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A historical perspective
Sport specialisation, conceptually understood to involve mono-training and repetition for the purpose of skill acquisition and athlete development for a single sport, is increasingly common in youth sports. However, it has not always been this way. Over the past 30 years, research on expertise and skill acquisition has profoundly influenced the focus and structure of youth sport programme. Particularly, Ericsson, Kramp and Tesch-Römer’s (1993) work in music renewed research interests related to the importance of deliberate practice in the development of expertise.1 Some studies in sport, using retrospective questionnaires, suggested that high volume of intense, sport-specific practice at a young age is necessary to attain expertise in one sport.2 This body of research has promoted the idea that a large quantity of intense sport-specific practice and early specialisation is a logical pathway towards adult elite sport performance, and has contributed to the popularity of youth sport specialisation.
Simultaneously, biographical studies of elite level athletes suggested that their childhood sport experiences involved sport-specific practice, and play activities and engagement in various sports. In contrast with the early specialisation approach, Côté (1999) defined sampling as an early sport participation environment characterised by diversity, both within (eg, play, practice) and between sports.3 Considering both distinctive lines of research led to equivocal results, Côté, Ericsson and Law (2005) developed a structured retrospective interview procedure for collecting quantitative data and objective measures of performance and participation to examine different pathways of athlete development.4
Their interview method, when used to compare elite and less-elite athletes in various studies, supported the biographical studies showing adult elite and less-elite athletes had youth sport experiences that included sampling both within and between sport, and that elite athletes often specialised during adolescence. Furthermore, the early sampling pathway was associated with a range of positive physical and psychosocial outcomes that should be central to any youth sport programme (eg, physical health, reduced signs of burn-out). This sampling approach formed the foundation of the Developmental Model of Sport Participation, a framework that offers a valuable lens for evidence-informed policies.5
Defining sport specialisation
These developmental and expertise models set the framework for our current understanding of youth sport specialisation: year-round training in a single main sport at the exclusion of all other sports. Numerous prior studies have used a binary definition (ie, participation in a single sport vs multisport) to describe the association between youth sport specialisation and performance and injury outcomes. Jayanthi et al first introduced a degree of specialisation, which has been associated with a dose-dependent increased risk of overuse injury6 and dropout as degree of specialisation increases. Bell et al later confirmed this definition to be more effective than a binary definition to determine injury association.7 Pasulka et al further suggested using the phrase ‘single sport specialised athletes’ to accurately classify athletes who only ever participate in and thus focus on one sport (eg, gymnasts).8 Others, including the American Orthopaedic Society for Sports Medicine, have deemed ‘early specialisation’ as occurring prior to 12 years old as there may be performance benefit to specialisation in middle to late adolescence.9 However there are insufficient data to support a clear age of appropriate specialisation.
The need for an evidence-based definition of youth sport specialisation
The research surrounding youth sport specialisation has drastically increased over the past decade, yet an agreed on, validated definition with testable constructs simply does not exist. One advancement to define youth sport specialisation is Jayanthi’s degree of specialisation scale (table 1), however, this measure may fall short of capturing the true level of specialisation among youth by not including all elements that affect an early specialisation pathway.
Based on conclusions of the 2019 Youth Early Sport Specialisation Summit initiated by the American Medical Society for Sports Medicine, we recommend that a priority be placed on developing a consistent, reliable definition with measurable constructs that can accurately discriminate between different patterns and levels of specialisation (online supplementary file 1). This definition may differ depending on the sport, type of sport (eg, individual vs team sport) and outcomes studied (injury, performance, psychosocial, etc). We recommend that in addition to the three key elements already described (table 1) in a degree of specialisation scale, other important elements to consider include: specialising at age <12 years, prepubescent developmental stage, weekly organised sports versus age or weekly free play hours, and a child’s autonomy in training. While none of these elements alone fully define youth sport specialisation, all may play a role in measuring an athlete’s specialisation status and in developing an evidence-based definition.
We also acknowledge that accumulation of hours in a particular sport during childhood is an important determinant of athletic success and is linked to the concept of specialisation. However, hours in sport can accumulate via participation in multiple sports or through a specialised sampling model within one sport (eg, practice with play hours). Sampling before mid to late adolescence may ultimately lead to greater success and less injury instead of solely increasing the time or intensity dedicated to one sport. As such, we believe that training volume, intensity and specialisation are separate, yet closely related concepts that should be accounted for in a future research definition of youth sport specialisation.
In conclusion, our challenge is to determine and refine through research the necessary elements of the definition of youth sport specialisation and conduct validation studies to assess this definition in a sport-specific manner. As sport-specific research grows, an evidence-based definition of sport specialisation will be vital to collect reliable data that inform strategies for optimal youth sport participation, injury prevention, long-term health and performance.
The authors thank the contributions of co-chairs of the AMSSM (American Medical Society for Sports Medicine) YESSS (Youth Early Sport Specialisation Summit). The following have read, provided feedback, and approved the editorial to be consistent with the findings and goals of this summit.
Collaborators A Beutler, S Marshall, D Herman, K Nagle, C La Bella, A Tenforde.
Contributors NJ, SAK and JC all made substantial contributions to the conception of this editorial with all editing and revisions and gave final approval of the version to be published. The authors are to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.