Gymnastik- och idrottshögskolan, GIH

BACKGROUND: Self-perceived mental health problems among adolescents has had an upward trend. Concurrently, adolescents' physical activity (PA) has been falling whilst sedentary time (SED) has increased. There is a lack of research using accelerometer measured PA and SED to study their relationships to perceived stress and psychosomatic symptoms, both frequently observed mental health problems among adolescents. Whether coping strategies is one of the mechanisms underlying such relationship is less clear.

METHODS: A total of 2283 13-year olds were enrolled in the baseline examination of the STARS (STudy of Adolescence Resilience and Stress) study in Western Sweden. Light-, moderate-, vigorous-intensity PA (LPA, MPA and VPA) and SED were measured using hip-worn ActiGraph GT3X+ accelerometer. A total of 1284 adolescents provided valid accelerometer data (at least 4 days with ≥10 h per day). PA and SED during school-time and leisure-time were analysed separately. Surveys were utilized to monitor perceived stress, psychosomatic symptoms and the use of coping strategies "shift-persist". Logistic regression and mediation analyses were performed adjusting for gender, ethnicity, socioeconomic status and puberty development.

RESULTS: We observed that more time spent in PA was associated with less stress in adolescents. The associations were observed for LPA (Odds ratio for LPA per 60 min: 0.557 (95% CI 0.399-0.776), VPA (Odds ratio for VPA per 15 min: 0.688 (95% CI 0.588-0.806) and MVPA (Odds ratio for MVPA per 15 min: 0.795 (95%CI 0.718-0.879) during leisure time, but not during school time. Similar associations were observed between leisure time PA and psychosomatic symptoms. The associations remained statistically significant even after adjusting for the confounders. Further, our data showed that adolescents who engaged more time in PA during leisure time were more likely to adopt the coping strategies of "shift-persist". Mediation analysis showed that the use of "shift-persist" mediated the associations between leisure time PA and stress/psychosomatic symptoms.

CONCLUSIONS: Leisure time physical activity, irrespective of intensity, may facilitate successful coping with stress and stress-related mental health problems in adolescents.