Emitting a Monica Seles-style grunt as you wallop a ball across the court has more than a few benefits. Most people link the biggest advantage to breath control—kind of like yelling hi-ya when a karate expert chops a board in half. And in fact, studies have shown that you do get extra oomph from a short, sharp yell, helping you exert more focused energy than you would without it.
But there’s another advantage to letting out a belly groan with every shot: distraction!
For highly skilled tennis players, hearing how a ball comes off a racket is useful information in processing a quick response. A grunt obscures that information, and it isn’t just the world’s best who get affected. According to a 2012 study from the University of Hawaii and the University of British Columbia, players are significantly worse at anticipating the ball’s direction and speed when a hitter grunts. As The Conversation put it, “if a shot is traveling at 50mph, the relatively small delay in response that grunting causes (about 30ms) would result in the ball traveling an extra two feet by the time the opponent responds.” That might not sound like a lot, but a little grunt could actually throw off your opponent’s footwork and help you eke out a win.