EMS Workouts Seem Cool — But Are They Safe?

Maybe you've seen photos of Hannah Bronfman or Ashley Graham on Instagram, working out in a futuristic suit with wires hooked up to their muscles. Maybe you heard about the new workout that "shocks" your muscles into working. Maybe you went to physical therapy for an injury and are well-acquainted with electrical muscle stimulation (EMS). Or maybe you've never heard of any of this and you are suddenly very intrigued?

To the uninitiated, EMS is a tool that physical therapists use to help people recover from surgery or rehabilitate injuries, explains Ryan Yelle, PT, DPT, OCS, CSCS, clinical director at Professional Physical Therapy. Typically, EMS is used in situations where a person has muscular inhibition and weakness, due to pain, swelling, and immobilization, he says. For example, after anterior cruciate ligament (ACL) knee surgery, people tend to have weakened quads. EMS can "involuntarily activate" or wake up the quads, so that people don't totally lose their muscle mass or function, he says.

But lately, boutique workout aficionados and fitness influencers have been buzzing about workouts that incorporate EMS technology. These EMS workouts involve sending electrical impulses to your muscles in order to recruit more muscle fibers and increase the intensity of a strength-training routine. Sound hardcore? People claim you can work more muscles and improve your fitness in a shorter amount of time using EMS, which is why so many people are drawn to it.

As far as workouts go, EMS is very extra, and some might say it's gimmicky. So, we asked Milo Bernstein, the owner of Epulse, an EMS workout in New York City, to answer some of our questions. Whether you're curious about trying EMS yourself, or aren't sure about the whole trend, here's what you need to know:

In order for a muscle to contract, your brain has to send an electrical impulse to neurons in muscle fibers. EMS basically mimics what your brain does in this scenario: By applying electrode pads to different parts of a muscle, trainers can send a small electrical impulse to a muscle that tells it to contract. (That's why EMS is particularly useful for people who have experienced an injury or have had a stroke and need to "re-teach" their brain how to activate a muscle.)

"The first time you do it it feels odd," Bernstein says. It doesn’t hurt, necessarily, but it feels like a pulse or like somebody’s flicking you with a rubber band quickly, he says. "More like a vibration almost," he says. Despite the catchy name, the electricity and shock you'd typically experience during an EMS workout is pretty minimal. It's not enough electricity to start a car or run a battery, in other words.

According to Bernstein, EMS machines allow you to activate more muscle fibers than you could if you were to just do a standard strength exercise without EMS. "It's really much more complete in terms of individual muscles you're working," he says. At Epulse, you wear a vest and pair of shorts that have electrodes on them. Then, a trainer will walk you through a series of simple bodyweight exercises (lunges, pushups, squats, and crunches), and adjust the level of electricity sent to your muscles. This workout model might be somewhat legit: A 2016 study found that people who did a six-week squat program with EMS had greater strength improvements than those who did not use EMS.

Well, not all EMS devices are 100% safe. If you're getting EMS treatment by a doctor of physical therapist, then they are most likely using a device that is approved by the Food and Drug Administration (FDA). The FDA has received reports of shocks, burns, bruising, skin irritation, and pain from unregulated EMS devices. Because EMS involves electricity, there's a chance that the wires or cables could lead to electrocution, according to the FDA. So, it's important to do your research and inquire about what kind of EMS device the trainer or gym is using.

Additionally, EMS is not for everyone, Berstein says. People who have pacemakers or defibrillators shouldn't use EMS, because it can interfere with the devices. Pregnant women and people with epilepsy also shouldn't try it, because there hasn't been enough research to determine that it's safe, he says. But talk to your doctor before you try EMS if you're not sure.

As exciting as EMS sounds, simply wearing an EMS suit and pressing a bunch of buttons will not have the same effect on your body as actually exercising. And while EMS can temporarily strengthen, tone, or firm muscles to some extent, it will not cause long-term improvements in health and fitness, according to the FDA. Not to mention, EMS is incredibly expensive. A studio workout at Epulse is $125 a session — so that's a steep price to pay for a workout that probably isn't going to change your life.

TL;DR: EMS is not a magic shortcut for exercise.