"Cordyceps improves athletic performance
In 1993, the women athletes of Chinese National running team achieved nine world records at the World Track and Field Meet in Germany. One of them broke the record for the 10,000 meter-run by an astounding 42 seconds. What was their secret? They gave credit to an intense training schedule and the use of Cordyceps. Since then, this mushroom has received international attention, and its pharmacological properties have been evaluated in detail. It may be useful as an anti-aging aid; lowering high cholesterol, protecting liver, increasing sex drive, and supporting heart."
Never actually tried it, but they say it works. If I were you, I'd just lower my time the old fashion way...train hard and eat smart.