Analysis of Plantar Foot Pressure According to the Hardness of Combat Boots Insoles during Walking and Standing Seung-Bum Park 1, Kyung-Deuk Lee 1, Dae-Woong Kim 1, Jung-Hyeon Yoo 1, Kyung-Hun Kim 1, Jae-Young Park 2, Jin-Hoon Kim 3 1 Footwear Biomechanics Team, Footwear, Busan, Korea 2 Department of Leisure Sports, College of Sports Science, Dong-Eui, Busan, Korea 3 Treksta INC., Busan, Korea ABSTRACT Objective: The purpose of this study was to analyze foot pressure distribution of combat boots insole. Background: Hardness is an important aspect for footwear and insole. Insole hardness has an influence on comfort and fatigue. The development of new shape hardness is consider as the important point for manufacturing functional combat boots insole. Method: 1)subjects: Ten healthy male were participated in this study. Each subject's foot was pre-screened by Podoscopy(Alfoots, Korea) to see if they had any foot abnormalities. 2)equipment: Foot pressure device(pedar-x, Germany), treadmill(pulsefitness, UK). 3)testing procedure: Each subjects was Three different hardness insole type(soft, hard, normal) during walking trials on a treadmill at a constant speed of 4.2km/hour. Pressure distribution data(contact area, maximum force, maximum peak pressure, maximum mean pressure) was collected with pressure device at a sampling rate of 100Hz. Results: New combat boots soft functional insole wearing were increase contact area and were decrease force and foot pressure. Conclusion: New combat boots soft functional insole can provide increase comfort and decrease fatigue. Keywords: Combat boots, Pressure distribution, Functional insole, Shoes, Hardness 1. Introduction 전투화는군인이일반생활, 훈련및전시에서신고사용하는신발로산악및비포장도로와같은굴곡지고불규칙한지형에서사용된다. 국토의 70% 이상이산악지형인우리나라의경우거친지형에서업무수행을해야하는군인의특성상일반전투화는발과하지의상해방지및착용감증가보다는훈련과전투시활동에적합하도록내구성에초점을맞추어제작되었다. 현재군에서일반적으로사용되고있는전투화는내구성에주안점을두어충격을흡수해줄수있는연질경도의바닥이나인솔이사용된전투 화는보급이되지못하고있는실정이다 (Choi & Kim 2001; Suh, Kim & Cho, 2008). 일반인보다험난한지형에서의활동이많은군인들은지면에서발생하는충격력이발을통해고스란히하지및신체로전달된다. 이러한반복적인충격력은다양한신체피로, 발의상해및신체부하를발생시키고장기적으로는전투력약화및손실에도영향을미칠수있다 (Nigg, Hintzen & Ferber, 2006; Ramanatahn, Kiran, Arnold, Wang & Abboud, 2010, Brüggemanna, Brüggemannb, Heinricha, Müllerb & Niehoffa, 2011). 신발의무게, 미드솔과아웃솔, 인솔의재질및경도차이는활동시에너지소모에영향을미칠수있으며신체피로와도밀접한상관관계를가진다. 또한미드솔과아웃솔이딱딱한신발을착용하고산행같은야외활동시하지의조기
피로가발생할수있으며장기적인활동시발목의피로를예방하기위해서는활동성이보장되는부드러운재질로된신발을착용하는것이효과적이다 (Harald & Matthias 2009; Kim, Cho, Jung, Kim & Chung, 2010; Peter, Anders, Gerrit, Bernd, Axel & Dieter, 2008; Stefanyshyn et al., 2000). 이에본연구에서는전투화의성능개선을위해새로개발된신형전투화와기존전투화에대한성능비교및신형전투화의인솔경도에따른기능성우위를판단하기위해, 족저압력측정을통한생체역학적성능평가를실시하였다. 이를통해신형전투화의기능성에대한정량적인데이터를제공함으로써업무수행및능률향상에도움이되는신형전투화를개발하고자한다. 경도는 38±2 이고하드타입의경우경도는 42±2 이다. 인솔경도측정은 ASKER 사의 TYPE D 경도계를사용하여측정하였다. 개발된전투화의아웃솔의경우일반적으로사용되는 BR, NBR, 천연고무가혼합된재질로만들어졌으나아웃솔의구조와일반전투화와다른구조적인특성을통해기능성을구현하도록설계되었다 (Figure 2). 2. Method Figure 1. Testing combat boots 2.1 Subject 본연구에참여한피실험자는정상적인보행형태를가진피실험자중족부경검사 (Podoscope) 를실시하여편평족과요족같은족부의변형이없고과거하지상해발생경험이없는 20 ~ 30 대남성 10 명을대상으로실시하였다. 실험에사용된전투화사이즈는 265mm 로통일하여신발크기에따른변인을통제하였다. 피실험자의발사이즈도신발과동일한사이즈를가진피실험자를선별하여실험을실시하였다. Mean (S.D) Table 1. Characteristics of the subjects(n=10) Height (cm) Weight (kg) Age (year) 172.2± 67.1± 23± 4.66 7.39 0.47 2.2 Measurement & System Shoe size (mm) 265 실험에사용된전투화는개발된전투화의기능성비교를위해현재사용중인일반전투화와의새로개발된기능성전투화를사용하여분석하였다. 기능성전투화에는인솔사용에따른기능성변화를관찰하기위해경도가다른두가지인솔을삽입하여총 3 가지전투화를실험하였다 (Figure 1). 새로개발된전투화에삽입된인솔은소프트타입 (soft) 과하드타입 (hard) 인솔로나누어실험하였고소프트타입의경우 Figure 2. Development combat boots structure 개발된기능성전투화와일반전투화에대한접촉면적의변화및압력, 힘에대한분석을위해족저압력분포측정을실사하였다. 족저압력측정실험은독일 Novel 사의 Pedar-X 장비를사용하여외부환경에따른변인과보행속도에따른변인을최소화하기위해트레드밀위에서측정하였다. 보행속도는평균일반보행속도인약 4.2 km/h 로실시하였다. 측정전피실험자에따른변인을제어하기위해 Calibration 을실시후측정하였다. 데이터수집및분석은샘플링프리퀀시를 100 Hz 로하여보행시안정화단계에이른후총 60 분간의보행후왼발과오른발의데이터가동일하다는전제조건하에오른발 20 보에대한평균값데이터를총 3 회반복수집하여평균값을사용하였다. 족저압력데이터분석은 Novel Multimask 13.3.24 프로그램을사용하여, 발전체 (Total), 전족부
(M1), 중족부 (M2), 후족부 (M3) 로총 4 부위로나누어분석하였다. 부위별접촉면적 (Area), 최대힘 (Maximum force), 최대압력 (Maximum Peak pressure), 최대평균압력 (Maximum Mean pressure) 분석을실시하였다. 개발전투화와일반전투화데이터의유의성에대한검증은 Minitab 15 프로그램을이용하여비교전투화간 α =.05 의유의수준에서 One-way ANOVA 분석을이용하여비교하였다. 중족부에서는 Type A > Type B > Type C 순으로발전체와동일한경향이나타났으며유의한차이가나타났다 (p<.05). 전족부는 Type A > Type C > Type B, 후족부에서는 Type B > Type C > 순으로나타났으나유의한차이는관찰되지않았다 (Figure 4). 3.2 Maximum Force Figure 3. The Foot Pressure measurement mask 보행시발전체발전체 (Total), 전족부 (M1), 중족부 (M2), 후족부 (M3) 에대한최대힘분석결과발전체 (Total) 에서 Type A 가 609.36 N 로가장작게나타났고 Type B 가 619.84 N 로나타났으며 Type C 가 727.97 N 로가장높게나타났다. 후족부 (M3) 에서도동일한 Type C > Type B > Type A 순으로나타났으며통계적유의한차이 (p<.05) 가관찰되었다. 전족부에서 (M1) 는 Type B 가 467.31 N 로가장작게나타났으며, Type C 가 507.37 N 로가장큰값을보였다. 통계적유의성은전족부에서유의한차이 (p<.05) 가관찰되었으나중족부 (M2) 에서는관찰되지않았다 (Figure 5). 3. Results 개발된기능성전투화의발의압력변화에따른부하및충격흡수에대한족저압력분석결과는다음과같다. 3.1 Contact Area 전투화에대한접촉면적분석결과발전체 (Total) 에서 Type A 가 143.51 cm2 로가장넓게나타났고 Type B 가 139.07 cm2 로나타났으며 Type C 가 131.76 cm2 로가장좁은접촉면적을보였다. 전체적인결과는 Type A > Type B > Type C 순으로나타났으며각신발들간에유의한차이가나타났다 (p<.05). Figure 4. Contact Area 3.3 Peak Pressure Figure 5. Contact Area 각전투화에발생하는최대압력에대한분석결과발전체에대한최대압력변화를살펴보면 Type A 가 197.25 kpa 로가장작게나타났으며, Type C 가 346.2 kpa 로가장큰값을보였다. 발전체결과는 Type C > Type B > Type A 순으로나타났으며통계적유의한차이 (p<.05) 가관찰되었다. 전족부 (M1), 중족부 (M2), 후족부 (M3) 에서도 Type A 가 195.43 kpa, 106.13 kpa, 136.60 kpa 로가장낮은값이관찰되었으며, 발전체와동일하게 Type C > Type B > Type A 순으로나타났다. 통계적유의한차이역시세부위모두유의한차이를보였다 (p<.05).
Figure 6. Peak Pressure 3.4 Maximum Mean Pressure 전투화대한최대평균압력에대한분석결과발전체에대한최대평균압력은 Type A 가 80.23 kpa 로가장작게나타났으며, Type C 가 87.41 kpa 로가장큰값이나타났다. 전체적인결과는 Type C > Type B > Type A 순으로나타났으며통계적유의한차이 (p<.05) 가관찰되었다. 전족부 (M1) 와후족부 (M3) 에서도발전체와동일하게 Type C > Type B > Type A 순으로나타났으며, 두부위모두통계적으로유의한차이를보였다 (p<.05). 중족부 (M2) 에서는 Type A 가 52.86 kpa 로가장작게나타났으며 Type B 가 58.01 kpa 로가장크게관찰되었다. 중족부에서의통계적유의성은관찰되지않았다. 변화를분석하였다. 보행시발생하는족저압력분석결과접촉면적에서는새로개발된신형전투화 Type A, Type B 가일반전투화 Type C 에비해넓게나타났다. 이는발형상에가깝도록설계된신형전투화의기능성으로인해접촉면적이증가한것으로판단된다. 신형전투화의비교에서도경도가낮은 (Soft) 인솔이삽입된 Type A 의접촉면적이 Type B 보다넓어착화시발의편안함과안정성이증가할것으로생각된다. 최대힘, 최대압력, 최대평균압력의경우에서도발전체분석시새로개발된신형전투화 Type A, Type B 가일반전투화 Type C 에비해작은힘과낮은압력이나타났다. 신형전투화의비교에서도경도가낮은 (Soft) 인솔이삽입된 Type A 가경도가높은 (Hard) 인솔이삽입된 Type B 에보다최대힘과압력이낮게관찰되어보행시발생하는충격및발의피로를경감시키는데효과적일것으로판단된다. 추후기능성전투화의기능성향상개발연구를위해장시간활동시근육의피로를경감시킬수있는방안에대한추가적인연구가진행되어야할것으로사료된다. Acknowledgements 본연구는 2012 년도 트렉스타의지원에의하여수행되었음. References Figure 7. Maximum Mean Pressure 4. Conclusion 본연구에서는새로운구조와기능을가진기능성신형전투화와일반전투화에대한보행시발생하는압력변화및충격부하를비교하기위해족저압력 Brüggemanna G. P., Brüggemannb, L., Heinricha, K., Müllerb, M. and & Niehoffa A., Biological tissue response to impact like mechanical loading, Footwear Science, 3(1), 13-22, 2011. Choi, J. Y. and Kim, W. Y., Comparison of Biomechanical Characteristics for the Different Types of Army Boots in Running, Korean Journal of physical Education. 40(3), 987-1000, 2001 Harald B. and Matthias H., Effect of boot shaft stiffness on stability joint energy and muscular co-contraction during walking on uneven surface. Gait & Posture. 30(2), S43-S44, 2009. Kim, E. H., Cho, H. K., Jung, T. W., Kim, S. S. and Chung. J. W., The Biomechanical Evaluation of Functional Insoles, Korean Journal of Sport Biomechanics, 20(3), 345-353, 2010. Nigg, B. M., Hintzen, S. and Ferber, R., Efeect of an unstable shoe construction on lower extremity gait characteristics, Clinical
Biomechanics, 21(1), 82-88, 2006. Peter, H., Anders, H., Gerrit, M., Bernd, J., Axel, E. and Dieter, R., Analysis of pressure distribution below the metatarsals with different insoles in combatboots of the German Army for prevention of march fractures, Gait & Posture, 27(3), 535 538, 2008 Ramanathan, A. K., Kiran, P., Arnold, G. P., Wang, W. and Abboud, R. J., Repeatability of the Pedar-X in-shoe pressure measuring system, Foot and Ankle Surgery, 16, 70-73, 2010. Stefanyshyn, D. J. and Nigg, B. M., Energy aspects associated with sport shoes. Sportverletz Sportschaden 14(3), 82-89, 2000. Suh, S. H., Kim, R. B. and Cho, Y. Jae., The Evaluation of LOWER Extremity Muscles in Combat shoes Custom Foot Orthotics. Korean Journal of Sport Biomechanics. 18(2), 115-124, 2008 Agency Jae Young Park : pjy@deu.ac.kr Highest degree: PhD, Department of Physical Education, Dong-Eui Position title: Professor, Department of Leisure Sports, Sport Biomechanics Major Areas of interest: Sports Biomechanics, Footwear Biomechanics Jin Hoon Kim : jhkim@treksat.co.kr Highest degree: Master, Ergonomics, Dong-eui Position title: Assistent manager, Design Center, Treksat INC. Author listings Seung Bum Park: sbpark@shoenet.org Highest degree: PhD, Department of Physical Education, Pusan National Position title: Head of Team, Footwear Biomechanics Team, Footwear Kyung Deuk Lee: leekd79@shoenet.org Engineering, Dong-Eui Position title: Manager, Footwear Biomechanics Team, Footwear Dae Woong Kim: dwkim@shoenet.org Engineering, Dong-Eui Position title: Assitant Manager, Footwear Biomechanics Team, Footwear Joon Hyeon Yoo: jhyoo@shoenet.org Engineering, Dong-Eui Position title: Assitant Manager, Footwear Biomechanics Team, Footwear Kyung Hun Kim: kimkh@shoenet.org Highest degree: Master, Department of Physical Education, Kyungsung Position title: Assistant Manager, Footwear Biomechanics Team, Footwear Industrial Promotion Center, Busan Economic Promotion