I'm standing in a black three-quarter-length Terminator-looking suit at the Core Club in midtown Manhattan. This suit is made of broad, flexible pads that cover muscles in my limbs, hips, and trunk. Before I put it on, Mohamed Elzomor, a New York City–based personal trainer, misted the pads with water — all the better to conduct the electric current that would soon be flowing. Wires on each pad snake back to a standing console beside me, which will ply my muscles with electricity for the next 20 minutes. This is my first taste of training with electric muscle stimulation, or EMS.
Elzomor slowly turns up the voltage. Every two to three seconds, an electric pulse triggers an involuntary contraction deep in my muscles. It feels like a dozen vibrating cellphones have been surgically implanted in my body. I begin to laugh.
"Holy shit, this feels weird."
"That sounds about right," says Elzomor.
EMS — basically, applying a current to muscles to trigger involuntary twitches — has been used for years in rehab settings to help repair spinal cord injuries and address paralysis, and at physical therapy offices to strengthen weak muscles and correct imbalances. But now EMS is making its way into the fitness world, fueled by a handful of companies claiming it can help burn hundreds of calories and beef up muscles, all with basic movements, minimal time, and minimal effort. At the boutique Core Club, members pay $145 for an EMS session. But several U.S. companies, such as E-Fit and 4U-Fitness, offer the service for between $50 and $100.
Elzomor takes me through a body-weight workout that, on its own, looks more like a warm-up — squats, lunges, push-ups. But with the EMS unit sending juice to my muscles and forcing them to contract, by the end of the 20 minutes, I feel spent. It's not the same kind of crushed I feel after an intense workout like CrossFit, but the fact that I'm even fatigued from a few squats and lunges is noteworthy. The next day, soreness deep in my glutes tells me that the EMS has targeted muscles that apparently don't get enough work.
What is going on? Normally, if you’re doing, say, a push-up, your brain will signal the nerves in your chest, shoulders, and triceps to contract a certain number of muscle fibers, explains Glenn Wright, professor of exercise and sports science at the University of Wisconsin–La Crosse. The greater the load, the more muscle fibers you need to fire. For low loads like push-ups, the brain starts by recruiting endurance-oriented muscle, or slow-twitch muscle fibers. For a heavy bench press, it engages your quick-to-fatigue, fast-twitch muscle fibers.
With EMS, you engage both kinds of fibers. Buzz your muscles during a push-up, and while your brain tells nerves to contract slow-twitch muscle fibers, signals from the EMS machine cue fast-twitch fibers to engage. You’re working more muscle than you'd normally need to do a push-up, and that's why fatigue sets in more quickly.
Maybe you feel like you've heard this sales pitch before — during, say, those late-night infomercials for electric ab belts that supposedly jolt you a six-pack while you sit and watch TV. There is a key difference, though, between EMS training and gimmicky gadgets: actual exercise. You're doing a real workout (albeit a light one), while your muscles are additionally engaged by the EMS.
But while websites for E-Fit and 4U-Fitness tout undefined results like muscle building and a higher fat burn, trainers for some EMS companies told me that you'll torch hundreds of calories in a 20-minute session, or that EMS will activate 95 percent of your muscle groups at once. Maybe not: A recent German study calculated the calorie expenditure for a 20-minute EMS training session at just 82 calories (12 more than the same body-weight workout without EMS).
"One can at least state that you can recruit more muscle fibers by EMS," says lead study author Wolfgang Kemmler, but he estimates that the technology probably engages closer to 65 to 75 percent of the body's muscle groups. (That's not a total loss: Do a lunge and you recruit lower-body muscles. Do a lunge in an EMS suit and you're firing fibers in your upper body, too.)
But there is at least one potential pitfall. Strength training is a complex motor-learning process, and many experts I talked to worried that interfering with the brain's natural way of firing muscle fibers might be detrimental to overall function. Instead of your central nervous system telling muscles to engage, now a machine is doing some of that work. "From a bodybuilding standpoint, you might get a bigger muscle," says Wright. "From an athlete standpoint, you get on a football field or a basketball court and you may not move faster or more powerfully, because you still need that central nervous system to turn muscles on."
Nevertheless, EMS already has its fans. Jack Doughtery, a 43-year-old hotelier in Florida, started with once-a-week sessions at 4U-Fitness, a Tampa area "e-fit" personal training outfit, and quickly ditched his other personal training workouts because of the results he saw with EMS. "Within nine months, I went from about 150 pounds to 180 pounds," a gain that was mostly muscle, Doughtery notes. "And all with less work," he says.
That efficiency seems to be the consistent selling point for EMS.
"Eighty percent of our clients train twice a week for 20 minutes, and that's it," says Daniel Nyiri, owner of 4U-Fitness. To illustrate the workout’s popularity, Nyiri nods to his gym schedule: His nine EMS trainers field back-to-back client appointments from 5 a.m. to 10 p.m. daily.
Might we soon see gyms nationwide lined with EMS machines and filled with wired-up exercisers moving through basic squats and lunges? Maybe. Who doesn't want more results with less time and effort. But I can't help but think about what the technology leaves out. Halfway through my EMS workout, I got a gnawing sense that something was being done to me, rather than feeling like I was actually doing something with my body. I shared my reservations with Dan Buettner, author of The Blue Zones.
The problem he sees is thinking of EMS as a cure-all — a way to get everything we need from exercise in the quickest way possible. "The healthiest and happiest people in the world are getting small bouts of physical activity throughout the day," he counters.
While concentrated bouts of exercise are helpful in a pinch, EMS, like most fitness-industry offerings, is a quick fix. Our bodies are made to move, and move often, and the more we tailor our lives to make that happen, says Buettner, the more mental and physical benefits we'll get. How he sums up EMS: "Don't bank your long-term health on it."