Fadel, B., Department of Sport Medicine Clermont-Ferrand, France.
Gaucherot, A., Pereira, B., Egron, C., et al

Pediatr Res 2026 Sep 26 Online ahead of print.

BACKGROUND: Respiratory function (RF), body composition (BC), and cardiorespiratory fitness (CRF) links remain underexplored during multidisciplinary weight loss interventions (MWLI) in adolescents with obesity.
OBJECTIVES: To investigate the impact of a 16-week MWLI on resting and exercise RFs and their associations with BC and CRF.
METHODS: RFs were measured in 92 adolescents (13.1 +/- 1.19 years, 58%female, BMI 34.31 +/- 4.93 kg/m(2)) by spirometry and at several intensities during cardiopulmonary exercise tests (CPET) before MWLI (T0) and after (T1). BC and CRF were measured by dual X-ray absorptiometry and peak oxygen consumption (VO(2peak)).
RESULTS: Between T0 and T1, forced vital capacity (FVC), expiratory volume in one second (FEV1) and median expiratory flow (MEF25-75) increased (p < 0.001). Ventilatory efficiency increased (p < 0.01), while VO(2) and minute ventilation (VE) at similar calibrated exercise power outputs during exercise decreased. Body mass, total, trunk and visceral fat mass (FM) decreased while lean mass (LM) and CRF increased (p < 0.001). DeltaFVC, DeltaFEV1 and DeltaMEF25-75 were associated positively with DeltaLM% and DeltaCRF (FVC, FEV1: p < 0.001; MEF25-75: p < 0.05) and negatively with Deltatotal, Deltatrunk and Deltavisceral FM% (FVC, FEV1: p < 0.001; MEF25-75: p < 0.05). DeltaVO(2) and DeltaVE were associated negatively with DeltaLM% and DeltaCRF and positively with Deltatotal, Deltatrunk and Deltavisceral FM% (p < 0.001).
CONCLUSION: MWLI improves respiratory health and exercise tolerance in association with BC and CRF. IMPACT: This study is among the first to examine the effects of a multidisciplinary weight-loss intervention on both resting and exercise respiratory function in adolescents with obesity. The intervention improved respiratory function, body composition, and cardiorespiratory fitness. Respiratory improvements were associated with decreases in total, trunk, and visceral fat mass percentages and increases in lean mass percentage and cardiorespiratory fitness. The observed improvements in ventilatory efficiency and breathing reserve suggest a lower work of breathing and fewer ventilatory limitations during exercise, supporting multidisciplinary lifestyle interventions to improve respiratory health and exercise tolerance.