http://www.lifehack.org/articles/lifestyle/how-we-energize-ourselves-avoid-the-world%e2%80%99s-top-three-productivity-enhancing-drugs.html

From the page: “Independently, green tea has been found by Japanese researcher Takatoshi Murase to boost exercise endurance in mice up to 24% while spurring the use of fat as energy. It might become added to the list of substances that baseball players and other athletes are tested for. Dr. Murase estimates that to match the effects on the mice, these athletes would need to drink about four cups of green tea a day over several weeks.”