The science of grunting while weightlifting

Is there any benefit to making noises when you lift weights or hit a tennis ball? Or are you just being annoying?

My gym is the Planet Fitness in Fishtown, and if you’re a member you’ve probably heard the lunk alarm. It’s an alarm that goes off if you make too much noise lifting weights. It kind of sounds like a World War II-era air-raid siren.

The other day, I was working out with my bro, Julian Miller of West Philadelphia. Julian’s a personal trainer, and we go to the gym together pretty often. He taught me everything I know about lifting weights, but when I asked him why we grunt at the gym, his answer was less than satisfying.

“I think it’s because it’s a way to push yourself to go hard,” he said with a shrug, unsure of his reply.

“I actually don’t like people that grunt at the gym,” a female gym-goer told me. “It’s annoying. You can’t handle that much weight, put it down. Get weight that you can handle, Honey.”

I talked to several people about why we grunt, but nobody seemed to really know, so I went to my trusty resource for all questions: YouTube, where a video called “There Will Be Grunts” espoused a theory contrary to my gym’s. “Grunting equals force,” the guy in the video yelled in between reps of heavy weight.

But does grunting really equal force? Well, it turns out Chris Rodolico and Sinclair Smith, researchers at Drexel University Health Sciences Program, recently did an experiment to try and answer that very question. Their study actually won the Biomedical Sciences Award for undergraduates at Drexel Research Day.

“Like a lot of people involved in exercise physiology research, we were both athletes growing up,” says Rodolico. “We both played a lot of sports where, consciously or subconsciously, you yelled whenever you performed a particularly hard activity. So, for example, I was a martial artist growing up. Whenever I punched or kicked, I was always instructed to yell, and it kind of became second nature. Bbasically, we wanted to know if there’s any point to doing that.”

So Rodolico and Sinclair came up with a simple experiment to find out. They took 30 people and had them squeeze a handgrip as hard as they could, and the handgrip would record the force. There were three different ways subjects could squeeze the handgrip. First, they just squeezed. Second, they squeezed and exhaled at the same time. Lastly, and most importantly, they squeezed and made some type of vocalization. The noise that the subjects made was up to them.

“They basically grunted,” chuckles Rodolico, “although some grunted and some scared some people down the hall with how loud they were screaming.”

The researchers had the 30 participants do this over and over. They randomized the order each time and allowed for recovery breaks. Finally, they sat down with the data to figure out which method of squeezing created the most force on average.

They found that more force was created when exhaling than just squeezing alone. But the discovery came when comparing the amount of force generated when the subjects yelled (or grunted) and squeezed simultaneously. “[What] we found was that there was actually an additional 10 percent increase in force when yelling, which was really cool for us,” says Rodolico. “So, comparatively speaking, the exhalation was more than the passive, and the screaming was more than both. And I’m speaking significantly more.

But why?

Sinclairs takes a stab at an explanation: “We’ve actually thought a lot about that, and one of our hypotheses is that yelling may activate the autonomic nervous system, which is the nervous system that controls the fight or flight response — that feeling you get when you become startled or scared, that adrenaline rush that a lot of people speak of. And that may help the muscle contractions be more complete and more forceful.”

Back at Planet Fitness in Fishtown, the findings of Rolodico and Sinclair didn’t stir management to rethink their use of the lunk alarm.

“The lunk alarm is for people that are bodybuilders that want to intimidate the other members by dropping the weight, grunting, making a whole bunch of noise,” a manager on the night shift told me. “So we shine a light on them by lunking the lunk alarm … They have other gyms for people that want to grunt and make noises like that.”