Low Cardiorespiratory Fitness is Partially Linked to Ventilatory Factors in Obese Adolescents

Aim: To examine the role of ventilatory constraint on cardiorespiratory fitness in obese adolescents. Methods: Thirty obese adolescents performed a maximal incremental cycling exercise and were divided into 2 groups based on maximal oxygen uptake (VO2peak): those presenting low (L; n = 15; VO2peak: 72.9 +/- 8.6% predicted) or normal (N; n = 15; VO2peak: 113.6 +/- 19.2% predicted) cardiorespiratory fitness. Both were compared with a group of healthy controls (C; n = 20; VO2peak: 103.1 +/- 11.2% predicted). Ventilatory responses were explored using the flow volume loop method. Results: Cardiorespiratory fitness (VO2peak, in % predicted) was lower in L compared with C and N and was moderately associated with the percent predicted forced vital capacity (FVC) (r = .52; p < .05) in L. At peak exercise, end inspiratory point was lower in L compared with N and C (77.4 +/- 8.1, 86.4 +/- 7.7, and 89.9 +/- 7.6% FVC in L, N, and C, respectively; p < .05), suggesting an increased risk of ventilatory constraint in L, although at peak exercise this difference could be attributed to the lower maximal ventilation in L. Conclusion: Forced vital capacity and ventilatory strategy to incremental exercise slightly differed between N and L. These results suggest a modest participation of ventilatory factors to exercise intolerance.