The purpose of this study is to find out the muscle activation depending on the intensity of Dead-lift, Squat, Kettlebell swing exercises that are widely used in the field for hip extensor exercise, and provide exercise types appropriate for strengthe...
The purpose of this study is to find out the muscle activation depending on the intensity of Dead-lift, Squat, Kettlebell swing exercises that are widely used in the field for hip extensor exercise, and provide exercise types appropriate for strengthening hip extensors and effective exercise data in improving extension movements by identifying the onset time of extensor muscle contraction which appears in extension pre, during, and post exercise.
The subjects were men in 20s living in Seoul, and the result was derived targeting on 29 persons using random sampling method among persons with one year or longer experience of weight training. After attaching surface EMG (sEMG) on both erector spinae, gluteus maximus, and semitendinous muscles, the onset time was measured using prone hip extension test to find out the changes in the hip extensors pre and post exercise. Also, the muscle activation and onset time were measured, and the results of this study are summarized as follows.
1. The muscle activation were increased with significance in all muscles when the intensity was increase to 1RM 75% from 50% of Dead-lift, Squat, Kettlebell Swing exercises (p<.001).
2. The difference in muscle activation by hip extensor muscle parts according to 1RM 50% intensity of Dead-lift, Squat, Kettlebell Swing exercises was that gluteus maximus and semitendinous muscles showed to be higher with significance (p<.001) during Dead-lift compared to Squat, and during Kettlebell Swing compared to Dead-lift.
3. The difference in muscle activation by hip extensor muscle parts according to 1RM 75% intensity of Dead-lift, Squat, Kettlebell Swing exercises was that gluteus maximus and semitendinous muscles showed to be higher with significance (p<.001) during Dead-lift and Kettlebell Swing compared to Squat.
4. The differences of onset time of hip extensors during Dead-lift, Squat, and Kettlebell Swing exercises with 1RM 50% were that gluteus maximus was slower than semitendinous with significance (p<.049) during 1RM 50% Dead-lift exercise, and during 50% and 75% of 1RM Squat exercise, gluteus maximus appeared to be slower than other muscles with significance (p<.001). Same as Squat, gluteus maximus appeared to be slower than other muscles with significance (p<.001) during 1RM 50% Kettlebell Swing exercise as well. During Kettlebell Swing 75%, gluteus maximus and semitendinous appeared to be slower than both erector spinae with significance (p<.001).
5. In the pre-prone hip extension test, the difference of the onset time between the extensor muscles was that gluteus maximus appeared to be slower than other muscles with significance (p<.001).
6. In the prone hip extension test after the 1RM 50% and 75% of Dead-lift, Squat, and Kettlebell Swing exercises, the difference of onset time between extensor muscles was that the gluteus maximus appeared to be slower than other muscles after Squat with significance (p<.001).
By summarizing above results, the three types of exercises are considered to be effective in strengthening hip extensor muscles as the muscle activation of hip extensors increased when the intensity as increased from 1RM 50% to 75%. However, it is thought to be effective to select Dead-lift and Kettlebell Swing exercises to intensively strengthen gluteus maximus and semitendinous muscles, and select Kettlebell Swing exercise to enhance the power of the two muscles. In addition, to normalize the onset time between the hip extensors, selecting Dead-lift and Kettlebell Swing exercise is thought to be effective, and since Dead-lift exercise, which is identified to have no difference in onset time even during exercise, can be widely used in rehabilitation, retraining of hip movements, and etc., it is thought to be effective in prevention and preventing relapse without having interfered by movement patterns.