Whole-body electromyostimulation (WB-EMS) uses electrodes across most of the body’s main muscle groups to trigger contractions with electrical impulses, often while the user performs simple movements. It is promoted as a fast route to muscle and a leaner body. This article summarises the abstracts of two systematic reviews with meta-analyses, published in 2021 and 2023, and states what they can and cannot support. It is general information about training equipment, not medical advice, and it does not cover any particular device or brand.
What was counted as WB-EMS
The definition matters, because the reviews pooled studies of a specific kind of system. The 2021 review, by Kemmler and colleagues in Frontiers in Physiology, included WB-EMS trials in which the stimulation was the primary physical intervention and used at least six electrodes covering most muscle groups, in non-athletic adults. A single belt or pad over one muscle group would not meet that definition, so the findings should not be applied to small consumer stimulators of that kind. Nor do the abstracts describe whether the control groups did conventional exercise, so they do not show that WB-EMS beats ordinary training.
The 2021 meta-analysis: 16 studies, 897 participants
Kemmler and colleagues pooled 16 controlled studies with 19 WB-EMS groups representing 897 participants, searching eight databases up to 30 June 2020. The studies varied considerably in age, body mass index and physical condition, and in training frequency (one to five sessions a week) and length (6 to 54 weeks). The average standardised mean difference (SMD) was 1.23 for muscle mass parameters, 0.98 for maximum leg extension strength and 1.08 for maximum trunk extension strength, all statistically significant. The SMD for body fat change was -0.40, but the confidence interval (-0.98 to 0.17) included zero, so this did not reach significance. The authors reported substantial heterogeneity between trials for muscle and fat mass changes, and concluded that the review provided further evidence for significant, large-sized effects of WB-EMS on muscle mass and strength, but not on body fat mass.
The 2023 meta-analysis: 26 studies, 1,183 participants
Rodrigues-Santana and colleagues, in the journal Medicine, pooled 26 studies with 1,183 participants (586 in WB-EMS groups and 597 in control groups), aged from 20.4 to 77.4 years on average across studies, with interventions lasting 4 to 54 weeks. They searched five databases up to 30 July 2021 and assessed risk of bias using the PEDro scale and the GRADE approach. The SMD was 0.36 for muscle mass, -0.38 for body fat, 0.54 for strength and 0.36 for power, all with statistically significant differences between groups. Heterogeneity was low for muscle mass (15 per cent) and power (0 per cent), and medium for body fat (45 per cent) and strength (55 per cent). The authors concluded that WB-EMS has significant positive effects on muscle mass, body fat, strength and power.
Reading the two together
- Both found gains in muscle mass and strength. The 2021 effect sizes (around 1.0 to 1.2) are much larger than the 2023 ones (0.36 to 0.54), which included more studies.
- The reviews disagree on body fat. The 2021 review found no significant change; the 2023 review found a significant reduction (SMD -0.38). The difference may reflect the studies included, which the abstracts do not resolve.
- Studies vary a lot. Session frequency ranged from one to five a week and length from 4 to 54 weeks, so no single “dose” is supported by these abstracts.
- Effect sizes are relative to control groups. The abstracts do not say what the control groups did, so they do not show how WB-EMS compares with conventional resistance training.
What these reviews do not show
The abstracts report no comparison between brands, suits or settings. They do not show results for single-region devices, or for people using stimulation at home without supervision. They say nothing about long-term use beyond 54 weeks. They give no cost-effectiveness figures. Nor do they support claims that stimulation can replace movement with heavy loads.
Questions to ask before buying
- Does the product stimulate most major muscle groups with at least six electrodes, as in the reviews, or only one region?
- Do sellers cite trials of the specific device, or only the general meta-analyses?
- Are marketing claims about fat loss consistent with the 2021 review, which found no significant fat change?
- Is the review of equipment independent, or affiliate-funded? The guide to sponsored and affiliate reviews explains what UK rules require reviews to disclose.
The guide to fitness gadgets and gimmicks applies the same evidence test across other products, and the guide to choosing a vibration plate covers another gadget category.
The bottom line
Two meta-analyses of whole-body electromyostimulation (the 2021 one restricted to systems with at least six electrodes) found improvements in muscle mass and strength compared with control groups. Results for body fat were mixed: not significant in 2021 and significant in 2023. Neither abstract shows that stimulation beats conventional resistance training, and neither applies to single-region gadgets. Anyone considering a suit should look for trial evidence for the specific product.
Sources
- Kemmler et al., “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 (2021)
- Rodrigues-Santana et al., “The effects of whole-body muscle stimulation on body composition and strength parameters: A PRISMA systematic review and meta-analysis”, Medicine (2023)