Dynamic hyperinflation is not the main limiting factor during exercise in obese asthmatics

Background: Obese and asthmatic patients present dynamic hyperinflation (DH) during exercise; however, no previous study has investigated DH as a cause of reduced capacity exercise in obese asthmatics. Aim: to assess if DH is involved in exercise intolerance and to examine other limiting factors during exercise in obese asthmatics. Methods: This cross sectional study included 54 asthmatics with either non obese (NOb-G; BMI≤24.9kg/m 2 ; n=18) or grade II obesity (Ob-G; BMI≥35kg/m 2 ; n=36). Patients performed a cardiopulmonary test to quantify peakVO 2 and a submaximal exercise test to assess DH. Anthropometric measurement, quadriceps muscle endurance and lung function test were also evaluated. Chi-square test was used to compare categorical and t-test or Mann-Whitney test for numerical outcomes. A forward stepwise regression was used to evaluate the association between exercise tolerance and limiting exercise factors. Results: Ob-G had a lower peakVO 2 15 (14-16) vs. 21 ml/kg/min (16-23; 50% interval confidence) compared with NOb-G, respectively (p vs. -4%; p 2 =0.67). Conclusion: DH is a frequent condition among obese asthmatics; however, the peripheral limitation seems the main cause of exercise intolerance in these patients.