High-Dose Inhaled Salbutamol Does Not Improve 10-km Cycling Time-Trial Performance.


Background: [beta]2-agonists are on the World Anti-Doping Agency´s (WADA) list of prohibited substances; however, athletes are allowed to treat symptoms of exercise-induced bronchoconstriction with a maximal daily dose of 1600 [mu]g of salbutamol when taken up by inhalation.

Purpose: To investigate if 1600 [mu]g of salbutamol lead to an enhanced time-trial performance in trained, competitive male cyclists, with and without exercise-induced bronchoconstriction, based on inhaled dose per kilogram of body weight (kg/BW).

Methods: In a randomized, crossover design, 20 trained male cyclists (8 with a positive eucapnic voluntary hyperpnea challenge (EVH+) and 12 with a negative EVH challenge (EVH-) performed two simulated 10-km time-trials on a cycle ergometer 30-min after the inhalation of either 1600 [mu]g of salbutamol or placebo. Lung function, assessed by forced expiratory volume in 1 second (FEV1), was measured immediately before and 15 min after inhalation. The main performance outcome was mean power output.

Results: After the inhalation of salbutamol, FEV1 was significantly increased by 6.4% (4.9%) vs. 1.0% (4.4%) with placebo (p < 0.001). Despite this increase in FEV1, mean power output during the salbutamol time-trial was not increased, regardless of relative dose per kg/BW and asthma status. Mean heart rate (p = 0.01), respiratory rate (p = 0.01) and minute ventilation (p = 0.03) and perceived leg discomfort (p = 0.03) were significantly increased in the salbutamol condition.

Conclusions: The inhalation of 1600[mu]g salbutamol improved FEV1 regardless of EVH-status, but did not improve 10-km time-trial performance in trained, competitive male cyclists, regardless of relative dose per kg/BW or EVH-status. Significant increases in heart rate and minute ventilation occurred secondary to stimulation of the adrenergic nervous system.

(C) 2015 American College of Sports Medicine


Autor / Fonte:Koch, Sarah; Ahn, Joeungyoen Rei; Koehle, Michael Stephen. Medicine & Science in Sports & Exercise: Post Acceptance: April 8, 2015 doi: 10.1249/MSS.0000000000000679
Link: http://journals.lww.com/acsm-msse/Abstract/publishahead/High_Dose_Inhaled_Salbutamol_Does_Not_Improve.97773.aspx