A randomized controlled trial of continuous activity, short bouts, and a 10,000 step guideline in inactive adults

Abstract 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 (10 K), (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 10 K 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 10 K ( 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.