Aerobic conditioning in mild asthma decreases the hyperpnea of exercise and improves exercise and ventilatory capacity.

STUDY OBJECTIVE: To determine the effect of an aerobic conditioning program on fitness, respiratory physiology, and resting lung function in patients with mild asthma.

DESIGN: Prospective cohort study.

SETTING: Outpatient rehabilitation facility.

METHODS: Five patients with mild intermittent asthma and five normal control subjects completed a 10-week aerobic conditioning program. Pulmonary function studies and noninvasive cardiopulmonary exercise tests were performed before and after the conditioning program.

RESULTS: After aerobic conditioning, there were significant gains in maximum oxygen consumption (VO(2)max; 22.73 mL/kg/min vs 25.29 mL/kg/min, p = 0.01, asthma; 22.94 mL/kg/min vs 27.85 mL/kg/min, p = 0.03, control) and anaerobic threshold (0.99 L/min vs 1.09 L/min, p = 0.03, asthma; 0.89 L/min vs 1.13 L/min, p = 0.01, control) in both groups. Although FEV(1) was unchanged, the maximum voluntary ventilation (MVV) improved in the asthma group (96.0 L/min vs 108.2 L/min, p = 0.08, asthma; 134.0 L/min vs 131.2 L/min, p = 0.35, control). During exercise, minute ventilation (VE) for each level of work was decreased in the asthma group after conditioning, while little change occurred in the control group (68. 48 L/min vs 51.70 L/min at initial VO(2)max, p = 0. 02, asthma; 65.82 L/min vs 63.12 L/min at initial VO(2)max, p = 0.60, control). A significant decrease in the ventilatory equivalent (VE/oxygen consumption, 40.8 vs 30.4 at VO(2)max, p = 0.02, asthma; 37.2 vs 35.8 4 at VO(2)max, p = 0.02, control) and the dyspnea index (VE/MVV) at submaximal (0.44 vs 0.38, p = 0.05, asthma; 0.32 vs 0.38, p < 0.01, control) and maximal exercise (0.72 vs 0.63, p = 0.03, asthma; 0.49 vs 0.62, p = 0.02, control) occurred in the asthma group.

CONCLUSIONS: Exercise rehabilitation improves aerobic fitness in both asthmatic and nonasthmatic participants of a 10-week aerobic fitness program. Additional benefits of improved ventilatory capacity and decreased hyperpnea of exercise occurred in patients with mild asthma.