The most popular use of caffeine is to increase mental alertness during drowsiness or weakness by stimulating the central nervous system. It is readily absorbed into the bloodstream and can remain in the body for three to five hours. Caffeine has numerous performance enhancement effects, including improved muscle contractability, increased time to exhaustion, improved concentration, enhanced alertness, and reduced fatigue. What most people don’t know is that it can also increase muscle pumps! Caffeine acts directly on the endothelial cell, stimulating the production of nitric oxide. Nitric oxide is a gas molecule secreted by the inner lining of your blood vessels, the production of nitric oxide helps the muscle layer of blood vessels to relax and dilate and improves blood flow to exercising muscles. Scientists in Japan investigated the effects of acute caffeine consumption on blood vessel function in healthy young men. Subjects received 300mg of caffeine or a placebo and then had their forearm blood flow response measured. Scientists observed that those in the caffeine group experienced increased forearm blood flow due to an increase in nitric oxide production compared with those who had a placebo. Another study reviewed the literature regarding the impact of caffeine consumption on vascular health. They discovered that caffeine consumption increases the production of the nitric oxide synthase enzyme, which converts the amino acid L-arginine into nitric oxide. Caffeine also increases the force of the muscle contractions by influencing calcium kinetics and the sodium-potassium pump activity in the exercising muscle. If you are looking for good caffeine-based product to increase pumps, try Animal Rage.
REFERENCE: Umemura T, Am J Cardiol., 98(11):1538-41, 2006 Dec 1; Epub 2006 Oct 16.