Psychological mediators of exercise adherence among older adults in a group-based randomized trial.

To examine the psychological mediators of exercise adherence among older adults in a group-based physical activity randomized controlled trial.Older adults (≥65 years) were randomized to one of three conditions as part of the "GrOup-based physical Activity for oLder adults" (GOAL) randomized controlled trial. These included similar age same gender (SASG) and similar age mixed gender (SAMG) exercise programs that were informed by the tenets of self-categorization theory, and a "standard" mixed age mixed gender (MAMG) exercise program. Participants represented a subgroup (n = 483, Mage = 71.41 years) from the larger trial (n = 627) who completed measures of the trial's putative psychological mediators (i.e., group cohesion and affective attitudes) over the course of the 24-week exercise programs.Piecewise latent growth modeling revealed different trajectories between participants in the two intervention conditions (SASG, SAMG) when compared with the comparison MAMG condition with regard to perceptions of group cohesion and affective attitudes. Results of subsequent cross-lagged panel modeling revealed that better program adherence in the two intervention conditions, when compared with the referent MAMG condition, was mediated by perceptions of group cohesion.The findings provide insight into how the two intervention programs differentially strengthened perceptions of group cohesion and affective attitudes over time. Consistent with self-categorization theory, the results also shed light on the role of group cohesion, in particular, as a psychological mechanism of action to promote older adults' exercise adherence behaviors. (PsycInfo Database Record (c) 2021 APA, all rights reserved).