Change in Objectively Measured Activity Levels Resulting from the EMPOWER Study Lifestyle Intervention.

Purpose: To examine changes in physical activity (PA) during a behavioral weight-loss intervention and determine baseline factors associated with PA goal achievement.

Methods: Overweight/obese community-dwelling adults with valid PA accelerometer data (N=116; mean age 51.7 years; 89% female; 83% non-Hispanic White) were recruited into a single-arm prospective cohort study examining the effects of a 12-month intervention that included 24 in-person group sessions, weight-loss, calorie, fat gram, and PA goals, self-monitoring, and feedback. Minutes of moderate-to-vigorous (MV) PA and steps were measured using a waist-worn accelerometer (ActiGraph GT3x) at baseline, 6 months, and 12 months. Achievement of the 150 minute/week MVPA goal was examined using total minutes and bout minutes (i.e., counting only PA occurring in bouts ≥10 minutes in length). Change in PA was analyzed using non-parametric tests for multiple comparisons. Associations of factors with meeting the PA goal were modeled using binary logistic regression.

Results: At 6 months, there were increases from baseline in MVPA (median [p25, p75]: 5.3 [-0.9, 17.6] minutes/day) and steps (863 [-145, 2790] steps/day), both p<0.001. At 12 months, improvements were attenuated (MVPA: 2.4 [-2.0, 11.4] minutes/day, p=0.047; steps: 374[-570, 1804] p=0.14). At 6 months, 33.6% of individuals met the PA goal (using total or bout minutes). At 12 months, the percent meeting the goal using total MVPA [31%] differed from bout MVPA [22.4%]. Male gender (OR=4.14, p=0.027) and an autumn program start (versus winter; OR=3.39, p=0.011) were associated with greater odds of goal achievement at 6 months.

Conclusions: The intervention increased PA goal achievement at 6 and 12 months with many making clinically meaningful improvements. Our results suggest female participants may require extra support toward improving PA levels.