Cardiorespiratory and sensory responses to exercise in well-controlled asthmatics.

Objectives: The purpose of this study was to evaluate detailed ventilatory, cardiovascular and sensory responses to cycle exercise in sedentary patients with well-controlled asthma and healthy controls.

Methods: Subjects included sedentary patients meeting criteria for well-controlled asthma (n = 14), and healthy age- and activity-matched controls (n = 14). Visit 1 included screening for eligibility, medical history, anthropometrics, physical activity assessment, and pre- and post-bronchodilator spirometry. Visit 2 included spirometry and a symptom limited incremental cycle exercise test. Detailed ventilatory, cardiovascular and sensory responses were measured at rest and throughout exercise.

Results: Asthmatics and controls were well matched for age, body mass index and physical activity levels. Baseline forced expiratory volume in 1 second (FEV(1)) was similar between asthmatics and controls (98 ± 10 versus 95 ± 9% predicted, respectively, p > 0.05). No significant differences were observed between asthmatics and controls for maximal oxygen uptake (31.8 ± 5.6 versus 30.6 ± 5.9 ml/kg/min, respectively, p > 0.05) and power output (134 ± 35 versus 144 ± 32 W, respectively, p > 0.05). Minute ventilation (V(E)) relative to maximum voluntary ventilation (V(E)/MVV) was similar between groups at maximal exercise with no subjects showing evidence of ventilatory limitation. Asthmatics and controls achieved similar age-predicted maximum heart rates (92 ± 7 versus 93 ± 8% predicted, respectively, p > 0.05). Ratings of perceived breathing discomfort and leg fatigue were not different between groups throughout exercise.

Conclusions: The results of this study indicate that sedentary patients with well-controlled asthma have preserved sensory and cardiorespiratory responses to exercise with no evidence of exercise impairment or ventilatory limitation.