If you're an athlete who regularly pushes your limits and could benefit from faster recovery between workouts, neuromuscular electrical stimulation, also known as e-stim might be for you, says Cedric Bryant, PhD, exercise scientist and chief science officer for the American College of Exercise. The treatment does seem to improve muscle tone and reduce post-workout pain and soreness.
But the machines aren't cheap—they range from $250 to over $1,000—and the idea of hooking yourself up to electrodes and sending jolts through your body may not sound too tempting. So before you give it a go, or rule it out completely, here's what you should know.
How E-Stim Works
Before it was the next big thing in recovery, e-stim was primarily used for rehabilitation after surgery or for immobilization. "It sends an electrical pulse that contracts the muscle, much in the same way the central nervous system does," says Bryant. "It was used for muscle reeducation—teaching muscles how to move again."
In recent years, however, fitness experts have realized that electrical stimulation also has benefits for healthy, active muscles, especially those that have been worked hard.
"The low-grade current causes physiological changes that help blood to flow to the region," says Bryant. It also speeds up the removal of metabolic wastes, like lactic acid, that are a byproduct of high-intensity training. "It's basically turning on one of the body's natural mechanisms for promoting healing and active recovery."
And over time, e-stim can even increase muscle strength and size. In a 2010 study using over-the-counter Compex devices, soccer players who combined e-stim with their regular training for five weeks saw bigger boosts in quadricep strength than those who trained without e-stim. A 2013 study found similar results using the MarcPro: Athletes who used the devices on their calves for 10 weeks had increased strength gains and reduced feelings of fatigue.
What to Expect
Over-the-counter e-stim devices, which are becoming more and more common, must prove to the FDA that they're safe to use and effective at what they claim to do—mainly to improve muscle tone and facilitate faster recovery. (The Marc Pro Plus device is also approved for pain relief.)
FDA-approved e-stim devices are safe when used as directed, says Bryant. And it doesn't hurt, although the low-grade electrical current may feel strange or disconcerting if you're not used to the sensation of involuntary muscle contractions.
"It feels a bit like a cramp or a Charley horse," he says, "not in a painful way, but in the sense that the muscle is working and tightening." Depending on how much you use the device, you may also feel some soreness the next day, too, just as if you had done a hard workout or lifted heavy weights.
And while it's true that e-stim will help tone your muscles, it can't take the place of actual exercise. "You may get modest aesthetic results, but it's not going to give you the cardiovascular or metabolic benefits that a real workout will give you," says Bryant. (It won't help you lose weight, either—so those toned muscles may still be hidden under layers of fat.)
The biggest benefit of using an e-stim device, says Bryant, seems to be reduced soreness and muscle fatigue. "It hasn't quite yet been supported by a large body of data, but there is a growing sentiment that these devices do produce feelings of enhanced recovery."
Choosing a Product
If you want to try e-stim at home, choose a device that's FDA-approved for muscle toning and recovery purposes; don't confuse them with less expensive Transcutaneous Electrical Nerve Stimulation (TENS) units, which can provide temporary pain relief but do not cause muscle contractions.
As for whether they're worth it? That depends on how you serious you are about your fitness gains. Casual exercisers who rarely feel sore the next day won't notice much benefit, says Bryant. But for high-intensity or endurance athletes doing punishing workouts several times a week, e-stim could help them get more out of their training. "If an athlete was really looking for an alternative way to optimize his or her recovery, I would recommend they at least give it a try."