RESUMO
OBJECTIVE: Although several studies have examined the effect of accumulated bouts on health outcomes, the impact of recommending short bouts on activity-related behavior in health promotion efforts has received minimal investigation. METHOD: During this 5-week study in 2007-2008, 43 university employees (8 male, 35 female) in the Southeastern United States were randomly assigned to a group recommended to achieve (a) 10,000 steps (10K), (b) 30-minutes (30 min) of continuous physical activity, or (c) 30-minutes of activity in bouts of at least 10 minutes (bouts). RESULTS AND CONCLUSIONS: Repeated measures ANOVA revealed that the 10K group showed the largest increase in step counts whereas the bouts group showed the smallest change over the intervention period, p=0.01. Condition differences were most pronounced on days in which participants met their activity recommendation. Accelerometer results revealed that the 10K (d=1.1) and 30 min groups (d=0.89) showed large increases in minutes of moderate to vigorous activity (MVPA), whereas the bouts group showed minimal change (d=0.11). Although activity recommendations did not differentially affect self-efficacy, participants from all conditions showed decreased self-efficacy across the intervention (p=0.02), highlighting the need to develop strategies to increase self-efficacy in activity promotion efforts.