Analysis of knee movements on leg extension machine: an electromyography study of the rectus femoris muscle

The Rectus Femoris muscle was analyzed by electromyography in 10 female subjects between 19 and 22 years old. Surface electrodes were utilized by placing them at the middle of the muscle. The course of the flexing/extending movements of the knee were analyzed on a Leg Extension Machine. The results showed that the MIC value was greater in the series with loads than in the series without loads. For the Maximum Isometric Contraction (MIC) the value was 144.00. In the movement executed without load the value was 73.96. In the first series with the initial 15 Kg load the value was 163.7 and in the last series of the initial load the value was 194.9. With the 19 Kg load in the first series the value was 182.5 and in the last series the value was 205.1. In the first series with the 21 Kg load the value was 165.1 and in the last series with the 21 Kg load the value was 23.09. The values reflecting the need to recruit more muscle fibers to continue executing the movement. The value 23.09 shows the difficulty in proceeding with the movements and can be considered the beginning of a muscular fatigue process in the Rectus Femoris muscle.