Archives of Physical Medicine and Rehabilitation
Volume 89, Issue 5 , Pages 856-864, May 2008

The Effectiveness of Progressively Increasing Stimulation Frequency and Intensity to Maintain Paralyzed Muscle Force During Repetitive Activation in Persons With Spinal Cord Injury

  • Li-Wei Chou, PhD

      Affiliations

    • Biomechanics and Movement Science Program, University of Delaware, Newark, DE
    • ,
  • Samuel C. Lee, PhD

      Affiliations

    • Department of Physical Therapy, University of Delaware, Newark, DE
    • Research Department, Shriners Hospitals for Children, Philadelphia, PA.
    • ,
  • Therese E. Johnston, PhD

      Affiliations

    • Research Department, Shriners Hospitals for Children, Philadelphia, PA.
    • ,
  • Stuart A. Binder-Macleod, PT, PhD

      Affiliations

    • Biomechanics and Movement Science Program, University of Delaware, Newark, DE
    • Department of Physical Therapy, University of Delaware, Newark, DE
    • Corresponding Author InformationReprint requests to Stuart A. Binder-Macleod, PT, PhD, Dept of Physical Therapy, University of Delaware, 301 McKinly Laboratory, Newark, DE 19716

Abstract 

Chou L-W, Lee SC, Johnston TE, Binder-Macleod SA. The effectiveness of progressively increasing stimulation frequency and intensity to maintain paralyzed muscle force during repetitive activation in persons with spinal cord injury.

Objective

To compare the effectiveness of progressively increasing stimulation intensity, progressively increasing frequency, or progressively increasing both frequency and intensity on paralyzed quadriceps femoris muscle force maintenance during repetitive activation.

Design

Factorial design with different stimulation protocols as independent variables.

Setting

A muscle performance laboratory.

Participants

People (N=8) with spinal cord injury (SCI) (age, 14.63±1.77y).

Interventions

Not applicable.

Main Outcome Measure

Number of contractions when the peak force was 90% or more of a subject's maximal twitch force.

Results

The protocol involving progressively increasing stimulation intensity and then frequency generated more successful contractions (189.88±53.33) than progressively increasing the frequency followed by intensity (122.75±26.56 contractions). Regardless of the order, progressively increasing both intensity and frequency generated more successful contractions than progressively increasing intensity (97 contractions) or frequency (62 contractions) alone.

Conclusions

Our findings suggest that during repetitive electric activation, progressively increasing both stimulation frequency and intensity can produce more successful contractions than progressively increasing only frequency or intensity. These findings can help researchers and clinicians design more effective stimulation protocols for persons with SCI during functional electric stimulation applications.

Key Words: Electric stimulation, Rehabilitation, Spinal cord injuries

 

 Supported by the National Institutes of Health (grant no. HD-36379).

 No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.

PII: S0003-9993(08)00111-1

doi:10.1016/j.apmr.2007.10.027

Archives of Physical Medicine and Rehabilitation
Volume 89, Issue 5 , Pages 856-864, May 2008

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