Relationship between waist circumference and cardiorespiratory fitness in Chinese children and adolescents: Results from a cross-sectional survey

Background: This article assessed the relationship between waist circumference (WC) and cardiorespiratory fitness (CRF) of children and adolescents aged 7–18 years. Methods: Using a stratified cluster random sampling method, 92,574 children and adolescents (47,364 males and 45,210 females) were extracted. CRF was measured by performance in the 20 m shuttle run test (20mSRT) and the subsequent estimation of maximal oxygen consumption (V˙O_2max) using the Léger equations. Participants were divided into five groups of WC percentiles and three groups of CRF percentiles by the Lambda Mu Sigma (LMS). The correlation between WC and CRF was examined by one-way ANOVA and curvilinear regression analysis. Results: WC increased with age, while V˙O_2max showed an age-related decline. Controlling for gender, urban, and rural factors, for children and adolescents aged 10–12, 13–15, and 16–18 years, the V˙O_2max Z-score of the normal WC group was significantly higher than the very low WC group (P < 0.05). Controlling for gender, urban, and rural factors, for participants aged 7–18 years, the V˙O_2max Z-score of the normal WC group was significantly higher than the high WC group and the very high WC group (P < 0.05). Conclusions: It generally shows a “parabolic” trend between WC-Z and V˙O_2max-Z. The CRF among children and adolescents in the normal WC group is significantly higher than that in the low and the high WC groups.