School-Based Randomized Controlled Trial of a Physical Activity Intervention among Adolescents

Abstract Purpose To evaluate the effects of a middle school physical activity intervention, new in combining an environmental and computer tailored component; and to evaluate the effects of parental involvement. Methods A clustered randomized controlled design was used. A random sample of 15 schools with 7th and 8th graders was randomly assigned to one of three conditions: (a) intervention with parental support, (b) intervention alone, and (c) control group. The intervention was new in combining environmental strategies with computer-tailored feedback to increase levels of moderate to vigorous physical activity. The intervention was implemented by the school staff. Physical activity was measured through a questionnaire in the total sample and with accelerometers in a sub sample of adolescents. Results The intervention with parental support led to an increase in self-reported school-related physical activity of, on average, 6.4 minutes per day ( p ≤ .05, d = .40). Physical activity of light intensity measured with accelerometers decreased with, on average, 36 minutes per day as a result of the intervention with parental support ( p ≤ .05, d = .54). Physical activity of moderate to vigorous intensity measured with accelerometers significantly increased with on average 4 minutes per day in the intervention group with parental support, while it decreased with almost 7 minutes per day in the control group ( p ≤ .05, d = .46). Conclusions The physical activity intervention, implemented by the school staff, resulted in enhanced physical activity behaviors in both middle school boys and girls. The combination of environmental approaches with computer-tailored interventions seemed promising.