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High-Dose Inhaled Salbutamol Does Not Improve 10-km Cycling Time-Trial Performance.
Med Sci Sports Exerc. 2015 Apr 8;
Authors: Koch S, Ahn JR, Koehle MS
Abstract
BACKGROUND: ?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 ?g of salbutamol when taken up by inhalation.
PURPOSE: To investigate if 1600 ?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 ?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?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.
PMID: 25856682 [PubMed – as supplied by publisher]
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