In recent years, electrical muscle stimulation (EMS) devices have gained popularity as a potential tool for weight loss and muscle toning. These devices deliver electrical impulses to the muscles, causing them to contract. While proponents claim that EMS can help improve abdominal muscle tone, burn fat, and promote weight loss, it's essential to examine the scientific evidence and understand the true effectiveness of these machines.
What is Electrical Muscle Stimulation?
Electrical stimulation involves applying small electrical charges to a muscle through a device. Doctors and physical therapists have used electrical devices to treat injured or paralyzed muscles for decades. Functional electrical stimulation (FES) uses an electrical pulse to force muscles to contract, preventing muscle wasting, encouraging blood flow, and potentially repairing damage. FES has proven effective for conditions like multiple sclerosis (MS), helping improve physical performance and muscle strength, and preventing muscle mass loss.
Ab stimulators are wearable devices that promise to strengthen abdominal muscles via electrical stimulation. However, they are not the same as the devices used by physical therapists. The Food and Drug Administration (FDA) regulates these devices as medical devices, but unregulated devices are also available, especially from manufacturers outside the United States.
Claims vs. Reality: What Ab Stimulators Promise
Ab stimulator manufacturers often market their devices to the general public, claiming they support weight loss or build strong ab muscles without exercise. Some of the most popular ab stimulators are available online, with reviewers promising rapid results and significant changes in body shape. However, many of these reviews are fake, and people should be mindful of short reviews, extreme claims, and reviewers who haven't reviewed other products or leave five stars for every product.
Most ab stimulators are adhesive pieces of cloth or belts that deliver an electric current to the abdominal muscles, causing contractions that a person might not even feel. Some offer apps to track progress, and most allow users to adjust the intensity of muscle contractions.
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The Science Behind Muscle Stimulators
At present, there is very little research assessing how well ab stimulators work for toning muscles. Instead, most research suggests that these devices are ineffective for toning and strengthening the abdominal muscles. The limited research that has looked at these devices has reported very small changes that were insufficient to change a person’s appearance significantly. For example, a 2019 study involving trained athletes found that 12 weeks of FES did not increase the size of the abdominal muscles.
While FES works well as a physical therapy tool for people with serious muscle injuries, there is less evidence that abdominal stimulators can train the abs in people seeking increased muscle strength, better posture, or a slimmer waistline.
Can Ab Stimulators Burn Fat?
Ab stimulators cannot burn fat. To burn fat, a person must create a calorie deficit, using more calories through exercise and movement than they eat each day. Even if ab stimulators can help to slightly strengthen muscles, a person will not notice a difference in their appearance if they are not also burning fat.
Risks and Safety Considerations
Unregulated ab stimulators present the most significant risk. These devices may burn the skin, contain toxic chemicals or adhesives, or deliver a shock that is too intense to be safe. Even FDA-regulated stimulators, however, present some dangers. These devices may interfere with other electrical devices, such as pacemakers. They may also cause a person to believe that they are getting exercise or doing something healthful, deterring them from more beneficial exercise and lifestyle changes. The stimulator should not hurt, sting, or burn, and it should not cause muscle spasms.
The FDA has received reports of shocks, burns, bruising, skin irritation, and pain associated with the use of some of these devices. There have been a few recent reports of interference with implanted devices such as pacemakers and defibrillators. Some injuries required hospital treatment.
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Alternatives to Ab Stimulators
People who wish to improve their posture or address muscle injuries should consider physical therapy. A physical therapist offers targeted exercises and massage and may also recommend electrical stimulation to improve muscle health. People seeking a more muscular core or a trimmer waistline should focus on two goals:
Burning fat by creating a caloric deficit: A person must use more calories than they eat to create a deficit. Increasing their activity level - with both intense exercise and more overall movement, such as by walking each day - can help a person gradually burn fat, including on the stomach.
Strengthening the abdominal muscles with targeted exercises: These exercises will not burn fat, but they can improve posture and core strength while making the muscles more visible as a person loses body fat. Some of the most effective core exercises include:
- Abdominal bridges
- Planks
- Opposite arm and leg raise
The Role of EMS in Rehabilitation
Functional electrical stimulation (FES) is a treatment option that can help individuals with paralyzed or weakened muscles due to damage in the brain or spinal cord. Doctors may use electrical muscle stimulators for patients who require muscle re-education, relaxation of muscle spasms, increased range of motion, prevention of muscle atrophy, and for treating other medical conditions which usually result from a stroke, a serious injury, or major surgery. Evidence indicates that FES is effective for older adults after they experience a stroke. A 2020 article adds that FES is effective for individuals with paralysis resulting from stroke or spinal cord injury. Additionally, health experts may suggest FES as a therapy option for conditions such as MS.
EMS and Calorie Expenditure: A Closer Look
While ab stimulators may not be effective for weight loss, electrical muscle stimulation, in general, can increase energy expenditure. Research shows EMS can increase energy expenditure by 10-20% during sessions, with some studies reporting calorie burns of 300-500 calories per 20-minute session. However, the calorie burn is generally lower than traditional cardio exercises like running or cycling.
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A 2011 study found that neuromuscular electrical stimulation increased energy expenditure in a dose-dependent way, meaning higher intensity settings burned more calories. At the sensory level, participants burned an extra 2.96 calories per hour above their resting rate. When they cranked it up to the motor threshold, that number jumped to 6.80 calories per hour. At the maximal comfortable intensity, people burned an additional 10.37 calories per hour. Another study found that EMS at rest increased energy expenditure by 19.4% and oxygen consumption by 17.4%. Even when people walked while using EMS, they still burned 4.4% more calories than walking alone.
Based on the research, conservative estimates from scientific studies suggest a 20-minute EMS session burns approximately 300-500 calories, which translates to roughly 15-25 calories per minute during active stimulation, with your baseline metabolic rate increasing by 10-20% during sessions. However, these numbers can vary quite a bit between individuals, as age, gender, fitness level, and body composition all influence your metabolic rate.
One of the most intriguing findings relates to what happens when you're done with your session. The 2011 study found that energy expenditure remained significantly higher during the 10-minute recovery period after NMES, with participants burning an additional 5.00 calories per hour above baseline. This afterburn effect, technically called excess post-exercise oxygen consumption or EPOC, suggests that your metabolism stays revved up even after the electrical stimulation stops.
EMS vs. Traditional Exercise: A Comparison
In a typical 20-minute session, EMS training burns about 300-500 calories, which puts it right in the ballpark with many traditional exercises. If you're running at 7 mph, you'll burn roughly 280-320 calories in the same timeframe. Moderate cycling comes in at 133-160 calories, while swimming burns about 160-200 calories. Traditional strength training typically burns 126-150 calories.
EMS shines in several key areas. The time efficiency is hard to beat - getting a solid calorie burn in just 20 minutes appeals to busy parents and professionals. It's also incredibly low impact, which makes it perfect for people recovering from injuries or dealing with joint issues. What's particularly fascinating is how EMS activates deep muscle fibers that are tough to engage through regular exercise.
However, EMS doesn't give you the same cardiovascular benefits as aerobic exercise. Your heart and lungs aren't getting the same workout they would from a good run or bike ride. It also doesn't improve your coordination, balance, or sport-specific skills the way functional movement does. EMS works best as a complement to traditional exercise, not a replacement.
Factors Influencing Calorie Burn with EMS
Not all EMS sessions are created equal. The answer depends on several key factors that can dramatically affect your results.
- Stimulation intensity: Research shows a clear linear relationship between how high you can tolerate the electrical intensity and how many calories you'll burn.
- Muscle mass: People with more muscle tissue naturally burn more calories during EMS sessions because muscle is metabolically active tissue.
- Session duration: Most research focuses on 16-20 minute sessions, which seem to give you the best bang for your buck without leaving you completely exhausted.
- Electrode placement: Professional sessions typically target major muscle groups like your abdomen, glutes, quadriceps, and hamstrings all at once.
The key insight from research is that only the motor threshold and maximal comfortable intensities produce significant calorie burn. If you're staying in the comfortable sensory zone, you're not getting the metabolic benefits you're looking for. Optimal settings for calorie burn include a frequency of 20-85 Hz, with higher frequencies better for strength and lower for endurance. The pulse width should be 200-400 microseconds, with a duty cycle of 4 seconds on and 4 seconds off to prevent excessive fatigue. Sessions should last 16-20 minutes of active stimulation.
EMS and Muscle Building
While immediate calorie burn gets most of the attention, EMS may provide lasting metabolic benefits through muscle building and toning. EMS can stimulate muscle growth, particularly in people who haven't been training regularly. Studies show 20-40% strength improvements with consistent EMS training, and the electrical stimulation can activate fast-twitch muscle fibers that are difficult to engage during regular exercise.
The long-term metabolic impact is where things get really interesting. Each pound of muscle burns approximately 6-7 calories per day at rest, so building muscle through EMS can increase your resting metabolic rate. Greater muscle mass also improves insulin sensitivity and helps your body handle glucose more effectively.
A Study on EMS and Abdominal Obesity
A 12-week study on adults with abdominal obesity found that EMS produced a 5.2 cm reduction in waist circumference compared to 2.9 cm in the control group. The electrical muscle stimulation group achieved a mean 5.2±2.8 cm decrease in waist circumference while the transcutaneous electrical nerve stimulation group showed only a 2.9±3.3 cm decrease (P=0.005). About 20 (70.0%) of the electrical muscle stimulation group lost more than 4 cm of waist circumference but that only 8 (33.3%) of the transcutaneous electrical nerve stimulation group did so (P=0.008). Furthermore, fasting free fasting acid levels were significantly higher in the electrical muscle stimulation than in the transcutaneous electrical nerve stimulationgroup at week 12 (P=0.006). In the electrical muscle stimulation group, slight decreases in visceral abdominal fat and total abdominal fat areas by computer tomography were observed at 12 weeks, but these decreases were not significant.
The study revealed that EMS is capable of producing physiological responses similar to those of cardiovascular exercise at mild to moderate intensities, despite the fact that EMS is performed without producing gross movement of limbs or loading joints. The EMS group achieved a modestly greater decrease in WC than the control group at week 12 (5.8% vs. 3.3%, P = 0.007). Furthermore, the proportion in the EMS group that achieved a WC reduction of >4cm was twice as high as that observed in the control group. TENS only stimulates sensory nerves, whereas EMS excites motor nerves and results in the constriction skeletal muscle fibres, which means its metabolic benefits are similar to that of exercise.
The present study revealed that EMS is capable of producing physiological responses similar to those of cardiovascular exercise at mild to moderate intensities, despite the fact that EMS is performed without producing gross movement of limbs or loading joints.
In summary, the 12-week EMS program was found to modestly reduce WC in abdominal obese adults without any evidence of side effects. These findings suggest EMS is an effective, safe auxiliary treatment for abdominal obesity in adults.
Safety Considerations for EMS
While EMS can be an effective tool for burning calories, proper screening and application are absolutely necessary for getting results without risking injury.
The FDA doesn't allow devices to be marketed specifically for weight loss because the calorie burn is considered marginal compared to traditional aerobic exercise. EMS devices fall into two main categories: over-the-counter devices for muscle toning and strengthening, and prescription devices for therapeutic rehabilitation.
There are several important contraindications to consider before starting EMS. Pregnancy is an absolute no-go since we don't know how electrical stimulation might affect fetal development. Pacemakers and other cardiac devices can malfunction with electrical interference. People with epilepsy might experience seizures, and anyone with open wounds, burns, or skin infections at electrode sites should wait until they heal.
The key to successful EMS use is proper integration into your overall lifestyle. The patients who see the best results combine EMS sessions with balanced nutrition, traditional exercise for cardiovascular health, proper sleep for recovery, and effective stress management techniques.
Who Benefits Most from EMS?
Not everyone gets the same benefits from EMS, but certain groups tend to see particularly good results. People with limited mobility often find EMS invaluable - this includes spinal cord injury patients, stroke survivors, individuals with joint problems that prevent traditional exercise, and post-surgical patients during recovery. Postpartum women represent another group that can benefit significantly from EMS, though only after getting medical clearance. Athletes in rehabilitation use EMS to maintain muscle mass during injury recovery and target specific muscle groups for strengthening.