6.3. Footwear- Movement Control - Journal of Biomechanics

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Footwear- Movement Control. 6444. Mo-Tu, no. 29 (P61). Mechanical properties of different midsole materials in running shoes. J. Heidenfelder, S. Odenwald, ...


Journal o f Biomechanics 2006, Vol. 39 (Suppl 1)

6.3. F o o t w e a r - Movement Control 6444 Mo-Tu, no. 29 (P61) Mechanical properties o f different midsole materials in running shoes J. Heidenfelder, S. Odenwald, T. Milani. Technische Universit~t Chemnitz, Institut fEtr Sportwissenschaft, Chemnitz, Germany Polymers are essential for the development of running shoes. From casual shoes to custom-made sprint shoes reinforced with carbon fibers, the field of application is wide and requirements for running shoes vary accordingly. The midsole, in its design and material compound, has a significant influence on the properties of running shoes. Foamed ethylene vinyl acetate (EVA) and thermoplastic polyurethane (TPU) are proven to be adequate as midsole material. The study focuses a comparison of the mechanical properties of these copolymers used as midsole materials in running shoes. Unlike impact tests (Frederick et al., 1984), the used test procedure determines material parameters which are specific for running shoes, like energy loss, stiffness and deformation. Load velocities and maximum forces are based on studies on ground reaction forces at different running velocities (Hennig et al., 1993; Cavanagh and Lafortune, 1980). This real force-time curve allows new application-specific conclusions during use. Testing of these specific material properties for more than 250.000 cycles allows conclusions about material fatigue and stability characteristics of the running shoe. The comparison of the two materials (EVA and TPU) over the used cycles revealed explicit differences. This could be verified for energy loss, stiffness of material, and material fatigue. For the interpretation of the results, the microscopic structure of the polymers and specific characteristics of the midsole construction were taken into consideration. The test revealed specific advantages and disadvantages of the midsole materials and confirmed that both materials may be used as midsole materials in running shoes even though the usage may be restricted to certain fields of application only. Cavanagh P.R., Lafortune M.A. (1980). Ground reaction force in distance running. J. Biom. 13:398-406 Frederick E.C., Clarke T.E., Hamill C.L. (1984). The effect of running shoe design on shock attenuation. In: Sport Shoes and Playing Surfaces, Frederick E.C. (ed.). Human kinetics, Champaign, IL, pp. 190-198. Hennig E.M., Milani T.L., Lafortune M.A. (1993). The use of ground reaction force parameters for the prediction of peak tibial accelerations in running with different footwear. J. Appl. Biom. 11(3): 306-314 4770 Mo-Tu, no. 30 (P61) The development o f hallux valgus index using plantar image X.-L. Kuo 1, J.-L. Xie 2, T.-Y. Shiang 3. 1Institute ef Sports Equipment Technology, Taipei Physical Education College, Taipei, Taiwan, 2fostitute of Sports Equipment Technology, Taipei Physical Education College, Taipei, Taiwan, 3Institute of Sports Equipment Technology, Taipei Physical Education College, Taipei, Taiwan Hallux valgus is one of the over use injury caused by the repetitive stress on the foot which will affect the foot function and performance. Current hallux valgus measurement techniques include X-ray and photographic methods. Traditional X-ray approach may obtain accurate results, but it is not suitable for massive surveys considering the cost and radiation effect. Photographic approach may get good result without the problems of cost and radiation, but the repeatability and reliability problems caused by manual operation limit the application. Therefore, the aim of this study was trying to develop a hallux valgus index using plantar image to better quantify hallux valgus. Our previous study pointed out that photographic approach has significant correlation with X-ray approach. Current study compared various hallux valgus index using plantar image with photographic approach. The subjects consisted of 20 female high school students (10 dancers and 10 normal students). The results show that hallux valgus index using appropriate landmarks has significant correlation with the photographic approach. 5070 Mo-Tu, no. 31 (P61) Quasi-static tarsal bone motion o f dynamically categorised runners P. Wolf 1, A. Stacoff 1, R. Luechinger 2, E. Stuessi 1. 1Laboratory for Biomechanics, ETH Zurich, Zurich, Switzerland, 2Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland The relationship between static or passive foot categories and their dynamic and possibly unphysiological behaviour is still uncertain but is important in view of an effective prevention and treatment of running injuries [1]. The current work is the first to investigate the mentioned relationship based on dynamically categorised runners whose quasi-static tarsal bone motion was investigated. Video motion analysis was performed on fifteen healthy volunteers during heel strike running. To consider a phase that is likiest to be influenced by bone

Poster Presentations morphology, calcaneal motion relative to the tibia within the first 50 ms of stance was used to classify dynamic foot function: Eight subjects showing 2-40 calcaneal eversion and 3-50 calcaneal abduction constituted the reference group; the other subjects with more than 60 eversion and/or abduction constituted the flexible foot group. Until now, quasi-static tarsal motions and tarsal morphology of three subjects of each group has been investigated with a newly developed magnetic resonance imaging procedure. The results show that in 150 foot pronation/supinatien combined with an axial foot load of half bodyweight, tarsal joint rotations of the reference group were as follows: 3-80 eversion/5-10 ° inversion, 0-20 dorsiflexion/0-1 ° plantarflexion, and 3-50 abd uction/5-10 ° adductien in the subtalar joint; 8-120 eversion/5-17 ° inversion, 0-10 plantarflexion/O- 3° dersiflexien, and 4-7°abduction~5-15 ° adductien in the talo-navicular joint. Considerably less motion was found in the other tarsal joints. The dynamically more flexible subjects showed similar rotations and were not distinguishable from the reference group including also their subtalar axis positions or joint curvatures. In conclusion, no evidence was given for a dependency of tarsal bone morphology and rearfoot motion conforming that rearfoot motion is rather influenced by joint curvatures than by ligaments and (pre-) activated muscles. Financial support: Swiss Federal Sports Commission; ISB Dissertation Grant 2005

References [1] Razeghi M., Batt M.E. Foot type classification: a critical review of current methods. Gait and Posture 2002; 15,282-291. 5078 Mo-Tu, no. 32 (P61) Two-segment foot kinematics during running R. List, S. Untern~hrer, A. Stacoff, T. Ukelo, E. StLissi. Laboratory for Biomechanics, D-MAVT, ETH Zurich, Zurich, Switzerland

Introduction: Gait analysis models typically treat the foot as one rigid segment. As it is known that the foot deforms during dynamic activities such as running (Nachbauer et al., 1992), the consequence is to split the foot in at least two segments. For walking, multi-segment foot models have been used to analyze the kinematics (Hunt et al., 2001). The goal of this study was to provide forefoot and rearfoot kinematic data during running and to discuss consequences for future investigations. Methods: 10 healthy subjects, all active runners (males >30 km/week, females >20 km/week) were evaluated using a 12 camera 3D motion analysis system (Vicon). Forefoot and rearfoot were each redundantly equipped with five, respectively four skin markers. Each subject performed ten running trials, whereas only rearfoot running was accepted. The estimation of joint rotations was based on a least-squares fit of two point clouds and an orthogonal anatomically defined joint coordinate system (Dettwyler, 2005). Results and Discussion: All forefoot to rearfoot motion graphs showed a clear characteristical shape. Joint kinematics featured a good repeatability within each subject. During the first 50% of the stance phase the following forefootrearfoot mean range of motion values over all subjects were found: dorsiflexion 10.50 (±3.0°), abduction 5.60 (±2.2°), eversion 7.70 (±2.4°). Between 50 and 100% stance phase 24.90 (±4.4 °) plantarflexion, 12.20 (±1.9 °) adduction and 4.10 (±2.50 ) inversion occurred. Thus, relevant motion was present between the forefoot and the rearfoot. Summary: When modeling the foot as one segment the motion between forefoot and rearfoot is neglected, thus the one-segment-approach overestimates the motion between rearfoot and shank. Therefore, it is recommended to use two segments for future investigations on lower extremity kinematics during running. References Dettwyler M.T. (2005). Dissertation. ETH Z~irich Nr. 15968. Hunt et al. (2001). Clin Biomech. 16: 592~00. Nachbauer et al. (1992). Med Sci Sports Exerc. 24: 1264-1269. 6675 Mo-Tu, no. 33 (P61) Development of a lining for a comfortable sport shoe M. Neves 1, J. Cunha 1, J. Teixeira2, P. Lobarinhas 2. 1University of Minhe, Department of Textile Engineering, Guimar&es, Portugal, 2 University of Minho, Department of Mechanical Engineering, Guimar&es, Portugal Various studies have shown that feet are one of the most sensitive parts of the human body when referring to body comfort. The feet are consistently cooler than other parts and their protection and comfort becomes an important aspect concerning human comfort. The study of shoe comfort is of great importance to sport and leisure footwear manufactures, because in these applications, moisture disposal over a number of hours is a main issue. The aim of the present study is the development and testing of functional knitting which can be used with success in the interior of a sport shoe.