NMES – Can it power up your workout?

Neuro-Muscular Electrical stimulation, also known as NMES, became popular in some gyms in and around in 2016, but it has been around on a small scale since the late 80s. As with all fitness crazes, some people swear by it.

What it is and how it works in simple terms.
In each set of muscles, there are neuro-muscular junctions (NMJ) where the signal from the spinal cord (originating in the brain), connects to the muscle fibres. If the brain asks for a contraction, the signal travels down the spinal cord, to the NMJ and a number of muscle fibres are recruited. If the signal is stronger, more fibers are recruited.
NMES mimics this by applying a small electric signal directly to the skin, which can travel through to the NMJ of the muscle. This can cause a contraction. A stronger signal may recruit more fibres.
NMES was originally developed to build or maintain muscle in individuals with spinal cord or brain injuries. Without signals from the brain going to the muscles, muscles would atrophy and waste away. Muscle is important to overall health. Maintaining muscle in people who are unable to move them themselves, makes NMES is an important therapeutic tool.
Later it was applied to people after some surgeries. Sometimes pain signals may interfere with the brain’s signal to contract a muscle. A therapist could apply a dose of NMES and the patient would also attempt the contraction. The movement would happen, and the feeling of the movement would travel back to the brain. Gradually the patient would be able to independently contract the muscle.
NMES machines are often not bigger than a mobile phone. There may be transmission cables and stickers that are attached to the skin, or the machine may be embedded in a belt-like structure such as a classic 80s ab-belt. It can be challenging to know exactly where to place the electrodes or belt for best effects as each person has a slightly different structure. There is no consensus about how to dose – i.e. how much electricity to put in the get the best effect. This is largely determined by preference – what feels tolerable. If you use such a device, you should try to act with the contraction.

Should I use it?
NMES can effectively improve strength in younger adults. However, it hasn’t been shown to improve the muscle mass, or ‘bulk’ of the muscle. But this is the key takeaway: It doesn’t outperform a conventional strength training program. If you work effectively in the gym, this gadget won’t help you improve your performance. You will be just as sore if you use NMES as if you train in a traditional way. (Sorry, there is no cheating).
Furthermore, strength training has lots of other benefits which have not been demonstrated by, or studied, in NMES. In particular, bone density is improved by strength training. It is unknown if NMES training in any way improves bone density. This is an important factor to consider in an increasingly sedentary (sitting) world.

My take: traditional strength training is best. It’s also cheaper. NMES should stay in the domain of rehabilitation.


Doucet BM, Lam A, Griffin L. Neuromuscular electrical stimulation for skeletal muscle function. Yale J Biol Med. 2012 Jun;85(2):201-15. Epub 2012 Jun 25. PMID: 22737049; PMCID: PMC3375668.
Kim KM, Croy T, Hertel J, Saliba S. Effects of neuromuscular electrical stimulation after anterior cruciate ligament reconstruction on quadriceps strength, function, and patient-oriented outcomes: a systematic review. J Orthop Sports Phys Ther. 2010 Jul;40(7):383-91. doi: 10.2519/jospt.2010.3184. PMID: 20592480.
Rahmati M, Gondin J, Malakoutinia F. Effects of Neuromuscular Electrical Stimulation on Quadriceps Muscle Strength and Mass in Healthy Young and Older Adults: A Scoping Review. Phys Ther. 2021 Sep 1;101(9):pzab144. doi: 10.1093/ptj/pzab144. PMID: 34106246.
Happ KA, Behringer M. Neuromuscular Electrical Stimulation Training vs. Conventional Strength Training: A Systematic Review and Meta-Analysis of the Effect on Strength Development. J Strength Cond Res. 2021 Aug 19. doi: 10.1519/JSC.0000000000004119. Epub ahead of print. PMID: 34417404.