A Biomechanical research for incorates a rounded sole with a 20 degree heel lift in functional shoes

박승범,Darren Stefanyshyn,박상균 대한인간공학회 2006 대한인간공학회 학술대회논문집 Vol.- No.-

후족부 경사각을 이용한 신발(이하 스타필드 신발)에서 신발의 주요 기술적 혁신은 신발의 힐 부분을 20° 각도로 경사를 지게 하여 보행 시 바른 자세와 균형을 유지할 뿐만 아니라, 지지 시 충격을 완화하도록 고안되었다. 따라서 이 연구의 목적은 새로 개발된 신발과 기존 운동화를 비교하였으며, 보행동작과 서 있는 동작간 인체의 움직임과 지면반력 및 하지의 근육의 활동의 차이를 스타필드 신발과 일반 운동화간에 비교하였다. 실험을 위해서 9 명의 피험자가 연구에 참여하였다. 자료는 2 회에 걸쳐서 수집되었으며, 1) 스타필드를 처음 착용하였을 때와 2) 스타필드를 2 주간 하루 6 시간씩 착용 후 자료가 수집되었다. 자료는 서있는 동작과 보행동작 시 수집되었고 스타필드화로부터 얻은 자료는 아디다스사의 일반 운동화로부터 얻은 자료와 비교되었다. 30 초간 서있는 정적인 동작 간에 피험자의 하지근육의 활동과 압력분포 중심의 움직임의 변화를 산출하였다. 보행 동작 간에는 하지근육의 활동과 지면반력을 비롯해 발목과 무릎관절의 움직임과 각 관절에서 발생하는 부하를 측정하였다. 피험자들이 서있는 동안, 스타필드 신발을 신었을 때 기존의 운동화와 비교했을 시 압력분포 중심의 움직임은 약 60% 정도 증가하였다. 결과적으로 스타필드 신발을 신었을 시 기존 운동화와 비해 정강이 부근의 근육들을 100% 이상으로 활동을 증가시켜 인체의 균형을 유지하는데 이용되었다. 피험자들이 보행 간에는 스타필드 신발을 신었을 때, 신발의 힐 부분의 20° 경사각으로 인해 힐이 지면에 접할 때 발목이 약 14° 정도 보다 발등 쪽으로 굽혀짐을 보였다. 또한 무릎에서는 이를 상대적으로 보완하려고 2° 정도 굴곡 되었다. 결과적으로는 보행의 형태가 변함으로써 지면반력에서 최대 지면반력이 일어나는 시점은 앞당겨지나 최대 지면반력의 크기에는 변화가 없었다. 스타필드 신발을 신었을때, 보행 시 일반 운동화와 비교에서는 허벅지근육이나 대퇴근과 종아리 근육 등에서는 변화가 없었으나 앞 정강이 근육은 약 10%정도 근육활동이 감소하였다. 또한 발목과 무릎관절에서 발생하는 부하는 착지 시 약 21 ~ 60% 정도 감소하였다. 스타필드 신발의 주요 효과를 요약하면: ▷ 서있는 동안에는 일반신발에 비해서 안정성이 낮았다. 이에 따라 몸이 흔들림이 증가하고 균형을 유지하기 위해서 종아리근육의 활동이 증가하였다. 따라서 스타필드 신발은 하지 근육들의 단련시키는 효과를 나타냈다. ▷ 보행 동작 간에는 스타필드 신발은 움직임을 변화시키고 발목과 무릎각의 굴곡각을 증가시켰다. 결과적으로 보행의 지지기시 몸이 곧게 서도록 하였다. ▷ 스타필드 신발은 보행 간 앞정강이 근육의 활동의 감소를 제외한 하지 근육들의 활동량을 변화시키지는 않았다. ▷ 스타필드 신발은 착지 시와 체중을 지탱하는 지지기의 초기에 발목과 무릎에서 발생하는 부하를 감소시켰다. ▷ 스타필드 신발은 즉각적인 효과를 나타내며 2 주의 신발 착용 후에는 신체에 변화를 주지 않았다.

평지와 오르막경사의 트레드밀 걷기와 달리기 동안 발보장구가 발바닥근막염과 관련된 발아치 스트레인에 미치는 영향

김승재,Stefanyshyn, Darren,김로빈 한국운동역학회 2005 한국운동역학회지 Vol.15 No.1

S. J. KIM, D. Stefanyshyn, R. B. KIM. Effects of Foot Orthotics on the Foot Arch Strain related to PIantar Fasciitis During Treadmill Level and Uphill Walking and Running. Korean Journal of Sport Biomechanics, Vol. 15, No. 1, pp. 155-176, 2005. There is some evidence that one of major factors to produce plantar fasciitis depends on the magnitude of the foot arch strain. The orthotics that can reduce the foot arch strain during locomotion may be effective to prevent or treat plantar fasciitis. Therefore, the purpose of this study was to investigate the effect of control condition and three types of foot orthotics on 3-dimensional foot arch strain that can produce plantar fasciitis during treadmill level and uphill walking and running. Sixteen male subjects are recruited and the arch length and height strain according to three types of foot orthotics with respect to control condition were measured by using two digital video cameras. The first hypothesis which the comfort of foot orthotics would be increased from arch pad, half length orthotics to full length orthotics was mostly accepted. It suggested that the types of the foot orthotics could be properly prescribed according foot regions that is pain or abnormal. The second hypothesis which the foot arch strain can be reduced by foot orthotics during level heel-toe walking and running and the third hypothesis which the foot arch strain can be reduced by foot orthotics during uphill heel-toe walking and running were rejected. The foot arch length and height strain during walking and running showed small and subject-specific characteristics and could not be optimal biomechanical variable to prove the overall comfort. The forth hypothesis which the foot arch strain cannot be reduced by foot orthotics during uphill toe walking and running was accepted. With the foot arch length and height strain during uphill toe walking and running the windlass mechanism suggested by Hicks can be explained successfully and excessive uphill toe walking and running can be one of cause of plantar fasciitis. The dynamic investigation on the foot arch such as walking and running should be carefully observed with integrated insights considering ligaments and foot bones as well as plantar fascia, extrinsic muscles and tendons, and intrinsic muscles and tendons.

Foot arch strain of athletes and non-athletes during weight-bearing, walking and running

김승재,Darren Stefanyshyn 한국체육학회 2006 한국체육학회지 Vol.45 No.1

생체조건에서의 발아치의 동역학적인 특성은 잘 이해되지 않고 있다. 또한 고급수준의 경기력 훈련이 발아치 스트레인의 기계학적 특성에 영향을 미칠 수 있는 가에 대한 여부 역시 알려지지 않고 있다. 그러므로 본 연구의 목적은 체중지지, 걷기, 달리기 조건에서 일반인, 태권도선수, 럭비선수, 아이스하키선수, 발레리나의 발아치 스트레인 특성을 조사하는데 두었다. 본 연구의 목적을 달성하기 위하여 발아치 스트레인은 체중지지, 걷기, 달리기 조건 간에 유의한 차이를 보일 것이라는 첫 번째 가설과 선수들과 일반인 사이에 유의한 차이를 보일 것이라는 두 번째 가설을 세웠다. 13명의 일반인, 11명의 태권도선수, 10명의 럭비선수, 10명의 아이스하키선수, 11명의 발레리나 등 총 55명의 대상자들이 본 연구를 위하여 지원하였다.체중지지, 걷기, 달리기 조건에서 안쪽세로아치의 움직임이 고속카메라는 이용하여 촬영되었으며, 발아치 길이스트레인(신장성과 단축성)과 높이스트레인(하강성과 상승성)이 세로 발아치의 세 해부학적 경계점을 이용하여 계산되었다. 체중지지, 걷기, 달리기 조건에서 발아치 길이스트레인은 유의한 차이를 보이지 않은 반면에 높이스트레인은 유의한 차이를 보였다. 고급수준의 경기력 훈련이 발아치에 미치는 영향은 일관성이 없는 것으로 나타났다. 단순화된 수동적인 발아치 모델은 동적인 발아치 특성을 완전히 기술하는데 불충분하다. 인대는 물론 내재적, 외재적 근육활동은 걷거나 달리는 동안 발아치의 기능을 완전히 이해하는데 고려될 필요가 있다. 발아치 훈련에서 전반적인 차이는 동적인 발아치 기능에 구조적인 영향을 미치는 것으로 보이지는 않는다. 이러한 발견점들은 족저근막염과 같은 발과 관련된 상해 기전을 이해하고 발아치의 동역학적인 모델을 개발하는데 도움을 주는 통찰력을 제공한다.

Kinematics and Kinetics of the Lower Limbs of a Walking Shoe with a Plate Spring and Cushioning Elements in the Heel during Walking

Park, Seung-Bum,Stefanyshyn, Darren,Pro, Stergiou,Fausto, Panizzolo,Kim, Yong-Jae,Lee, Kyung-Deuk Korean Society of Sport Biomechanics 2010 한국운동역학회지 Vol.20 No.1

The purposes of this study was to investigate the biomechanical influence of the walking shoe with a plate spring in the heel and interchangeable heel cushioning elements. Eighteen subjects walked in three conditions: 1) the walking shoes Type A-1 with a soft heel insert, 2) the Type A-2 shoe with a stiff heel insert, 3) a general walking shoe(Type B). Ground reaction forces, leg movements, leg muscle activity and ankle, knee and hip joint loading were measured and calculated during overground walking. During walking, the ankle is a few degrees more dorsiflexed during landing and the knee is slightly more flexed during takeoff with the Type A shoes. As a result of the changes in the walking movement, the ground reaction forces are applied more quickly and the peak magnitudes are higher. Muscle activity of the quadricep, hamstring and calf muscles decrease during the first 25% of the stance phase when walking in the Type A shoes. The resultant joint moments at the ankle, knee and hip joints decrease from 30-40% with the largest reductions occurring during landing.

Kinematics and Kinetics of the Lower Limbs of a Walking Shoe with a Plate Spring and Cushioning Elements in the Heel during Walking

( Seung Bum Park ),( Darren Stefanyshyn ),( Stergiou Pro ),( Panizzolo Fausto ),( Yong Jae Kim ),( Kyung Deuk Lee ) 한국운동역학회 2010 한국운동역학회지 Vol.20 No.1

The purposes of this study was to investigate the biomechanical influence of the walking shoe with a plate spring in the heel and interchangeable heel cushioning elements. Eighteen subjects walked in three conditions: 1) the walking shoes Type A-1 with a soft heel insert, 2) the Type A-2 shoe with a stiff heel insert, 3) a general walking shoe(Type B). Ground reaction forces, leg movements, leg muscle activity and ankle, knee and hip joint loading were measured and calculated during overground walking. During walking, the ankle is a few degrees more dorsiflexed during landing and the knee is slightly more flexed during takeoff with the Type A shoes. As a result of the changes in the walking movement, the ground reaction forces are applied more quickly and the peak magnitudes are higher. Muscle activity of the quadricep, hamstring and calf muscles decrease during the first 25% of the stance phase when walking in the Type A shoes. The resultant joint moments at the ankle, knee and hip joints decrease from 30-40% with the largest reductions occurring during landing.

Comparisons of Age-Related Changes in Impact Characteristics Between Healthy Older and Younger Runners

Sang-Kyoon Park,Darren Stefanyshyn,Sihyun Ryu,Hojong Gil,Young-Seong Lee,Jongbin Kim,Ji-Seon Ryu 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.12

The purpose of this study was to investigate whether there are any age-related differences in impact characteristics during running between healthy older and younger men. Ten healthy older (age: 58.7 ± 2.5 years) male and ten healthy younger (age: 22.3 ± 1.6 years) male recreational runners ran on a treadmill at three different running speeds (i.e. 2.2 m/s, 2.8 m/s, and 3.2 m/s). Tri-axial accelerometers (Noraxon, USA) were firmly attached to the tibia and the sternum. Gait parameters, three-dimensional peak tibial accelerations, peak sternum accelerations and shock attenuation were calculated during the stance phase of running. The ANOVA repeated measures was applied at an alpha level of .05. Older runners showed greater impact on the sternum, leading to reduced shock attenuation compared with younger runners (p < .05). In addition, older runners showed a shorter lag between peak resultant accelerations experienced by the upper body and peak acceleration experienced by the lower leg compared with younger runners (p < .05). This study suggests that the intensity (i.e. speed and duration) and types of exercise should be carefully considered for older adults because of lower shock attenuation of the body and changes in coordination strategy between the segments in high-impact activities like running.

AFTS 로봇 시뮬레이터를 이용한 전문 태권도화 아웃솔 형태에 따른 발차기 동작의 수행력 비교연구

박승범,이정호,이경득,Darren J. Stefanyshyn,박상균,황영순,이승환 대한인간공학회 2007 대한인간공학회 학술대회논문집 Vol.- No.-

The purpose of the study is to make compartive rssearch of mechanical friction and taekwondo performance. we make an experiment on the taekwon performacne test, AFTS(Automated Footwear Testion System) and questionaire for the fitting. Depend on taekwondo shoes the result of mechanical frction was significant difference statistically on all the types. In the round house kick there were significant difference statistically in the peak free moment and peak plnatar pressure between type A and type B. In comfort testing there were significant difference statistically between type A and Type B in the five fields(overall comfort, Forefoot cushioning, Upper cushioning, Stability, Traction) but not between type B and Type C. Depend on Taekwondo shoes mechanical frction was significant difference statistically but had not an effect on taekwondo performacne and It had nothting to do between the result of questionare and taekwondo performance.

Effects of Foot Orthotics on the Foot Arch Strain Related to Plantar Fasciitis during Treadmill Level and Uphill Walking and Running

( Seung Jae Kim ),( Stefanyshyn Darren ),( Ro Bin Kim ) 한국운동역학회 2005 한국운동역학회 논문 영문초록집 Vol.2005 No.-

The effect of running shoe midsole hardness on foot biomechanics

박상균,길호종,유시현,Darren Stefanyshyn 한국체육대학교 체육과학연구소 2019 스포츠사이언스 Vol.37 No.1

The purpose of this study was to investigate whether placing harder midsole materials on the medial and posterior side of the outsole in a running shoe can change biomechanics variables during the stance phase of running. Ten healthy young recreational male runners (age: 20.5±0.7 yrs, mass: 73.1±3.8 kg, height: 176.8±2.9 cm) participated in this study. A shoe company (FILA, Korea) produced the same shoe with four different types of midsole density. Each subject wore the four different running shoes in randomized order while running on an instrumented treadmill at two speeds (3.5 m/sec and 4.5 m/sec). The positions of the markers and the ground reaction forces were recorded using a system of eight high speed motion capture cameras and force plates at a sampling frequency of 100 Hz and 1000 Hz, respectively. The variables of this study were the running parameters, ground reaction forces, and joint angles. This study was intended to investigate whether medially posted midsole materials in a running shoe effectively reduce foot pronation and other running biomechanics variables. However, there was no modified shoe effect on most running kinematics and kinetics except the impact loading rate. It is concluded that other features of shoe manufacturing in terms of structures and materials should be considered to understand the function of anti-pronation in a running shoe.

3-Dimensional Performance Optimization Model of Snatch Weightlifting

( Young Jin Moon ),( Darren Stefanyshyn ) 한국운동역학회 2015 한국운동역학회지 Vol.25 No.2

Object: The goals of this research were to make Performance Enhanced Model(PE) taken the largest performance index (PI) through artificial variation of principle components calculated by principle component analysis for trial data, and to verify the effect through comparing kinematic factors between trial data (Raw) and PE. Method: Ten subjects (5 men, 5 women) were recruited and 80% of their maximal record was considered. The PI is a regression equation. In order to develop PE, we extracted Principle components from trial position data (by Principle Components Analysis (PCA)). Before PCA, we made 17 position data to 3 row matrix according to components. We calculated 3 eigen value (principle components) through PCA. And except Y (medial-lateral direction) component (because motion of Y component is small), principle components of X (anterior-posterior direction) and Z (vertical direction) components were changed as following. Changed principle components = principle components + principle components × k. After changing the each principle component, we reconstructed position data using the changed principle components and calculated performance index (PI). A Paired t-test was used to compare Raw data and Performance Enhanced Model data. The level of statistical significance was set at p ≤ 0.05. Result: The PI was significantly increased about 12.9kg at PE (101.92±6.25) when compared to the Raw data (91.29±7.10). It means that performance can be increased by optimizing 3D positions. The difference of kinematic factors as follows : the movement distance of the bar from start to lock out was significantly larger (about 1cm) for PE, the width of anterior-posterior bar position in full phase was significantly wider (about 1.3cm) for PE and the horizontal displacement toward the weightlifter after beginning of descent from maximal height was significantly greater (about 0.4cm) for PE. Additionally, the minimum knee angle in the 2-pull phase was significantly smaller (approximately 2.7cm) for the PE compared to that of the Raw. PE was decided at proximal position from the Raw (origin point (0,0)) of PC variation). Conclusion: PI was decided at proximal position from the Raw (origin point (0,0)) of PC variation). This means that Performance Enhanced Model was decided by similar motion to the Raw without a great change. Therefore, weightlifters could be accept Performance Enhanced Model easily, comfortably and without large stress. The Performance Enhance Model can provide training direction for athletes to improve their weightlifting records.