Differences on Thigh Muscles' Activity by Types of Squat

OBJECTIVES Thigh strength has many features in our life. Many people perform vary squat types to stimulate different thigh muscles. However, there is a lack of information on which squat is the most effective on targeted muscles. Therefore, the purpose of this study was to compare thigh muscles’ activity by squat types and suggest the correct squat for strengthening thigh. METHODS Total of 20 men and women (age: 23.9±1.5yrs, height: 173.3±6.6cm, weight: 75.1±13.2kg, BMI: 24.9±3.1kg/m2) who had no musculoskeletal pathologies within last one year, and had weight training experience for more than 1 year were participated. Squat types were classified into standard (SS), narrow (NS), wide (WS), jump (JS), and Smith machine squats (SMS). Surface electromyography was used to collect the muscle activity of the thigh during three repetitions of each squat without weights. Time points during squat are defined as follows: E1 (start), E2 (maximum knee flexion, MKF), E3 (returned), P1 (from start to MKF), and P2 (from MKF to return). Repeated measured ANOVA was used to verify differences in lower limb muscle activity between squat types. RESULTS At the E2, significant differences were found in RF (p=.00) and ST (p=.00). In the P1, significant differences were found in RF (p=.00), VL (p=.00), and BF (p=.02). In the P2, significant differences were found in RF (p=.00), VM (p=.00), and ST (p=.01). CONCLUSIONS For more activity of both quadriceps and hamstrings, plyometric-based JS is the most effective squat, but by considering the performer's lack of exercise experience, postural control may not be performed correctly which may lead to injury. In addition, stable squat using the Smith machine should be considered and the intensity, number of repetitions, and weight should be carefully set according to type of squat.