You just watch, they'll be sweating next. So unmannerly.
Honestly. People hitting things as hard as they can making a noise while they do it? Whatever next?
Sarcasm aside, I really don't see the problem. I'm a competitive powerlifter and coach, and know that different people make different noises at different levels under maximum load - nobody HERE is doing it to put off an opponent, since only one person lifts at a time! Maybe a very occasional player is trying to unsettle opponents, but frankly I doubt it - it's going to take a lot more than that to break concentration mid-rally. Of course some viewers dislike it - clearly many here, and no doubt it's a hot topic on "grumpy old men" or whatever they call it now - in which case there's the mute button or the off-switch.
Reminds me of this week's prize letter (!) in the RT in which a gentleman opines that he will only return to watching the tennis when they stop grunting, bouncing the ball more than six times before serving, and using both hands on the handle. Sir, I doubt you will be missed.