Researchers at the University of British Columbia and University of Hawaii at Manoa think that grunting might could help tennis players win their matches.

They viewed videos of grunting and non-grunting players and found the former evoked slower response times and more mistakes by the opposition.

"Conservatively, our findings suggest that a tennis ball struck along with a loud grunt can travel an extra two feet in the air before the opponent is able to respond," says Sinnett, adding that some professional tennis players' grunts are as loud as 100 decibels. "This could increase the likelihood that opponents are wrong-footed, or out of position, and make returning the ball more difficult."

Loud grunts may give tennis players a competitive edge: Study [University of British Columbia]

(H/T Bob's Blitz)