Cross-sectional and longitudinal relationships between cardiorespiratory fitness and health-related quality of life in primary school children in England: the mediating role of psychological correlates of physical activity

Abstract

Abstract
Purpose. The aims were (i) to analyse the cross-sectional and longitudinal associations between children’s cardiorespiratory fitness (CRF) and health-related quality of life (HRQoL), and (ii) to examine whether these associations were mediated by physical activity self-efficacy and physical 32 activity enjoyment.
Methods. This study involved 383 children (10.0±0.5 years) recruited from 20 primary schools in northwest England. Data were collected on two occasions 12 weeks apart. The number of laps completed in the 20m Shuttle Run Test was used as the CRF indicator. HRQoL was assessed 36 using the KIDSCREEN-10 questionnaire. Physical activity self-efficacy and enjoyment were assessed with the social-cognitive and Physical Activity Enjoyment Scale questionnaires, respectively. Linear mixed models with random intercepts (schools) assessed associations between CRF and HRQoL cross-sectionally, and longitudinally. Boot-strapped mediation procedures were performed, and indirect effects (IE) with 95% confidence intervals (CI) not including zero considered as statistically significant. Analyses were adjusted for sex, time of the year, socioeconomic status, waist-to-height ratio, maturation and physical activity.
Results. CRF was cross-sectionally associated with HRQoL (β=0.09; 95%CI=0.02, 0.16, 44 p=0.015). In the longitudinal analysis, CRF at baseline was associated with HRQoL at 12 weeks 45 after additionally controlling for baseline HRQoL (β=0.08; 95%CI=0.002, p=0.15, p=0.045). 46 Cross-sectionally, physical activity self-efficacy and enjoyment acted individually as mediators 47 in the relationship between CRF and HRQoL (IE=0.069; 95%CI:0.038; p=0.105 and IE=0.045; 95%CI:0.016; p=0.080, respectively). In the longitudinal analysis physical activity self-efficacy 49 showed a significant mediating effect (IE=0.025; 95%CI=0.004; p=0.054). 50
Conclusions. Our findings highlight the influence of CRF on children’s psychological correlates 51 of physical activity and their overall HRQoL.