My small contribution is about observation in humans. In this TV series, http://en.wikipedia.org/wiki/Sport_Science_(TV_series) , they tested a female boxer performing in training with and without sex the previous night, they found that she did better with sex.
It is also known that eastern european female athletes, the pioneers in doping, used to participate in every major competition while beeing in early pregnancy, their hormonal status would be in a favorite state and they would perform better.