Date of Award
Master of Science (MS)
Kinesiology & Public Health Education
Sports medicine specialists, researchers, and rehabilitation specialists are frequently concerned with quantifying muscular activity for the purpose of studying muscle function. Two instruments that are currently used are the Cybex II Isokinetic Unit and integrated electromyography (IEMG). The Cybex measures torque and IEMG measures the neuro-muscular activity associated with a contracting muscle.
When measuring muscle function on the Cybex and IEMG, one would not expect linear relationship to exist between the two values if biomechanical, anatomical, and physiological factors are allowed to change. One would expect a linear relationship to exist if these factors were held constant.
The hypotheses were tested in a two part study using thirty female subjects. For the first phase, the subject was required to perform a maximal static exercise of knee extension for 10 seconds at 90 degrees, 60 degrees, 30 degrees, and 10 degrees of knee flexion. Simultaneous readings of torque and IEMG were recorded for each contraction. There was no linear relationshipo between torque and IEMG at varying joint angles (r = -0.101).
For the second phase, the subject was required to perform a sub-maximal static exercise of knee extension for 10 seconds at 20 percent, 40 percent, 60 percent, and 80 percent of their maximal torque produced at 60 degrees of knee flexion in phase one. All measurements were taken with the knee at 60 degrees of flexion. A linear relationship was found to exist between IEMG and torque of an isometric contraction when all biomechanical, anatomical, and physiological factors were constant.
The Cybex II Isokinetic Unit and IEMG have both proven to be useful tools in studies of human skeletal muscle. Under certain restricted conditions, the two evaluative tools tell us relatively the same thing about muscle activity. Under changing conditions, the two evaluative tools cannot be related.
Leikas, Mary Lee Metelak, "The Relationship Between Integrated Electromyography and Torque at Varying Joint Angles and Intensities of The Static Contraction of the Rectus Femoris Muscle in Normal Female Subjects" (1983). Theses and Dissertations. 1146.