Ergogenic Effects of Intake of Salbutamol, Caffeine and Theobromine on Non-Asthmatic Subjects
Inhaled short acting β2–agonists are commonly used in the treatment of asthma, exercise induced bronchoconstriction (EIB) and airway hyperresponsiveness (AHR). The World Anti-doping Agency (WADA) permits asthmatic athletes to use inhaled salbutamol with an accumulated dosage not exceeding 1600 µg over a 24-hour period. A key driver for the inclusion of β2-agonists on the WADA restricted list is associated with its potential impact on athletic performance according to previous research. However, the findings from previous studies are equivocal and focus almost exclusively on endurance performance. Furthermore, there are no available data examining the ergogenic effect of inhaling a single bolus of the upper daily limit of 1600 µg or the impact on urine concentration of the short-acting β2-agonist and its relationship with the WADA code. Meanwhile, caffeine and theobromine have been regarded as bronchodilators and whilst the potential ergogenic effects of caffeine have led to its WADA monitored status no such information exists for theobromine. Study 1 investigated the ergogenic effect of 800 µg and 1600 µg of salbutamol in a randomised, single-blind and cross-over design on 5-km running time-trial performance in non-asthmatic endurance athletes (n = 7). The study revealed no significant improvement in performance after the inhalation of either doses of salbutamol (t = 1683.29 ± 179.74 sec for 800 µg and t = 1683.57 ± 190.69 sec for 1600 µg) compared with placebo condition (t = 1714.71 ± 186.22 sec). Study 2 employed a simulated football protocol following the inhalation of 800 µg and 1600 µg of salbutamol in a randomised, single-blind placebo controlled trial in male (n = 7) and female (n = 6) football players. Results demonstrated there is an improvement of inhaled salbutamol on performance. Whilst the average urine salbutamol concentrations did not breach the WADA urinary threshold (1000 ng·mL-1), five individuals, two male and three female, recorded urine drug concentrations that exceeded the threshold. Study 3 examined the urine concentration of salbutamol following passive body mass loss of 2% or 5% following the inhalation of 800 µg and 1600 µg of salbutamol across ethnicity and gender (n = 32). The study demonstrated that following the inhalation of 1600µg it is possible to present urine salbutamol concentrations above the current WADA upper limit that imposes a urinary drug threshold of 1000 ng·mL-1. Study 4 explored the ergogenic effect of caffeine and theobromine on non-asthmatic athletes during a 3-km time trial (n = 10). The findings suggest that both caffeine and theobromine resulted in an improved time-trial performance (t = 1168.7 ± 78.12 sec and t = 1176.5 ± 75.15 sec, respectively) compared with placebo condition (t = 1260.6 ± 110.65 sec), while caffeine resulted in a larger and more rapid enhancement compared to theobromine. Overall, salbutamol, the intake of which is restricted by WADA, did not have an ergogenic effect on athletes, while on the other hand, caffeine and theobromine, the usage of which are not controlled at all in sports competitions, had a performance enhancing effect on athletes, according to our results. Furthermore, although the inhalation of salbutamol did not improve the overall performance, athletes inhaling these substances might record urine concentration exceeding the WADA threshold, resulting in an adverse analytical finding (AAF).
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