Electric muscle stimulators are great for helping you achieve your fitness goals through increasing your strength and aiding in your recovery. However, there are many myths, misconceptions and concerns around electric muscle stimulators and rightly so. Using a device that sends an electric current through your body sounds dangerous and painful. But medical devices like the Compex Electric Muscle Stimulator are reviewed and approved by the FDA, designed to perform very specific functions that are mirrored after the body’s own processes and are very safe.
Q: What does a Neuromuscular Electrical Stimulator (NMES) like Compex do?
A: The principle of electrostimulation is very simple; it reproduces the processes that occur when our brain orders muscles to contract. It works almost like a relay race; when we decide to contract a muscle, our brain sends an electrical current down through our nerve fibers. Once it reaches the muscle, the terminal motor neurons fire and stimulate the muscle fibers to contract.
When you use an electric muscle stimulator, the signal is sent directly to the motor neurons using brain-like electrical pulses. In fact, muscles cannot tell the difference between a contraction triggered by the brain and one caused by a NMES device. The difference is that with a NMES device, you bathe the entire length of the motor neurons. The result is a more thorough and complete muscular contraction. There is also less impact on bones and joints since the stimulation is coming from the device and not from an activity such as weight lifting.
Q: Are NMES devices legal?
A: Yes. Neuromuscular Electrical Stimulators are considered medical devices and are regulated by the Federal Food and Drug Administration (FDA). Only FDA-certified devices can be lawfully sold in the US without medical prescription. Most FDA approved NMES devices are intended for physical therapy and rehabilitation under the direction of a health care professional.
However, Compex has been approved as a level 2 medical device. In order to get that approval and be allowed to be sold directly to consumers, Compex had to prove that the device can be used safely and effectively in that setting, which has been done.
Q: Are there any side effects when using a NMES device?
A: Side effects are limited; Compex is a very safe device. However, if you are looking to build strength and start off with too high of a setting, you can experience soreness, the same way you would if you work out too hard at the gym. There has also been reports of skin irritation from the pads.
It should also be noted that improper use of a muscle stimulation unit can easily lead to skin burns, according to research published in “The Journal of Arthroplasty” in 2005. Dr. Daryl Lawson states that if a strong electrical current is delivered through a small electrode, the skin is exposed to a higher concentration of electricity per unit of area, which can cause burns. Again, start off slow and figure out what levels are best for you and that you’re most comfortable with.
Q: What is the difference between Compex Muscle Stimulators and ones used for medical purposes like muscle re education, physical therapy or to prevent venous thrombosis?
A: There are a lot of different types of electrical stimulators that stimulate nerves. Physical therapists often use one called Transcutaneous Electrical Nerve Stimulation or TENS. TENS units use a different kind of wave / frequency that stimulates sensory nerves instead of motor nerves like Compex. TENS units work with sensory nerves to block pain. When using a TENS device, you’ll feel a buzzing but no contraction of the muscle.
Compex is a NMES: Neuromuscular Electrical Stimulator. Compex works on a “all or nothing” principle. Once the motor neuron fires, the muscle fibers that it innervates will contract. The nerve cell and the muscle fibers it innervates is called a motor unit. One nerve cell will innervate anywhere from 10 to 1000 muscle fibers depending on the muscle fiber types, e.g. slow twitch vs. fast twitch. Either all of the motor unit fires, or none of it does. The strength of a contraction is determined by how many motor units fire synchronously.
When the pulse is sent, you will feel a twitch, a variety of twitches or very short contractions when running warm up or recovery programs. This type of response is common in the MarcPro unit, which is for recovery only. Compex not only delivers the recovery twitches, but also delivers twitches to warm the muscle up before an activity. On top of that, Compex has as many as four programs that contract the muscle for seconds at a time; enough so that when repeated throughout the length of a program, increased strength is developed after 10 sessions.
When you compare Compex with other similar products, the technology is the same, but the range of frequencies is different. Compex has 4 circuits. What that means is that four different muscle groups can be stimulated at the same time. A lot of muscle can be covered each time a program is run.
The muscle is the conduit for the current. At the proper frequency and pulse duration, it will stimulate motor nerves and only motor nerves. The Compex can be very powerful – more powerful than other popular NMES devices. It has the ability to penetrate deeply to contract more muscle than can be achieved with a maximum voluntary contraction. When the current penetrates more deeply, you stimulate more motor nerves and more muscle fibers. However, you choose the degree to which the muscle contracts. The stimulation levels are finely graded so you can select the exact level of current you want based on your comfort level.
Compex delivers a biphasic square wave of electricity. What that means is instead of a gradual build up, the current comes almost instantly so the nerve does not accommodate or hesitate. It sounds like it would be more painful this way however, this type of wave is actually more comfortable. Without the hesitation, the nerve and muscle fibers are stimulated at a lower level of energy.
Do you have more questions about Compex or electric muscle stimulators in general? Please ask away in the comments!