Caffeine, CYP1A2 genotypes and exercise performance: just a matter of timing?

Abstract

Caffeine, an adenosine receptors antagonist, has well known effects on the central nervous system and has been used as an ergogenic aid to improve cognition for centuries and more recently as a sports supplement. However, a few factors have been described as moderators of its effects, especially genetic factors. A single nucleotide polymorphism on the CYP1A2 gene has been proposed to be responsible for most of the differences in the responses to caffeine consumption. Not enough evidence exists to support this affirmation and some studies point to an influence of this genotype on the ideal timing of caffeine consumption instead. Therefore, this study aims to evaluate the influence of genotype on the ideal timing of caffeine supplementation before an exercise bout. Seventy-five individuals will be recruited to perform three visits separated by a minimum of 2 and a maximum of 7 days which will include a familiarization session and two experimental sessions. On the experimental sessions individuals will receive either 4mg/kg BM of caffeine or placebo and then perform a series of three consecutive 20-m sprints and a visual reaction time test on the following intervals: 1) prior to the consumption of the supplement (BASELINE) and 2) 30 min (30M), 3) 60 min (60M) and 4) 90 min (90M) after ingesting the capsule (s). Blood samples will be drawn once for DNA extraction/genotyping, and for caffeine and metabolites concentrations in each of the 4 points in time. A caffeine related symptoms questionnaire will be provided before, and measurements of blood pressure and heart rate after the bouts. Our hypothesis is that the effects of caffeine will be different between genotypes across time, with a greater effect of caffeine at the earlier point in time (30M) for the AA homozygotes, with similar responses between genotypes at 60M and greater response for C-allele carriers at the 90M point. This study could be a new step towards personalized sports nutrition, increasing the efficiency and efficacy of sports supplement interventions. (AU)