Obese adults with asthma are more likely to develop dynamic hyperinflation (DH) and expiratory flow limitation (EFL) than nonobese asthmatics, and weight-loss seems to improve the breathing mechanics during exercise. However, studies evaluating the effect of weight loss on DH in obese adults with asthma have not been performed. We sought to evaluate the effect of a weight loss program on DH in obese adults with asthma. Forty-two asthma patients were enrolled in a weight loss program (diet, psychological support, and exercise) and were subsequently divided into two groups according to the percentage of weight loss: a ≥5% group ( n = 19) and a <5% group ( n = 23). Before and after the intervention, DH and EFL (constant load exercise), health-related quality of life (HRQoL), asthma control, quadriceps muscle strength and endurance, body composition, and lung function were assessed. Both groups exhibited a decrease of ≥10% in inspiratory capacity (DH) before intervention, and only the ≥5% group showed clinical improvement in DH compared with the <5% group postintervention (-9.1 ± 14.5% vs. -12.5 ± 13.5%, respectively). In addition, the ≥5% group displayed a significant delay in the onset of both DH and EFL and a clinically significant improvement in HRQoL and asthma control. Furthermore, a correlation was observed between reduced waist circumference and increased inspiratory capacity ( r = -0.45, P = 0.05) in the ≥5% group. In conclusion, a weight-loss of ≥5% of the body weight improves DH, which is associated with waist circumference in obese adults with asthma. In addition, the group with greater weight-loss showed a delayed onset of DH and EFL during exercise and improved asthma clinical control and HRQoL. NEW & NOTEWORTHY This is the first study to evaluate dynamic hyperinflation (DH) after a weight loss program in obese patients with asthma. Our results demonstrate that moderate weight loss can improve DH in obese patients with asthma that is associated with a decrease in abdominal fat. Moreover, a minimum of 5% in weight loss delays the onset of DH and expiratory flow limitation besides inducing a clinical improvement in asthma quality of life and clinical control.
Keywords: asthma; dynamic hyperinflation; expiratory flow limitation; obesity; weight loss.