Electrical muscle stimulation, or EMS for short, is a common addition to training and rehabilitation. In this guide, we cover the most popular portable sports EMS brands and their systems. Selecting the right system can be daunting with so many general health models in the market, but we have done the research to help you make the right decision.
Professional electrotherapy systems—the ones you would see at rehabilitation clinics—are not portable and are a different market. Coaches use consumer price options with professional athletes due to their portability, similar features to clinical systems, and settings that deliver specific benefits to the body. Five brand leaders exist globally, and we cover what makes a great EMS unit for all athletes, not just the pros or elites.
How an Electronic Stimulator Works
Neuromuscular stimulation simply uses electrical current from a device and transmits it through a wire to a select muscle. The electrical current activates the muscle’s action potential, thus creating a muscular contraction. This contraction is not the same as a volitional contraction from training, but some benefits exist to using it in conjunction with training. EMS requires the application of two surface electrodes on the skin in order for the electrical impulses to trigger a muscle contraction.Benefits from sport EMS systems support the complementary benefits of actual muscle contractions. Click To Tweet
Electrical muscle stimulation, also known as e-stim, is not the same as TENS (transcutaneous electrical nerve stimulation) or microcurrents. Electrotherapy comes in many different forms, and coaches use EMS to contract their athlete’s muscles with as much current as the athlete can tolerate. You can do non-contractile electrotherapy with different units, but the benefits from sport EMS systems support the complementary benefits of actual muscle contractions.
The neurophysiology is very specific with EMS, and confusion still exists over what precisely is going on with the muscle with the application of superficial external current. The contractions from the central nervous system and from EMS have similarities and differences. An electrically induced muscle contraction is not nearly as effective as actual training in developing qualities that athletes need, and while the benefits are small, they are still notable based on the research available. EMS is not a replacement, but an adjunct benefit for those already involved in a quality training program. It’s fair to summarize that without the involvement of conventional training, EMS has severe limitations because it can’t provide more than light comfort during travel or similar.
A nerve cell is “excitable,” meaning it has a discharge ability and, using external electrical impulses from devices, can override the CNS and cause a muscle contraction. Most of the scientific literature discusses the resting membrane potential of muscle, and the stylus of electrical current can change the status of the tissues. In order to induce a contraction, the pulse duration and amplitude of the current must be high enough to overcome the threshold (resting) or the muscle will not contract. The motor units of muscles will respond to electrical current in a different organization than a voluntary contraction. In fact, the contraction pattern is the opposite of a training or natural contraction, and that difference is still under investigation with researchers. Overall, the consensus is that the EMS effects are similar enough to training to deliver benefits, but not to render it a primary solution for health and performance.
From a technology standpoint, the process is rather similar to what was done 100 years earlier, but most coaches, athletes, and medical professionals are investing in its accessibility and convenience. A modern stimulator is basically a battery, a set of electrodes, and enough onboard processing or software to apply current to a muscle. Nothing in terms of technology creates an advantage of one system over another, as most of the differences in units are the programs selected by the companies. Research on current types or specific waveforms is available now for consumers to decide on what is useful and what is likely not valid. When shopping for an e-stim unit, focus most of your attention on the available programs and how they fit your needs with neuromuscular development.
Device Settings, Electrodes, and Waveform Protocols
One area that can frustrate even the experienced physical therapist or physiotherapist is the marketing hype behind therapeutic currents and how they affect patient outcomes. Very little effect, if any, occurs if EMS is used in isolation. Additionally, some research shows that combined treatments are also very limited in effectively changing function and strength in injured subjects.
Most of the marketing arguments for the failure of EMS to deliver results stem from the argument that the right waveform of the current was not used or the general protocol needed to be applied more frequently. In defense, most of the research doesn’t jive with the clinical practices, so a disconnect between science and practice does exist. Still, the specific type of waveforms is often made overly complex to disguise the fact that EMS is a complementary option and not a magic bullet.Very little effect—if any—will occur if you use EMS in isolation. Click To Tweet
Typical device settings are either manual selection of current output or a pre-programmed “recipe” of current characteristics and duration. Manual settings tend to be for professional products where there is an expectation of training and expertise, and programs are common with portable consumer products. Like a volume knob, many devices allow for the use of the same waveform, just enhancing the setting with more current. Most programs are more marketing than science, as it’s popular to create very specific protocols of “speed” or “endurance” with athletes, but most of the research only supports a neuromuscular enhancement or light circulatory benefit for lymphedema or similar.
Most semi-permanent electrodes use snap, pigtail, and pin connectors and need replacing after a few uses or months of use, depending on the quality of the brand. Most of the portable systems use semi-permanent electrodes. The clinical ARP Wave has a reusable set of electrodes and features straps for functional EMS use.
Waveform, or the structure of how electricity travels out of the device, is a very difficult process to understand in just a paragraph. In simple terms, current runs from the battery to the muscle in a structure that resembles a wave, with very specific characteristics. It’s easy to get lost in terminology like voltage, ampere, pulse form, and phase charge. The takeaway is that manipulating the waveform of an electric current will modulate comfort, safety, and its physiological effects.
Marketing text throws around Russian current, DC current, and other terms, but they are simply modifications of the waveform and not major variables to concern yourself with. Inducing current that is tolerable, safe, and broad is enough to create general strength changes and mild contractions that are usually adequate to help facilitate an effect on the lymphatic system. The active pumping mechanism of exercise is far superior to EMS, but some settings done constantly (long durations) with weaker levels of current will provide a small benefit worth doing with athletes.
Advances in Wireless Technology and Design
The most noticeable changes to the EMS market in recent years are the wireless models and the rise of smartphone-guided options. The primary reason for the popularity of wireless is because it allows for freedom of movement by having electrodes and current directly on the body without wires from a device. The new EMS devices are not fully wireless, as the batteries still send current through a small wire to the electrode, but the difference is that the controller sends the information or instructions wirelessly through Bluetooth connectivity.
PowerDot, like many technology companies, realized that the cost of most EMS devices is the controller, and the smartphone could replace most of the expense and development. Instead of building a controller for their EMS unit, PowerDot focused on miniaturizing the battery to fit on the electrode. Compex followed suit.
The portability of EMS units is a primary reason that battery technology is important when considering a device. Because the playing field is rather level, no advantage exists between brands, but overall the battery life is far higher than it was years ago. Every system includes a charging cord or adapter, and the length of charge and recharging rate are typical with comparable products in the consumer technology space. PowerDot is the most portable, followed by the other systems, as they are small enough to fit in a carry-on travel bag without compromising storage.EMS electrode surface size has limited bearing on muscle fiber action. Click To Tweet
The electrodes themselves are very important; however, from a development standpoint, not much has changed besides the gel and adhesive manufacturing process. While the electrodes may be made more cheaply now, they don’t perform much better than they did 20 years ago. The reason for the lack of advancement is the electrodes are semi-disposable and designed to throw away. Some electrodes are manufactured to be cleaned and are more permanent, but conductive gels are messy and not popular with all consumers. The size and shape of the electrodes have no impact on performance, but most of them are just large enough to cover a sizable area to induce a contraction. We should note that not all of the muscle contracts during an EMS session, and electrode surface size has limited bearing on muscle fiber action.
Besides wireless advancements, not much has changed with EMS technology over the last few decades. We can see most of the evolution in the market in the modern styles of the EMS enclosures. The cases of the new controllers are sleeker and the LCD screens are updated to current standards. Generally speaking, the EMS market has not changed in 20 years, save for small incremental adjustments to batteries and subtle visual aesthetics.
Compex: Compex is an international industry leader in medical and sport muscle stimulators. For decades, the company has focused on both the rehabilitation and sport markets, and has pioneered advancements such as the Mi-Sensor, a feature that helps users calibrate the appropriate current setting. The Mi-Sensor uses a combination of accelerometry and the ramping up of current to calculate a chronoaxie, a measurement similar to an optimal threshold for electrotherapy. The Mi-Sensor is not available in the U.S., but you can purchase it in Canada and other countries.
Compex has evolved its higher-end products to include a wireless option that uses a controller and Bluetooth technology to operate the system. The included access to its cloud software enables practitioners to program and monitor client use, and the product is useful for functional approaches to EMS.
Globus: This Italian company is highly successful in the elite sport and aesthetics space, and promotes itself through the programs it delivers with its EMS line. The major influence on the Globus Sport line is Derek Hansen, one of the leading experts in sports training and a specialist in high-performance EMS with teams and elite athletes. Globus has several model options, ranging from aesthetic to professional grade muscle stimulation. None of the systems are wireless, but you can still use them for functional EMS because the length of the wires is sufficient for freedom of movement.
Globus offers the most extensive and precise set of programs, including settings designed to modulate long-term adaptations of the athlete. All of the settings outside of light circulation are highly sensitive to the program design of actual training, and you can find most of the information on periodization online on SimpliFaster or Derek’s website.
Marc Pro: A California-based EMS company focused on recovery, Marc Pro is a strong player in the pro sport and CrossFit markets. The strongest advocate is the sports medicine community that doesn’t use cryotherapy as a modality and favors movement or light muscle contractions. The strongest feature of the product is its enclosure—a gorgeous design that allows for the simplest user experience of all the products. Although it’s not wireless, it’s very portable and has two product models. Marc Pro uses a current setting that favors light circulation and doesn’t have research yet to demonstrate muscle performance. Users are extremely loyal and the system is consumer-priced, with monthly payment plans available.
PowerDot: PowerDot is the newest company on the list. It developed with assistance from a crowdfunding campaign and is a domestic player in the EMS sport space. PowerDot took advantage of smartphone components and focused their resources on the wireless future. Leveraging the smartphone, the PowerDot’s strength is its battery and electrode design, which enables the simultaneous administration of multiple muscle groups. The current settings are similar to Compex, and the product is the smallest and most portable system on the market.
Due to its wireless features and compact design, the PowerDot system is compatible with combined methods of training, specifically functional EMS. In addition to combined strength training and EMS protocols, the PowerDot is extremely useful for travel, as no wires are needed to feed from a controller. The system is also scalable, meaning you can start with one set and expand to more muscle groups with the purchase of additional electrodes.
ARPwave: The last product is the ARPwave, a system popularized by Jay Schroeder in the early 2000s. Recently, the company overhauled their product line by offering a portable and more clinical option. The selling points of the ARPwave are the DC current and its aggressive protocols. Much of the promise from the company is the business model and leasing agreement adopted by clinicians, but ARPwave is not truly a consumer product company.
Other Systems: There are more than 100 products claiming to be muscle stimulators, but most of the units are simply TENS devices. TENS is a current setting that was popular in treating pain, but the present literature is conflicting and most of the recent research shows TENS isn’t a valuable option for the treatment of injury. It does have a sensory response that the user can feel, but most of the results that favor TENS hint at a placebo effect. Sports performance benefits must have current settings that actually stimulate a muscle contraction, and recovery from EMS is yet to be established outside general comfort during post-competition periods.
A simple way to decide what system to buy is to look at the research and what it supports. The basic strength setting used by the Compex system, due to the popularity of the device, demonstrates value in different studies. Beyond that, the science doesn’t support much more than an athlete wellness effect with recovery or, more accurately, mild circulation and possible lymphatic activity. Extreme blockage within the body’s tissues post surgery is clinically popular, and all systems should provide benefit there.
Enterprise Solutions, Mixed Environments, and Final Suggestions
Coaches who make purchasing decisions for teams will want to look at the benefits of keeping technology uniform and weigh support demands with the benefits of having different EMS devices. A mixed environment—one with different models and brands—is perfectly fine with a well-organized team or organization. We recommend you use the model or set of models that fits your needs, and make sure you purchase enough electrodes and replacement batteries. The costs to support the use of existing products are about a quarter to half the cost of the device each year, due to the need to replace electrodes, swap out wires, and refresh batteries.When buying an EMS device, make sure you also buy enough electrodes and replacement batteries. Click To Tweet
Some systems, like the PowerDot and Compex, have enterprise management options that allow for remote monitoring of use and compliance, along with the ability to push a protocol to the athlete from the cloud. ARPwave has similar functions, but most of those are more for simple access of the equipment with settings than true management functions. Individuals may still want to use EMS devices that allow for remote access, as it’s useful to have the organizational benefits of the software and let experts access the information if needed.
Electrical muscle stimulation is a complementary solution for athletes that need a little bit more in their training or rehabilitation. Selecting the right device can be overwhelming at first, but focus on simple needs and try to experiment with a device beforehand by borrowing one from a friend or colleague. Each year, there is a new model released or a refinement made to existing models, and you should only consider upgrading when the benefits will make a difference in your setting.
Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF