earticle

영어

KINESIOLOGY, 2010, 12(4): 81-94. The Study of Optimal Bending Stiffness of Marathon Shoe Sole by using Energy Return(Joint Power Method) in Lower Extremity Joint. [INTRODUCTION] The purposes of this study were to determine optimal bending stiffness of a marathon shoe which increased bending stiffness, rearfoot control and impact force absorption of marathon shoe sole, and to compare usual methodology with energy return method(joint power method) for determining optimal midsole hardness. [METHOD] The subjects employed for this study were 13 college students who did not have lower extremity injuries for the last one year and whose running pattern was rearfoot striker of normal foot. The shoes used in this study had 4 different midsole hardness of shoe A 40, shore A 50, Shore A 60, Shore A 70 and bending stiffness was 0.05 N.m/deg - 0.4 N.m/deg. The lower leg motion during at the speed of 4m/sec were measured using a force platform and motion analysis system. [RESULT] The findings of the study were as follows : 1. It was appeared that total contact time of each phase was decreased as the increment of marathon shoe midsole hardness. 2. Maximal impact force and maximal impact force loading rate increased except shore A 40 as the midsole hardness increased. It was shown that Shore A 40 and Shore A 70 were not fitted for a marathon shoe. 3. Initial achilles tendon angle of each midsole hardness was shown similar results, and a maximal achilles tendon angle and a angular displacement of achilles tendon angle was the largest at shore A 40 and the smallest at shore A 50. 4. Initial rearfoot angle was the smallest at shore A 60 and the largest at shore A 70. A minimum rearfoot angle and the displacement of rearfoot angle was the largest at shore A 50 and the smallest at shore A 60. 5. Maximal power in 1st contact contact phase was not shown any particular tendency, but in 2nd contact phase maximal power was increased as midsole hardness was increased and distal joint. 6. The energy in 1st phase was produced at hip joint and absorbed at knee joint and ankle joint, in 2nd contact phase the energy was largest at knee joint and increased as midsole hardness was increased. [CONCLUSION] The study confirmed the previous findings that the midsole hardness of marathon shoe did influence on impact force absorption, rearfoot stability and joint energy. The optimal midsole hardness of marathon shoe was most fitted at shore A 50 and the next shore A 60 by usual shoe methodology study. It was proved that shore A 40 and shore A 70 were not fitted for marathon shoe sole. Also it was appeared that shore A 50 was the most fitted for marathon shoe sole by new attempted joint power method results that the joint energy was largely generated as midsole hardness was most flexible or hard. However, the study suggests that the similar studies like energy return were performed verified optimal bending stiffness because these conclusions were based only on tendencies of current results.

한국어

운동학 학술지, 2010, 12(4): -94. 달리기 시 하지관절의 에너지 반환 방법(Joint Power Method)을 이용한 마라톤화 Sole의 Optimal Bending Stiffness산출 [서론] 본 연구의 목적은 마라톤화 바닥의 Bending Stiffness도 증가되고 후족제어나 충격력 흡수가 잘 되는 최상의 조합(stiffness)을 규명하며, 종래의 연구방법과 Joint Power Method의 적정 신발바닥의 강도를 결정하기 위한 연구방법을 상호 비교하는데 있다. [방법] 본 연구에 동원된 피험자는 최근 1년 이내에 하지에 부상경험이 없는 남자 대학생 13명이었다. 본 연구에 사용된 마라톤화는 Bending Stiffness가 0.05 N.m/deg∼0.4 N.m/deg이며, 중저의 경도가 Shore A 40, Shore A 50, Shore A 60, Shore A 70의 4종류이었다. 달리기 시 하지동작을 3차원 영상분석법과 지면반력 측정을 통하여 분석하였다. [결과] 마라톤화의 경도가 증가함에 따라 구간별 걸린 시간도 감소하는 것으로 나타났고 충격흡수변인과 후족제어변인을 분석한 결과 마라톤화 중저의 경도는 50도가 적합한 것으로 나타났다. 하지관절의 에너지와 파워는 굴곡강도가 클수록 통계적인 차이는 없지만 증가하였으며 원위관절로 갈수록 증가하는 것으로 나타났다. [결론] 기존의 신발평가방법과 에너지 반환법을 비교했을 때 평가방법 성격의 차이에 의하여 적정굴곡강도를 선정하는데 차이를 보였다. 에너지 반환법을 이용한 마라톤화 바닥의 적정굴곡강도는 경도가 클수록 증가하는 경향을 보였지만 통계적인 차이를 나타내지 않아 현재의 연구결과로서 현장에 적용하기 어렵다고 사료된다.