Effect of salbutamol on muscle strength and endurance performance in nonasthmatic men

Purpose: The ergogenic effect of acute beta 2-adrenergic agonist administration in nonasthmatic individuals has not been clearly demonstrated Therefore, the acute effects of oral administration of the beta 2-adrenergic agonist salbutamol (4 mg) on muscle strength and endurance performance were studied in 16 nonasthmatic men in a double-blind randomized cross-over study. Methods: Peak expiratory flow (Mini Wright Peakflowmeter), isokinetic strength of the knee extensors and knee flexors at four angular velocities (Cybex II dynamometer), and endurance performance in a cycle ergometer test until exhaustion at 70% of maximal workload were measured. Results: Peak expiratory flow increased from 601 +/- 67 L.min(-1) to 629 +/- 64 L.min(-1) after salbutamol (P < 0.05). Peak torque was higher after salbutamol than after placebo (4.4% for the knee extensors, 4.9% for the knee flexors) (P < 0.05). Mean endurance time increased from 3039 +/- 1031 s after placebo to 3439 +/- 1287 s after salbutamol (P = 0.19). When four subjects complaining about adverse side effects were excluded from the analysis, the increase in endurance time (729 +/- 1007 s or 29%) was statistically significant (P < 0.05). Salbutamol did not affect (V)over dotO(2), respiratory exchange ratio, heart rate, and plasma free fatty acid and glycerol concentration during exercise; plasma lactate and potassium concentrations were increased (P < 0.05). Conclusions: Under the conditions of this study, oral salbutamol appears to be an effective ergogenic aid in nonasthmatic individuals not experiencing adverse side effects.