Could Caffeine Be Ineffective (or Worse)?

Who you gonna believe? For decades, caffeine has been touted as a legal performance enhancer and used by countless athletes.

Now comes a study that says caffeine may impair peak heart function.

As reported in the Jan. 17 issue of the Journal of the American College of Cardiology, 18 young, healthy volunteers were tested on stationary bikes after taking the caffeine equivalent (200 mg) of two cups of coffee.

Result: The caffeine dose did not affect blood flow within the heart while the participants were at rest. However, blood-flow measurements taken immediately after exercise were 22% lower. And they were 39% lower in participants that were tested in a chamber that simulated high altitude.

Explained Philipp A. Kaufmann, MD, one of the researchers, "Whenever we do a physical exercise, myocardial blood flow has to increase in order to match the increased need of oxygen. We found that caffeine may adversely affect this mechanism. It partly blunts the needed increase in flow."

He noted that the study was not designed to measure athletic performance, but the findings indicate that caffeine may be ineffective or even counterproductive for that purpose.

"We now have good evidence that, at the level of myocardial blood flow, caffeine is not a useful stimulant," Dr. Kaufmann said. "It may be a stimulant at the cerebral level in terms of being more awake and alert, which may subjectively give the feeling of having better physical performance. But I now would not recommend that any athlete drink caffeine before sports. It may not be a physical stimulant, and may even adversely affect physical performance."

Dr. Kaufmann added that the study raises special concerns for people with heart disease. "Any advice would be based on results of healthy volunteers and would be a bit speculative. Nevertheless, my advice [for those with coronary artery disease] would be: Do not drink coffee before doing physical activities."