This study evaluates the responsiveness of the Platelet Function Analyzer (PFA-100) to the effect of energy drinks on platelet function. Participants' will have blood drawn prior to and 60 minutes after ingesting 250ml of a commercially available sugar-free energy drink.

Two previous studies have demonstrated increased platelet aggregation 60 minutes after drinking a commercially available sugar-free energy drink. These studies utilized traditional platelet function studies, such as light transmission aggregometry (LTA), where platelet function is examined while adding varying concentrations of a panel of agonist to platelets. These studies are technically difficult, time intensive studies requiring specialized laboratories. They are relatively non-physiologic and do not mimic platelet response to vessel wall damage. Other tests better represent the reactions to vessel wall damage, including the PFA-100, which measures platelet aggregation and adhesion under conditions of high shear.

Overall, PFA-100 is less expensive, requires less technical skill, and is less time consuming than LTA. It has been utilized in bleeding disorders and is demonstrating promise as a marker of thrombophilia. PFA-100 has demonstrated sensitivity to drug and dietary effects. It has also shown differences in closure time between sedentary and athletic individuals PFA-100 has not been used to investigate the effect of energy drinks.

Inclusion Criteria:

• a history of consuming at least one energy drink beverage in the past 6 months without adverse effects;
• engage in moderate to strenuous physical activity more than 3 days per week.

Exclusion Criteria:

• Known thromboembolic risk including protein C or S deficiency, anti-thrombin III deficiency, Factor V Leiden;
• history of thromboembolic event;
• current or previous anti-coagulation therapy, anti-platelet therapy, calcium antagonists; - current tricyclic antidepressant therapy, current selective serotonin re-uptake inhibitor therapy; antibiotic therapy; or famotidine therapy;
• acute illness;
• pregnancy;
• hemophilia;
• significant history of cardiovascular disease and/or diabetes mellitus;
• history of adverse effect of energy drinks.
• Inability to comply with pre-test dietary and activity requirements.

No plan to share individual participant data with other researchers