The mechanism of poor exercise tolerance in patients with severe asthma is poorly understood. In preliminary data, the investigators have identified increases in air trapping in patients with obese asthma and metabolic dysfunction and patients with asthma and mucus plugs. The investigators have also found air trapping on CT (Computerized Tomography) scans of severe asthma patients with mucus plugs. Therefore, the investigators hypothesize that obese patients with metabolic dysfunction (MD) and severe asthma patients with mucus plugs develop changes in lung function during exercise.~To test this hypothesis, this protocol will plan for cardiopulmonary exercise testing in patients with obesity or severe asthma. The analyses will compare dynamic hyperinflation, expiratory flow limitation, and the RV/TLC ratio (ratio of residual volume to total lung capacity) before and after exercise between obese patients with and without MD and severe asthma patients with and without mucus plugs.
This is a single-center study of 80 subjects with asthma including those with obesity and metabolic dysfunction (MD), those with obesity and without metabolic dysfunction, those with severe asthma and mucus plugging and those with severe asthma and without mucus plugging. Screening data will be reviewed to determine participant eligibility. Participants who meet all inclusion criteria will participate in a cardiopulmonary exercise testing (CPET) visit to compare lung function markers and change in oxygen saturation between obese patients with and without MD and severe asthma patients with and without mucus plugging.