Typical studies of youth physical activity ignore the dependence among family members, examining only individual levels of data rather than individual and family levels. The current study examined physical activity among siblings (mean age = 12.2 years), using hierarchical linear modeling. Individual-and family-level covariates of physical activity were included in the model. Data from 930 siblings nested within 371 families were analyzed in a four-level multilevel design. Results indicated that siblings were similar in their levels of physical activity, and that levels of physical activity varied across families. At the individual level, age was a significant predictor of physical activity. At the family level, higher levels of family support were related to higher levels of sibling physical activity, as were single-parent status and higher income. Perceptions of neighborhood opportunities and observed neighborhood physical activity facilities were negatively related to family levels of physical activity.
Susan C. Duncan, Terry E. Duncan, Lisa A. Strycker and Nigel R. Chaumeton
Fuzhong Li, Edward McAuley, Peter Harmer, Terry E. Duncan and Nigel R. Chaumeton
The article describes a randomized, controlled trial conducted to examine the effects of a Tai Chi intervention program on perceptions of personal efficacy and exercise behavior in older adults. The sample comprised 94 low-active, healthy participants (mean age = 72.8 years. SD = 5.1) randomly assigned to either an experimental (Tai Chi) group or a wait-list control group. The study length was 6 months, with self-efficacy responses (barrier, performance efficacies) assessed at baseline, at Week 12, and at termination (Week 24) of the study. Exercise attendance was recorded as an outcome measure of exercise behavior. Random-effects models revealed that participants in the experimental group experienced significant improvements in self-efficacy over the course of the intervention. Subsequent repeated-measures ANOVA revealed that participants’ changes in efficacy were associated with higher levels of program attendance. The findings suggest that self-efficacy can be enhanced through Tai Chi and that the changes in self-efficacy are likely to improve exercise adherence.
Susan C. Duncan, Lisa A. Strycker, Terry E. Duncan and Nigel R. Chaumeton
It is important that studies on youth health behavior obtain sufficiently large representative samples so that power is adequate and results are generalizable. However, few researchers have documented procedures and methods for recruitment of a random stratified youth sample for studies on health-related behavior, specifically physical activity. This study describes the recruitment methods used to attain a stratified sample of 360 target youth (boys and girls from 10-, 12-, and 14-year-old cohorts), and a parent of each child, representing families in 58 neighborhoods. A peer of each target youth was also invited to participate. Recruitment was conducted primarily by telephone, using computer-assisted telephone interviewing (CATI) software. Approximately 38% of calls resulted in person contact, of which about 98% of families did not qualify. Of those qualified, about 68% agreed to participate. The telephone recruitment was supplemented by door-to-door recruitment in selected neighborhoods. The average cost of recruitment was approximately $99 per family by telephone and $64 door to door. Advantages and limitations of the recruitment method are discussed.