본 연구의 목적은 고관절 신전근 운동으로 현장에서 많이 사용되는 Dead-lift, Squat, Kettlebell swing 운동을 이용하여 강도에 따른 근활성도를 알아보고 신전시 나타나는 신전근의 수축 개시시간을 사전, 운동 중, 사후 확인함으로써 고관절 신전근 강화에 적합한 운동 유형과 신전 움직임 개선에 효과적인 운동 자료를 제공하는데 있다.
연구대상은 서울에 거주하는 20대 남성으로 웨이트 경험이 1년 이상인 사람을 임의표집법을 사용하여 29명을 대상으로 결과를 도출하였다. 양측 척주기립근(erector spinae), 대둔근(gluteus maximus), 반건양근(semitendinous)에 표면 근전도(sEMG)를 부착하여 운동 전·후 고관절 신전근의 변화를 알아보기 위해 고관절 신전 기능 검사(prone hip extension)를 이용하여 수축 개시시간을 측정하였다. 또한 세 가지 운동 수행 중 근활성도와 수축 개시시간을 측정하였다. 본 연구의 결과를 정리하면 다음과 같다.
1. Dead-lift, Squat, Kettlebell Swing 운동의 1RM 50%에서 75% 강도로 증가 시 모든 근육에서 근활성도가 유의하게 증가하였다(p<.001).
2. Dead-lift, Squat, Kettlebell Swing 운동의 1RM 50% 강도에 따른 고관절 신전근 부위별 근활성도는 대둔근과 반건양근이 Squat 운동보다 Dead-Lift 운동에서, Dead-lift 운동보다 Kettlebell Swing 운동에서 유의하게 높게 나타났다(p<.001).
3. Dead-lift, Squat, Kettlebell Swing 운동의 1RM 75% 강도에 따른 고관절 신전근 부위별 근활성도는 대둔근과 반건양근에서 Squat 운동보다 Dead-Lift 운동과 Kettlebell Swing 운동에서 유의하게 높게 나타났다(p<.001).
4. 1RM 50%, 75% Dead-lift, Squat, Kettlebell Swing 운동 중 고관절 신전근의 수축 개시시간은 1RM 50% Dead-lift 운동에서 대둔근이 반건양근보다 유의하게 느리게 나타났으며(p<.049), 1RM의 50%, 75%의 Squat 운동에서 대둔근이 다른 근육에 비해 유의하게 느리게 나타났다(p<.001). 1RM 50% Kettlebell Swing 운동에서는 Squat 운동과 동일하게 대둔근이 다른 근육에 비해 유의하게 느리게 나타났다(p<.001). 1RM 75% Kettlebell Swing 운동에서는 대둔근과 반건양근이 양측 척주기립근보다 유의하게 느리게 나타났다(p<.001).
5. 사전 고관절 신전 기능 검사에서 신전근 간의 수축 개시시간 차이는 대둔근이 다른 근육에 비해 유의하게 느리게 나타났다(p<.001).
6. 1RM 50%, 75% Dead-lift, Squat, Kettlebell Swing 운동의 사후 고관절 신전 기능 검사에서 신전근 간의 수축 개시시간은 Squat 운동에서 대둔근이 다른 근육에 비해 유의하게 느리게 나타났다(p<.001).
이상의 결과를 종합해보면 1RM 50%에서 75%로 강도 증가 시 고관절 신전근의 근활성도를 유의하게 증가시켜 고관절 신전근 근력을 강화시키는데 세 가지 운동이 효과적일 것으로 사료된다. 하지만 대둔근과 반건양근의 집중적인 근력 강화를 위해서 Dead-lift운동과 Kettlebell Swing 운동을 선택하며, 대둔근과 반건양근의 파워 향상을 위해서는 Kettlebell Swing 운동이 효과적일 것으로 사료된다. 또한 고관절 신전근 간의 수축 개시시간의 개선을 위해서는 Dead-lift 운동과 Kettlebell Swing 운동을 선택하는 것이 효과적이며, 운동 중에도 근 수축 개시시간의 차이가 없는 것이 확인된 Dead-lift 운동은 재활, 고관절 움직임의 재교육 등 광범위하게 사용 가능하여 움직임의 패턴을 방해하지 않고, 상해 재발 및 예방에 효과적일 것으로 사료된다.

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.