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

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.

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).

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.