Quick Overview
Scientists at Yonsei University in South Korea ran a randomised trial with 50 healthy adults.
Volunteers used an Ab EMS trainer for 23 minutes, twice a day, for 8 weeks.
One group added crunches. MRI scans showed the six-pack muscle grew about 21–25% in both groups.
Side ab muscles grew up to 9%. Core control improved too, by up to 70% when EMS was paired with exercise.
The study was published in the peer-reviewed Journal of Sport Rehabilitation. It suggests EMS may support fitness in healthy adults.
Future research may show benefits for other groups and goals. Read on to see the full results.
We always provide direct links to the original research at the end of every article so you can review the evidence yourself.
50 People, 8 Weeks, MRI Scans: What an EMS Study Found Inside Their Abs
Can an Ab EMS trainer that sends signals to your abs really change your muscles?
A team of university scientists wanted a real answer. They didn’t want a guess or a sales pitch. So they ran a proper experiment.
They used MRI scanners to look inside people’s bellies. Then they measured what changed after 8 weeks of EMS training.
The results are worth a closer look.
Who Ran This Study?
The research came from Yonsei University in South Korea. The team works in the university’s Department of Physical Therapy.
South Korea is a world leader in science and technology. Its top universities are respected around the globe.
The study was published in 2020 in the Journal of Sport Rehabilitation. This is a peer-reviewed journal. That means other experts checked the work before it was printed.
The publisher is Human Kinetics. It has published sports science research for decades.
The study was also approved by an ethics board. It was officially registered with Korea’s clinical research registry. These are signs of careful, trustworthy science.
How the Experiment Worked
The scientists recruited 50 healthy adults. Their average age was about 25.
The volunteers were split into two groups at random. This keeps the comparison fair.
Group 1: EMS only.
These people wore an Ab EMS trainer over their stomach. They relaxed and let the device do the work.
Group 2: EMS plus exercise.
These people wore the same Ab EMS trainer with the same settings. They also did crunches while the EMS was running.
Both groups trained 23 minutes, twice a day. They did this for 8 weeks. They aimed for at least 5 days each week.
The scientists phoned every volunteer daily to check they stuck to the plan.
Volunteers were not allowed to do any other ab workouts. That way, the scientists could see the effect of the training itself.
What the Scientists Measured
They tested two things before and after the 8 weeks.
1. Muscle size.
MRI scans measured the size of the abdominal muscles. This included the “six-pack” muscle, the rectus abdominis. It also included the side muscles, called the lateral abdominal wall.
2. Core control.
Volunteers lay on their backs with their legs raised. Then they slowly lowered their legs. The goal was to keep the lower back and hips steady.
A sensor tracked how far the legs could go down before control slipped. Lower legs mean better core control.
Result 1: Ab Muscles Got Bigger in Both Groups
The MRI scans showed real muscle growth.
In the EMS-only group, the six-pack muscle grew a lot:
- Right side: from 5.18 to 6.45 cm². That’s about 25% bigger.
- Left side: from 5.27 to 6.39 cm². That’s about 21% bigger.
The side ab muscles grew too. They increased by about 9% on each side.
The EMS plus crunches group grew as well. Their six-pack muscle grew about 21–22% on each side.
Here is the interesting part. Both groups grew by similar amounts. The scientists found no clear difference between them.
So in this study, EMS alone matched EMS plus crunches for muscle size.
Result 2: Core Control Improved
The single-leg test was the easier one. Both groups improved here.
- EMS-only group: scores rose about 33%.
- EMS plus crunches group: scores rose about 26%.
The double-leg test was much harder. Here, one group stood out.
- EMS plus crunches group: scores rose about 70%.
- EMS-only group: scores rose about 25%. But this change was too small to call a clear result.
The scientists had an explanation. Doing exercise during EMS may train your brain and muscles to work together. EMS alone may not train that teamwork as much.
What Does This Mean for You?
Healthy adults saw results. This is the group the study tested directly. Both training styles grew ab muscle and improved core control.
Combining EMS with exercise gave the best core control. The scientists said this approach suits fitness and athletic training.
Consistency mattered. Volunteers trained regularly for 8 weeks. Their progress came from steady, repeated sessions.
Other groups may benefit too. The scientists said future studies should test older adults and other groups. Early signs are promising, but more research is needed.
The Honest Fine Print
Good science shows its limits. This study did too.
- It did not include a group that did no training at all.
- All volunteers were young and healthy.
- This is one study. Individual results will vary.
People with pacemakers or electronic implants were not allowed to use EMS in this study. Always read your product’s instructions. Talk to your doctor if you’re unsure whether EMS suits you.
The Bottom Line
Scientists looked inside people’s bellies with MRI. After 8 weeks of EMS, they saw bigger ab muscles.
They also measured better core control. The best results came from pairing EMS with exercise.
That’s not hype. That’s what the scans showed.
Source: Hwang U-J, Jung S-H, Kim H-A, Kim J-H, Kwon O-Y. Effect of Abdominal Electrical Muscle Stimulation Training With and Without Superimposed Voluntary Muscular Contraction on Lumbopelvic Control. Journal of Sport Rehabilitation. 2020;29(8):1137–1144. doi:10.1123/jsr.2019-0348
Featured Product
ORIEMS FIT ULTIMATE KIT 💪 is a 100% Australian award-winning product.
Voted YEAR’S BEST ⭐ for 2024 and 2025.
It is a wide-range targeted muscle stimulator enhanced with EMS technology, designed to support your fitness and relaxation routine. 🌟
Trusted by more than 10,000 happy users with over 450 five-star Google reviews. 😊
Check availability.
Product Disclaimer:
This product is designed only to support fitness and relaxation routines. It is not a medical device and has not been evaluated or registered by the TGA. It is not intended to diagnose, treat, cure or prevent any disease or medical condition. It may not be suitable for everyone. Please consult your doctor or healthcare practitioner before using it.
Like this Research Digest? 📚Share it with your friends 💬👇 |
About Our Health Research Digest
We bring you the latest and most important health research papers — simplified and easy to understand.
Each study is broken down into clear, concise summaries and engaging podcasts, with direct links to the original research so you can explore further whenever you like.
We also create content based on your requests. If you’re curious about a specific health topic or would like us to find relevant studies, simplify the findings, and turn them into a podcast, just let us know.
Don’t hesitate to reach out — we’re here to help make health research accessible and useful for you. Contact us anytime.
More EMS Research Scientists Are Studying
1. Can EMS reduce fat?
2. Can EMS increase calorie burn while sitting?
3. Can EMS support muscle toning and muscle gains?
4. Can EMS improve athletic training?
5. Can EMS play a role in muscle loss & frailty?
6. Can EMS reduce pain?
7. EMS vs TENS: What are the differences?
8. Can EMS play a role after stroke?
Research Summary
| Detail | Summary |
|---|---|
| Study title | Effect of Abdominal Electrical Muscle Stimulation Training With and Without Superimposed Voluntary Muscular Contraction on Lumbopelvic Control |
| Authors | Ui-Jae Hwang, Sung-Hoon Jung, Hyun-A Kim, Jun-Hee Kim, Oh-Yun Kwon |
| Research institution | Department of Physical Therapy, Yonsei University, Wonju, South Korea |
| Journal | Journal of Sport Rehabilitation, Vol. 29, No. 8, pages 1137–1144 (peer-reviewed) |
| Publisher and year | Human Kinetics, 2020 |
| Link to original study | https://doi.org/10.1123/jsr.2019-0348 |
| Ethics and registration | Approved by Yonsei University’s ethics board; registered with Korea’s Clinical Research Information Service (KCT0002990) |
| Study design | Randomised trial comparing two training groups |
| Participants | 50 healthy adults, average age about 25; 25 in each group |
| Group 1: EMS only | Wore an Ab EMS trainer over the stomach and relaxed during sessions |
| Group 2: EMS plus exercise | Same Ab EMS trainer and settings, plus crunches during the EMS session |
| Training schedule | 23 minutes, twice a day, for 8 weeks; at least 5 days a week encouraged |
| How muscle size was measured | MRI scans of the six-pack muscle and the side abdominal muscles |
| How core control was measured | Single-leg and double-leg lowering tests, tracked with a pressure sensor and motion sensor |
| Six-pack muscle growth (EMS only) | Right side about 25% bigger (5.18 → 6.45 cm²); left side about 21% bigger (5.27 → 6.39 cm²) |
| Six-pack muscle growth (EMS plus exercise) | Right side about 22% bigger (5.32 → 6.51 cm²); left side about 21% bigger (5.41 → 6.55 cm²) |
| Side abdominal muscle growth | EMS only: about 9% bigger on both sides; EMS plus exercise: about 4% (right) and 8% (left) |
| Single-leg lowering test | Both groups improved: EMS only about 33%, EMS plus exercise about 26% |
| Double-leg lowering test | EMS plus exercise improved about 70%; EMS only rose about 25%, but this change was not statistically clear |
| Key conclusion and limits | EMS grew ab muscle size in both groups; adding exercise gave the best core control. No untrained comparison group, and only young healthy adults were tested |
| Platform | Listen Now |
|---|---|
 Apple Podcasts |
Listen on Apple |
 Spotify |
Listen on Spotify |
 YouTube |
Watch on YouTube |
 Amazon Audible |
Listen on Audible |
 Podbean |
Listen on Podbean |
Disclaimer
This article is published for general information and educational purposes only. It does not constitute medical advice, health advice, diagnosis, or treatment of any kind.
All content on this website, including any studies, research, or information mentioned, is provided for informational purposes only and does not imply or guarantee any specific health outcomes.
We are not affiliated with, endorsed by, or connected in any way to any researchers, universities, research centres, journals, or institutions referenced in any article. No reference to any study, researcher, or publication should be interpreted as an endorsement or recommendation of any products sold or featured on this website.
Our products (and any products featured or linked in this article) are not intended to diagnose, treat, cure, prevent, or manage any disease or medical condition. Individual results may vary significantly. No guarantees or warranties are made regarding effectiveness, safety, or specific outcomes.
Always consult a qualified healthcare professional before using any product mentioned on this website or making any changes to your health routine, especially if you have a pre-existing medical condition, are pregnant, breastfeeding, have a pacemaker, or are taking medication.
To the fullest extent permitted by law, ORIEMS FIT, its directors, employees, authors, affiliates, and agents disclaim all liability for any loss, damage, cost, expense, or injury (whether direct, indirect, consequential, special, or incidental) arising from the use of, or reliance upon, any information in this article or from the purchase or use of any products featured or sold on this website.
© [ORIEMS FIT] – All Rights Reserved.
