Sex Differences in 1600-m Running Performance and Participation for Children Aged 6–12 yr

ABSTRACT Introduction In children, females participate in sport and physical activity less than males and have lower peak oxygen intake values. How this sexual dimorphism in the aerobic capacity of children affects the aerobic performances of children in a 1600-m race and whether the reported discrepancy in sport and physical activity participation accounts for any sex differences in aerobic performance are unknown. The purpose of this study was to 1) identify sex-based differences in aerobic running performance at 1600 m for children aged 6–12 yr and 2) investigate sex-based differences in participation in children and any relationship between participation and sex differences in aerobic performance. Methods We compared 1600-m running velocities (in m·s −1 ) and participation for 3621 children in the United States in grades 1–6 (ages 6–12 yr) for the years 2007–2014 that were obtained from a publicly available website (runnercard.com). We correlated the female participation with the performance difference between the sexes for each year and grade. We also created a mathematical model to predict the mean velocity ( ) needed to equalize the sex difference in performance if participation was equalized. Results Male children were faster (3.00 ± 0.53 m·s −1 ) than female children (2.77 ± 0.49 m·s −1 ) at every grade level, with an average difference of 7.7% ( P < 0.001). Participation was lower for female children (46.2%; χ 2 = 13.0, P = 0.02) and there was no correlation between female participation and the performance difference between sexes (Pearson’s r = 0.255, P = 0.96). needed to equalize the sex difference in performance if participation was equalized was 4.39 m·s −1 , which was greater than the observed female mean plus two standard deviations. Conclusions Male children are faster than female children at running 1600 m at ages 6–12 yr. This sex difference was not a result of lower female participation and suggests that innate physiological sex differences may be responsible.