Physical activity and emotional problems amongst adolescents : a longitudinal study.

BACKGROUND: Promotion of physical activity (PA) is at the top of the public health agenda. However, there are few longitudinal studies investigating the relationship between PA and children's mental health. Therefore, we aimed to investigate the association between self-reported physical activity (PA) and emotional problems 1-year later in a cohort of schoolchildren.
METHODS: A total of 1,446 children aged 11-14 years from 39 schools in the North West of England completed a self-report questionnaire in class. Each child reported the total number of sessions of sporting activities (lasting more than 20 min) in which they participated during the previous week, including activities both in school and out of school. This total was averaged for the week in order to determine whether the child was physically active at recommended levels (1 h per day). Childhood emotional problems were measured using the Strengths and Difficulties Questionnaire (SDQ) (self-report) at baseline and 1-year later. Data on potential confounders were also collected by self-report questionnaire at baseline.
RESULTS: In unadjusted analyses, children who, on average, participated in at least 1 h of sporting activity on a daily basis had fewer emotional problems at 1-year follow-up. This attenuated substantially after adjustment for gender (girls were less active but more likely to report emotional problems than boys). After adjustment for additional confounders including emotional problems at baseline, children who met recommended levels for PA had, on average, a score on the emotional problems sub-scale that was 0.29 units lower (-0.29 (95%CI: -0.61, 0.022)) at 1 year follow-up compared to children who did not undertake recommended levels of PA. Children who were physical activity also had higher scores on the hyperactivity sub-scale of the SDQ 1 year later, but there was no evidence to support an association between PA and other behavioural problems.
CONCLUSIONS: Children who met recommended levels for PA had fewer emotional problems 1-year later, although the magnitude of this difference was reduced after adjustment for confounders, particularly gender. Future longitudinal studies need to record both PA and emotional problems at more frequent intervals in order to enable us to determine the effect of maintaining a physically active lifestyle on adolescent mental health outcomes.