The inter-relatedness and demographic predictors of physical activity, self-rated health, and mental well-being: A three-wave study in secondary school children.

Introduction: The World Health Organisation recommends that children and adolescents engage in at least 60 min of moderate-to-vigorous physical activity per day. Previous research has shown that physical activity is related to other constructs such as mental well-being and self-rated health. This study examined the inter-relatedness of these constructs in Northern Irish school children.

Methods: This study was a secondary analysis of data gathered as part of a longitudinal study. Participants were n = 1791 adolescents in their final years of secondary (high) school (age range 15-18; female = 64.6%). Data were gathered on three occasions over a 2-year period on self-rated health, physical activity, mental well-being, heavy episodic drinking, lifetime smoking, psychological and somatic symptoms, as well as a range of socio-demographic measures.

Results: Descriptive results showed extremely low levels of self-reported physical activity within the past week, with <6% of the sample attaining the WHO guidelines at each wave of data collection. There were significant gender differences on all variables assessed. Results further showed a small-sized relationship (statistically significant for girls only) between physical activity and mental well-being. There was also a small-sized relationship between physical activity and self-rated health. Notably, effect sizes for the relationship between self-rated health and both physical activity and mental well-being were higher. In terms of socio-demographic predictors of lower physical activity, being female, lifetime cigarette smoking, and higher somatic and psychological symptoms were all statistically significant factors.

Conclusion: Self-rated health emerged as the most important predictor of physical activity among adolescents.