Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Award

Spring 2014

Document Type


Degree Name

Master of Science (MS)


Department of Kinesiology


Research has continued to provide conflicting results of caffeine’s effect on acute coronary events; although it is now apparent that a single nucleotide polymorphism at intron 1 of the cytochrome P450 (CYP1A2) gene may explain these equivocal findings. Despite the fact that markers of coagulation potential and fibrinolytic potential are associated with risk for myocardial infarction, the extent to which caffeine affects these markers is unknown. The purposes of this study were to determine the acute effects of caffeine on coagulation and fibrinolytic potential at rest and following maximal exercise and to determine if hemostatic responses engendered by caffeine are influenced by the aforementioned CYP1A2 polymorphism. 20 healthy, recreationally active, males (age, 21.4± 1.2 SD; weight, 81.9 ± 10.4 SD; 180.6 ± 7.1 SD; VO2peak 46.4 ± 6.17 SD mL∙kg∙min-1) participated in this study. Subjects performed two graded maximal exercise tests (GXT’s) after consuming either 6 mg/kg of caffeine or placebo 1 hour before trials. DNA was obtained from whole blood samples and genotyping was done using restriction fragment length polymerase chain reaction. Subjects were categorized as possessing the C allele (C allele carriers) or being homozygous for the A allele (AA homozygotes). The effects of treatment (caffeine, placebo), time (pre-exercise, post-exercise), and treatment x genotype were assessed using Repeated Measures Analysis of Variance (RMANOVA). Caffeine was shown to increase plasma Factor VIII levels when compared to placebo, but this was no longer significant when covarying for the increased exercise time engendered by caffeine. Fibrinogen values significantly increased post-exercise (p < 0.05) for C allele carriers but not for AA homozygotes. Finally, caffeine caused a significantly higher resting plasma tPA activity and a larger tPA response to exercise. Our results suggest that caffeine may increase Factor VIII response to graded exercise (GXT) secondary to an effect on time to fatigue (TTF). Caffeine also appears to increase fibrinolytic potential at rest and after exercise. Additionally, the aforementioned CYP1A2 polymorphism appears to impact the fibrinogen response to exercise.

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