Abstract
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·min) 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 < 0.001]; however, this did not lead to an improvement in 10-km cycling time trial performance. Neither the bronchodilatory response nor the time trial performance after salbutamol was affected by genotype at any of the 3 SNPs.
CONCLUSIONS
In cyclists, FEV1 was significantly improved after salbutamol administration regardless of genotypic variation at the ADRB2 (rs1042713 and rs1042714) and SCNN1A (rs2228576) genes. Despite this improvement in lung function, 10-km time trial performance was not altered after the inhalation of salbutamol.
CLINICAL RELEVANCE
Our findings did not show genotype-dependent differences in bronchodilatory responses and athletic performance to inhaled salbutamol, suggesting that genotype-specific drug therapy will not improve asthmatic athletes' care nor athletic performance.
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