Force Optimization of Skeletal Muscle (Grant # HD-41254)



Electrical stimulation of skeletal muscle can be used to assist individuals paralyzed due to central nervous system dysfunction to perform functional movements.  Muscle fatigue, however, is a major limitation in the practical use of this approach.  Previous work has shown that patterns of activation using variable-frequency trains (VFT’s) that exploit the catch-like property of skeletal muscle produce greater forces than traditionally used constant-frequency trains (CFT’s), particularly in fatigued muscle.  The proposed studies will extend these previous findings and will provide information that is needed to identify stimulation patterns that maximize force and minimize fatigue under a variety of physiological conditions.  The overall goal of this work is to enhance our understanding of the factors that affect the force responses of skeletal muscle to electrical stimulation using brief trains of pulses.


The long-term goal of these studies is to contribute to the development of techniques and hardware that improve the usefulness of FES.  The immediate goal of this study is to determine the stimulation frequencies and patterns both within and across trains that maximize performance during repetitive electrically elicited contractions of muscles from subjects with spinal cord injuries.  A combination of experimental and modeling work is proposed to attack this problem.  


          Specific Aim 1 attempts to extend our understanding of variable-frequency train stimulation to include its effect on the forces and fatigue produced from muscles of subjects with spinal cord injuries (SCI).  



          Specific Aim 2 continues the development and testing of mathematical models that predict the force output and fatigue produced in response to a wide range of stimulation frequencies and patterns. 


These models will allow us to identify the stimulation frequencies and patterns that optimize any aspect(s) of the muscle’s response that we determine to be important and will predict the “optimal activation pattern” for individual subjects based on their responses to a brief period of testing.  Both of these aims include the study of isometric and non-isometric contractions.



Link to relevant publications

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Last Updated 1/14/2005