BACKGROUND: Although cross-sectional evidence exists regarding the association between sport specialization and health outcomes, sport-specific, prospective research is lacking. The aim of this study was to determine the relationship between sport specialization status and in-season injury and illness risk in elite female adolescent soccer players. METHODS: 80 female youth soccer players (ages 13-18) from a local youth soccer organization underwent preseason evaluation of maximal aerobic capacity (VO2max) and sport specialization and provided self-reporting of daily training load (session-rating of perceived exertion), injury and illness for two four-month competitive soccer seasons. Mixed effects logistic regression models were used to predict individual injury and illness (yes/no) during the study period, using sport specialization, age, and training load as fixed effects and individual athlete as a random effect. RESULTS: Specialized (N.=46) athletes did not differ from non-specialized (N.=34) athletes with respect to age, preseason physical activity, VO2max or in-season training load (all P>0.05). 28 athletes participated in both years, representing 108 player-years. No differences were seen in the proportion of individuals from each group that reported an in-season injury (specialized = 25% vs. 20%, P=0.55) or illness (46% vs. 38%, P=0.41). After adjusting for age and training load, individual injuries (OR=0.86 [0.26, 2.8], P=0.81) and illnesses were not significantly predicted by specialization (OR=1.06 [0.45, 2.5], P=0.89). CONCLUSIONS: After adjusting for age and training load, late sport specialization was not associated with in-season injury or illness risk in elite female soccer players.
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