Athletes have long perpetuated the theory that sex before competition zaps energy. Muhammad Ali, for one, reportedly wouldn't make love for six weeks before a fight.
But scientists say there is no physiological evidence to suggest that sex before competition is bad. In fact, some studies suggest that pre-sports sex may actually aid athletes by raising their testosterone levels, for example.
It is unclear, however, what psychological effects sex may have on an athlete's performance. Some scientists suggest that abstinence could help some athletes concentrate better.
"There are two possible ways sex before competition could affect performance," said Ian Shrier, a sports medicine specialist at McGill University in Montreal, Canada.
"First, it could make you tired and weak the next day," Shrier said. "This has been disproved.
"The second way is that it could affect your psychological state of mind. This has not been tested," he said.