Associations of cardiorespiratory fitness and physical activity with health-related quality of life in Austrian middle school children

Declining physical activity (PA) and increasing sedentary behaviour may negatively affect cardiorespiratory fitness (CRF) and health-related quality of life (HRQoL) in adolescents. This cross-sectional study examined the relationship between CRF and HRQoL and the influence of adherence to the World Health Organization (WHO) recommendation of at least 420 min/week of moderate-to-vigorous physical activity (MVPA), sports club participation, screen time, sitting time, and sex. A total of 162 middle school students (12.2 ± 1.2 years; 75 boys, 87 girls) completed the KIDSCREEN-52 and self-reported PA and sedentary behaviour. CRF was assessed using the 6-minute walk test (6MWT). Correlation, regression, and group comparison analyses examined associations between CRF, lifestyle factors, and HRQoL. The mean 6MWT distance was 788.8 ± 70.8 m, and 49.4% of participants met the WHO PA recommendation. CRF showed weak positive correlations with physical well-being ( r = 0.192), psychological well-being ( r = 0.165), moods and emotions ( r = 0.193), and peer relationships and social support ( r = 0.169) (all p < 0.05). Although the regression model was statistically significant ( R = 0.405, p = 0.045), its explanatory value was modest. Students meeting the WHO PA recommendation and those participating in sports clubs reported significantly higher physical well-being. CRF was only weakly associated with HRQoL, whereas meeting PA recommendations and participating in organised sports were more consistently associated with better physical and psychosocial well-being. Regular PA may therefore be more strongly associated with well-being than CRF alone.