Consumption of energy drinks increases blood pressure and heart rate, and should therefore be avoided by people with hypertension or heart disease, according to results of a small prospective study.
The beverages, marketed to enhance cognitive function and stamina, usually contain caffeine, taurine, sugars, vitamins, and other nutritional supplements, Dr. James S. Kalus, at Henry Ford Hospital in Detroit, and co-authors note in The Annals of Pharmacotherapy (2009, 43).
To look into this, the researchers studied 15 healthy volunteers, 20-39 years of age.
The subjects drank 500 mL (2 cans, each containing 100 mg taurine and 100 mg caffeine) of an energy drink over 30 minutes daily for 7 days. On days 1 and 7, blood pressure, heart rate, and electrocardiograms were obtained prior to consuming the drinks and 5 times during the 4 hours afterward.

Heart rate increased by 7.8% on day 1 and by 11.0% on day 7.
Systolic blood pressure increased by 7.9% on day 1 and 9.6% on day 7.
Diastolic blood pressure increased by 7.0% on day 1 and 7.8% on day 7.

"Increases in blood pressure and heart rate of the magnitude observed in our study could be significant in persons with known cardiovascular disease," Dr. Kalus and his associates maintain. Young individuals with undiagnosed, premature cardiovascular disease could also be at risk.
Our advice: Get a check-up before undergoing an exercise regimen. Avoid taking energy drinks.

Note: Sports drinks (ex. Gatorade) are not the same as Energy drinks. Sports drinks have no caffeine although it has sugar and calories. You may take sports drinks in moderation