They'll be happy to know that the coaches of many teams are regulating their players' sex lives in order to make sure this is true.
According to TIME.com:
Sex is permitted on these teams: Germany, Spain, the United States, Australia, Italy, Netherlands, Switzerland, Uruguay and England
Sex is banned on these teams: Russia, Bosnia and Herzegovina, Chile and Mexico
And the rules are complicated on these teams: France (you can have sex but not all night), Brazil (you can have sex, but not“acrobatic” sex), Costa Rica (can’t have sex until the second round) and Nigeria (can sleep with wives but not girlfriends)
The rules for the remaining teams are unknown.
Are some sex rules excessive? Probably. The two most common concerns about pre-game sex are that intercourse might make a player tired and weak or it could affect him psychologically. Studies have shown that the former is a myth.
Many coaches and athletes believe that abstaining from sex builds up aggression, a belief that probably stems from ancient civilizations like the Greeks, who thought that men derived strength from their semen. This theory is so pervasive that even Muhammed Ali refused to have sex six weeks before a fight, fearing that ejaculation would release the testosterone (and therefore aggression) he needed for a boxing match.
For sure reason, this amuses me, partially because of how awkward it must be for the coaches to implement these rules. How does the Brazilian coach define what is acrobatic and what isn't?
Some teams believe the opposite:
“The Netherlands national soccer team, at the 1978 World Cup in Argentina, is an example of this,” Juan Carlos Medina, general coordinator of the sports department at Tecnologico de Monterrey in Mexico told CNN. “Some of those players were accompanied by their wives, and they won the second place. I don’t say this is a determinant factor, but it brings support.”
“Even Pele confessed that he never suspended sexual encounters with his wife before a game, I mean, that thing about sex helping to relax is a verified truth,” he added.