As TIME Magazine (of all places) writes, a bunch of the national teams have some bizarre rules about pre-game sex. Though in general, sex has been shown to de-stress, there are at least a handful of coaches who believe it will be detrimental to their teams to permit it.
Quartz did some research on respective national publications and reported the following data:
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.
TIME notes that some of the countries prohibiting sex may be acting on the age-old notion that sex releases testosterone, causing players to be less aggressive, however, there are actually studies proving this to be false—in fact, testosterone output increases after sex.
“Acrobatic” sex, on the other hand, sounds like a pretty risky idea.