How Electric Ab Stimulators Work in Building Muscle

Doing scores of ab exercises can deliver that coveted "six-pack" with consistent effort and correct technique, but there's an easier way. Electrical ab stimulators contract muscles without the sweat or strain, improving strength and tone, according to the U.S. Food and Drug Administration (FDA).

The ab muscles, or core, are easy to overlook in a fitness training routine. After cardio, upper-body and lower-body work, spending time targeting exercises on abs alone often get shorted. However, taking the time to strengthen the core muscles can decrease overall fatigue, increase endurance and lessen the risk of injury, according to the Mayo Clinic.

Abs are also crucial muscles in many sports, such as swimming, weightlifting, volleyball and tennis. Although few recent studies have been conducted on the effect of electrical muscle stimulation on abdominal muscles specifically, a May 2017 review by the University of Delaware of EMS studies in sports training revealed that using electrical muscle stimulation was effective in strengthening the muscles of the body when used in conjunction with isometric exercises.

What's more, EMS may promote strength gains in untrained athletes — in addition to trained and elite athletes — according to a September 2012 review in the ​Journal of Strength and Conditioning Research​.

Contractions of your abdominal muscles during exercise come from your brain or spinal cord. EMS, such as those found in stomach muscle stimulators, bypasses your body's systems and works by delivering electrical current directly to the nerves leading to your abdominal muscles.

EMS activates contractions in the targeted muscle group. When you perform an abs exercise with the proper technique at a moderate tempo, you contract your muscles several times per minute, according to exercise physiologist Len Kravitz, Ph.D., of the University of New Mexico.

EMS devices can increase the contractions up to 500 times per second. However, units delivering this level of contraction are approved by the FDA for therapeutic and sports training settings by healthcare professionals.

Home-use EMS units in the form of stomach muscle stimulators deliver far fewer contractions — about 150 every 30 minutes. Gel pads that carry the electric current are correctly situated in a belt that gets fastened around the waist. Make sure that any device you use at home is FDA-approved to avoid an increased risk of skin burns, electric shock or even electrocution.

Electromyostimulation — commonly referred to as EMS or electrical muscle stimulation — targets motor neurons to activate fast-twitch muscle fibers. When you exercise, your brain sends signals through the spinal cord via interneurons that communicate with your motor neurons to move your muscles to perform crunches, sit-ups or other movements.

EMS completely bypasses your brain and spinal cord, sending impulses directly to your muscles and activating contractions at a much faster rate and for more extended periods than you consciously could make your body move.

Although this seems like you could work out while you're sitting on the couch watching TV, the studies show that the EMS is effective when done in conjunction with targeted exercise at the same time.

That's because as you are initiating your slow-twitch muscle fibers consciously, the machine is stimulating the fast-twitch muscle fibers as well. With all your targeted muscle fibers contracting rapidly, a 20-minute session two times weekly is usually all that's needed to produce results over several weeks.

Not every electrical ab stimulator will help build stomach muscles. Transcutaneous electrical nerve stimulation units — commonly called TENS units — for example, stimulate the nerves to provide pain relief. Although you feel a pulse and might even feel the muscle contract slightly, the TENS unit is stimulating the nerve in a single part of the body, not building muscle.

That's because TENS units target sensory neurons in your body that send pain signals back to the brain. The current is designed to confuse the pain signal and stimulate the release of endorphins. Compared to EMS, the type of stimulation from TENS doesn't fully contract the muscle. So, you won't tone your abs no matter how long you use a TENS unit.

Electronic pulse massagers (EPM) focuses on relaxing a specific muscle, not contracting them. EPMs can be an enjoyable way to wind down after heavy exercise, but they won't build muscle either.

Most ab-building exercises, such as crunches, sit-ups, hanging leg lifts and planks, primarily engage your hip flexor muscles, leaving the abdominals relatively static, according to Kravitz. Your abs come into play for the first 30 to 45 degrees of each movement, which is akin to doing sit-ups by just lifting your shoulders off the ground.

So, do ab simulators work? Although EMS does cause muscle contractions that can strengthen and tone your abs, you won't get a ripped six-pack solely by hooking up daily. According to the FDA, no studies show that EMS alone will get you those rock hard abs you see on TV commercials touting EMS devices; diet and exercise are essential.

Not all EMS units are equal when it comes to strengthening and toning muscles, either. With an intensity that varies from one to 130 megahertz, EMS units focus on improving muscle blood flow and decreasing inflammation.

Units for home use include ab stimulator belts and personal-sized units that have electrodes you can position on your abs or other muscles. Flex Belt and Slendertone both manufacture ab stimulator belts with pre-positioned electrodes. TENS makes EMS devices that let you choose between muscular contraction for toning or pain relief waves.

You can also receive more powerful EMS treatments from medical or fitness professionals. ARP Wave offers a free in-home trial, and fitness centers like E-Fit offer whole-body suits with 10 electrodes that claim to build not only your abs, but other major muscle groups as well.