The mediating role of self-esteem in the association between physical fitness and risk of depression in adolescents: DADOS Study

Background: Previous literature showed an inverse association between physical fitness and risk of depression in adolescents, but the mechanisms involved in this association remain unclear. Aims: The primary aim of the study was to test the mediating role of self-esteem on the association between physical fitness components and risk of depression. The secondary aim was to investigate sex differences in these mediation models. Methods: A total of 225 participants (44% girls), aged 13.9 +/- 0.3 years, from the DADOS (Deporte, ADOlescencia y Salud) study were included in the analyses. The results presented in this study belong to baseline data obtained between February and May of 2015. ALPHA-Fitness Test-Battery was used to evaluate physical fitness components. The Spanish version of the Behaviour Assessment System for Children-3 questionnaire was used to asses self-esteem and risk of depression. Boot-strapped mediation procedures were performed and indirect effects (IE) with confidence intervals (CI) not including zero were considered statistically significant. Results: Self-esteem was revealed as a mediator in the association between cardiorespiratory fitness and risk of depression (IE = -0.059; 95% CI= -0.098 to -0.015) and in the association between speed-agility and risk of depression (IE = -1.800; 95% CI = -3.117 to -0.623). Stratified mediation analyses by sex showed similar results in girls, but self-esteem did not act as a mediator in boys. Conclusion: Our findings indicate that high levels of cardiorespiratory fitness and speed-agility may improve self-esteem, which could have positive effects in mental health by reducing risk of depression in adolescents, especially in girls.