Zealand – In a cross-sectional study of 414 football (ie, soccer) players ranging in age from 10 to 15 years, 43 percent were highly specialized, 38 percent were moderately specialized, and 19 percent were minimally specialized [28]. While high specialization was more common among boys, this was likely because of the limited athletic opportunities for girls. In a cross-sectional survey study of 914 youth athletes younger than 13 years, 25 percent were highly specialized, 43 percent were moderately specialized, and 32 percent were minimally specialized.
●Europe – Rates of early specialization vary among European nations. In a prospective cohort of 259 Norwegian high school students enrolled in a sports academy (school for elite athletes), only 39 percent decided to focus on their sport before the age of 12, and only 23 percent reported playing a single sport before the age of 12, suggesting that early specialization is not necessary to become an elite athlete [14]. Similar findings were noted in a retrospective cross-sectional survey of Swedish football (soccer) players selected for a high-level team at 15; specializing in soccer before the age of 12 did not increase the likelihood of attaining elite status [33].
Studies performed in Portugal and Italy report different findings. On average, football players in Portugal start playing at an earlier age (five to six years) and focus on football exclusively at a significantly earlier age (seven to eight years) compared with peers participating in other sports (basketball, handball, volleyball, water polo) [34]. On average, these children began playing their main sport later (eight to nine years) and quit their other sports later (9 to 11 years). In a study of youth athletes aged 7 to 18 in southern Italy, 49.1 percent were highly specialized, 44.4 percent were moderately specialized, and only 6.5 percent were minimally specialized [35].
AGE AND RATIONALE FOR EARLY SPECIALIZATION
When is early specialization appropriate? — Decisions about the appropriate age to specialize depend upon the child and their development, the sport in question, and the necessary balance between realistic performance goals and injury risk. Some degree of sport specialization is necessary to develop elite-level skill (when this is an appropriate goal). However, we believe that intensive training in one sport to the exclusion of all other athletic endeavors is almost always unnecessary and should be delayed until late adolescence, if at all. This approach allows for the attainment of elite skill while minimizing the risk of physical injury, psychological stress, and burnout. A narrative review from 2013 found no evidence that intense training and specialization before puberty were necessary to achieve elite status in sport, with the exception of girls' gymnastics [36].
Peak performance is achieved at an early age (ie, prior to full skeletal maturity) in some sports, such as gymnastics and diving [36]. For those seeking to perform at elite levels in these so-called "early entry" sports, early specialization is likely necessary.
For other individual sports, data are limited, but some experts suggest that to excel at technical individual sports (eg, tennis), some degree of early specialization (ie, begun before skeletal maturity) may be needed. Studies suggest that the mean age of specialization among junior tennis players is approximately 10.4 years. However, it is not clear whether early specialization in these technical sports results in improved performance at older ages. (See 'Unclear impact on athletic performance' below.)
The American Orthopedic Society for Sports Medicine (AOSSM) recommends 12 years as an appropriate age to specialize in a sport [37], but other societies, including the American Medical Society for Sports Medicine (AMSSM) [38] and the American Academy of Pediatrics (AAP), have not designated a specific age. Some organizations recommend against using chronologic age as a basis for decision-making [38,39] and advocate using physiologic markers, such as percentage of predicted adult height (PPAH), as a more useful method for assessing young athletes and their potential injury risks [40]. Such assessment might assign children to one of three groups [36,41]:
●Pre-adolescence (pre-peak height velocity [PHV]) – For some children, it may be acceptable to focus on gymnastics, diving, or figure skating at this stage.
●Adolescence (circa-PHV) – For some children, it may be acceptable to focus on a particular field or court team sport, tennis, or golf at this stage.
●Post-adolescence (post-PHV) – It may be acceptable to focus on endurance sports (eg, distance running, triathlon) at this stage. (See 'Developmental considerations in youth athletes' above.)
It is important to provide appropriate training recommendations for children and adolescents based on their age and stage of development. (See 'Guidance for clinicians' below.)
Children who have not reached skeletal maturity are at increased risk of different types of injuries compared with musculoskeletally mature adolescents and young adults [38]. Children can sustain fractures involving the physes (eg, Salter Harris fractures), avulsion injuries of apophyses (eg, Osgood-Schlatter disease), and injury of articular surfaces, as their bones, apophyses, and articular cartilage are less resistant to tensile, shear, and compressive forces than more mature tissues (or the bones of very young children). Children's relatively reduced bone density, lack of lean tissue mass, and increased joint mobility all may contribute to an increased risk for these types of injury.
Factors driving early specialization — A range of factors may influence the decision to specialize in a sport at an early age. Some factors are external to the child (ie, extrinsic) and include the influence of coaches and parents, while others are internal (ie, intrinsic) and include a belief that specialization will increase their chances of playing sport at a high level. One potentially important factor beyond the scope of this medical review is financial incentive. Coaches, sports clubs, athletic training facilities, and event venues all depend on the youth sports industry for their income, which can be substantial.
●Extrinsic factors – Direction from coaches and parents is a common factor in early specialization. In a survey study of 235 youth athletes attending a United States sports medicine clinic, 30 percent reported that their coach told them not to participate in other sports [42]. Specialized athletes reported this significantly more often. Twenty-two percent of children reported that their parents told them not to play other sports. In a similar survey study of 201 parents, just under one-half reported encouraging their child to specialize in a single sport [43].
●Intrinsic factors – A desire to play athletics at a high level and the perception that focusing exclusively on their primary sport will help them to achieve this goal is a common reason that young athletes specialize [42,44]. In an online survey of just under 1000 United States youth athletes, 91 percent expressed a belief that specialization increased their chances of getting better at their sport either "quite a bit" or "a great deal" [45]. Female athletes were more likely to believe that specialization increased their chances of improving, and specialized athletes in the United States were twice as likely to believe they would receive an athletic scholarship to college.
An online survey of 975 United States high school athletes found higher rates of early specialization among those who expressed greater enjoyment of competition [44]. The results of these studies suggest that high school-age athletes are more likely to specialize out of an intrinsic desire to compete and to play athletics at a high level (eg, collegiate athletics in the United States) rather than from extrinsic factors, such as the desires of coaches and parents and the need to keep up with their peers.
OUTCOMES —
Early specialization is promoted by some as a method to optimize performance and to accelerate and improve athletic development. However, early specialization may carry risks of injury, burnout, and possibly longer-term adverse effects on health and may not provide the desired long-term enhancements in performance.
Increased risk of musculoskeletal injury — Overall, youth athletes who specialize at an early age sustain overuse musculoskeletal injuries at higher rates than their nonspecialized peers. In a systematic review of studies involving several thousand youth athletes, high specialization was associated with higher rates of overuse injury compared with moderate specialization (RR 1.18, 95% CI 1.05-1.33) and low specialization (RR 1.81, 95% CI 1.26-2.60) [46]. In the included studies, an overuse injury was defined as one not caused by any specific acute trauma, while a serious overuse injury required over one month of rest from sport. As another example, in a three-year prospective study of several hundred youth athletes, sports specialization was an independent risk factor for overuse injuries [39].
The finding of increased injury risk is consistent across multiple observational studies that categorize the degree of early specialization among youth athletes [4,12,23,25,47-49]. However, studies using a single age or sport threshold to determine early specialization, rather than using multiple criteria to define degrees of specialization (eg, Jayanthi criteria), have not found a difference in injury rates [14,26,50]. As an example, after controlling for sex, sport, and training hours, no association between injury risk and specialization in a single sport prior to the age of 12 was found in a prospective study of elite Norwegian youth athletes [14]. (See 'Definitions' above.)
Whether the increased risk of injury extends to both chronic overuse and acute trauma is unclear. In a questionnaire study of over 2000 United States youth, highly specialized athletes were significantly more likely to sustain overuse and acute injuries than their nonspecialized peers [20]. However, similar studies have found statistically significant differences only in overuse injury rates [51].
Increasing degrees of specialization are associated with corresponding stepwise increases in the risk of sustaining an overuse or serious overuse injury [1,31]. These findings persist after adjusting for age, sex, or training volume [25]. As an example, according to a study of questionnaires completed by 1377 Japanese adults, the prevalence of overuse injuries was higher in athletes who played the same team sport from elementary school to high school compared with those who played multiple team sports in their youth [51]. Multiple studies of high school athletes in the United States confirm these findings [23-26].
Possible factors contributing to increased injury risk — It is not clear which aspects of early specialization drive the increased risk of overuse injury. Relevant factors may include:
●Training load
●Year-round participation
●Sport type
●Younger age
●Sex
●Biomechanical factors
●Geography
●Socioeconomic status
Training load and extended participation — Many youth athletes specializing in one sport exceed the time limits in participation guidelines [21]. Whether early specialization alone or the year-round participation and increased training loads associated with early specialization account for the increased risk of overuse injury is unclear, as evidence is limited and contradictory. Differences among study populations, outcome measures, and how sport specialization is defined may account for some discrepancies.
As examples, in a retrospective case-control study of nearly 1200 youth athletes, sports specialization alone, independent of child age and training volume, was associated with an increased overall risk for injury and serious overuse injury [1]. In another retrospective study of 414 New Zealand youth football (soccer) players, athletes who were highly specialized were over four times more likely to sustain an overuse injury compared with their low-specialization counterparts after controlling for age and total training hours [28]. Other studies support the finding that sport specialization itself is a risk factor for overuse injury, independent of training load [12,20].
Conversely, some studies emphasize the importance of training load and extended participation, independent of specialization status, in accounting for higher injury rates. As examples, in a retrospective questionnaire study of 914 youth athletes, early specialization in a single sport before the age of 13 was not associated with an increased risk of overuse injury, while excessive training time (weekly hours for sport greater than age) and extended participation (playing single sport more than eight months in a year) were associated with increased risk [52]. In another retrospective study of 132 female youth figure skaters, age was significantly associated with low back injury while specialization was not, suggesting that cumulative training load was the important risk factor [18].
Sport type — Athletes training and competing in individual sports (eg, tennis, gymnastics, dance) tend to have higher rates of overuse injury than those playing team sports [16]. This may be due to the nature of individual sport training (which is often more focused on repetitive, technical movement patterns), the younger ages of specialization, or both.
Multiple observational studies report higher rates of overuse injury among youth specializing in individual sports. As an example, in a sample of more than 500 high-level junior tennis players surveyed about their training patterns, specialization occurred at a mean age of 10.4 years old, and athletes were more likely to report a history of injury [17].
Nevertheless, youth who specialize early in a wide range of team sports also experience higher injury rates. As examples, in a retrospective study of youth hockey players who specialized at an average age of 10.7 years, those who were moderately or highly specialized were more likely to develop a symptomatic cam hip deformity compared with their nonspecialized peers [53]. In another retrospective study of over 1500 female high school volleyball players, specialization was associated with significant increase in injury rates [54]. Additional examples are discussed above. (See 'Increased risk of musculoskeletal injury' above.)
Sex — Although evidence is limited, several observational studies report a higher frequency of serious overuse injuries (requiring at least one month of recovery time) associated with increased levels of sports specialization among female youth athletes compared with their male counterparts [39,55-59]. As an example, a retrospective study of 546 female junior high school and high school athletes reported that those specializing in a single sport (volleyball, basketball, or soccer) had a 1.5 times greater risk of developing patellofemoral pain (95% CI 1.0-2.2) and a four times greater risk of developing Osgood-Schlatter apophysitis, Sinding-Larsen-Johansson apophysitis, or patellar tendinopathy than their multisport counterparts (95% CI 1.5-10.1) [4].
However, well controlled, prospective studies are not available, and not all observational evidence confirms these findings. As an example, in a study of 611 female secondary school athletes, the rate of injury was no different between multisport and specialized single-sport athletes [60].
The possible discrepancy in injury rates by sex may stem from differences in sport selection (increased participation in individual versus team sports), training type and load, and biomechanical factors. In addition, the higher baseline rate of overuse injury among young female athletes, regardless of specialization, should be considered when interpreting these studies [1,61].
Risk of burnout and effects on quality of life — Early specialization in sport may increase the risk of burnout and contribute to other adverse psychological effects, but evidence is limited and mixed [37,62-64]. The results of some observational studies suggest that multisport athletes are less likely to quit sport compared with early specializers [27,37,65]. In a prospective study of 756 children (aged 10 or 11 when the study began), those who sampled multiple sports at younger ages were more likely to continue with recreational sport and less likely to quit sports altogether during adolescence compared with those who played only one sport or did not participate in sport [27].
However, not all studies report an association between early specialization and burnout. In a survey study of 267 United States Division I college athletes, those who specialized in their sport before the age of 15 did not report significantly higher levels of burnout than athletes who specialized at 16 years or older [66]. Burnout was assessed using the validated Athlete Burnout Questionnaire, which includes a reduced sense of accomplishment, exhaustion, and sport devaluation among its measures.
Evidence about the effects of early specialization in sport on general quality-of-life measures is limited. A systemic review of three studies reported that early sport specialization was associated with lower health-related quality of life (HRQOL) measures in United States college students [67]. A survey study involving 356 young adults categorized participants based on their degree of specialization during childhood and high school and found that high specializers reported significantly lower scores in lower extremity health and function despite not having played collegiate sport [68]. United States Division I, freshman college athletes who had specialized in a single sport before enrolling had a lower average cognitive performance on the ImPACT concussion assessment than those who played multiple sports in one uncontrolled study [69].
Other studies report no adverse effects on quality-of-life measures from early specialization. In a qualitative study of parents and youth athletes using a semi-structured interview, HRQOL was similar in specialized youth athletes from supportive environments and resilient young athletes generally [70]. Supportive environments included less emphasis on winning and positive parental and coaching influences. After controlling for injury, a study of female high school volleyball athletes found no difference in quality-of-life scores across a range of domains, including emotional and social [22].
Early specialization may adversely affect sleep, but evidence is scant and of low quality. In a retrospective study of surveys completed by just under 1500 female youth volleyball players, highly specialized athletes reported significantly more daytime sleepiness than less specialized peers [22]. Youth athletes with high levels of specialization had higher scores on the Pediatric Daytime Sleepiness Scale (PDSS) compared with peers with low levels of specialization in a small observational study [71].
Unclear impact on athletic performance — A basic belief among many advocates of early specialization in sport is that this approach improves athletic performance and increases the likelihood of achieving elite status (eg, United States Division I collegiate sport, Olympic competition, professional sport). Many Americans believe that early specialization increases one's chances of playing high-level collegiate sport [45]. However, available evidence, while largely retrospective, does not support these assertions [15,72-74]. Exposure to a range of sports during youth is likely beneficial for enhancing overall athletic development and reducing injury risk [1,15,75]. (See 'Increased risk of musculoskeletal injury' above.)
In a systematic review of 22 studies of youth sport specialization and performance outcomes, researchers noted that elite athletes specialized in their sport later (between 14 and 15 years) compared with their peers who did not achieve elite status (under 13 years) and that physical performance measures did not differ by age of specialization [15]. Another systematic review of 71 studies assessed the outcomes of over 9000 athletes participating in a range of sports worldwide, many at a high level (eg, national and regional teams) [72]. This review noted that adult world-class athletes engaged in more coach-led practices of sports other than their main sport as children and adolescents compared with their peers and began specializing in their main sport at an older age. While improved junior-age (teenage years in most cases) performance was associated with earlier specialization and more time spent practicing a primary sport, this did not hold true at the highest levels of senior-age performance. More generally, a systematic review of studies involving over 13,000 elite athletes from multiple countries found that junior performance did not predict senior performance [73].
In a study comparing survey results from 273 United States Division I college athletes and 155 nonathlete peers, athletes were significantly more likely to have begun specializing at a later age (most after 15 years) but were more likely to have a parent or first-degree relative that played collegiate or professional sports [76]. In a similar study of 266 United States Division I intercollegiate athletes and 180 club athletes, the number of years of high specialization during high school did not differ between groups [77].
Effects on biomechanics and motor skills — Biomechanical flaws increase the risk for anterior cruciate ligament (ACL) tears and other injuries. Limited evidence suggests that biomechanical flaws may contribute to the higher rates of overuse injury seen in specialized youth athletes, particularly females.
As examples, in a prospective case-control study, specialized female adolescent athletes (n = 79) exhibited larger increases over two to three years in peak knee abduction angle and moment when performing a drop-vertical-jump (DVJ) test compared with multisport athletes (n = 79) [78]. A biomechanics laboratory study of over 700 adolescent female athletes performed by the same research group noted increased variability in hip and knee motion during DVJ testing among sport-specialized athletes [79]. These results suggest that specialized adolescent female athletes have worse neuromuscular control than their multisport peers, placing them at greater risk for unstable landing and related injury. In another observational study of 735 prepubescent boys, 10- to 12-year-olds who sampled multiple sports demonstrated greater strength, speed, and gross motor coordination compared with their specialized peers [80]. Specialized young female soccer players exhibited more regular (ie, less complex) movement patterns during a virtual reality header drill than nonspecialized athletes [81].
However, not all evidence is consistent with these findings. In a study of 238 Canadian junior high school students, no significant difference between high specializers and other athletes was noted in several tests of agility and athletic performance, including vertical jump height, single-leg and Y balance testing, and predicted maximal oxygen uptake (VO2 max) [11].
GUIDANCE FOR CLINICIANS —
Although evidence is limited and recommendations vary, many leading sports medicine and pediatric medicine organizations advise against early specialization in sport, particularly in prepubescent youth, primarily due to the increased risk of injury [63,82-85]. Nevertheless, depending on the sport and location, as many as one-third of youth athletes will continue to specialize.
For these reasons, we believe it is appropriate for pediatricians, family physicians, and other clinicians who care for children and adolescents who participate in competitive sport to initiate a discussion about sport specialization during a health care visit. During such visits, clinicians can share basic principles about appropriate participation and discuss the potential risks and benefits associated with early specialization with parents, caretakers, and young athletes. It also affords clinicians an opportunity to learn about the child's level of participation and to perform a formal assessment of injury risk.
General guidelines for youth sport participation — We advocate that youth athletes, parents, and coaches follow the guidelines below. Adhering to these measures reduces the risk of musculoskeletal injury, psychological burnout, and other problems associated with early specialization:
●Limit hours per week – Youth athletes should not participate in their primary sport for more hours per week than their age. Doing so increases their risk of injury [24,39,50]. As an example, a 16-year-old athlete should not practice or play their sport more than 16 hours each week.
●Limit days per week – Youth athletes should take one to two days off from sport each week [86].
●Appropriate ratio of training to competition – The ratio of intense game competition to training sessions should be appropriate to the athlete's age [40]. For most sports, a ratio of around 1:4 is appropriate for pre-adolescent athletes, while 1:2 is appropriate for adolescents. A 1:1 ratio may be acceptable for some post-adolescent athletes, particularly those participating in individual sports, who may have greater control over their play and rest schedules.
●Adjunct strength and conditioning exercises – Youth athletes should participate in a well-rounded training program that includes general strength and conditioning exercises in addition to sport-specific skills [41]. Well-designed programs of this type promote overall health and reduce injury risk.
●Limit months per year – Youth athletes of all ages should not participate in their sport for more than eight months out of the year. Doing so increases their risk of injury [24,42,87].
●Off-season – Youth athletes should observe an off-season period of at least one month duration on two separate, nonconsecutive occasions during the year.
During this time, athletes should play a different sport or have limited competition and training in their main sport. We encourage abstaining from the main sport and playing a different sport, as this allows athletes to avoid repetitive movements associated with overuse injury and enables them to use their minds and bodies in novel ways, which may improve perceptual skills and reduce burnout risk.
●Free play – For youth athletes of all ages, the ratio of sports training (ie, formal practice) to free play (sport without organized coaching or formal instruction) should not exceed 2:1, as exceeding this ratio increases the risk of injury [1,20,39].
Whenever possible, we support the use of bio-banding programs [88]. Bio-banding involves organizing youth athletes based on their stage of physiologic development rather than their birth or school year. This approach enables coaches to match the intensity and frequency of training to a child's physiologic development, thereby making competition more equitable and reducing the injury risks associated with large discrepancies in size and strength.
Providing guidance about risks and benefits — Many parents and coaches are unaware of guidelines for youth participation in sport or the risks associated with early specialization, and some may believe that early specialization is beneficial [57,89,90]. Children and adolescent athletes too are often unaware of appropriate limits to their participation, and many do not believe that specialization is associated with an increased risk of injury [45,91]. (See 'Increased risk of musculoskeletal injury' above.)
We believe it is important that clinicians make athletes, parents, and caretakers aware of the risk of overuse injury associated with early specialization and of the importance of following the guidelines listed above to reduce such risk and enhance the athletic experience. (See 'General guidelines for youth sport participation' above.)
Furthermore, youth athletes, parents, and caretakers should be made aware that for many sports, early specialization does not ensure improvements in performance, and in some instances may be detrimental. Specialization may be needed to achieve elite performance in some sports, but this should be deferred until middle or late adolescence in most cases and whenever possible. (See 'Unclear impact on athletic performance' above and 'When is early specialization appropriate?' above.)
Early specialization in sport may increase the risk of burnout and contribute to other adverse psychological effects, but evidence is limited and mixed. Athletic experience that promotes wellbeing is possible for the child who is intrinsically motivated to train and compete and who has supportive caretakers and coaches with appropriate priorities. (See 'Risk of burnout and effects on quality of life' above.)
History and examination during the well child visit — As part of the standard well child or adolescent history and physical examination or the preparticipation evaluation, we encourage clinicians to ask about the following when assessing youth athletes (see "Sports participation in children and adolescents: The preparticipation physical evaluation"):
●Total training hours and days per week, including any recent changes (see 'General guidelines for youth sport participation' above)
●Frequency and number of competitions
●Degree of specialization (table 1) (see 'Definitions' above)
●Sports-related injuries (in addition to standard injury history)
●Symptoms associated with burnout (eg, chronic fatigue, loss of interest or enjoyment in sport)
Determining the child's stage of development (using percentage of predicted adult height [PPAH] or similar clinical tools) helps to determine the risk for different injuries. The distal-to-proximal scheme described above may provide a useful framework for assessing possible sites of injury. (See 'Developmental considerations in youth athletes' above.)
In addition to the standard, age-appropriate physical examination, we encourage clinicians to assess regions susceptible to sport-related overuse injury. Areas to include in the examination include:
●Medial elbow, including palpation of medial epicondyle (figure 1 and figure 2 and image 1) (see "Elbow injuries in active children or skeletally immature adolescents: Approach", section on 'Medial elbow pain')
●Proximal humerus/shoulder
●Low back, including low back extension (picture 1) (see "Spondylolysis and spondylolisthesis in child and adolescent athletes: Clinical presentation, imaging, and diagnosis", section on 'Physical examination')
●Anterior knee, including palpation of tibial apophysis (picture 2)
●Heel, including palpation of calcaneus and Achilles tendon insertion (figure 3 and picture 3)
Guidance for early specializers — Some youth athletes and their families may choose to specialize knowing the increased risk for overuse injury and other possible adverse effects. They may be seeking guidance about how to train and compete to minimize these risks. Clinicians should counsel such families about appropriate training and competition schedules, including the relevant guidelines discussed above. Adhering to these guidelines will help to reduce the risk of overuse injury, burnout, and other possible problems. (See 'General guidelines for youth sport participation' above.)
A core principle when considering or managing the mental health ramifications of early sport specialization is that young athletes enjoy the experience [62]. Participation in sport promotes the emotional and social wellbeing of many children, but this occurs primarily when the athletic experience is fun and developmentally appropriate. For athletes who choose to specialize, it is important that these features remain high priorities.
In addition to ensuring that sport remains enjoyable for early specializers, the following practices can help to improve performance and reduce injury risk [40]:
●Avoid sudden increases in training volume, especially during the period of peak adolescent growth. As a rule, total training volume (time spent in practices plus games) should not increase by more than 10 percent per week. In addition, a youth athlete's “training load” (time spent in practices plus other organized training) should not increase by more than 25 percent of the average load over the previous four weeks.
Moderate, age-appropriate, consistent training loads are best for adolescent athletes. Such loads allow for training adaptations to occur and performance to improve without increasing the risk of injury. Large fluctuations in training loads, and excessive total loads, increase injury risk and are unnecessary for improving performance.
●Ensure age-appropriate training loads. Loads should be reduced during periods of peak adolescent growth when injury risk is relatively high. Total training time in hours should not exceed the athlete's age.
●Ensure adequate sleep (minimum of eight hours per night) and recovery. (See "Assessment of sleep disorders in children".)
●Be alert for signs of stress (including academic, emotional, psychological, and physical) and intervene early as needed. Signs may include diminished interest in sport, decline in school performance, moodiness, disturbed sleep, and unexplained somatic symptoms (eg, headache, abdominal pain). (See "Anxiety disorders in children and adolescents: Epidemiology, pathogenesis, clinical manifestations, and course".)
Surveillance of early specializers — The author suggests that clinicians caring for children who specialize in a sport assess them for risk of injury and perform regular surveillance based on their risk. Assessment may be done in person or virtually (eg, video conference). The Sports Training Assessment of Risk (STAR) or other standardized assessment tools may be used. The tools needed for this brief assessment are provided in the following tables (table 1 and table 2).
Formal evaluation allows for appropriate surveillance informed by the child's growth rate and stage of development, training load and degree of specialization, and musculoskeletal assessment.
●High risk – Child and adolescent athletes deemed to be at higher risk of injury based on this assessment likely need to be monitored more frequently (eg, every three months), particularly during vulnerable periods (eg, peak growth).
●Moderate risk – Athletes at moderate risk may need some additional monitoring depending on their stage of development and other factors, but a check-in every six months is likely sufficient.
●Low risk – Athletes at low risk generally do not need additional monitoring beyond the usual annual checkup. Such athletes typically include skeletally mature adolescents without a history of serious overuse injuries who have established, appropriate training and competition loads.
Some clinics use counseling interventions to attempt to reduce injury risk. A multicenter randomized trial involving 357 youth athletes to assess the impact of online counseling performed every three months using the safe-sport recommendations reported a possible association with lower injury rates over the course of 12 months [91]. However, although injury rates were lower in the intervention group, compliance with the safe-sport recommendations did not differ between the intervention and control groups, making the study results difficult to interpret. Noncompliant athletes often cited their coaches as the reason, highlighting the importance of coaching education.
SUMMARY AND RECOMMENDATIONS
●Epidemiology and definitions – The number of children and young adolescents limiting their participation in athletics to a single sport continues to grow around the world and involve a wider range of sports. While specialization is more common in certain individual sports (eg, tennis, gymnastics), it is also common in some team sports (eg, football [soccer]). (See 'Epidemiology' above.)
Early specialization in sport can be categorized as low, moderate, or high using criteria described in the following table (table 1). The concepts and history behind early specialization and the risks posed at each stage of child and adolescent development by this approach are reviewed in the text. (See 'Terminology, background, and key concepts' above and 'Age and rationale for early specialization' above.)
●Increased injury risk and other adverse effects – Youth athletes who specialize at an early age sustain overuse musculoskeletal injuries at higher rates than their nonspecialized peers. Whether early specialization alone or the year-round participation and increased training loads associated with early specialization account for this is unclear. Early specialization in sport may increase the risk of burnout and contribute to other adverse psychological effects, but evidence is limited. (See 'Outcomes' above.)
●Unclear impact on performance – Advocates of early specialization in sport claim it improves performance and increases the likelihood of achieving elite athletic status. Many Americans believe it increases the likelihood of playing high-level collegiate sport. However, available evidence, while largely retrospective, does not support these assertions. Exposure to a range of sports during youth is likely beneficial for enhancing overall athletic development and reducing injury risk. (See 'Unclear impact on athletic performance' above and 'Effects on biomechanics and motor skills' above.)
●General guidelines for youth sport participation – In order to promote well-being and reduce injury risk, we advocate that youth athletes, parents, and coaches follow these guidelines:
•Limit hours per week – Youth athletes should not participate in their primary sport for more hours per week than their age.
•Limit days per week – Youth athletes should take one to two days off from sport each week.
•Free play – For youth athletes, the ratio of sports training (ie, practice) to free play should not exceed 2:1.
•Use an appropriate ratio of training to competition – The ratio of intense game competition to training sessions should be appropriate to the child's age. For most sports, a ratio of around 1:4 is appropriate for pre-adolescent athletes, while 1:2 is appropriate for adolescents.
•Incorporate strength and conditioning exercises – Youth athletes should participate in a well-rounded training program that includes general strength and conditioning exercises in addition to sport-specific skills.
•Observe off-season periods – Youth athletes should observe an off-season period of at least one month duration on two separate, nonconsecutive occasions during the year.
●Assessment during well child or sport preparticipation visit – As part of the standard well child or adolescent visit for those participating extensively in sport, we encourage clinicians to include the elements listed below. (See 'History and examination during the well child visit' above and "Sports participation in children and adolescents: The preparticipation physical evaluation".)
•History
-Total training hours and days per week, including any recent changes (see 'General guidelines for youth sport participation' above)
-Frequency and number of competitions
-Degree of specialization (table 1) (see 'Definitions' above)
-Sports-related injuries (in addition to standard injury history)
-Symptoms associated with burnout (eg, chronic fatigue, loss of interest or enjoyment in sport)
•Physical examination
-Medial elbow, including palpation of medial epicondyle (figure 1 and figure 2 and image 1)
-Proximal humerus/shoulder
-Low back, including low back extension (picture 1)
-Anterior knee, including palpation of tibial apophysis (picture 2)
-Heel, including palpation of calcaneus and Achilles tendon insertion (figure 3 and picture 3)
●Guidance for working with early specializers – Additional guidance for clinicians working with youth athletes and their families who understand the risks but choose to specialize early in a sport is provided in the text. It includes information about risk assessment, surveillance, and advice about reducing risk. (See 'Guidance for early specializers' above and 'Surveillance of early specializers' above.)
