The discriminating ability of multiple body composition measures in assessing cardiorespiratory fitness in Chinese adolescents aged 12–18

Background Body mass index (BMI) and waist circumference (WC) are widely used as traditional indicators of body composition. However, the relationship between the weight-adjusted waist index (WWI), the a body shape index (ABSI), and the body roundness index (BRI)—as newer derived indices—and cardiopulmonary fitness (CRF) in adolescents remains unclear. The purpose of this study is to discriminating ability the effectiveness of BMI, WC, WWI, ABSI, and BRI in identifying cardiorespiratory fitness among Chinese adolescents. The aim is to provide a reference and basis for improving their cardiorespiratory fitness levels. Methods This study conducted a cross-sectional assessment of 45,917 adolescents aged 12–18 years in mainland China, evaluating their height, weight, WC, 20-meter shuttle run test (20 m-SRT), as well as family background and lifestyle factors. Using univariate analysis of variance, Spearman’s rank correlation, multivariate logistic regression, and ROC analysis, we compared the associations between BMI, WC, WWI, ABSI, and BRI and cardiorespiratory fitness, as well as the effectiveness of these indices in identifying adolescents with insufficient cardiorespiratory fitness. Results The mean values for BMI, WC, WWI, ABSI, and BRI among Chinese adolescents were (20.19 ± 3.43) kg/m 2 , (69.7 ± 10.05) cm, (9.41 ± 1.03), (0.06 ± 0.01), and (2.06 ± 0.92), respectively. The average 20-meter SRT score for adolescents was (40.63 ± 18.35) laps. ROC analysis showed that WWI had the highest effectiveness in identifying insufficient cardiorespiratory fitness among girls, with an AUC of 0.73 (0.72–0.73), followed by BRI (0.72). For boys, BRI (0.66) and WWI (0.65) performed best in identifying insufficient cardiorespiratory fitness. Overall, WWI and BRI demonstrated the best identification performance (both with an AUC of 0.69), followed by WC (0.65), while ABSI (0.60) and BMI (0.56) were relatively weaker. Conclusion Various body composition measures in Chinese adolescents demonstrate a certain ability to identify insufficient cardiorespiratory fitness; however, there are significant differences in predictive performance based on sex and between different measures. Future interventions targeting cardiorespiratory fitness in adolescents should take into account sex differences in the influence of various body composition measures.