Correlates of objectively measured physical activity in preadolescent youth

Objective: The purpose of this study was to identify the psychosocial and e nvironmental correlates of objectively measured physical activity behavior in a diverse sample of sixth-grade students. Design: Cross-sectional. Participants and Setting: One hundred ninety-eight sixth-grade students fro m 4 public middle schools in Columbia, South Carolina. The study group was 52.0% female, 55.1% African-American, with a mean age of 11.4 +/- 0.6 years . Main Outcome Measures: Time spent in moderate physical activity (MPA) and v igorous physical activity (VPA) was assessed using a uniaxial accelerometer (CSA WAM 7164) (Computer Science and Applications Inc., Shalimar, FL). Det erminant variables included: age, gender, race/ethnicity (demographic); phy sical activity self-efficacy, social norms related to physical activity, an d beliefs regarding physical activity outcomes (psychosocial); and perceive d physical activity habits of parents and peers, involvement in community p hysical activity organizations, involvement in community-based sports progr ams, access to fitness/sporting equipment at home, and self-reported hours spent watching television or playing video games (environmental). Results: For boys, physical activity self-efficacy, social norms related to physical activity, and involvement in community physical activity organiza tions were salient predictors of MPA and VPA. Among girls, only physical ac tivity self-efficacy emerged as a clear predictor of objectively measured p hysical activity. Conclusions: These findings are consistent with previous studies using self -reported physical activity and suggest that interventions to increase phys ical. activity in preadolescent youth should endeavor to boost physical act ivity self-efficacy by offering a wide selection of enjoyable, developmenta lly-appropriate physical activity options.