Journal of Rehabilitation Research & Development (JRRD)

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Volume 49 Number 2, 2012
   Pages 323 — 332

Matching initial torque with different stimulation parameters influences skeletal muscle fatigue

C. Scott Bickel, PT, PhD;1* Chris M. Gregory, PT, PhD;2 Andres Azuero, PhD3

1Department of Physical Therapy, University of Alabama at Birmingham, Birmingham, AL; 2Ralph H. Johnson Department of Veterans Affairs Medical Center, and Department of Health Sciences and Research, Medical University of South Carolina, Charleston, SC; 3Department of Community Health, Outcomes and Systems, School of Nursing, University of Alabama at Birmingham, Birmingham, AL

Abstract — A fundamental barrier to using electrical stimulation in the clinical setting is an inability to maintain torque production secondary to muscle fatigue. Electrical stimulation parameters are manipulated to influence muscle torque production, and they may also influence fatigability during repetitive stimulation. Our purpose was to determine the response of the quadriceps femoris to three different fatigue protocols using the same initial torque obtained by altering stimulator parameter settings. Participants underwent fatigue protocols in which either pulse frequency (lowHz), pulse duration (lowPD), or voltage (lowV) was manipulated to obtain an initial torque that equaled 25% of maximum voluntary isometric contraction. Muscle soreness was reported on a visual analog scale 48 h after each fatigue test. The lowHz protocol resulted in the least fatigue (25% +/– 14%); the lowPD (50% +/– 13%) and lowV (48% +/– 14%) protocols had similar levels of fatigue. The lowHz protocol resulted in significantly less muscle soreness than the higher frequency protocols. Stimulation protocols that use a lower frequency coupled with long pulse durations and high voltages result in lesser amounts of muscle fatigue and perceived soreness. The identification of optimal stimulation patterns to maximize muscle performance will reduce the effect of muscle fatigue and potentially improve clinical efficacy.

Key words: electrical stimulation, fatigue, frequency, NMES, pulse duration, rehabilitation, skeletal muscle, stimulation parameters, torque, voltage.

View HTML  ¦  View PDF  ¦  Contents Vol. 49, No. 2
This article and any supplementary material should be cited as follows:
Bickel CS, Gregory CM, Azuero A. Matching initial torque with different stimulation parameters influences skeletal muscle fatigue. J Rehabil Res Dev. 2012;49(2): 323–32.

Last Reviewed or Updated  Wednesday, April 4, 2012 12:34 PM

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