The effectiveness of interventions to increase physical activity among young girls: a meta-analysis.

CONTEXT Pre-adolescent girls are an important target population for physical activity behaviour change as it may enhance tracking into the crucial period of adolescence. The quantification of intervention effectiveness for this age group of girls has not been previously reported. EVIDENCE ACQUISITION Studies published in English up to and including August 2013 were located from computerised (MedLine, PsychInfo, Science Direct, Web of Science, EPPI centre databases, and Cochrane Library database) and manual searches. Intervention studies aimed at promoting physical activity, which included pre-adolescent girls aged 5-11 years, and a non-physical activity control/comparison group were included. EVIDENCE SYNTHESIS A random effects meta-analysis was conducted. The average treatment effect for pre-adolescent girls involved in physical activity interventions was significant but small (g=0.314, p<.001). Moderator analyses showed larger effects for interventions that catered for girls only and used educational and multicomponent strategies. CONCLUSIONS Interventions to increase physical activity in pre-adolescent girls show small but significant effects, suggesting that behaviour change may be challenging, but results suggest some strategies that could be successful.