Distinct physical activity and sedentary behavior trajectories in older adults during participation in a physical activity intervention: a latent class growth analysis

Background This study aimed to identify latent moderate-to-vigorous intensity physical activity (MVPA) and sedentary behavior (SB) trajectories in older adults participating in a randomized intervention trial and to explore associations with baseline social-cognitive predictors. Methods Data were assessed at baseline (T0, participants were inactive or had recently become active), after a ten-week physical activity intervention (T1), and a second 24-week intervention phase (T2). Latent class growth analysis was used on accelerometer-assessed weekly MVPA and daily SB, respectively (n = 215 eligible participants). Activity changes within trajectory classes and baseline social-cognitive predictor differences between trajectory classes were analyzed. Results A “stable insufficient MVPA” (n = 197, p for difference in MVPA level at T0 and T2 (pT0-T2) = .789, effect size (Cohen’s d) = .03) and a “stable high MVPA” trajectory (n = 18, pT0-T2 = .137, d = .39), as well as a “slightly decreasing high SB” (n = 63, p for difference in SB (pT0-T2) = .022, d = .36) and a “slightly increasing moderate SB” trajectory (n = 152, pT0-T2 = .019, d = .27) emerged. Belonging to the “stable high MVPA” trajectory was associated with higher action planning levels compared to the “stable insufficient MVPA” trajectory (M = 5.46 versus 4.40, d = .50). Belonging to the “decreasing high SB” trajectory was associated with higher action self-efficacy levels compared to the “increasing moderate SB” trajectory (M = 5.27 versus 4.72, d = .33). Conclusions Change occurred heterogeneously in latent (not directly observed) subgroups, with significant positive trajectories only observed in the highly sedentary. Trial registration German Registry of Clinical Trials, DRKS00016073, Registered 10 January 2019.