Moderators in a physical activity intervention for adolescent girls.

Abstract

BACKGROUND:The purpose was to explore whether baseline sociodemographic and physical characteristics moderated effects of an intervention on moderate-to-vigorous physical activity (MVPA), percent body fat, body mass index z-score, and cardiorespiratory fitness (CRF) at post-intervention, relative to the control condition.METHODS:A secondary analysis of data from a group randomized trial including 24 schools (12 intervention and 12 control; N=1519 girls) was conducted. Age, ethnicity, race, socioeconomic status, and pubertal stage were assessed via survey. Height, weight, MVPA (min/hr), percent body fat, and CRF were measured. Mixed-effects linear models were performed.RESULTS:Compared to the control, the intervention increased overweight and obese girls’ CRF (F=4.36, p=.037; F=6.56, p=.011, respectively), but not healthy weight girls’ CRF (F=0.01, p=.925). Pre- to mid-puberty girls in the intervention group had slightly lower post-intervention MVPA than those in the control (3.04 vs. 3.31, p=.055), while late to post-puberty intervention and control girls’ post-intervention MVPA was similar (3.12 vs. 3.04, p=.542).CONCLUSIONS:A PA intervention can improve overweight and obese girls’ CRF, possibly attenuating their cardiovascular risk. Effective strategies are needed to assist adolescent girls, especially those in pre- to mid-puberty, in maintaining their MVPA after an intervention ends.