September 2, 2008

MUSCLE TONING WITH ELECTRICAL STIMULATION^©

Lyn Paul Taylor, A.A., B.A., M.A., R.P.T.

(Editing Assistant and Computer Consultant: Joanna Soon, B.S.)

Research has confirmed that electrical stimulation, if appropriately applied, may be used to effectively increase tone, strengthen muscle, improve endurance, and increase the size of innervated muscle.  Electrical stimulation has not been shown to be superior to traditional forms of voluntary exercise, for building tone and strength.  Nevertheless, several studies have shown electrical stimulation to be nearly as effective.  In fact, some research has demonstrated that high voltage pulsed electrical stimulation of at least 30 hertz (Hz) may be used to cause involuntary isometric muscular contraction (tetany against resistance) without causing the stress to the cardiovascular system associated with voluntary exercise.  Both isometric and isotonic exercise cause increases in heart rate and blood pressures as a normal consequence of voluntary exertion.

Review of the literature suggests that more study is needed to establish which types of electrical stimulation are most effective for increasing muscle tone and strength and which methods of application are most efficient.  In addition, more study is necessary to establish which types of muscle fibers (fast or slow twitch) will respond best to electrical stimulation.  Muscle toning with electrical stimulation seems to be most effectively accomplished by electrical stimulation units capable of producing currents strong enough to produce tetany (or near-tetany) while being fairly comfortable for the patient.  Such stimulation units generally provide a duty cycle of 10 to 15-seconds on and 10 to 50-seconds off.  Such stimulation is usually best provided by a high voltage, high frequency (medium frequency) unit.

Application:

• To tone muscle with electrical stimulation, the best results seem to come from putting the muscle or muscle group on stretch and fixing the involved joint in place to prohibit them from moving in response to provoked contractions (i.e., an isometric contraction).  The electrodes should be placed over the muscle or muscle group to be stimulated in a bipolar fashion (both the negative and the positive electrode over the same muscle or muscle group).  The negative electrode should be placed over the dominant muscle's motor point, and the positive electrode placed elsewhere on the same muscle or muscle group.

• The electrical stimulator should be turned on and the intensity slowly increased until a visible contraction develops.  As the patient gets used to the stimulation (shows signs of relaxing), the current should be gradually increased until tetany or near-tetany is produced.

• Stimulation should continue for 10 to 15 minutes.  A duty cycle of 10-seconds on and 10-seconds off should be used to produce maximum toning, if that option is available.  Treatment may occur daily, but suitable results have come from treatments every other day or twice a week.

Muscle toning with electrical stimulation has been shown to be remarkably effective for retrieving muscle tone lost as a secondary effect of long term inflammatory conditions (chronic tennis elbow or debilitating knee or ankle ailments) or disuse from prolonged bed rest.  If the electrical stimulation is applied correctly and appropriately, muscle strength can be improved without any risk of reinflaming the previously involved soft tissues through strain, which is often a consequence of voluntary exercise.

References:

G. Alon, "High Voltage Stimulation," Physical Therapy, 65:6, June 1985. Pp. 890-895

L.L. Baker, K. Parker and D. Sanderson, "Neuromuscular Electrical Stimulation for the Head-Injured Patient," Physical Therapy, 63:12, December 1983. Pp. 1967-1974

L.L. Baker, C. Yeh, D. Wilson and R.L. Waters, "Electrical Stimulation of Wrist and Fingers for Hemiplegic Patients," Physical Therapy, 59:12, December 1979. Pp. 1495-1506

U. Bogataj, N. Gros, M. Malezic, B. Kelih, M. Kljajic, R. Acimovic, "Restoration of Gait During Two to Three Weeks of Therapy with Multichannel Electrical Stimulation," Physical Therapy, 69:5, May 1989. Pp. 319-327

D.P. Currier, J. Lehman and P. Lightfoot, "Electrical Stimulation in Exercise of the Quadriceps Femoris Muscle," Physical Therapy, 59:12, December 1979. Pp. 1508-1512

D.P. Currier and R. Mann, "Pain Complaint: Comparison of Electrical Stimulation with Conventional Isometric Exercise," The Journal of Orthopaedic and Sports Physical Therapy, 5:6, 1984. Pp. 318-323

D.P. Currier and R. Mann, "Muscular Strength Development by Electrical Stimulation in Healthy Individuals," Physical Therapy, 63:6, June 1983. Pp. 915-921

A. Delitto, J.M. McKowen, J.A. McCarthy, R.A. Shively and S.J. Rose, "Electrically Elicited Co-contraction of Thigh Musculature After Anterior Cruciate Ligament Surgery," Physical Therapy, 68:1, January 1988. Pp. 45-50

A. Delitto, J.M. McKowen, J.A. McCarthy, R.A. Shively, S.J. Rose, "Electrically Elicited Co-Contraction of Thigh Musculature After Anterior Cruciate Ligament Surgery," Physical Therapy, 68:1, January 1988. Pp. 45-50

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A. Delitto and S.J. Rose, "Comparative Comfort of Three Waveforms Used in Electrically Eliciting Quadriceps Femoris Muscle Contractions," Physical Therapy, 66:11, November 1986. Pp. 1704-1707

L.F. Eckerson and J. Axelgaard, "Lateral Electrical Surface Stimulation as an Alternative To Bracing in the Treatment of Idiopathic Scoliosis," Physical Therapy, 64:4, April 1984. Pp. 483-490

C.B. Killian, "Electrical Stimulation Overview Introduction to High Frequency Stimulation," Presented at a Combined Section Meeting in Orlando, Florida, February 1985. [Reprint available from Mr. Clyde Killian, Department of Physical Therapy, 1400 East Hanna Avenue, Indianapolis, In., 46227.]

J. Kleinkort, Isoelectronic Rehabilitation Program, Dynatronics Research Corporation, Salt Lake City, U., 1986.

J.F. Kramer, "Effect of Electrical Stimulation Current Frequencies on Isometric Knee Extension Torque," Physical Therapy, 67:1, January 1987. Pp. 31-38

J. Kramer, D. Lindsay, D. Magee, S. Mendryk, and T. Wall, "Comparison of Voluntary and Electrical Stimulation Contraction Torques,” Journal of Orthopaedic and Sports Medicine Physical Therapy, 5:6, May/June, 1984. Pp. 324-331

R.K. Laughman, J.W. Youdas, T.R. Garrett, and E.Y.S. Chao, "Strength Changes in the Normal Quadriceps Femoris Muscle as a Result of Electrical Stimulation," Physical Therapy, 63:4, April 1983. Pp. 494-499

R.L. Lieber, M.J. Kelly, "Factors Influencing Quadriceps Femoris Muscle Torque Using Transcutaneous Neuromuscular Electrical Stimulation," Physical Therapy, 71:10, October 1991. Pp. 715-723

T. Mohr, B. Carlson, C. Sulentic and R. Landry, "Comparison of Isometric Exercise and High Volt Galvanic Stimulation on Quadriceps Femoris Muscle Strength," Physical Therapy, 65:5, May 1985. Pp. 606-609

A.J. Nitz and J.J. Dobner, "High Intensity Electrical Stimulation Effect on Thigh Musculature During Immobilization for Knee Sprain," Physical Therapy, 67-2, February 1987. Pp. 219-222

J. Owens and T. Malone, "Treatment Parameters of High Frequency Electrical Stimulation as Established on the Electro-Stim 180," Journal of Orthopaedic and Sports Physical Therapy, 4:3, 1983. Pp. 162-168

R. Packman-Braun, "Relationship Between Functional Electrical Stimulation Duty Cycle and Fatigue in Wrist Extensor Muscles of Patients with Hemiparesis," Physical Therapy, 68:1, January 1988. Pp. 51-56

C.A. Phillips, "Functional Electrical Stimulation and Lower Extremity Bracing for Ambulation Exercise of the Spinal Cord Injured Individual: A Medically Prescribed System," Physical Therapy, 69:10, October 1989. Pp. 842-849

D.M. Selkowitz, "Improvement in Isometric Strength of the Quadriceps Femoris Muscle After Training with Electrical Stimulation," Physical Therapy, 65:2, February 1985. Pp. 186-195

C-L. Soo, D.P. Currier and A.J. Threlkeld, "Augmenting Voluntary Torque of Healthy Muscle by Optimization of Electrical Stimulation," Physical Therapy, 68:3, March 1988. Pp. 333-337

L.P. Taylor, T. Hui, The Taylor Technique of Soft Tissue Management, Inflammation: Evaluation & Treatment, 2002.  Pp. 73-74

M.H. Trimble, R.M. Enoka, "Mechanisms Underlying the Training Effects Associated with Neuromuscular Electrical Stimulation," Physical Therapy, 71:4,  April 1991. Pp. 273-282

D.J. Twist, "Acrocyanosis in a Spinal Cord Injured Patient-Effects of Computer-Controlled Neuromuscular Electrical Stimulation: A Case Report," Physical Therapy, 70:1, January 1990. Pp. 45-49

Y. Urabe, "Strengthening the Quadriceps Femoris by Electrical Stimulation," Physical Therapy, 66:2, February 1986. p. 283

D.C. Walker, D.P. Currier and A.J. Threlkeld, "Effects of High Voltage Pulsed Electrical Stimulation on Blood Flow," Physical Therapy, 68:4, April 1988. Pp. 481-485

R.P. Walmsey, G. Letts, and J. Vooys, "A Comparison of Torque Generated by Knee Extension with a Maximal Voluntary Muscle Contraction vis-à-vis Electrical Stimulation," Journal of Orthopaedic and Sports Medicine Physical Therapy, 6:1, July/August, 1984. Pp. 10-17

R.A. Wong, "High Voltage Versus Low Voltage Electrical Stimulation, Physical Therapy, 66:8, August 1986. 1209-1214

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