吸入性支氣管擴張劑"Salbutamol"對漸進與耐力運動表現及心肺功能影響

　Sallbutamol is a selected β-adrenoreceptor agnoist which can relax the bronchial smooth muscle. The effect of salbutamol on the cardiorespiratory responses during a progressive maximal exercise test and a 30-min endurance exercise test were studied in nine male nonasthmatic trained runners (maximum oxygen uptake, VO2max: 60.9 ml．kg1．min-1). Sabutamol (2.5 mg/2.5 ml) or placebo (2.5 ml 0.9% NaCI) was administered by an air driven nebuliser, 30 minutes prior to testing in a double-blind, counterbalanced design. Vital capacity (VC), forced vital capacity (FVC), forced expiatory volume in one second (FEV1), forced mid-expiatory flow (FEF25%-75%), and maximun voluntary ventilation (MVV) were assessed before the progressive exercise, during which maximum heart rate (HR max), VO2 max, and maximum minute ventilation (VE max) were measured. After a minium of 48 hours, the subject was administered with the same medicine to test for the 30-min inclined treadmill running endurance test, during which heart rate (HR), minute ventilation (VE), oxygen uptake (VO2), carbon dioxide output (VCO2), and respiratory exchange ratio (RER) were measured. After each exercise, pulmonary funions were measured to compare with the values before exercise. The FEF25-75% (5.36±1.06 vs 4.78±1.17 L．s-1), MVV (192.9±28.3vs180.0±27.9 L．min1), and resting heart rate (HRrest: 63.1±8.4vs59.2±7.6 bpm) in salbutamol were significantly (p<.05) higher than that of placebo. The placebo' FEF25-75% (5.35±1.07 vs 4.78± 1.17L．s-1) increased significantly (p<.05) after the endurance exercise. No significant improvement was found on total work and average work rate in the endurance exercise after salbutamol treatment. The cardiorespiratory responses during the two exercise tests were found similar between the two conditions. It was concluded the effect of salbutamol on HRrest was more significant at rest than during exercise. Although endurance performance was not improved, salbutamol introduecd a large respiratory reserve, probably related to a decrease of airway resistance.