Objectives: We examined the pattern of change in sedentary behavior (SB) resulting from a physical activity (PA) intervention in older adults, and the influence of sex on changes in SB.
Methods: One hundred twenty (N = 120) inactive older adults from 2 12-week step/day-target interventions were included in this pooled reanalysis. Participants were randomly assigned to an intervention (STEP) or control group (CON). A Hip-worn accelerometer (Actigraph) was used to assess SB and PA.
Results: Significant decreases in SB (-25 minutes) were largely accounted for by the increase in moderate- to vigorous-intensity PA (MVPA; +17.3 minutes). More broadly, data showed that for every 1% increase in proportion of time spent in MVPA, SB decreased by 1.21%. Results of the pattern analysis showed significant pre-post decreases in the number of daily sedentary bouts lasting 10, 20, and 30 minutes and the number of sit-to-stand transitions in the STEP group. Males tended to decrease time spent in longer bouts and females tended to decrease the number of sit-to-stand transitions to achieve lower SB.
Conclusions: Decreases in SB were accomplished through reductions in shorter bouts of SB and likely through a variety of small changes that differed between individual participants and sexes.
Trial registration: ClinicalTrials.gov NCT01212978.