Electrical muscle stimulation units are becoming affordable enough for many athletes to have at home.

Athletes will try almost anything to heal an injury or get stronger, including, now, sending electrical pulses through their muscles. Several different types of electropulse therapies including TENS, NMES, and EMS, are popping up in physical therapy practices, chiropractic offices, and even units marketed for home use.

These three most common types of devices (TENS, NMES, and EMS) achieve mostly the same results—in fact, NMES and EMS (standing for neuromuscular electrical stimulation and electrical muscle stimulation, respectively) are often used interchangeably. TENS, which stands for transcutaneous electrical nerve stimulation, is slightly different in how it works, sending an electrical current to “pulse” the nerve and thus contract the muscle, says Brenna Canterbury, a Flagstaff-based physical therapist.
But its results are similar to what NMES delivers.

“Mostly we use it for its pain implications,” Canterbury says, adding that, “it’s not fixing anything, but it may be able to calm things down.” The idea works off of something called Gate Control Theory. Basically, when you’re in pain, your muscles scream about it by sending impulses to your brain via your spinal cord. These man-made electrical impulses, however, seem to have the ability to interrupt the muscle-to-brain pain conversation. “It also likely stimulates the production and release of endorphins,” which further help dull the pain, adds Canterbury.

The thing is, you’re not fixing anything, just alleviating pain. There is some research that TENS and NMES could be used to help preserve muscle mass in patients who were otherwise immobile, says Darryl Cochrane, a professor of exercise and nutrition at Massey University in New Zealand. But that’s not really what triathletes are using it for. So, what about the idea that it enhances recovery? “The concept of EMS enhancing blood flow to increase the washout of waste products is appealing and at least in part conceivable,” says Cochrane, adding, “however, from a ‘science perspective’ it is not conclusive.”

One other area where the verdict is still out is in EMS’ role in strength training. “Recently, the fitness industry has been quick to use this concept as a form of training,” Cochrane says. “When EMS is combined with static bodyweight exercises, it supposedly increases the muscle tension and provides an extra intense workout in a shorter time, thus reducing the total workout time.” But research results have been mixed. One 2015 study found a squat-only group did about the same as a squat-plus-EMS group after six weeks of training. However, a 2016 study did see a benefit for strength performance on leg curl machines among the group that used EMS.

Bottom line? An EMS or TENS unit isn’t going to be the one thing that turns your season around. But it’s not going to hurt you, and may even help you soothe sore muscles.

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