Timing and Reasons Behind Single-Sport Specialization in Soccer: A Survey of 64 Major League Soccer Athletes

Background: Single-sport specialization at the exclusion of other sports has become increasingly popular in youth sporting culture. The purpose of this study was to survey Major League Soccer (MLS) athletes to examine factors influencing the timing of single-sport specialization in soccer. Hypothesis: The majority of surveyed athletes will have participated in multiple sports prior to specialization and specialized primarily as a result of a coach’s recommendation, with no significant impact on specialization timing stemming from birth or high school location, obtaining a collegiate scholarship, MLS experience, or position. Study Design: Cross-sectional study. Level of Evidence: Level 4. Methods: Anonymous surveys were distributed to 3 MLS organizations and completed by MLS athletes during preseason physicals. Surveys evaluated the age and reason(s) behind an athlete’s decision to specialize in soccer, birth location, geographic high school location for US-born athletes, participation in a developmental league, college scholarship, years in the MLS, and position played. Results: Approximately 74% (64/86) of athletes returned completed surveys. Athletes reported beginning soccer at a mean age of 5.1 ± 2.1 years and specializing at age 12.6 ± 4.3 years. Athletes who participated in no other sports prior to specialization (P < 0.001), athletes reporting soccer to be their first sport played at an advanced level (P < 0.001), and athletes receiving a college scholarship (P = 0.02) specialized at a significantly younger age. Internationally born athletes specialized at significantly younger ages when compared with US-born athletes (P < 0.001). Conclusion: The majority of athletes participated in multiple sports prior to specialization and eventually specialized to focus exclusively on soccer. The timing of sport specialization in professional MLS athletes was not associated with multisport participation prior to specialization, playing soccer at an advanced level prior to other sports, receiving a college scholarship, or being born outside the United States. Clinical Relevance: Timing of sport specialization is associated with multiple factors prior to athlete promotion to the MLS that warrant further investigation to better understand the impact of specialization on injury incidence, performance, and career length.