Comparative Discrimination Of Obesity By Muscular And Cardiorespiratory Fitness: A Receiver Operating Characteristics Curve Analysis.

Abstract

PURPOSE: Muscular and cardiorespiratory fitness are associated with adiposity and cardiovascular disease risk in youth. The degree to which these measures discriminate obesity is not lucid. This study investigated muscular and cardiorespiratory fitness capacities to discriminate obesity. METHODS: Participants (N = 210; 116 males) (9.7 ± 1.08 years; 138.6 ± 9.4 cm; 42.3 ± 14.4 kg) (84% Hispanic/Latino) muscular and cardiorespiratory fitness were assessed using the 20-meter Progressive Aerobic Cardiovascular Endurance Run (PACER) and 90o push-up test, respectively, per FITNESSGRAM® protocols. Weight status was classified using CDC Growth Charts. Non-obesity was coded as “0” and obesity was coded as “1.” A Receiver Operating Characteristics (ROC) curve analysis was performed to identify the True Positive Rate (TPR) (i.e., Sensitivity) and False Positive Rate (FPR) (i.e., 1 - Specificity) using SPSS. The area under the curve (AUC) indicated the degree to which each fitness measure distinguishes between the presence and absence of obesity. The measurement threshold with the greatest TPR-FPR distance was considered optimally discriminative. Statistical significance was set at P < .05. RESULTS: Of the sample, 43% had obesity and 55% did not. PACER was fairly discriminative of obesity in girls (AUC = .748; P = .000; 95% CI [.651, .845]) and boys (AUC = .755; P = .000; 95% CI [.665, .845]). 90o push-up was fairly discriminative in girls (AUC = .732; P = .000; 95% CI [.632, .831]) and boys (AUC = .789; P = .000; 95% CI [.703, .876]). PACER thresholds of 8 and 8 laps were optimally discriminative in girls (TPR = .714, FPRs = .352) and boys (TPR = .635, FPRs = .190), respectively. 90o push-up thresholds of 7 and 5 repetitions were optimally discriminative in girls (TPR = .714, FPRs = .333) and boys (TPR = .692, FPRs = .175), respectively. CONCLUSIONS: Based on the probability of classifying individuals with and without obesity as having obesity (i.e., TPRs and FPRs, respectively), PACER and 90o push-up appear similarly discriminative of obesity. Notably, the optimal PACER threshold to discriminate obesity was considerably lower than cut-off scores (23 for boys and 15 for girls) for HFZ classification in the same age group. Cardiorespiratory-related disease risk may persist in subpopulations of Hispanic/Latino youth without obesity.