Effect of nebulised salbutamol on maximal exercise performance in men with mild asthma.

The effect of 5 mg nebulised salbutamol on the cardiorespiratory responses to a progressive maximal exercise test was investigated in eight asthmatic (mean forced expiratory volume in one second (FEV1) 3.48 (1.0) litres) and eight non-asthmatic men. Exercise tests were performed on a bicycle ergometer after administration of nebulised salbutamol or matched saline placebo. In the asthmatic subjects salbutamol increased the resting FEV1 by 11%. The mean (SD) percentage fall in FEV1 after exercise did not change significantly (salbutamol 9.4 (12.8); placebo 15.0 (8.0], but because the FEV1 before exercise was increased the lowest FEV1 after exercise was also significantly higher after salbutamol than placebo (3.60 (1.13) v 2.85 (0.80) litres). Despite the improvement in FEV1 before exercise there was no significant difference in maximal workload, oxygen uptake, heart rate, or ventilation during exercise after salbutamol compared with placebo in the asthmatic patients. Tidal volume was higher at maximal exercise after salbutamol but there was no change in perception of breathlessness or exertion in the asthmatic subjects. During submaximal progressive exercise the perceived rate of exertion was reduced in the asthmatic patients and oxygen pulse was reduced in both groups owing to a small and non-significant increase in heart rate. The FEV1 and cardiorespiratory response to the progressive maximal exercise test in the non-asthmatic subjects were otherwise unchanged after salbutamol. The results suggest that 5 mg nebulised salbutamol has little effect on the cardiorespiratory responses to progressive maximal exercise in patients with mild asthma and in non-asthmatic subjects. Salbutamol in this dose may reduce the severity of exercise induced asthma, but no ergogenic effect on maximal exercise performance was shown.