No fun, no gain: The stress-buffering effect of physical activity on life satisfaction depends on adolescents' intrinsic motivation

Objective: Many adolescents experience high levels of stress. While heightened stress can have a negative impact on their life satisfaction, evidence shows that physical activity can work as a stress buffer. Nevertheless, it is not known if intrinsic motivation moderates the relationship between stress, physical activity, and life satisfaction. In this study, we examined if perceived stress predicts adolescents' life satisfaction, if physical activity can buffer the effects of stress on life satisfaction, and if this stress-buffering effect is strengthened when intrinsic motivation for physical activity is high. Methods: We conducted a longitudinal study with N = 864 students (M-age = 17.87 years, range: 16-25, 43% female) from two vocational schools in Switzerland. All participants completed two identical self-report questionnaires over a 10-month period, assessing perceived stress, life satisfaction, physical activity, and intrinsic motivation levels. Multiple hierarchical regression analyses (using the PROCESS macro) were adopted to test our hypotheses. Results: Heightened stress at baseline was associated with lower life satisfaction levels at the 10-month follow-up. Moreover, a significant three-way interaction occurred between stress, physical activity, and intrinsic motivation. More specifically, a stress-buffering effect of physical activity was observable only when intrinsic motivation was high. Conclusion: The present study shows that among adolescents, physical activity works to buffer the effects of stress on life satisfaction only if it is intrinsically motivated. This result highlights the role motivation plays in improving life satisfaction or reducing stress through physical activity.