Dynamic hyperinflation and exercise limitations in obese asthmatic women

Obese individuals and patients with asthma can develop dynamic hyperinflation (DH) during exercise; however, no previous study has investigated DH as a factor associated with reduced exercise capacity in obese asthmatic women. The aim of the present study was to examine the occurrence of DH and exercise limitations in obese asthmatics. Obese grade II [obese group (Ob-G); BMI 35–39.9 kg/m²; n36] and nonobese [nonobese group (NOb-G); BMI 18.5-29.9 kg/m²; n18] asthmatic patients performed a cardiopulmonary test to quantify peak V O2 and a submaximal exercise test to assess DH. Anthropometric measurements, quadriceps endurance, and lung function were also evaluated. A forward stepwise regression was used to evaluate the association between exercise tolerance (wattage) and limiting exercise factors. Fifty-four patients completed the protocol. The Ob-G (n 36) presented higher peak V O2 values but lower power-to-weight ratio values than the NOb-G (P 0 .05). DH was more common in the Ob-G (72.2%) than in the NOb-G (38.9%, P 0.05). The Ob-G had a greater reduction in the inspiratory capacity (18 vs. 4.6%, P 0.05). Exercise tolerance was associated with quadriceps endurance (r 0.65; p0.001), oxygen pulse (r 0.52; p0.001), and DH (r 0.46, P 0.005). The multiple regression analysis showed that the exercise tolerance could be predicted from a linear association only for muscular endurance (r 0.82 and r² 0.67). This study shows that dynamic hyperinflation is a common condition in obese asthmatics; they have reduced fitness for activities of daily living compared to nonobese asthmatics. However, peripheral limitation was the main factor associated with reduced capacity of exercise in these patients.