EMS training raises many questions. In this article, we explain exactly what Electrical Muscle Stimulation is, what scientific research says about it, and for whom EMS can be a valuable addition.
What exactly is EMS training?
EMS stands for Electrical Muscle Stimulation. With whole-body EMS (WB-EMS), you wear a suit or vest with electrodes that sends mild electrical impulses to your muscles during movement. These impulses cause your muscles to contract extra, in addition to the contractions you already make during squats, planks, or lunges.
The idea behind it is simple: the more muscle fibers active simultaneously, the greater the training stimulus. And this is precisely what scientific research has focused on over the past fifteen to twenty years.
Higher muscle activation: the physiological premise
One of the core claims around EMS is that it activates a larger portion of your muscle fibers simultaneously than regular training alone. This is measured with electromyography (EMG), a technique that maps electrical activity in muscles.
During normal, voluntary muscle contractions, your body usually does not use all available motor units at once. There is, as it were, a reserve on hand. Electrical stimulation can tap into that reserve, increasing the training stimulus per repetition. This works best when EMS is combined with active, controlled movements, and not as a passive stimulus at rest.
What does strength research show?
The most researched area within EMS is muscle strength. A systematic review and meta-analysis by Kemmler and colleagues, published in Frontiers in Physiology, analyzed 16 studies with a total of 897 participants and concluded that WB-EMS is primarily investigated for its effects on lean body mass, muscle strength, and function. The researchers found significant, measurable improvements in both leg strength and trunk strength in participants who trained with WB-EMS compared to control groups.
For young, active athletes, the picture is more nuanced. A mini-meta-analysis of five randomized studies on WB-EMS in moderately trained young adults, published by Wirtz and colleagues, concluded that WB-EMS is a feasible additional training stimulus for performance enhancement, although the extra effects on strength, power, and performance indices appear to be limited beyond what regular training already provides. In other words: for beginners and recreational athletes, the added value of EMS is greatest, while for well-trained athletes, the additional gain is smaller and more dependent on the protocol.
Muscle mass and body composition
In addition to strength, muscle mass (lean body mass) has been extensively researched. The same meta-analysis by Kemmler et al. reported increases in lean body mass comparable to what one would expect from regular strength training research: the observed effects were in line with an earlier meta-analysis on resistance training and lean body mass, even though some studies involved measurements of skeletal muscle mass in the limbs.
This gain in muscle mass is particularly relevant for people with little training experience, seniors, or people returning from an inactive period. Research in older adults shows that WB-EMS can be used across a broad age range and with various health conditions, including recovery after bariatric surgery, cancer, and back pain, and can effectively increase muscle mass and strength.
EMS and fat loss: what does the data really say?
This is where it gets interesting, because this is precisely the area where exaggerated claims often go awry. The honest answer based on research is: EMS can reduce visceral fat and body weight, but almost always in combination with an adjusted diet.
A randomized study by Kemmler and von Stengel in older women with abdominal obesity (the TEST-III trial) investigated twelve months of WB-EMS training focused on the effect on skeletal muscle mass in the limbs and abdominal fat mass in people at increased risk of sarcopenia and abdominal obesity who were unable or unwilling to train conventionally.
Even more strongly substantiated is the FranSO study, in which WB-EMS was combined with protein supplementation in older men with sarcopenic obesity. After 16 weeks, total fat mass significantly decreased in the group that combined WB-EMS with protein supplementation, with an average decrease of 6.7%, while the control group showed a slight increase. Waist circumference also significantly decreased in the training groups.
A recent 2025 study in overweight or obese individuals with knee osteoarthritis specifically examined the effect on visceral fat and describes WB-EMS as a time-efficient and joint-friendly training technology, similar to the popularity of high-intensity interval training, but with less strain on the joints, which also makes it interesting for people who cannot exercise intensely due to injuries or joint complaints.
The conclusion from this line of research is consistent: EMS without diet and exercise adjustment usually has modest effects on fat mass. As soon as EMS is combined with a nutritional approach, as in the FranSO study, the effects become significantly greater.
Recovery, injury prevention, and pain complaints
EMS has been used in rehabilitation medicine for decades, long before the current generation of home devices came onto the market. Under the name NMES (neuromuscular electrical stimulation), it is used to maintain muscle activity when full loading is not yet possible, for example, after surgery.
For low back pain, a relatively large amount of research has been done on EMS as an addition to exercise therapy. Studies where core-focused EMS programs were added to regular exercise therapy generally show clear decreases in pain scores and improvements in functioning after six to twelve weeks of training.
📄 Source: PubMed – Electrical muscle stimulation and chronic low back pain, systematic review
What are the caveats?
Honest scientific communication also means stating the limitations. Several points are important to keep in mind:
- Study duration and group size. Many EMS studies last between 4 and 16 weeks and involve relatively small research groups. Long-term data over several years is still limited.
- Specific target groups. A significant portion of the research, including much work by the influential research group around Wolfgang Kemmler at the University of Erlangen-Nuremberg, has been conducted in older adults, overweight individuals, or specific clinical populations. This does not automatically make the results one-to-one applicable to young, fit athletes.
- Not a replacement, but an addition. In almost no study is EMS investigated as a complete replacement for traditional strength training. It is always used as an additional stimulus within a broader training program.
- Safety. For healthy adults using EMS according to recommended guidelines, it is generally a safe form of exercise, with temporary muscle soreness being the most common side effect. Extreme intensity or incorrect use can lead to muscle damage, which is a reason to always work with a responsible protocol and gradual buildup, and to take into account contraindications such as a pacemaker or certain heart conditions.
Conclusion: does EMS really work?
Based on the available research, the answer is nuanced, but predominantly positive. EMS is not a miracle cure that makes nutrition, sleep, and regular exercise unnecessary, but it is also not nonsense. There is a growing, reasonably consistent body of research showing that EMS can improve muscle activation, muscle strength, and lean body mass, with the strongest effects in:
- people with little training experience who want to build strength and muscle mass in a time-efficient manner
- busy professionals who don't want to go to the gym multiple times a week
- seniors and people who have difficulty with heavy, strenuous training
- people recovering from an injury, surgery, or inactive period
- people with back pain, as an addition to exercise therapy
For fat loss: EMS works best in combination with an adjusted diet, not as a standalone intervention. And for top athletes who are already training maximally, the added value of EMS remains more limited than for beginners.
In short: science supports EMS as a valuable, evidence-based addition to an active lifestyle, provided it is used realistically and combined with the basic principles of healthy movement and eating.
Consulted scientific sources
- Kemmler, W., Shojaa, M., Steele, J., Berger, J., Fröhlich, M., Schoene, D., von Stengel, S., Kleinöder, H. & Kohl, M. (2021). Efficacy of Whole-Body Electromyostimulation (WB-EMS) on Body Composition and Muscle Strength in Non-athletic Adults: A Systematic Review and Meta-Analysis. Frontiers in Physiology. pmc.ncbi.nlm.nih.gov/articles/PMC7952886
- Wirtz, N., Dörmann, U., Micke, F., Filipovic, A., Kleinöder, H. & Donath, L. (2019). Effects of Whole-Body Electromyostimulation on Strength-, Sprint-, and Jump Performance in Moderately Trained Young Adults. Frontiers in Physiology. pmc.ncbi.nlm.nih.gov/articles/PMC6857204
- Effects of whole-body electromyostimulation on health indicators of older people: Systematic review and meta-analysis of randomized trials (2022). ScienceDirect. sciencedirect.com/science/article/abs/pii/S1360859222000535
- Kemmler, W. & von Stengel, S. (2013). Whole-body electromyostimulation as a means to impact muscle mass and abdominal body fat in lean, sedentary, older female adults: subanalysis of the TEST-III trial. Clinical Interventions in Aging. pmc.ncbi.nlm.nih.gov/articles/PMC3795534
- Kemmler, W., Kohl, M., Freiberger, E., Sieber, C. & von Stengel, S. (2018). Effect of whole-body electromyostimulation and/or protein supplementation on obesity and cardiometabolic risk in older men with sarcopenic obesity: the randomized controlled FranSO trial. BMC Geriatrics. ncbi.nlm.nih.gov/pmc/articles/PMC5845205
- Burkhardt, F., Chaudry, F., Kast, S., von Stengel, S., Kohl, M., Roemer, F. W., Engelke, K., Uder, M. & Kemmler, W. (2025). The effect of whole-body electromyostimulation on visceral adipose tissue volume in overweight-to-obese adults with knee osteoarthritis: A randomized controlled study. PMC. pmc.ncbi.nlm.nih.gov/articles/PMC12037472
- PubMed database: Electrical muscle stimulation, chronic low back pain – systematic review. pubmed.ncbi.nlm.nih.gov
This article is periodically updated as new relevant studies or meta-analyses on EMS training appear.
