Does drinking coffee before you exercise increase performance?

Some studies have shown that drinking coffee before exercise can enhance exercise performance. To be more specific, events or activities requiring more endurance such as long distance running. Not all studies have shown a benefit though. A recent, well publicized study published in the Journal of the American College of Cardiology showed that "even moderate amounts of caffeine, the equivalent of two cups of coffee, can impair athletic performance. The caffeine in coffee alters the amount of blood flow that reaches the heart during an exercise session. Normally, blood flow to the heart increases with exercise, but when caffeine tablets were given to athletes, this increase in blood flow was reduced, meaning less oxygen and nutrients were reaching the heart muscle. "

"This effect of caffeine on blood flow to the heart is important not only for exercise performance, but could be problematic for those who have underlying heart disease or high blood pressure. The combination of caffeine and exercise raises the heart rate and significantly increases the body’s demands for oxygen. When this need isn’t met, the result can be lightheadedness or even serious changes in heart rhythm."

All the above answered by Sue Conrad is valid. ACE Certified News published an article in their January 2007/2008 issue with a table of Physiological Effects of Caffeine by Organ system. The study source was Armstrong, Casa, Maresh, and Ganio in Exerc Sport Sci Rev. 2007;35(3):135-140.
Briefly CNS- increased alertness, decresed pain and fatique; metabolism-
increased o2 consumption and fat breakdown and glycogen sparing; endocrine system - increased endorphins and cortisol; skeletal muscle- increased endurance; CV - increased heart rate, stroke volume and BP; Respiratory system- increased respiration; kidneys - increased urine, possible loss of electrolytes; temperature- no change in sweat rate.

The caveat it seems to me is the cortisol level. When is caffeine a detriment and when is it an enhancer? It is dose responsive.
Danielle

Great answers above, however, I do drink coffee before my am workouts. It is part of my morning motivation routine. According to the American College of Sports Medicine (ACSM), having caffeine before exercise increases performance during prolonged endurance exercise and short-term intense exercise lasting approximately five minutes.

yes

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Yes it does increase performance and mental focus. There are always studies coming out on the affects of caffeine on performance some contradict each other so it is important to look at the internal and external validity of such studies to make sure they are even relevant or reputable.