EGCG.. what is it:

Epigallocatechin-3gallate, a substance in green tea that increases the amount of oxygen your body uses, which improves your endurance When subjects took an EGCG supplement( equal to three cups of green tea), they were able to work harder for longer on a stationary bike than people who took a placebo. Freshly brewed green tea will give you the biggest boost.

There are so many kinds of green tea.. my favorite is Genmaicha Green at Coffee Bean. Iced or Hot!