Argibay said he was at a multi-press station, getting ready to squat about 500 pounds when the forbidden sin happened. "I let out a grunt, squatted down, back up, grunt again. That's it," explained Argibay. "Basically, grunt, grunt, basic breathing in heavy, and breathing out."
Grunting is commonplace at most gyms, but not Planet Fitness, which discourages so-called "musclehead behavior."
There's even a flashing light and siren on the wall, labeled a "lunk alarm," which sounds if someone grunts or drops weights on the floor.