The main aim of this study was to evaluate the comparative and additive effects of caffeine and albuterol (short-acting beta (2)-agonist) on the severity of EIB. Ten asthmatic subjects with EIB (exercise-induced bronchoconstriction) participated in a randomized, double-blind, double-dummy crossover study. One hour before an exercise challenge, each subject was given 0, 3, 6, or 9 mg/kg of caffeine or placebo mixed in a flavored sugar drink. Fifteen minutes before the exercise bout, an inhaler containing either albuterol (180 microg) or placebo was administered to each subject. Pulmonary function tests were conducted pre- and post-exercise. Caffeine at a dose of 6 and 9 mg/kg significantly reduced (p<0.05) the mean maximum % fall in post-exercise FEV (1) to -9.0+/-9.2% and -6.8+/-6.5% respectively compared to the double-placebo (-14.3+/-11.1%) and baseline (-18.4+/-7.2%). There was no significant difference (p>0.05) in the post-exercise % fall in FEV (1) between albuterol ( PLUS CAFFEINE PLACEBO) (-4.0+/-5.2%) and the 9 mg/kg dose of caffeine (-6.8+/-6.5%). Interestingly, there was no significant difference (p>0.05) in the post-exercise % fall in FEV (1) between albuterol ( PLUS CAFFEINE PLACEBO) (-4.0+/-5.2%) and albuterol with 3, 6 or 9 mg/kg of caffeine (-4.4+/-3.8, -6.8+/-5.6, -4.4+/-6.0% respectively). Similar changes were observed for the post-exercise % fall in FVC, FEF (25-75%) and PEF. These data indicate that moderate (6 mg/kg) to high doses (9 mg/kg) of caffeine provide a significant protective effect against EIB. It is feasible that the negative effects of daily use of short-acting beta (2)-agonists by asthmatic athletes could be reduced simply by increasing caffeine consumption prior to exercise.
Copyright Georg Thieme Verlag KG Stuttgart . New York.