The science of tennis grunts

The cancellation of Wimbledon this summer deprived fans of their annual exercise in moralising. There is one topic SW19-goers love to complain about every year: the grunting sounds that players emit as they hit the tennis ball.

Maria Sharapova, who retired in February, was called the Queen of Screams. Her grunts were once recorded at 101 decibels, more than a Boeing 707 as it touches down. They even inspired a series of ringtones.

‘I’ve done this ever since I started playing tennis and I’m not going to change,’ Sharapova once said. Yet her grunts were said to be mysteriously absent on the practice court.

Grunting can give players a tactical advantage. Emitting a grunt as they hit the ball helps their rhythm and lets them hit the ball harder without depleting their oxygen supplies. This is potentially crucial during a long, high-octane match under the blazing sun. When they grunt, skilled players hit the ball 4 per cent faster during rallies, and 7 per cent more quickly during the serve.

But the real benefit of grunting is in hurting the opponent, who must listen to the grunt before hitting their own return shot. A tennis match is a zero-sum game: what is bad for one player is good for the other.

‘You can’t be making noises like that on the court,’ Andy Murray once said of his opponent Carlos Berlocq, one of the most notorious grunters on the tour. ‘It was extremely, extremely loud… It’s like sometimes silence and then it comes out of nowhere.’ During one match between the two, Murray shouted ‘outrageous’ and complained to the umpire.

Leading athletes in all ball sports use a series of cues to deduce what will happen next. The best footballers twirl their heads around the most, to get a sense of where they are on the pitch in relation to other players, and avoid fixating on the ball. Rather than follow the ball after it hits their racket, the best tennis players look at an opponent’s body position, where they are on the court and how they shape to hit the ball to prepare themselves for the return.

One of the cues tennis players use is sound. Elite tennis players can partly judge a ball’s trajectory from the sound made when the ball is hit. If the contact is quieter, opponents can anticipate a drop shot; if it is louder, opponents can brace themselves for the ball bouncing near the baseline. But when a player grunts loudly, their opponents hear their grunt, rather than the sound the racket creates as it makes contact with the ball.

‘When you’re doing it that loud, but you aren’t doing that on every single shot, there is obviously a reason why you’re grunting like that,’ Murray said of Berlocq. ‘It’s making a noise when you’re hitting the ball… If it’s distracting your opponent and making them play worse, then you’re getting an advantage.’

Without the information provided by the sound of the racket hitting the ball, it is harder to judge where the ball is going. Opponents are 3 to 4 per cent less accurate in deducing the shot direction after a grunt. They have also been shown to take about 30 milliseconds longer to react, by which point the ball moves another two feet.

Most effective of all is the deafening grunt that conceals a crafty drop shot, leading opponents to anticipate a ferocious deep stroke. ‘If you grunt really loudly your opponent cannot hear how you hit the ball,’ Caroline Wozniacki, the former women’s No. 1, once explained. ‘Because the grunt is so loud, you think the ball is coming fast and suddenly the ball just goes slowly.’

Mischievous players can manipulate these cues to their advantage and deliberately vary how they grunt on certain types of shots. So they can suppress grunts when attempting deep winners, denying their opponents precious milliseconds to prepare for what’s coming, and reserve their loudest grunts for their drop shots. By the time their opponents realise it is a con, it will be much too late. In this way, tricksters can turn players’ powers of anticipation into a weapon to be used against them.

Best of all, the science of grunting is that rare thing: an insight into elite sport which can also help overweight, middle-aged players get an edge on court. For all the brutality of the noise, this is the beauty of the grunt.