With the great interest in exercising, competing, and winning in today's world, it is an interesting question to ask if caffeine, the most popular stimulant in the world, can help to improve performance in endurance exercise activities. This study looks to see if caffeine is an ergogenic aid in exercise activities requiring greater than 20 minutes to complete. We find that caffeine has, in fact, been shown, during this decade, to increase exercise performance in events that take greater than 20 minutes to complete. However, compounds consumed with caffeine can negate its ergogenic effect. We also see that, contrary to popular belief, caffeine does not significantly increase dehydration in exercising athletes, as it does in resting individuals. This is a significant result for athletes, such as marathoners and triatheletes, who consume caffeine during a long race. The mechanism by which caffeine acts as an ergogenic aid in endurance exercise is unknown, but has been proposed to be related to the reduction of the concentration of plasma K observed in athletes after consuming caffeine vs. placebo. Additionally, a psychological effect caused by caffeine is hypothesized to decrease one's perception of exertion.