Regular physical activity and its components as predictors of depressive symptoms in young Brazilians after mandatory military service: a prospective cohort study

Abstract

Background: The prevalence of depressive symptoms among recruits in mandatory military service is a growing concern owing to its potential impact on the physical and psychological functions essential for military activities. Regular physical activity, especially in militarized environments, may contribute to mental health. Nonetheless, the association between the two needs to be investigated further. Objective: This study examined the link between habitual physical activity and depressive symptoms in recruits. Furthermore, it assessed whether high levels of physical activity were a protective factor against depressive symptoms at the end of mandatory military service. Materials and methods: This longitudinal study included 156 Brazilian Army recruits who completed a period of mandatory military service. The Beck Depression Inventory was used to evaluate depressive symptoms, and the Baecke Physical Activity Questionnaire was used to measure habitual physical activity (HPA) levels. Poisson regression models were employed to determine the association between depressive symptoms and physical activity components. Results: High scores in total HPA, especially in the sports domain, were significant protective factors against depressive symptoms (p < 0.05). Poisson regression showed a reduced relative risk (RR) of depressive symptoms in case of high HPA levels: RR of 0.65 for total HPA and 0.46 for the sports domain. Optimal cutoff points for predicting depressive symptoms were ≤ 2.5 for sports and ≤ 8.75 for total HPA. This finding suggests that increased physical activity, especially in sports, may alleviate depressive symptoms in this population. Conclusions: Promoting structured physical activity, especially sports, may be an effective strategy to reduce depressive symptoms among young adults after mandatory military service. However, further research is required to explore the underlying mechanisms and develop optimized interventions for this population.