Prospective effects of pedometer use and class competitions on physical activity in youth: A cluster-randomized controlled trial.

Objective: To evaluate the immediate effects of a school-based multi-component program to foster a physically active lifestyle in adolescence.

Design/participants: In a cluster-randomized controlled trial with pre- and post-assessment in 2014, 29 schools with 1162 8th grade students (48% girls) from Germany were included. Age ranged from 12 to 17 years (M=13.74; SD=0.67).

Intervention: While the control group attended education as usual, students in the intervention group received pedometers and took part in a class competition over a time period of 12 weeks. Classes with the most steps and best creative ideas to promote physical activity in everyday life were awarded.

Main Outcome Measures: Primary outcomes included out-of-school sports activities (h/week), moderate to vigorous physical activity (days/week with a minimum of 60 min), active commuting (min/day), doing chores (min/day), and sedentary behavior (h/day) assessed through self-administered questionnaires as well as cardiorespiratory fitness measured using the 20-m shuttle-run test (completed laps).

Results: Significant interaction terms between group and wave of assessment were found on out-of-school sports activities (b=-1.09 [-1.89; -0.29], p=0.008), moderate to vigorous physical activity (b=-0.29 [-0.47; -0.10], p=0.002), and active commuting (b=-20.41 [-32.32; -8.49], p=0.001): students in the intervention group showed a higher increase of physical activity levels than students in the control group. The intervention effect on cardiorespiratory fitness missed significance marginally (b=-1.52 [-3.14; 0.98], p=0.065), There was no effect on students' sedentary behavior (b=0.06 [-0.72; 0.84], p=0.881).

Conclusions: An easy to administer school-based physical activity program (12 weeks) may enhance students' leisure-time physical activity.

Trial Registration Number: ISRCTN49482118.