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 either 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 × genotype or treatment × time × 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.

Caffeine Augments the Prothrombotic but Not the Fibrinolytic Response to Exercise.

Caffeine, a popular ergogenic supplement, induces neural and vascular changes that may influence coagulation and/or fibrinolysis at rest and during exercise. PURPOSE: The purpose of this study was to assess the effect of a single dose of caffeine on measures of coagulation and fibrinolysis before and after a single bout of high-intensity exercise. METHODS: Forty-eight men (age, 23 ± 3 yr; body mass index, 24 ± 3 kg·m) completed two trials, with 6 mg·kg of caffeine (CAFF) or placebo (PLAC), in random order, followed by a maximal cycle ergometer test. Plasma concentrations of fibrinogen, factor VIII antigen, active tissue plasminogen activator (tPA:c), tissue plasminogen activator antigen (tPA:g), and active plasminogen activator inhibitor-1 (PAI-1:c) were assessed at baseline and immediately after exercise. RESULTS: Exercise led to significant changes in tPA:c (Δ 8.5 ± 4.36 IU·mL for CAFF, 6.6 ± 3.7 for PLAC), tPA:g (Δ 2.4 ± 3.2 ng·mL for CAFF, 1.9 ± 3.1 for PLAC), fibrinogen (Δ 30.6 ± 61.4 mg·dL for CAFF, 28.1 ± 66.4 for PLAC), and PAI-1:c (Δ -3.4 ± 7.9 IU·mL for CAFF, -4.0 ± 12.0 for PLAC) (all P < 0.05), but no effect of condition or time-condition interactions were observed. Main effects of time, condition, and a significant time-condition interaction were observed for factor VIII, which increased from 1.0 ± 0.4 IU·mL to 3.3 ± 1.3 IU·mL with CAFF and 1.0 ± 0.4 IU·mL to 2.4 ± 0.9 IU·mL with PLAC. CONCLUSIONS: Coagulation potential during exercise is augmented after caffeine intake, without a similar increase in fibrinolysis. These results suggest caffeine intake may increase risk of a thrombotic event during exercise.