Bidirectional week-to-week relationships between weekly psychological stress across multiple life domains and engagement with an exercise intervention: secondary analysis of data from a randomized trial.

Background: Engaging in physical activity can reduce the risk of multiple morbidities and premature mortality. Psychological stress can hinder the development and maintenance of physical activity behaviors. There is a dearth of research on how these two processes interact.

Purpose: The purpose of this study was to identify the week-to-week bidirectional associations between weekly psychological stress across multiple domains (e.g. social, economic) and adherence to a six-week mHealth exercise program among a previously inactive sample.

Methods: The secondary analyses reported in this study examine data derived from adults randomized to one of three mobile application(s)-based exercise arms embedded within the COPE trial (N = 251). The interventions delivered to participants in each arm involved six weeks of at-home exercise requiring no additional equipment. Relationships between psychological stress (as measured by a modified version of the Chronic Burden Scale) and engagement with the commercially available exercise apps were explored using a random intercept cross-lagged panel model (RI-CLPM). This model simultaneously assessed the longitudinal and bidirectional associations between psychological stress and exercise engagement and vice versa.

Results: Both psychological stress and engagement with the exercise interventions demonstrated significant positive autoregressive effects across successive weeks. However, the cross-lagged associations between stress and engagement with the exercise intervention were not significant.

Conclusions: While the cross-lagged effects were non-significant, there was high variability between individuals. Future studies should use larger samples and methods that would allow an examination of an individual's relationship between psychological stress and exercise engagement.