Several teams participating in this year’s World Cup have team-wide bans on having sex before games, because coaches believe it could interfere with performance.
・ “There will be no sex in Brazil,” Bosnia and Herzegovina coach said.
・ French players are allowed to have sex, but not all night.
・ Some teams, like Nigeria, only allow players to have sex with their wives.

It’s often talked about, but it has not been shown to be true. There are lots of factors that could account for how a player performs.
In sports, people have all kinds of theories, even if it’s not medically substantiated. For instance: compression gear for speed and titanium necklaces for performance. We don’t have scientific evidence to back those claims, but if players think abstaining from sex helps them, it may give them a psychological edge.

Many athletes have pre-game rituals, or lucky tokens, and some research has shown that these superstitions actually improve performance.