Electro Muscle Stimulation

Electro-Muscle Stimulation, Electro Myostimulation or EMS for short, is a technique to elicit muscle contraction by delivering electric impulses to the muscles. The electric impulses are generated by an electric device and delivered through terminals (i.e. electrodes) to the skin in direct proximity to the muscles to be stimulated. The impulses which mimic the action potential coming from the central nervous system trigger a muscle contraction. The electrodes generally are pads that are made to adhere to the skin. EMS is used for medical therapy and its uses are regulated in the USA by the FDA [ [http://www.fda.gov/cdrh/ode/2246.pdf FDA Guidance Document for Powered Muscle Stimulator] , standard indications for use, page 4: Relaxation of muscle spasms; Prevention or retardation of disuse atrophy; Increasing local blood circulation; Muscle re-education; Immediate post-surgical stimulation of calf muscles to prevent venous thrombosis; Maintaining or increasing range of motion.] . EMS is also used as complementary technique for sport training [Numerous articles in research journals attest increased muscular performance by utilizing EMS; the Journal of Strength and Conditioning Research for instance lists the following articles
* [http://www.nsca-jscr.org/pt/re/jscr/abstract.00124278-200705000-00025.htm;jsessionid=Lh6RYP482GHqG4FzsSLgLTLLL1J2vxLy106cn6WlJNSTyfZYlfVG!2016747336!181195628!8091!-1?index=1&database=ppvovft&results=1&count=10&searchid=1&nav=search Effects of Electrostimulation Training on Muscle Strength and Power of Elite Rugby Players] ;
* [http://www.nsca-jscr.org/pt/re/jscr/abstract.00124278-200308000-00025.htm;jsessionid=Lh6RYP482GHqG4FzsSLgLTLLL1J2vxLy106cn6WlJNSTyfZYlfVG!2016747336!181195628!8091!-1?index=1&database=ppvovft&results=1&count=10&searchid=2&nav=search Effects of Electromyostimulation Training and Volleyball Practice on Jumping Ability.]
* [http://www.nsca-jscr.org/pt/re/jscr/abstract.00124278-199808000-00001.htm;jsessionid=Lh6RYP482GHqG4FzsSLgLTLLL1J2vxLy106cn6WlJNSTyfZYlfVG!2016747336!181195628!8091!-1?index=1&database=ppvovft&results=1&count=10&searchid=2&nav=search Supplemental EMS and Dynamic Weight Training: Effects on Knee Extensor Strength and Vertical Jump of Female College Track & Field Athletes.]
* [http://www.nsca-jscr.org/pt/re/jscr/abstract.00124278-199602000-00008.htm;jsessionid=Lh6RYP482GHqG4FzsSLgLTLLL1J2vxLy106cn6WlJNSTyfZYlfVG!2016747336!181195628!8091!-1?index=1&database=ppvovft&results=1&count=10&searchid=2&nav=search The Effects of Combined Electromyostimulation and Dynamic Muscular Contractions on the Strength of College Basketball Players.] ] .

History

Luigi Galvani (1791) provided the first scientific evidence that current can activate muscle. During the 19th and 20th century researchers studied and documented the exact electrical properties that generate muscle movement. [L. Ranvier, De quelques faits relatifa à l’histologie et à la physiologie des muscles striés,Arch. Physiol. Norm. Path. 6:1–15 (1874).] [D. Denny-Brown, On the nature of postural reflexes, Proc. Roy. Soc. (Biol.) 104:252–301(1929)] It was discovered that the body functions induced by electrical stimulation caused long-term changes in the muscles [A. J. Buller, J. C. Eccles, and R. M. Eccles, Interactions between motoneurones and muscles in respect of the characteristic speeds of their responses, J. Physiol. 150:417–439 (1960).] [D. Pette, M. E. Smith, H. W. Staudte, and G. Vrbová, Effects of long-term electrical stimulationon some contractile and metabolic characteristics of fast rabbit muscle, Pflüger’s Arch.338:257–272 (1973).] . Recent medical physiology research [G. Vrbová, T. Gordon, and R. Jones, Nerve-Muscle Interaction (Chapman & Hall, London, 1995)] [S. Salmons, and G. Vrbová, The influence of activity on some contractile characteristics of mammalian fast and slow muscles, J. Physiol. 201:535–549 (1969)] [D. Pette, and G. Vrbová, What does chronic electrical stimulation teach us about muscle plasticity? Muscle Nerve 22:666–677 (1999)] pinpointed the mechanisms by which electrical stimulation alters cells of muscles, blood vessels [C. G. Blomqvist, and B. Saltin, Cardiovascular adaptations to physical training, Annu. Rev. Physiol. 45:169–189 (1983).] [M. Cabric, H. J. Appell, and A. Resic, Stereological analysis of capillaries in electrostimulated human muscles. Int. J. Sports. Med. 8:327–330 (1987).] [B. A. Harris, The influence of endurance and resistance exercise in muscle capillarisation in the elderly: a review. Acta Physiol. Scand. 185:89–97 (2005).] and nerves.

Theory

EMS causes adaptation, i.e. training, of muscle fibers [Quoted from "National Skeletal Muscle Research Center"; UCSD, [http://muscle.ucsd.edu/musintro/es.shtml Muscle Physiology Home Page - Electrical Stimulation] ] . Because of the characteristics of skeletal muscle fibers, different types of fibers [Skeletal muscleCharacteristics of skeletal muscle fiber types] can be activated to differing degrees by different types of EMS, and the modifications induced depend on the pattern of EMS activity. [S. Salmons and Gerta Vrbová; The influence of activity on some contractile characteristics of mammalian fast and slow muscles; J Physiol. 1969 May; 201(3): 535–549. [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1351409] ] These patterns, referred to as protocols or programs, will cause a different response from contraction of different fiber types. Some programs will improve fatigue resistance, i.e. endurance, others will increase force production [Dirk Pette, Gerta Vrbová; [http://www3.interscience.wiley.com/journal/61500938/abstractWhat does chronic electrical stimulation teach us about muscle plasticity?] ; Muscle & Nerve, May 1999, vol.22 666-677] .

Use

EMS can be used both as a training [N. Babault, G. Cometti, M. Bernardin, M. Pousson, and J. C. Chatard, Effects of electromyostimulation training on muscle strength and power of elite rugby players. J. Strength Cond. Res. 21: 431–437 (2007).] [P. Banerjee, B. Caulfield, L. Crowe, and A. Clark, Prolonged electrical muscle stimulation exercise improves strength and aerobic capacity in healthy sedentary adults, J. Appl. Physiol. 99:2307–2311 (2005).] [J. P. Porcari, J. Miller, K. Cornwell, C. Foster, M. Gibson, K. McLean, and T. Kernozek, The effects of neuromuscular stimulation training on abdominal strength, endurance and selected anthropometric measure, J. Sports Sci. Med. 4:66–75 (2005).] and a therapeutic [D. A. Lake, Neuromuscular electrical stimulation. An overview and its application in the treatment of sports injuries, Sports Med. 13:320–336 (1992).] [A. Delitto, S. J. Rose, J. M. McKowen, R. C. Lehman, J. A. Thomas, and R. A. Shively, Electrical stimulation versus voluntary exercise in strengthening thigh musculature after anterior cruciate ligament surgery, Phys. Ther. 68:660–663 (1988).] tool.

In medicine EMS is used for rehabilitation purposes, for instance in the prevention of disuse muscle atrophy. However, this should not be confused with TENS (Transcutaneous Electrical Nerve Stimulator): the use of electric current in pain therapy.

Because of the effect that strengthened and toned muscles have on appearance (a stronger muscle has larger cross-section [Muscle force is proportional to physiologic cross-sectional area (PCSA)...; quoted from "National Skeletal Muscle Research Center"; UCSD, [http://muscle.ucsd.edu/musintro/arch.shtml Muscle Physiology Home Page - Skeletal Muscle Architecture] , Effect of Muscle Architecture on Muscle Function] ), EMS is also used by a niche of practitioners for aesthetics goals. [W. D. Currier, Effects of electronic stimulation of the VII nerve. On senescent changes of the face, Ann. Otol. Rhinol. Laryngol. 72:289–306 (1963).] [A. A. Al-Majed, C. M. Neumann, T. M. Brushart, and T. Gordon, Brief electrical stimulation promotes the speed and accuracy of motor axonal regeneration, J. Neurosci. 20:2602–2608 (2000).] [M. S. Agren, M. A. Engel, and P. M. Mertz, Collagenase during burn wound healing: influence of a hydrogel dressing and pulsed electrical stimulation, Plast. Reconstr. Surg. 94:518–524 (1994)] . The FDA regularly reject certification of devices that make these claims. The rationale of this rejection is that most manufacturers make claims of fat burning and weight loss. However, EMS devices cause a calorie burning that is marginal at best: calories are burnt in significant amount only when most of the body is involved in physical exercise: several muscles, the heart and the respiratory system are all engaged. This is not the case with EMS in which training is target to few muscular groups at the same time, for specific training goals.

The effectiveness of the devices for these uses has been debated but a few home devices have survived some scientific scrutiny for their advertised uses [http://jssm.uludag.edu.tr/vol4/n1/9/v4n1-9pdf.pdf Effects of Neuromuscular Electrical Stimulation Training on Abdominal Strength, Endurance, and Selected Anthropometric Measures - Journal of Sports Science and Medicine (2005)4,66-75 (pdf)] ] . Since the mid-1990s, wearable units in which EMS circuitry is contained in belt-like garments, neoprene shorts or other clothing items, have been present in the consumer market.

FDA Certification

Only FDA-certified devices can be lawfully sold in the US without medical prescription. These can be found at the corresponding FDA webpage for certified devices [http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPMN/pmn.cfm?start_search=1&Panel=&ProductCode=ngx&KNumber=K&Model=&Applicant=&DeviceName=&Type=&ThirdPartyReviewed=off&ExpeditedReview=&Decision=&DecisionDateFrom=&DecisionDateTo=&IVDProducts=off&PAGENUM=10&SortColumn=DecisionDate%20DESC FDA-Certified Devices] ] . Recently the FTC has cracked down on consumer EMS devices that made unsubstantiated claims [ [http://www.ftc.gov/opa/2002/05/projectabsurd.htm FTC Charges Three Top-selling Electronic Abdominal Exercise Belts with Making False Claims] ] ; most have been removed from the market.

References

External links

* [http://seattletimes.nwsource.com/pacificnw/2002/0526/fitness.html Seattle Times - opinion piece on personal electronic muscle stimulation belts]
* [http://www.healthylivingtoday.net/story47.php John Porcari @ University of Wisconsin-La Crosse next plans to study ems buttocks and thigh toners]