This study is being done to look at the cardiovascular response, if any, to intake of commercially available energy drink. We hypothesize that energy drink consumption compared to a control drink in healthy adults alters the cardiovascular hemodynamic system.The focus of this study is to elucidate the physiological/cardiovascular response to an energy drink consumption as compared to a control drink both at rest and during stressful conditions in healthy adults.

The study will collect data to determine the hemodynamic changes (magnitude of heart rate and blood pressure response) in healthy adults after consumption of an energy drink and compare these responses to those after a control drink. Study will be performed at a hospital Clinical Research Unit on two separate days; minimum 24 hours and maximum 1 month apart. Participants will be fasting 4 hours prior to the study and will be asked to abstain from caffeine and alcohol for at least 24 hours prior to initiation of this study. Baseline measurements will be obtained during and after 10 minutes of rest. After the end of baseline recordings, the subjects will be given up to 500 ml (1 can, approximately 16 fluid ounces) of caffeinated energy drink or a control drink, based on randomization. They will have 30 minutes to drink it. The second set of measurements will be obtained after an energy drink or control drink intake, using exactly the same protocol as at baseline. The second study visit, participant will receive the alternate intervention.

Inclusion Criteria:

• Adults 18 years of age and older
• Healthy subjects without known cardiovascular disease and thyroid disease
• Subjects who are on no medications (except oral contraceptive pill)
• Nonsmokers
• No prior history of caffeine sensitivity or allergy

Exclusion Criteria:

• Subjects with known cardiovascular and/or thyroid disease
• Subjects currently taking medications other than oral contraceptive pill
• Smokers
• Prior history of caffeine sensitivity or allergy
• Pregnancy