MYOELECTRICAL ACTIVITIES OF THIGH MUSCLES DURING THE MINI-SQUAT EXERCISE ACCORDING TO DIFFERENT LOWER EXTREMITY POSITION

Abstract

The mini-squat exercise has been widely accepted as an effective and safe exercise to improve thigh muscle strength in the early stage in the injured athlete rehabilitation. PURPOSE The purpose of this study was to investigate the difference of quadriceps and hamstring muscles according to three different lower extremity positions. METHODS 20 healthy men, ages from 17 to 35 years old, participated in this study. To investigate the myoelectrical activities, we used surface electromyography. Surface electrodes were attached on four muscles including vastus medialis(VM), vastus lateralis(VL), semitendinosus(ST), and biceps femoris(BF) in dominant lower extremity. We examined myoelectrical activities in three different lower extremity positions; neutral foot position, turn-out 30 degree from the neutral foot position, and turn-in 30 degree from the neutral foot position. In each position, the subjects did mini-squat exercise ten times. We assessed average integrated electromyography (AIEMG) in each muscle. We used ANOVA method for the statistical analysis (a < 0.05). RESULTS The mean value of AIEMG of ST muscle showed statistical difference(p < 0.05) between three different lower extremity positions(22.6 ± 15.8, 15.0 ± 7.4, 26.9 ± 17.7§Å in neutral, turn-out 30 degree, turn-in 30 degree respectively). The mean value of AIEMG of BF muscle showed statistical difference (p < 0.05) between three different lower extremity positions(17.0 ± 8.6, 13.1 ± 5.2, 23.0 ± 13.2) respectively. However, those of VM and VL muscle showed no difference between three lower extremity positions(48.5 ± 15.8, 47.1 ± 20.2, 50.6 ± 15.4 and 63.7 ± 21.9, 60.9 ± 22.9, 62.8 ± 19.2) respectively. CONCLUSION The mean value of AIEMG of hamstring muscles including ST and BF muscle in turn-in 30 degree foot position is higher than in other positions. So we may consider the foot position during mini-squat exercise to strengthen hamstring muscles.