Participation in Vigorous Sports, Not Moderate Sports, Is Positively Associated With Cardiorespiratory Fitness Among Adolescent Girls

Background: There is controversy regarding whether moderately-intense sports can improve physical fitness, which declines throughout adolescence among girls. The objective was to estimate the association between moderate and vigorous sports participation and cardiorespiratory fitness in a racially diverse sample of adolescent girls. Methods: Cardiorespiratory fitness was measured using a modified physical work capacity test in 1029 eighth-grade girls participating in the Trial of Activity for Adolescent Girls. Girls reported sports in which they participated in the last year on an organized activity questionnaire. Using general linear mixed models, the study regressed absolute and relative fitness on the number of vigorous and moderate sports in which girls participated, race/ethnicity, age, treatment group, fat mass, fat-free mass, and an interaction between race and fat-free mass. Results: The number of vigorous sports in which girls participated was positively associated with absolute fitness (beta = 10.20, P = .04) and relative fitness (beta = 0.17, P = .04). Associations were reduced, but not eliminated, after controlling for MET-weighted MVPA. Participation in moderate sports was not associated with either fitness measure. Conclusions: Vigorous sports participation is positively associated with cardiorespiratory fitness. Future longitudinal research should analyze whether promoting vigorous sports at an early age can prevent age-related declines in cardiorespiratory fitness among adolescent girls.