Electronic Muscle Stimulation for Strength, Athletic Performance and Recovery

Click here for more information on Electrical Muscle Stimulation

– Derek M. Hansen –

This article will be one of many on the topic of Electronic Muscle Stimulation (EMS) and related topics on electrotherapy and electrophysiology. It provides a general overview on the applications and benefits of electro-therapy devices. Future articles will delve further into the specific protocols for performance enhancement, injury management and recovery.

 

I’ve spent the better part of the last 12 years experimenting with EMS on myself and various speed athletes I’ve coached. My very first personal experience with EMS technology was back in 1986, when I severely sprained my ankle during a basketball game and the physiotherapist was trying to aid muscle re-education by stimulating my soleus muscles just above the ankle. Needless to say, it was an electrifying experience, with the muscle contracting to a point where it felt like an extraordinary cramp. And, the fact that you knew it was going to happen every 30 seconds for 6 seconds of contraction time was a little nerve racking. A small set of LED’s would either glow green for “ON” or red for “OFF” – much more intense than waiting for a traffic signal to turn green. I still vividly remember that first experience.

My own electronic muscle stimulation experimentation started with a small EMS unit that only allowed 1-10 seconds of contraction, with a fixed three second recovery. It also had a TENS (transcutaneous electrical nerve stimulation) function that permitted pulsing and tapping sensations in the muscle. The unit was promoted with a 1981 article by Charlie Francis, and a photo of Bruce Lee with the EMS pads strapped to his shoulders, biceps and pectoral muscles. Seeing that both of these individuals were inspirations to me, it was an easy sell and I purchased the unit for my own home-lab experiments.

 

Benefits of EMS Technology

When I had that first EMS treatment back in 1986, it was clear to me that something profound was happening. As a kid, I had the periodic “finger in the light socket experience” where you would get zapped and classical conditioning finally kicks in. However, once you experience direct stimulation on a large muscle group, you will feel a magnitude of contraction that you normally could not experience through voluntary means. From the standpoint of lifting a weight, a larger load typically means greater recruitment, leading to greater adaptation (i.e. greater maximal strength). Accordingly, one should expect a greater contraction through EMS to result in greater maximal strength abilities as well. Although this benefit of EMS is not readily known by the sporting and fitness public, it is well supported by research and practice.

Strengthening

Electronic muscle stimulation can strategically target specific muscles for isolated strengthening. Careful placement of adhesive electrodes can determine not only which muscle or muscles are to be recruited, but also how well these muscles are recruited. EMS used on glutes, hamstrings and calves can help with stride extension and power for running, while work on the quadriceps can assist with eccentric strength and reduce ground contact times. EMS has also been used for strengthening the bottom of the feet.

While EMS targets specific muscles isometrically, it must be combined with regular sprinting and running to allow for the gains in raw strength to be converted to coordinated strength and power. Studies have also show that there is a lag in adaptive response – with full gains in strength not realized until four to six weeks after an EMS training block has been concluded. It is important to note that the best results are realized under conditions of significant contraction – which can be quite uncomfortable, bordering on excruciating. It may take several sessions for an individual to get to a point where they can tolerate the higher levels of stimulation required for significant strength adaptation.

Muscle Re-Education and Atrophy Reduction

In cases where an injury has been incurred and an athlete must accelerate strengthening or off-set muscle atrophy, EMS can play an important role. This is very common when a joint injury occurs, the limb cannot be used and muscles are not being worked normally. A foot or ankle injury is a perfect example of this application. The EMS unit can be used to work quads, hamstrings, glutes and calves when the athlete cannot properly walk or run for the initial stages of rehabilitation. For the athlete that sprains their ankle or knee in the latter stages of their training cycle, EMS can help to maintain muscle strength until you are ready to resume conventional training.

Pain Management

Through the use of transcutaneous electrical nerve stimulation (TENS) and similar methods of electrotherapy, athletes can benefit from an analgesic effect to manage pain and discomfort. TENS selectively activates large diameter Type A nerve fibers without activating smaller diameter A and C (pain-related) nerve fibers or nerves that innervate muscle. It is often referred to as sensory-level stimulation – where stimulation occurs at or above the sensory threshold, but below the motor threshold. The level of current is determined by the perception of the patient, where current is increased until the patient feels a tingling sensation or “pins and needles” feeling. The mechanism of pain control is most likely either a block of pain transmission or activation of central inhibition of pain transmission by large-diameter nerve fiber stimulation.

Interferential current (IC) was developed by Dr. Hans Nemec in Vienna in the 1950s and became a popular method of electrotherapy in the 1970s. IC involves alternating medium frequency currents at approximately 4000 Hz in an effort to reduce skin resistance and discomfort. The theoretical mechanisms of pain control through IC is similar to that of conventional TENS therapy, including sensory-level stimulation and physiological block of nerve conduction. Others have also claimed that IC improves circulation and reduces swelling.

Circulation Enhancement and Massage

Use of low frequency electric currents have been used to induce a gentle pulsing of the muscle to physically increase circulation, thereby enhancing blood flow to the treatment area and remove waste products and fluid (venous and lymphatic systems). If you examine the treatment area, you would be able to see the muscle pulsing – unlike EMS for muscle strengthening, where you would see the muscle hold a contraction for anywhere from 3 to 10 seconds. For athletes who cannot access regular massage, EMS can be a useful means to achieve a flushing massage for specific areas of the body. It also can be very useful in cases where athletes have to travel regularly and are sitting for long periods of time in a car, on a bus or during a flight. This form of stimulation can also be used for warm-up routines (in cases where conventional warm-up cannot be implemented) and combined with harder contractions to create a potentiation program enhancing muscle readiness for high intensity work.

Reduction of Muscle Spasm

In 1997, I sustained a whiplash injury in a motor vehicle accident which has created problems for me ever since. Numerous times throughout the year I will experience a massive spasm in the muscles around the upper thoracic and cervical areas of my back. Historically, it has taken four to five days for the muscles to settle down, with normal range of motion in my neck returning in 5-6 days. In the last few years, I have been using my Compex muscle stim unit to help reduce recovery times from spasm. The Compex unit has a pre-programmed selection called “Cramp Prevention” that lasts 30-40 minutes in duration. This program helps to settle down the spasm in 1-3 days and restore range of motion in my neck in 2-3 days. The program consists of a series of low frequency pulsing cycles that work the muscles to bring down muscle tone. In essence, the program sequentially fatigues the spastic muscles – bringing down muscle tone – in a comfortable manner using a range of frequencies and pulse widths. When used alone or in combination with conventional massage, you can effect much quicker recoveries from cases of spasticity using strategically programmed electronic muscle stimulation.

Soft-Tissue Regeneration, Wound Recovery and Bone Healing

The use of direct current (DC) stimulation for the healing of tissue is based on the concept that it can enhance the naturally occurring DC potentials associated with natural repair, thereby stimulating the healing process. It has been postulated that living tissue possesses DC electro-potentials that regulate the healing process. When tissue damage occurs, the injury creates a current that triggers the body to biologically repair itself. Studies in both humans and animals have shown that electrical stimulation can actually enhance wound healing. In cases where wounds have shown to be chronic and/or have not healed within the expected time frame, it has been suggested that normal electro-biological healing processes have been arrested. The use of external electro-stimulation of such wounds theoretically produces a series of events which ‘jump-start’ the normal healing process.

Work by Robert Becker suggests that bioelectrical activity occurs throughout the body in a complex field that is closely related to the distribution of the central and peripheral nervous systems. Localized injuries, as well as disease, are thought to lead to a disturbance of this whole-body bioelectrical system, acting as a stimulus for the regeneration and repair process.

It has also been long reported that electrical stimulation can be used to enhance bone healing. When external forces are placed on bone, an electrical potential is generated. Negative electrical potentials have been recorded at fracture sites, which is in line with the “current of injury” theory proposed by Becker. Fukada and Yasuda suggested that the induced electrical potentials at the cathode (negative electrode) triggered the body’s piezoelectrical potentials, which enhance bone repair and growth. Although regarded with skepticism by many in the medical field, there is abundant evidence from clinical studies of the effectiveness of electrical stimulation for bone healing.

 

Conclusions and Implications

The exact mechanisms by which electrical stimulation enhances strength, circulation, muscle tone reduction, regeneration and recovery are still not clearly understood. It is obvious to me – through my personal experiences and discussions with peers – that there is significant value in working with EMS in coordination with other methods of training and recovery. And, I will continue to work with EMS in an effort to determine a coordinated approach to training and rehabilitating athletes. There is amazing “potential” for this technology that I look forward to discovering.

There are several choices in the marketplace for consumers who would like to purchase their own EMS device. In a future article on EMS, I will review a specific EMS device to give my personal opinion on its suitability for both athletes and coaches. I will also devote some time to looking at specific cases where EMS is appropriate, and the protocols required to maximize the effectiveness of this tool.

 

References

Dehail, P., C. Duclos and M. Barat. Electrical Stimulation and Muscle Strength. Annales de Readaptation et de Medecine Physique. 2008, 15: 441-451.

Kitchen, Sheila. Electrotherapy: Evidence-Based Practice. Churchill-Livingstone, 2002, London.

Nalty, Theresa. Electrotherapy: Clinical Procedures Manual. McGraw Hill, 2001, New York.

Maffiuletti NA, Zory R, Miotti D, Pellegrino MA, Jubeau M, Bottinelli R. Neuromuscular
Adaptations to Electrostimulation Resistance Training.
Am J Phys Med Rehabil. 2006, 85: 167–175.

Robinson, A.J. and Lynn Snyder-Mackler. Clinical Electrophysiology. Williams & Wilkins, 1995, Baltimore.

Siff, Mel. Applications of Electrostimulation in Physical Conditioning: A Review. Journal of Applied Sports Science Research. 1990, Volume 4, No. 1, pp. 20-26.

 

Available Consumer EMS Units

Compex Sport Electronic Muscle Stimulator

Compex Sport is designed for the serious athletes in support of their normal training regimes. The Compex Sport has five levels of progression and four channels for complete body training sessions. The six programs include Resistance, Endurance, Strength, Explosive Strength, Potentiation and Active Recovery. Thus, the Compex Sport can serve as your personal coach, massage therapist and rehabilitation specialist.

This type of electrical impulse muscle stimulation equipment has been used successfully in physical medicine for many years. Compex produces professional, top quality, muscle contraction training equipment. The included CD-ROM based Training Planner details each stage of the work out and helps to create a truly individualized training program. Whether you are a track and field athlete, basketball player, football player, cyclist or recreational runner, Compex Sport fits the athlete and fits their sport!

 

Compex Fitness Electronic Muscle Stimulator

The Compex Fitness electronic muscle stimulator is designed for is for individuals interested in building muscles, toning and shaping to improve general physical fitness. The Compex Fitness Trainer includes two training programs and one special program. Electronic muscle stimulation is effective for muscle and fitness training and well as muscle rehabilitation.

The Endurance program helps you cope with long-duration aerobic activities and increases muscle resistance to fatigue by building slow-twitch muscle fibers. The Resistance program provides an all-around program for endurance and strength, building both slow-twitch and fast-twitch muscle fibers. Finally, the Active Recovery program facilitates relaxation of muscles and reduces muscle soreness and stiffness following competition or demanding workouts.

This type of electrical impulse muscle stimulation equipment has been used successfully in physical medicine for many years. Compex produces professional, top quality, muscle contraction training equipment. The included CD-ROM based Training Planner details each stage of the work out and helps to create a truly individualized training program.

 

Compex Replacement Set of Electrode Wires and Replacement Electrodes

Also available are Compex brand accessories such as extra lead wires and replacement sticky pads, in both small and large sizes.

Globus Premium Sport Electronic Muscle Stimulator

The Globus Premium Sport Electronic Muscle Stimulator programs enhance Maximum Strength, Explosive Strength, Resistance and Reactivity of elite athletes. By stimulating the specific muscles needed for different sports, the Globus Premium Sport can supplement the training of every athlete. Sport programs include:

  • Maximum Strength
  • Resistance Strength
  • Explosive Strength
  • Reactivity
  • Aerobic Resistance
  • Active Recovery
  • Preparation (similar to Potentiation)
  • Basic Training

The Globus Premium Sport Electronic Muscle Stimulator has ten distinct libraries specifically conceived for the following sports: Football, Baseball & Softball, Basketball, Running, Tennis, Cycling, Golf, Sprinting, Cross-Country skiing and Downhill skiing. The training libraries include Conditioning and Maintenance programs. The Conditioning programs help athletes reach peak condition. During competitive periods athletes will then switch to the Maintenance programs to maintain the peak condition without unnecessary fatigue.

Globus Premium Fitness Electronic Muscle Stimulator

The Globus Premium Fitness Electronic Muscle Stimulator model includes fitness programs developed by coaches and personal trainers to improve your physical shape through electro-stimulation: balancing your strength, developing your resistance, preparing for exercise, recovering from exercise, as well as recoving from muscular fatigue.

The Globus Premium Fitness Electronic Muscle Stimulator with its jogging, basic training, aerobic resistance, active recovery and preparation programs, help develop your physique, and charge you full of energy. Total programs include:

  • Aerobic Resistance
  • Active Recovery
  • Preparation (similar to Potentiation)
  • Basic Training

The Globus Premium Fitness Electronic Muscle Stimulator will take care of your wellness and will help eliminate daily fatigue and stress.

Globus Replacement Set of Electrode Wires and Replacement Electrodes

Also available are Globus brand accessories such as extra lead wires and replacement sticky pads, in both small and large sizes.

>> Click here for accessories

>> Click here for 3 free ebooks on Electrical Muscle Stimulators

Comments

  1. Great article,

    So many devices to choose from!!
    Maybe you can help. I had few knee surgeries, and I have quite a bit of muscle atrophy in my left quad. I been doing my best trying to recover but I feel I need some extra help ( I’m into bodybuilding and I am so close to doing a show, but first I need to fix up my leg).
    I see there are few of the devices that are in the comments (Compex, Cefar and Globus, stimrx, and Therastim).
    There is also few different techniques EMS, russian stim and TENS.
    Is there any one that you would recommend for muscle recovery/building?

    Thanks, Robert.
    If there is a way to contact you to get a detail answer that would be great.

  2. Hi, what would you recommend to use to build up my leg/hip muscles to help support the hip bones. I am not ready for a hip replacement yet and want to know i this will help.

    • The Compex and/or Globus models will have a number of programs that would help with both strengthening, pain management and massage/spasm reduction. They would be very useful for delaying the need for hip replacement and keeping your musculature strengthened, as well as increasing circulation in the area.

  3. Which one would be better or my condition…Compex sport or Fitness or Globus sport or fitness units?
    Thanks
    Dave

  4. Is an EMS safe for someone with Multiple Sclerosis? Due to a rough relapse I was unable to walk for over 4here months. I have overcome that only to realize how rapid atrophy of the muscles happens. I am terrified of the gym. My balance is terrible so exercise is such a struggle. If I could strengthen my muscles again I know I could recover and feel confident again.
    MELISA

  5. Derek, I am very grateful to you for your website and for the informative response to my question. I ordered the EMS today! I am still nervous about placement for my specific needs. The article you posted mentioned the ankle and balance. I finally feel like I have hope again! Thanks again, gods blessings to you!

    • Melisa. As everyone is different in their responses to EMS training, you may have to experiment a bit. SImply start at lower intensities and build up over time – no different than an exercise program. I’m confident you will find some benefit, whether through strengthening or spasticity reduction. Best of luck and please keep us informed of your progress.

      • Derek,

        Can you please point me to EMS instructions/guidelines for electrode placement, waveform, pulse width and rates, and contraction, relaxation, and ramp times for strengthening quads.  Mine are atrophied 1 1/4″ from herniated disk (now fused) nerve damage.  

        My PT has been less than satisfactory and, while I am hoping to get a prescription for PT at a hospital (Shepherd Spine Clinic-Atlanta), I want a point of reference for discussion with them and my surgeon. My Physical Therapist never mentioned or put me on a leg extender weight machine, which i am told is the best quad builder.  He did perform weekly EMS sessions which, along with trigger point therapy did help, but he never suggested getting an EMS machine for home use.

        Thanks for any help you can provide. I also sent you a duplicate email.
        Robert

  6. Derek,
    I noticed that the website you provided for purchasing Compex and Cefar units no longer sells the Cefar, which was in my price range.($200 )

    Can you recommend a unit comparable to that Cefar which is no more than $300? (By the way, is Cefar no longer manufactured?)

    Thank you!
    Marci

  7. Hi Derek,

    I was looking to get the Compex Physio 5 stim, because it has a denervation mode. Seems like its not available in the US. Do you know of any distributors I can contact?

    Thanks,

    Dean

    • Dean – You probably have to contact the European division of Compex directly. Because of FDA regulations, only certain models of stims are approved for distribution in the U.S. Have you heard any specific information regarding the denervation mode?

  8. That’s what I thought. I found a few distributors in the UK willing to ship to the US. I would have prefered to buy within the US, but I guess thats not possible. I downloaded the manual for the Physio 5 and the Compex 3 Pro. These 2 units have a denervation mode – but the Physioi 5 is much cheaper. There are 2 Denervation wavelength settings: triangular and rectangular. And these settings have long pulse widths (as opposed to the standard short pulses that contract healthy muscle). From their manuals and reading I’ve done elsewhere (such as Kern’s FES study’s) – a long pulse (around 100ms) can excite and contract a muscle without a nerve supply. The shorter pulses can only contract a muscle by stimulating its nerves.

    The triangular wave pattern is preferred for partial denervation (as in my case, i have a portion of my pec that is denervated, but most of it is innervated). The rectangular wave pattern is better for a fully denervated muscle.

    I’m attempting to completely reverse the atrophy in my pec, based on Kern’s study: http://www.rehab.research.va.gov/jour/05/42/3suppl1/pdf/kern.pdf – this study has biopsies of completely denervated muscle that have been stimulated for several years. The results where almost 100% regeneration of myofibers (long term atrophy usually results in a muscle that is 20% myofibers, and the rest is adipocytes, connective tissue, and collagen). The unit used by Kern had 200mA. The strongest commercially available units today have around 120mA.

  9. Dave could you please reference the study that says a triangular waveform is better than a rectangular waveform for denervated muscles?

  10. Dean (sorry for writing Dave before),
    We actually have a model we sell in Europe with denervated currents, and a diagnostic mode to be able to measure progress in terms of chronaxie and rheobase. Contact me, and I may be able to let you test one.

  11. Hi Giovannie,

    Don’t worry, I knew what you meant. :)

    I learned about triangular wavelengths from the following book: Electrotherapy Explained, Principles and practice (Low, Reed).

    Exerp from the book:

    Long duration (of 1 ms or more) -
    Rectangular wave pulses: These are pulses of any duration between I and 600 ms separated by pulse intervals of anything from 1 ms to several seconds (Fig. 3.2 and Fig. 3.4). Such pulses can stimulate motor and sensory nerves and can be used to stimulate denervated muscle.

    Accommodation pulses: Triangular, trapezoidal, sawtooth, serrate, slowrising, shaped, selective and accommodation pulses are all synonymous terms. Again, these are relatively long-duration pulses, usually 300 to 1000 ms, separated by pulse intervals of one-half to several seconds (Fig. 3.4). These pulses are used to stimulate muscle (as opposed to nerve) tissue selectively and they are able to do so because of differences in muscle and nerve accommodation, hence the names (see Chapter 1).

    A terrific explanation based on the above book can be found here: http://denervatedmuscle.blogspot.com/2011/04/why-was-rectangle-jealous-of-triangle.html

    RISE 2 Italy – Project (Kern, et al) used a triangular waves (mentioned in abstract). Full study:
    http://www.bio.unipd.it/bam/PDF/19-4/Masiero.pdf

    Are you referring to the Globus Genesy 3000? I’d like to discuss with you – how can I contact you?

    Thank you,

    Dean

    • Dean,
      Please allow me to disagree on the explanation by the blogspot. I found it very unclear. The fact that it uses a lot of electrophysiology jargon doesn’t make an explanation good. Second, the books that are referenced to support the explanation in the blog are two standard textbooks. I’ve not read the UK textbook by I’ve read the 2nd more recent US textbook: Robinson AJ, Snyder-Mackler L. Clinical Electrophysiology: Electrotherapy and Electrophysiologic Testing. Third ed. Lippincott Williams & Wilkins; 2008.

      These are books that are rich in support of standard accepted theories, but that are a little thin on more recent stuff. Electrophysiology is a relatively young science that still has a lot to discover, and some concepts explained in the above book have been disproved by peer-reviewed research of the last 5 years. In the few relevant pages of which I have a Xerox copy, I couldn’t find anything supporting the superiority of triangular waveforms over rectangular waveforms for denervated muscles. The only valid principle presented is that of accommodation. I will borrow this textbook again from my local University and dig further into denervated research.

      However, just browsing the most recent research by the same researchers* that you also mentioned, one can immediately see that the studies that produced results all had rectangular waveforms.

      Note*:
      1. Kern H, Hofer C, Mödlin M, et al. Denervated muscles in humans: limitations and problems of currently used functional electrical stimulation training protocols. Artif Organs. 2002;26(3):216–218.
      2. Mödlin M, Forstner C, Hofer C, et al. Electrical stimulation of denervated muscles: first results of a clinical study. Artif Organs. 2005;29(3):203–206.
      3. Helmut Kern, Christian Hofer, Christian Hofer, et al. Functional electrical stimulation of denervated muscles: Clinical improvements. Basic Appl Myol. 2006;16(3-4):97–99.
      4. Kern. Muscle biopsies show that FES of denervated muscles reverses human muscle degeneration from permanent spinal motoneuron lesion. Journal of Rehabilitation research & Development. 2005;42(3):43–54.

      • Hey Giovanni – thanks for the great info. Please feel free to point out any contradictions – I’m not versed in electrotheraphy enough to spot errors. You’re right, much of Kern’s work used rectangular waves.

        However in Kern’s study I referenced above: http://www.bio.unipd.it/bam/PDF/19-4/Masiero.pdf, “triangular waves 150-200 msec long at 20-80 mAmp” were used.

        And from http://www.yorku.ca/lsergio/6150/Kern_FES_SCI.pdf, “The output stage provides four different charge-balanced impulse forms (1 biphasic rectangular or 3 biphasic triangular).”

        This certainly does not prove the superiority of triangular waves, I’m just pointing out that they were used. It looks like either will work (one may be better than the other), and that the main factor is a long pulse width.

        Thank you for your time and effort.

        Dean

      • I went through the textbook I referenced before. Unfortunately my local University has only the 1995 edition, but it’s interesting to note that there is no mention whatsoever of electrical stimulation for denervated muscles. Please note that this textbook is authored by very important names, which one can find behind very important research on EMS from the 80′s through the 2000.

        In my opinion this underlines the fact that in the field of electrical stimulation for denervated muscles we are very much at the beginning of the discoveries. One researcher uses one type of waveform and obtains result X, another tries with a different type obtaining result Y. Non one is certain as to what causes the difference: only hypothesis. Then by serendipity somebody, researcher or practitioner will hit on some effect that will point to the right theory reconciling the differences. Armed with that theory somebody will finally be able to optimize the parameters for the best outcome in the patient.

  12. Very good points Giovanni!

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