Within‐Person Link between Depressed Affect and Moderate‐to‐Vigorous Physical Activity in Adolescence: An Intensive Longitudinal Approach

During adolescence, young women and men frequently show low physical activity and elevated depressed affect. This study aimed to examine the within-person link between moderate-to-vigorous physical activity (MVPA) and depressed affect in everyday life.Within an intensive longitudinal approach, adolescents (N = 72; 37% young women; M age = 17.36 years; age range: 12-26 years; mid-90% age range: 13-22 years) wore accelerometers to assess their daily MVPA and reported next-morning and same-evening depressed affect in diaries over eight consecutive days. The within-person link between MVPA and depressed affect on the next morning (time-lagged prediction) and the same evening (same-day link) was analyzed with mixed-effects models.More-than-usual MVPA significantly predicted less next-morning depressed affect on weekdays in young women, to the extent that a 60-min increase in MVPA over the person mean significantly predicted 50 per cent lower next-morning depressed affect.This study encourages the development of individually tailored physical activity interventions that could help adolescents enhance their daily amount of unstructured, self-initiated MVPA to reduce depressed affect. This approach may be particularly suitable for young women who have the highest risk for an inactive lifestyle and elevated depressed affect.