Generalizability of an adult-validated model for predicting increased physical activity in after-school program children: Effects of treatment formats on fitness indicators

James J. Annesi, Kennesaw State University


Inappropriately high weight in children is a persistent problem in the United States, and physical activity is often reduced in schools due to academic demands. Effective after-school programs could positively impact both physical activity and overweight/obesity, however previous reviews and meta-analyses have indicated minimal effects. Both 4- and 3-day/week versions of a social cognitive theory-driven physical activity/nutrition after-school program were evaluated against unstructured care to assess effects in children (overall Mage = 10.00 years, SD = .80). For changes over 9 months in body mass index (BMI), effects sizes (Cohen’s d) were .68, .40, and .07 in the 4-day (n = 70), 3-day (n = 70), and unstructured (n = 50) groups, respectively. Similar patterns of effects were found for changes in free-time physical activity and cardiovascular endurance. Incorporating a theory-based prediction model previously supported in teens through older adults, with and without medical disorders and health-risk factors, improvements in exercise-related self-regulation and self-efficacy, and mood, significantly predicted increased free-time physical activity (R2 = .48). Effects significantly strengthened to R2 = .62 when completion/non-completion of the recommended 300 min/week of physical activity was also accounted for. Change in BMI was inversely related to physical activity change, β=-.14, p < .05. The present evaluation process indicated promising effects, and indicated theory-based targets to foster future program improvements.