Effects of Varying Electrode Site Placements on the Torque Output of an Electrically Stimulated Involuntary Quadriceps Femoris Muscle Contraction

Abstract

The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. At the time this study was performed, LTs Ferguson, Blackley, Knight, and Sutlive were students in the US. Army-Baylor University Graduate Program in Physical Therapy. This research was performed in partial fulfillment of their requirements for the Master of Physical Therapy Degrees.The purpose of this study was to evaluate the effects of varying electrode placement on the torque output of an electrically stimulated involuntary quadriceps femoris muscle contraction. Twenty-two volunteer subjects (18 men, 4 women) with a mean age of 21.7 years received electrical stimulation according to a randomized treatment order which included: Femoral nerve and 1) vastus medialis (VM), 2) rectus femoris (RF), 3) vastus lateralis (VL), 4) opposite quadriceps (OQ), and 5) the ipsilateral vastus medialis and vastus lateralis (VM/VL). The subject's knee was placed in 60 degrees of flexion, and the isokinetic dynamometer set at 0 degrees /sec. The peak torque produced by the involuntary quadriceps contraction was measured as a percentage of maximum voluntary isometric contraction (MVIC). An analysis of variance with repeated measures was used to examine the data. The results indicated the mean percentages of MVIC produced by stimulating the VM, VL, and RF sites were significantly greater (p </= 0.05) than the means of the OQ and VM/VL sites. Post hoc testing did not reveal a significant difference in the mean percent MVIC between the VM, VL, and RF sites. The VM, VL, or RF distal electrode site placement may be used clinically in conjunction with ipsilateral femoral nerve stimulation to produce a maximum involuntary isometric contraction of the quadriceps femoris muscle when stimulated electrically. J Orthop Sports Phys Ther 1989;11(1):24-29.