Paul J. Roby

Abstract

A kinesiological electromyographic study was completed to determine the relative changes in muscle activity as a person walks and stands with different degrees of knee flexion deformity. The ultimate aim was to establish criteria for appropriate preventive and corrective measures relating to knee flexion deformity.

Six different muscles were implanted with wire electrodes. The subjects performed a series of walking and standing experiments with the knee flexed at selected angles by a locking leg brace to simulate knee flexion deformity. The electromyographic action potentials were monitored by analog tapes, oscilloscopes and closed circuit television. The analog tapes were displayed on a visicorder printout chart for analysis.

Evidence is presented to support the view that action potential counts are related to muscle tension.

To eliminate the variabilities due to individual differences and to electrode placement each result was tabulated as a relative change from the 0° position.

The maximum isometric force of the Vasti and of the Soleus was determined and correlated with EMG counts to avoid the synchrony of motor units which could give a lower inaccurate count. The walking EMG counts were always much less than those obtained at maximum force.

Action potential counts increased in all muscles in both walking and standing as the knee flexion angle increased. The increase in counts was not uniform or regular in any one muscle or group of muscles.

The time or duration of action of each muscle increased as the angle increased which caused an increase in energy consumption and fatigue.

All Vasti participate in knee extension in a very asynchronous pattern regardless of the angle of flexion. No special function was noted for any of the Vasti, including the Vastus Medialis, contrary to the common opinion that the Vastus Medialis is instrumental only in the final 15° of extension.

The torque measurements and EMG counts were monitored while the subjects were in a sitting position extending the knee against a fixed resistance with maximum effort. The torque peaked at 60°, but the EMG counts were relatively high at all angles tested. The torque is a function of knee joint efficiency, whereas the EMG counts are a function of muscle tension.

The Vastus Lateralis and Medialis had higher counts than the Intermedius suggesting a more significant part in knee extension. The critical angle is 15° or more according to force studies but this could not be confirmed with EMG counts.

The amount of activity per unit of time established that walking activity is more demanding than standing at comparable angles.

The new action potential counter used in this experiment is deemed to be more accurate than previous counters that have been employed that measure only threshold levels. It gave refined EMG counts by detecting low as well as high voltage fluctuations.

LLU Discipline

Anatomy

Department

Anatomy

School

Graduate School

First Advisor

Walter H. B. Roberts

Second Advisor

William H. Taylor

Third Advisor

Guy M. Hunt

Fourth Advisor

Elwood S. McCluskey

Fifth Advisor

Clarence W. Dail

Degree Name

Doctor of Philosophy (PhD)

Degree Level

Ph.D.

Year Degree Awarded

1973

Date (Title Page)

3-1973

Language

English

Library of Congress/MESH Subject Headings

Knee; Kinesthesis

Type

Dissertation

Page Count

ix; 172

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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