Investigating the relationship between psychological stress and physical activity through individual-based geographic ecological momentary assessment

Physical Activity (PA) is known to buffer stress, yet evidence remains limited when examining real-time stress responses alongside objective measures of activity and environmental exposures in daily life. To address the gap, this study employs a Geographic Ecological Momentary Assessment (GEMA) framework that integrates accelerometer, GPS tracking, and survey data. The primary objective of this study is to assess the association between self-reported psychological stress and moderate-to-vigorous physical activity (MVPA) during the hours preceding GEMA prompts. Additionally, the study examines whether engaging in MVPA later in the day is associated with greater reductions in stress relative to morning baseline levels. Data were collected from 130 participants in the City of Mississauga, Ontario, over 7 days. Results revealed that higher levels of MVPA in the 5-h window preceding GEMA prompts were associated with significantly lower odds of reporting higher stress. On weekends, the stress-reduction effect was stronger after completing PA later in the day than on weekdays. Lower-income participants engaged in outdoor MVPA in environments perceived as safer, more beautiful, and greener compared to those of higher-income participants. Yet, no significant association was found between stress and environmental exposures, possibly because aggregated exposure measures were not sensitive enough to capture short-term changes in the daily context. The findings demonstrate the value of GEMA in capturing interactions among behaviour, environment, and health, and suggest that future research should apply more dynamic GEMA approaches to better assess short-term environmental exposures and stress.