Revisiting the Achievement of Maximal Effort During Graded Exercise Testing Among Hispanic Children and Adolescents with Obesity

Objective: To evaluate the achievement of maximal effort during graded exercise testing (GXT) using heart rate (HR-max), respiratory exchange ratio (RER-max), and rate of perceived exertion (RPE-max) among Hispanic children and adolescents with obesity. Methods: Thirty-two children (18 girls, 14 boys; age: 10–18 years) with obesity completed a GXT on a cycle ergometer. Maximal effort was assessed using multiple HR-max criteria (including 220-age and Tanaka equations), RER-max (≥1.0 and ≥1.1), and RPE-max (≥17). Independent t -tests and regression analyses were used to examine sex differences and associations with physiological variables. Results: All participants achieved RPE-max, 94% met the RER-max criterion of ≥1.0, and 53% met ≥1.1. In contrast, only 3.1% met the 220-age HR-max criterion, and fewer than half met any HR-max threshold. HR-max was significantly associated with age but not with resting heart rate or body fat percentage. VO 2 max was significantly higher among those who achieved higher HR-max thresholds. Conclusions: RER-max and RPE-max are more consistently achieved than HR-max during GXT in Hispanic youth with obesity, suggesting they are more reliable indicators of maximal effort in this population. When RER-max ≥1.0 is attained, maximal effort can be assumed, and the corresponding HR-max may be used to guide individualized exercise prescription for obesity management.