ZURICH, Switzerland, Jan. 13 (UPI) -- In healthy Swiss adults, the caffeine of two cups of coffee reduced the body's ability to boost blood flow to the heart muscle in response to exercise.
The effect was stronger when the volunteers were in a chamber simulating high altitude, said Dr. Philipp A. Kaufmann of University Hospital in Zurich.
The caffeine dose did not affect blood flow within the heart muscle while the participants were at rest, but the blood flow measurements taken immediately after exercise were significantly lower after the participants had taken caffeine tablets -- the equivalent of two cups of coffee.
The effect was pronounced in the group in the high-altitude chamber. Blood flow normally increases in response to exercise, and the results indicate that caffeine reduces the body's ability to boost blood flow to the muscle of the heart on demand.
The study was published in the Journal of the American College of Cardiology.
