Inhaled β₂-Agonists and Ergogenic Potential in Non-Asthmatic Competitive Athletes

Background: The prevalence of asthma is significantly higher in elite athletes compared to the general population, with the highest risk observed in endurance athletes, swimmers, and winter-sport athletes such as cross-country skiers. Asthmatic athletes commonly use inhaled β₂-agonists to prevent and treat asthmatic symptoms. However, these substances are prohibited according to the World Anti-Doping Agency Prohibited List, with exceptions made only for formoterol, salbutamol, salmeterol, and terbutaline by inhalation when a therapeutic use exemption has been granted. This regulatory framework raises the critical question of whether inhaled β₂-agonists possess ergogenic benefits that justify their prohibition in non-asthmatic competitive athletes. Methods: This comprehensive review synthesizes evidence from randomized placebo-controlled trials examining the ergogenic potential of inhaled β₂-agonists in non-asthmatic competitive athletes. Studies investigating formoterol, salbutamol, salmeterol, and terbutaline across various performance domains including endurance capacity, anaerobic power, and strength performance were systematically evaluated. The influence of administration route and dosage on performance outcomes was critically examined. Results: Across ۱۷ of ۱۹ randomized placebo-controlled trials in non-asthmatic competitive athletes, performance-enhancing effects of inhaled β₂-agonists could not be demonstrated. This finding holds across endurance performance, anaerobic power, and strength performance domains. Even supratherapeutic doses of salbutamol (۸۰۰–۱۲۰۰ μg) failed to produce ergogenic effects in three of four studies. In contrast, oral administration of salbutamol appears capable of improving muscle strength and endurance performance, suggesting that administration route is a critical determinant of ergogenic potential. Conclusion: Current evidence provides no justification for prohibiting inhaled β₂-agonists in non-asthmatic competitive athletes from an ergogenic perspective. The lack of performance-enhancing effects, even at supratherapeutic doses, challenges the current regulatory framework. Future research should continue to monitor emerging evidence and inform evidence-based anti-doping policy decisions.

کلیدواژه ها:

β₂-agonists ، Ergogenic potential ، Non-asthmatic athletes ، Doping ، Asthma ، Performance enhancement