Comparative Effects of Caffeine and Albuterol on the Bronchoconstrictor Response to Exercise in Asthmatic Athletes

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 mu g) 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.