William F. Riner

Correlates of objectively measured physical activity in preadolescent youth.

OBJECTIVE The purpose of this study was to identify the psychosocial and environmental correlates of objectively measured physical activity behavior in a diverse sample of sixth-grade students. DESIGN Cross-sectional. PARTICIPANTS AND SETTINGS One hundred ninety-eight sixth-grade students from 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 vigorous physical activity (VPA) was assessed using a uniaxial accelerometer (CSA WAM 7164) (Computer Science and Applications Inc., Shalimar, FL). Determinant variables included: age, gender, race/ethnicity (demographic); physical activity self-efficacy, social norms related to physical activity, and beliefs regarding physical activity outcomes (psychosocial); and perceived physical activity habits of parents and peers, involvement in community physical activity organizations, involvement in community-based sports programs, 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 organizations were salient predictors of MPA and VPA. Among girls, only physical activity self-efficacy emerged as a clear predictor of objectively measured physical activity. CONCLUSIONS These findings are consistent with previous studies using self-reported physical activity and suggest that interventions to increase physical activity in preadolescent youth should endeavor to boost physical activity self-efficacy by offering a wide selection of enjoyable, developmentally-appropriate physical activity options.

Correlates of physical activity among U.S. young adults, 18 to 30 years of age, from NHANES III.

Young adults are often in periods of transition, and lifestyle changes such as a decline in physical activity can occur during this period. The purpose of this study was to determine the relationships between demographic, biologic, lifestyle, social support index, environmental factors, and physical activity in young adults. The participants were 4,152 young adults from 18 to 30 years of age enrolled in the Third National Health and Nutrition Examination Survey (NHANES III). A moderate to vigorous physical activity (MVPA) score was calculated from responses to nine activities and up to four activities not previously listed. Multiple regression analyses were used to assess the relationship between MVPA and independent variables separately for men and women. Non- Hispanic Blacks were more active than non-Hispanic White or Mexican American men, whereas, among women, non-Hispanic Whites were more active. Education, social support index, and trying to lose weight were positively associated with MVPA, whereas being married was inversely related in both men and women. Among women, those who were unemployed, in better health, had smaller families, had lower body mass indexes (BMIs), and were not from the South had higher MVPA. Men who were in school during the past 12 months were more active than those who were not in school. The results from this study suggest that demographic and social factors are important determinants of physical activity in young adults and should be considered when planning interventions.

Determinants of Physical Activity in Active and Low‐Active, Sixth Grade African‐American Youth

This study compared the determinants of physical activity in active and low-active African-American sixth grade students ( N = 108, 57 F, 51 M). Objective assessments of physical activity over a seven-day period were obtained using the CSA 7164 accelerometer. Students were classified as active if they exhibited three or more 20-minute bouts of moderate to vigorous physical activity over the seven-day period. Relative to low-actives, active boys reported significantly higher levels of self-efficacy, greater involvement in community physical activity organizations, and were significantly more likely to perceive their mother as active. Relative to low-actives, active girls reported significantly higher levels of physical activity self-efficacy, greater positive beliefs regarding physical activity outcomes, and were significantly less likely to watch television or play video games for ≥ 3 hrs/day. These observations provide preliminary guidance as to the design of physical activity interventions targeted at African-American youth.