Pharmacogenetic Effects of Inhaled Salbutamol on 10-km Time Trial Performance in Competitive Male and Female Cyclists

Objective: To determine the effects of single nucleotide polymorphisms (SNPs) in the adrenergic β2-receptor gene (ADRB2, rs1042713, and rs1042714) and epithelial Na+ channel gene (SCNN1A, rs2228576) on cycling performance after the inhalation of salbutamol. Design: Randomized double-blind, mixed-model repeated measures. Setting: University Research Setting. Participants: Sixty-nine trained (maximal oxygen consumption: 62.3 ± 7.6 mL·kg−1·min−1) male and female cyclists, aged 19 to 40 years. Interventions: Participants performed two 10-km time trials 60 minutes after the inhalation of 400 μg of salbutamol or placebo. Subjects were genotyped for the three SNPs (rs1042713: AA 8, AG 30 GG 31; rs1042714: CC 19, CG 35, GG 15; rs2228576: GG: 31 GA: 34 AA: 4). Main Outcome Measures: Forced expiratory volume in 1 second (FEV1) was assessed immediately before and 30 minutes after inhalation. Performance was measured by mean power output maintained over the duration of the time trial. Results: There was a significant increase in FEV1 after the inhalation of salbutamol [mean (SD) = 5.68% (4.7)] compared with placebo [0.84% (2.8); P

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