A Comparative Analysis Through EMG of the Lower Half of the Body When Doing Full and Half Squats

Hyun Su Kim

Department of Physical Education
The Graduate School
Pukyong National University
Directed by Professor Yong Jae Kim, Ph.D

Abstract

The purpose of this research is to provide a comparative analysis using EMG of the physical effect on each section of the lower half of the body when doing a full or half squat, which will not only useful for athletes, but also for professional trainers who require an effective approach of training regular people in a safe way that reduces the risk of injury. The final 10 subjects chosen for this research are male physical education students in their 20s at Pukyung National University in Busan City who have more than 2 years of weight training experience.

While each subject performed the movement of the full squat with optimal weight 1RM was calculated. After 1RM was measured 50% of the weight of 1RM was implemented. In addition, the measured 1RM was
implemented based on the recommended Earle(1999) method from the National Strength & Conditioning Association (below the NSCA). In order to measure the ENG, 8 muscles were chosen for electrodes to be attached to, including both feet’s Rectus Femoris, Vastus Lateralis, Vastus Mediali and Lumbar Erector Spinae. Electrodes were attached to the beginning, middle and end section of each muscle. In order to understand the characteristics of each movement in the full and half squat, 3 events and 2 different kinds of situations were set up. The squat can be divided by the degree of the knee joint into semi-squatting (40 degrees), half-squatting (70-100 degrees) and deep-squatting (more than 100 degrees). The data compiled and results of this research were carried out using the NORAXON TeleMyo 2400T G2, after which statistics were processed using SPSS Ver 20.0. The difference in EMG of each section of the lower half of the body when doing full and half-squats was analyzed with One-way ANOVA and posteriori tests were conducted using Duncan Test. All statistical significance probability was chosen with(p<.05). The following conclusion has been reached on the EMG analysis of each section of the lower half of the body of each subject who performed the squat

1. The comparison of the EMG of the lower half of the body when doing the full squat. When doing the full squat, there is a noticeable statistical and a higher EMG result in the second position, than in the first and third positions of the muscles Vastus Medialus, Vastus Lateralis, Rectus Femoris and Lumbar Erector Spinae(p<.05).

This result of the doing the full squat demonstrates that the second part (lifting a barbell while in the lowest seated position) is a more muscular active position than the first position (the start of the squat) and the third position (beginning to stand from the lowest seated position). A noticeable
statistical difference is also seen according to the analyzed EMG result of each position when doing the full squat(p<.05). In addition, the measured results of the EMG when doing the full squat demonstrate an increase in activity of the Vastus Medialus and Vastus Lateralus muscles compared to the Rectus Femoris and Lumbar Erector Spinae.

2. The comparison of the EMG of the lower half of the body when doing the half squat. When doing the half squat, there is a noticeable statistical and a higher EMG result in the second position, than in the first and third positions of the muscles Vastus Medialus, Vastus Lateralis, Rectus Femoris and Lumbar Erector Spinae(p<.05). This result of the doing the half squat demonstrates that the second part (lifting a barbell while in the lowest seated position) is a more muscular active position than the first position (the start of the squat) and the third position (beginning to stand from the lowest seated position). A noticeable statistical difference is also seen according to the analyzed EMG result of each position when doing the full squat(p<.05).

3. The comparison of the EMG of the lower half of the body when doing the full and half squat.
When analyzing and comparing the results of the EMG on each section of the lower half of the body after doing the full and half squat, the second position is also more active muscularly than the first and third. However, there is no noticeable statistical difference of each position seen in the results of the EMG of the lower half of the body. The only major difference seen from the EMG results in each position is that the left side of the Vastus Lateralis had a higher EMG result when doing the half squat than when doing the full squat.