A new study suggests that drinking coffee just before a workout might not be the best idea. The Journal of the American College of Cardiology reports that the amount of caffeine in just two cups of coffee limits the body's ability to increase blood flow to the heart during exercise. This is problematic since blood flow to the heart must increase during exercise in order to meet the body's higher demand for oxygen and nutrients.
Study participants were regular coffee drinkers. After abstaining from coffee for 36 hours, their blood flow was measured before and after exercise. Then they ingested caffeine tablets (equal to 2 cups of coffee) and repeated the same test to measure blood floor prior to and after exercise. The caffeine did not affect heart blood flow when the participants were at rest. However, measurements taken immediately after exercise showed a 22% reduction in heart blood flow after they'd taken the caffeine tablets, compared to their previous results. Participants who exercised in a chamber simulating high altitude (15,000 feet) experienced an even greater reduction in blood flow—39% lower.
While caffeine is a stimulant, and previous studies suggest that it may enhance athletic performance, this study suggests the opposite. Caffeine does stimulate the brain, increasing awareness and concentration. Athletes who ingest caffeine before performing may feel that they are enhancing performance, but these researchers suggest that the athletes are simply more alert, awake and focused.
Action Sparked: These study results are especially important for exercisers in high altitudes and cardiac patients who already experience diminished blood flow. When blood flow to the heart is lower than the demands of the body, you won't be able to deliver enough oxygen to the muscles, brain and to the heart itself. This can result in lightheadedness, dizziness or fainting, and these effects can be much worse if a person already has high blood pressure or another heart condition. However, all exercisers should consider abstaining from coffee—and caffeine in general, whether from soda, chocolate, or pills—before working out to decrease their risk.
Instead of hitting the coffee shop on your way to the gym,try filling up your water bottle before you head out the door. Check out the article Drinking Water During Workouts to learn why water is so important before, during and after exercise.