An active lifestyle explains sex differences in physical performance in children before puberty.

The aim of this study is to analyze differences according to sex in physical performance in children before puberty, as well as other health-related variables. Study population was 137 boys and 156 girls (9.99 +/- 0.79 years). We measured weight and height, physical performance using five field tests previously validated in children, habitual physical activity and diet quality. A multinomial logistic regression coefficient was established to calculate odd ratios (OR's) and 95% confidence intervals (CI's), to determine sex differences in performance, weight status, habitual physical activity and diet quality, and a t-test was calculated between active boys and active girls in order to establish differences in performance fitness test taking account habitual physical activity. Boys were more actives (OR 1.90, CI 1.03-3.49) and had better weight status than girls, while there was no difference in diet quality between sexes (OR 1.13, CI 0.67-1.89). In total sample, it was more probable to find greater physical fitness values in boys in all test performed. However, when both groups had a similar physical activity pattern, assessed physical fitness variables reached similar values and girls had better results only in flexibility. Sedentary patterns were more frequent in girls although there were no differences in diet quality between sexes. Girls tended to overweight more than boys did. Both sexes had a similar fitness performance before puberty for the same reported physical activity, except for flexibility, inferior in male subjects independently of their physical activity pattern.