An Electromyographic Study of the Effects of Lateral Asymmetry on the Upper Leg Muscles Used in Normal Walking on a Treadmill

The purpose of the study was to determine through electromyography whether a non-pathological fault, such as lateral asymmetry at the pelvic level, would hinder, in significant manner, efficient functioning of the body. A review of the literature revealed that although previous experiments had been conducted to determine the effects certain postural deviations had on the normal, efficient functioning of the body and that previous experiments had been conducted to determine which muscles performed which task as related to walking, none dealt with the specific effects of lateral deviations at the pelvic level on the upper leg muscles used in walking. In this study twenty-five female students were screened to determine whether or not they demonstrated one half inch lateral deviation at the pelvic level. On the basis of the results of the screening session five test subjects and five reference subjects were selected. Electromyograms of five muscles (the biceps femoris, the semitendinosus, the sartorius, the gluteus maximus, and the gluteus medius--stance phase and swing phase of each) were taken. Amplitudes for the action potentials of each of the five muscles of the five test subjects and five reference subjects were computed. The results were compared between the two groups by the two-way analysis of variance statistical method. Girth measurements and strength measurements for the right and left leg of each subject were taken and then the results of the test group were compared with those of the reference group. The conclusions arrived at, within the limitations of the study, were a (1) lateral asymmetry has no effect on the difference of strength measurements and girth measurements between the right and left leg of subjects with lateral asymmetry and subjects without lateral asymmetry, and (2) the data collected for the study fail to provide enough difference (since only one phase of one muscle demonstrates an important amount of difference between groups) to warrant rejection of the null hypothesis. Therefore, the statement that there would be no difference in the action potentials of certain muscles in the upper leg of subjects with lateral asymmetry recorded electromyographically while the subject walked on a treadmill when compared with similar recordings of the muscle action potentials of the subjects with no lateral asymmetry of the pelvis must stand. Further research concerning the effect of specific postural deviations on the normal functioning of the human body as related to physical education should be encouraged