The within-person bidirectional association between physical activity and loneliness in the daily lives of adolescents and young adults

Adolescents and young adults are at high risk for experiencing loneliness, a well-established risk factor for mental health symptoms. Being physically active is known to reduce feelings of loneliness. We explored the association between physical activity and loneliness using the experience sampling method, allowing us to investigate moment-to-moment variations on the within-person level. The sample consisted of 784 participants (58.0% females), aged 15–25 years (mean 16.9 years). They responded to a questionnaire ten times a day for six days. We hypothesized an inverse bidirectional relationship between within-person physical activity and within-person loneliness. Additionally, we hypothesized an interaction effect of the within-person affective valence and of depression and anxiety symptoms. Univariate multilevel models were used. Results did not show a significant association between physical activity and loneliness on the within-person level, but there was a significant interaction effect where physical activity was associated with less subsequent loneliness at moments with high affective valence. These findings indicate that only when physical activity is experienced as something young people enjoy doing, feel competent about and when it does not require too much effort, it decreases feelings of loneliness the subsequent moment. There was no significant interaction effect with depression and anxiety symptoms. In conclusion, the results of this study give us a better understanding of the association between physical activity and loneliness in young people. This study highlights the importance of contextual factors when investigating psychosocial outcomes of physical activity.