Comparison of Muscle Activity of Vastus Lateralis and Medialis Oblique among Knee Extension Angles at 90°, 135°, 180° in Sitting Position

ABSTRACT

Purpose@#This study compared the muscle activities of the Vastus medialis oblique (VMO) and the Vastus lateralis (VL) at three different knee extension angles 90°, 135°, and 180° in the sitting position. @*Methods@#Twenty subjects between 20 and 30 years of age participated in the study. A mobile phone application called the Clinometer was used to measure the knee joint angle. Electromyography (EMG) was performed to measure the muscle activities of the VMO and VL muscles during knee isometric extension exercises. The pulling sensor was used to maintain 70% of the maximum strength of the knee extensor continuously in the sitting position. After attaching the EMG sensor, the subjects were asked to perform isometric knee extension exercises randomly among three knee extension angles (90°, 135°, or 180°) in the sitting position. One-way repeated measures analysis of the variance and a Bonferroni post hoc test was used to identify the VMO and VL muscle activity during knee extension angles among 90°, 135°, and 180°. @*Results@#The VMO and VL muscle activities increased with increasing knee extension angle in the sitting position (p<0.01). @*Conclusions@#Knee extension exercise at a 180° angle in the sitting position can be recommended to increase the muscle activity of the VMO and VL muscle activities efficiently.