Olympic viewers have noticed many puzzling athlete behaviors as the Tokyo games continue this summer.

Another odd practice you may have noticed happens amongswimmers, who slap themselves before a race.

So you’ll see people go up and down their arms and across their chest."

Michael Phelps pre-race

This explains why during a quick, pre-race warm up,swimmersare slapping their bodies.

Indeed,NPRconfirms the practice assists in getting a swimmer’s blood flowing before a race.

Katie Ledecky is warming up