Caffeine And Exercise

KYW Medical Reports Sponsored By Independence Blue Cross

By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) -- It is a daily ritual for many people. Wake up early. Grab a cup of coffee. And run on the treadmill, or get some sort of workout.

But there may be a downside -- researchers suggest the amount of caffeine in just two cups of coffee can cut down the body's ability to increase blood flow to the heart during exercise. Fortunately it is not a dramatic amount but it is worth mentioning because this means that vital blood flow to the heart can be cut back when the body needs it most.

Cardiologists are aware of this phenomenon and the theory is that caffeine may block certain receptors in the walls of blood vessels interfering with the normal signaling processes that cause blood vessels to dilate in response to exercise. If you enjoy a cup of coffee or two you may want to reach for when you are cooling down. In fact it is a good idea to limit all forms of stimulants around exercise time. Stick with water—we know that is safe in all cases.