In the months leading up to the Olympic Games around 444 B.C., Ikkos of Tarentum, a legendary pentathlon champion, began routine preparations for competition. He hit the gymnasium to practice javelin throwing and long jumps. He coated himself in olive oil to make his rippled body gleam.

But there was one thing that made Ikkos' training regimen, which Plato described in a dialogue around 347 B.C., particularly noteworthy: He gave up sex. Ikkos, who went on to win the Olympic pentathlon, believed that abstinence before competition was essential for preserving athletic vigor.

Twenty-five centuries later, Ikkos' theory still is widely held by athletes. In preparation for Torino, Chad Hedrick, an American speed skater competing in five events, said he planned to avoid sex for at least two weeks before the Olympics in an effort to conserve strength and adrenaline.

Some say the theory that sex before competition is risky is simply an urban legend propagated by coaches who are eager to make sure rowdy young athletes get enough sleep.

However, others support the theory. The abstinence tradition is particularly strong in such sports as boxing and football, where the theory holds that sexual frustration leads to increased aggression.