Dose-response relationships of inhaled salbutamol in competitive non-asthmatic athletes : effects on performance and urine concentrations

Currently, the World Anti-Doping Agency (WADA) permits asthmatic athletes to use inhaled salbutamol (SAL) to help attenuate compromised lung function during exercise. Although the majority of previous research shows no benefit in non-asthmatic athletes, there lacks an examination of the dose-response effect of SAL on performance using a sport-specific evaluation. Additionally, there lacks a description of how dose affects the concentration of SAL in the urine (cSAL). We hypothesized that salbutamol would have no effect on performance in non-asthmatic athletes and that cSAL would be affected by dose and be highly variable. Three projects were completed. Study 1 established the typical error and reliability of time-trial performance using the Velotron cycle ergometer. Highly trained, male cyclists performed three 20-km time-trials (TT) demonstrating the test to be highly reliable with low coefficients of variance for power and time (1.8-2.0% and 0.8-1.0% respectively). In Study 2, lung function was positively affected by SAL and urine analysis revealed a dose-response relationship with cSAL while at rest, up to a dose 800μg. Peak values were observed at 60min post-inhalation and cSAL was highly variable at each time point. Although several samples approached the WADA limit of 1000 ngml⁻¹, none exceeded this value. Using doses of 200μg, 400μg, and 800μg, Study 3 revealed no effects of SAL on time-trial performance or physiological measures over placebo. Additionally, athlete perception of leg and breathing effort was unaffected across conditions. Similar to Study 2, cSAL was related to dose and highly variable, with no samples resulting in a doping violation. SG was found to be significantly related to cSAL and when corrected to a dehydrated state, several samples exceeded the WADA limit. In summary, these findings allow us to accept the hypothesis that acute inhalation of SAL lacks ergogenic properties in non-asthmatic athletes and does not affect ventilation or metabolic parameters during exercise. Additionally, inhaled SAL does not appear to alter athlete perceptions of effort. The findings further suggest that urine samples will generally fall below the WADA limit following therapeutic doses of SAL, although this may be affected by hydration.Education, Faculty ofKinesiology, School ofGraduat