p The influence of the CYP1A2-163 C>A polymorphism on the hemostatic response to exercise following caffeine supplementation

BACKGROUND: Prior work from our group suggests that caffeine increases thrombotic potential after acute exercise. The aim of this study was to determine if hemostatic responses to exercise affected by caffeine are influenced by the CYP1A2-163 C>A polymorphism. METHODS: Forty-two healthy men performed two trials in which a graded maximal exercise test was completed one hour after consuming ei-ther 6 mg/kg of caffeine or placebo. Subjects were categorized as possessing the C allele (N.=21) or being homozygous for the A allele (N.=21).RESULTS: Factor VIII increased more (265%) during exercise in the caffeinated condition than the placebo condition (178%) (P<0.05). Tissue plasminogen activator (tPA) activity also increased more following caffeine as compared to placebo (increase of 8.70 +/- 4.32 IU/mL vs. 6.77 +/- 3.79 IU/mL respectively, P<0.05). There was no treatment x genotype or treatment x time x genotype interactions. CONCLUSIONS: Although caffeine increases factor VIII and tPA responses to maximal exercise, these changes are not influenced by the CYP1A2-163 C>A polymorphism.