Physical activity is associated with a variety of positive health outcomes, as well as improved metabolic profiles and reduced inflammation. However, levels of moderate to vigorous physical activity (MVPA) diminish dramatically as children move into the middle school years. To address this problem, this study tests a behavioral intervention, called "Zamzee," designed to motivate middle school-aged children to increase their levels of MVPA. The Zamzee intervention consists of a 3-axis accelerometer that tracks individual physical activity rates over time and a website that displays individual physical activity rates and provides rewards for maintaining or improving physical activity rates. The primary aim of this randomized, controlled trial is to test whether middle school-aged children randomly assigned to the Zamzee intervention will show significantly greater levels of physical activity levels over six months, compared with control group participants who wear the accelerometer but have no access to the rewards website. A secondary aim is to test the intervention's impact on biological parameters that may contribute to the long-term health effects of inactivity (including C-reactive protein as a measure of inflammation, and hemoglobin-A1C as a measure of metabolic status) in a sub-set of study participants who agree to provide blood samples.
