Do Muscle Stimulators Work? Unveiling the Science & Benefits

By MaryAnn DePietro CRT

What if there were a way to mimic muscle contraction, improve strength, and help muscle recovery with one modality? Electrical muscle stimulation may help with all of the above.


Electrical muscle stimulation involves using a device to deliver controlled electrical impulses through electrodes placed over the targeted muscle. The electrical impulse causes involuntary muscle contraction, similar to contraction from regular exercise. Muscle stimulators have the potential to strengthen muscles, aid in rehabilitation, and reduce pain.


As research continues and technology evolves, there is increasing interest in EMS devices and the need for reliable information.


The article below provides a comprehensive, evidence-based answer to the question, "Does electrical muscle stimulation work?" The article also addresses various concerns and uses of EMS.

II. The Science Behind Muscle Stimulation

How EMS Works Physiologically

Normal muscle contraction involves a complex physiological process. EMS works similarly to a voluntary muscle contraction. The EMS device delivers an electrical signal through the electrodes to the motor neurons in the muscle fibers. This electrical impulse, called an action potential, causes motor neurons to depolarize, leading to involuntary muscle contraction.


Involuntary and voluntary muscle contractions differ. The brain's motor cortex stimulates voluntary muscle contractions. Electrical muscle stimulation leads to muscle contraction through the peripheral nervous system, not the motor cortex. The electrodes on the skin deliver the electrical impulse that bypasses the brain.


The FDA classifies muscle stimulators as medical devices because:

  • Their intent is to improve muscle strength.

  • And they can be used in physical therapy and rehabilitation.

Types of Electrical Stimulation

Neuromuscular electrical stimulation and transcutaneous electrical nerve stimulation (TENS) are both E-stim forms but have different purposes.


  • Electrical muscle stimulation (EMS) uses electrical impulses to stimulate muscle contraction and strengthen the muscles.

  • Transcutaneous electrical nerve stimulation (TENS) reduces pain instead of stimulating muscle contraction.

EMS Settings and Parameters

Users can set various parameters on EMS devices, including waveforms, frequency, intensity, and pulse duration.


  • Waveform: The waveform is the pattern of the electrical impulse used to stimulate muscle contraction. Waveforms have differing characteristics that affect muscle response and comfort level.

  • Frequency: Frequency refers to how often the waveform repeats itself per second.

  • Intensity: The intensity determines how many muscle fibers become recruited and how strongly they contract. Higher-intensity treatments generally lead to stronger contractions, but they also have the potential for discomfort.

  • Pulse duration: This is the time that the electrical current flows during each pulse of electrical stimulation.


Selecting the best parameters to use varies depending on the goal of EMS and the individual. For example, a healthy person using EMS to strengthen muscles may need different settings than a patient with muscle atrophy.


Different studies and research also indicate differing parameters. For example, there is no exact consensus on which frequency is most beneficial. However, according to an article published in Medicine, high-frequency stimulation generates greater adaptations of the level of fast-twitch fibers. It also enhances strength better than lower frequency.


However, it should not exceed 75 Hz, which can lead to muscle fatigue. In general, acceptable parameters include:

  • A frequency of 20-50 Hz

  • Pulse duration of 150-200 microseconds for small muscles and 200-300 for large muscle

  • A biphasic waveform is a versatile waveform for electrical muscle stimulation. It can be used to re-educate and strengthen muscles.

Scientific Studies and Research

Various studies and research have examined electrical muscle stimulation to improve strength, prevent atrophy, and improve rehabilitation outcomes. For example, the Journal of Orthopedic and Sports Physical Therapy examined eight studies. These studies compared electrical muscle stimulation with exercise to exercise alone in people recovering from ACL surgery.


Research reports did not indicate the combined number of study participants. Researchers theorized that EMS may help restore quadriceps strength by facilitating the recruitment of muscles inhibited by swelling or pain.


Post-ACL repair participants were assigned to a traditional physical therapy program or a combination of physical therapy and electrical muscle stimulation.


The studies varied widely in treatment time. They ranged from 30 minutes to over an hour of EMS daily or every other day. The treatment duration ranged from 3 to 11 weeks, with an average of 6 weeks. Research indicated the EMS with physical therapy group had greater quadricep strength improvement than the group receiving PT alone.


Another study in Brain Sciences looked at the effect of EMS on muscle mass and function in older sedentary adults with dementia. The study included 32 adults with dementia over the age of 80. The participants were randomly assigned to an intervention or control group.


The intervention group underwent general rehabilitation exercises and EMS for 23 minutes thrice a week for 23 weeks. The control group underwent rehabilitation alone for the same timeframe. Results indicated the intervention group receiving EMS had a significant increase in muscle mass. Muscle mass in the control group did not change.

III. Potential Benefits of Muscle Stimulators

A woman holding an electrical muscle stimulator in a gym

Muscle Strengthening and Conditioning

Electrical muscle stimulation may have muscle strengthening and conditioning benefits for athletes and individuals looking to improve muscle strength.


A 2023 study published in the journal PeerJ investigated the effects of EMS combined with resistance training on athletes:


  • Strength

  • Power

  • And muscle mass.


The study involved 28 individuals, 14 male and 14 female. The individuals were assigned to two groups. One group received daily EMS and resistance training; the other received just resistance training for 8 weeks.


The results indicated that the group that received EMS and resistance training combined:


  • Significantly improved muscle mass and strength

  • And reduced body fat more than the resistance training-only group.


Researchers theorized that resistance training combined with EMS may lead to greater muscle fiber recruitment than resistance training alone. This may potentially produce greater training intensity and can be beneficial for athletes.


Another study involved a meta-analysis and systematic review of 89 trials. It was published in the Journal of Strength and Conditioning Research and examined the effect of EMS on athletic performance.


The analyzed studies involved different types of frequency currents and various treatment times, averaging three times a week. The trials covered a period of 10 days to 14 weeks. A biphasic waveform involving lower body muscles was used in most studies.


Results indicated that strength, power, and speed improved after 3 to 6 weeks of stimulation. For example, the squat jump enhanced by 21%, and the vertical jump height improved by 25%.

In addition to increasing strength, EMS has the potential for muscle hypertrophy. But the extent is still being studied.

A woman holding a electrical muscle stimulator in a gym with electrodes on her elbow

Rehabilitation and Recovery

EMS can also play a role in muscle re-education after injury or surgery. It can also be used as part of physical therapy. By stimulating muscle contraction, EMS may help prevent muscle atrophy during immobilization and improve strength during rehabilitation.


Research published in the journal Critical Care Research and Practice analyzed using EMS for immobile hospitalized patients. The study involved 142 patients who received either EMS or were assigned to the control group. Researchers evaluated muscle strength before EMS sessions in both groups.


Study participants in the EMS group had 55 minutes of EMS applied daily to the following:


  • Vastus medialis

  • Vastus lateralis

  • And peroneus longus of both legs during their hospital stay.


Muscle strength was re-evaluated before discharge. Researchers found that EMS preserved or enhanced the strength of critically ill immobilized patients.


EMS can also help reduce muscle soreness. This may allow individuals to participate in their rehabilitation and exercise program, which can promote recovery.

A woman holding a electrical muscle stimulator at a desk

Pain Management

Electrical muscle stimulation (EMS), specifically TENS, can be helpful for pain relief. EMS may block pain signals from reaching the brain. EMS can also decrease muscle spasms and tension, which can decrease pain. The exact mechanism of how this occurs is not fully understood, but it may be due to the release of endorphins.

A woman holding a electrical muscle stimulator toward the camera

Cosmetic Applications (Ab Stimulators)

In addition to therapeutic and fitness uses for EMS, some manufacturers promote cosmetic applications such as:


  • Promoting abdominal fat loss

  • And muscle toning.


But do muscle stimulators work to burn fat?


Evidence is lacking to definitively state that muscle stimulators burn fat. It's true that EMS can help stimulate muscle contraction, which may strengthen and tone muscles. Strengthening and firming muscles may give the appearance of tighter abs.


However, according to the FDA, EMS devices are not cleared for weight loss or waist circumference reduction. EMS devices can be beneficial in certain circumstances. However, they are not a substitute for regular exercise and a healthy diet.

IV. Limitations and Considerations

Effectiveness Varies

The effectiveness of EMS may vary depending on the parameters used, the goal of treatment, and individual factors. It's essential to have realistic expectations. Don't expect EMS to get you toned and fit if you're not taking other steps, such as proper exercise and diet.


Varying perspectives exist on the benefits, effectiveness, and limitations of EMS. For example, EMS proponents or manufacturers of EMS devices have the potential to overpromise and use misleading marketing. Whether intended for rehabilitation or strength benefits for athletes, EMS is one tool. However, it should not be interpreted as the only tool.


Safety Precautions and Contraindications

EMS may not be appropriate for everyone. Individuals with the conditions below should avoid EMS.


  • Pregnancy

  • Implantation of a pacemaker

  • Peripheral vascular disease

  • History of arrhythmias

  • Epilepsy


EMS is typically safe, but potential side effects and risks can occur. The FDA guidelines include using EMS devices according to the manufacturer's directions to avoid adverse side effects.


Potential risks and side effects of EMS include:


  • Skin irritation, which can consist of redness and itching at the site of electrode placement

  • Headache

  • Muscle damage if used at high intensity

Proper Usage and Expectations

It is vital to use EMS appropriately and have reasonable expectations. EMS is most effective when combined with regular exercise and a healthy lifestyle. Electrical muscle stimulation cannot replace healthy lifestyle choices. Instead, it can be used as a complement to exercise.


When using an EMS device at home, following the manufacturer's instructions is essential. Individuals with a medical condition should consult their healthcare provider to determine if EMS is appropriate.


EMS users shared their experiences on forums, such as Reddit, and there were various opinions. Some users felt it helped reduce pain.

Many users asked, "Can EMS build muscle?" The consensus was that while EMS may help build muscle, it does not replace exercise. Instead, it may play a part in a fitness regime.


Remember that individual experiences vary; professional guidance is always your best bet.

V. Conclusion

EMS can be an effective technique for building muscle mass, re-educating muscles, and helping with rehabilitation. It may also reduce atrophy for immobile individuals.


Although EMS appears helpful for strengthening muscles, it works best with exercise and a healthy diet.


Remember that EMS may not be appropriate for everyone and has limitations.


Before using EMS, it is essential to consult with a healthcare professional and make an informed choice.


EMS offers an option for enhancing fitness and helping in pain management and rehabilitation. It can be one helpful tool and play a complementary role in treatment or training.

Brandon Landgraf

About the Author

MaryAnn DePietro CRT is a licensed respiratory therapist with over 15 years of clinical experience in critical care, emergency medicine, and pulmonary rehabilitation. She is also an American Council on Exercise certified personal trainer and holds specialty certifications in orthopedics, senior fitness, and weight management. MaryAnn has a degree in Rehabilitation from Penn State University and a degree in respiratory therapy.


In addition to her clinical experience, she has written extensively about all things medical, as well as health, fitness, and aging for various websites, magazines, and newspapers.

About TENS 7000

Pain sucks. It affects millions of people each year with adverse physical and mental side effects. TENS 7000 provides tools to combat pain and let people live life on their terms, pain-free. Our TENS 7000 TENS Unit is one of the top-rated over-the-counter TENS units, having sold over two million since 2008. Stop letting aches and pain hold you back — live life on your terms.

Brandon Landgraf