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.