In recent years the concept of sustainability has gained increased importance as the planet's living systems have declined and many of its vital resources depleted. Corporate organisations are required now to address the "triple bottom line" by demonstrating the value of their products and services to the business alongside social and environmental values. In particular, design and manufacturing practices are changing to reflect this paradigm shift. Sustainability has become a design objective rather than a constraint, which has the potential to enhance the value of the product to the business, customer and community in general, without compromising product's performance. In order to meet the new challenges and make sustainability a reality in emerging and future products, organisations need to develop and/or adopt new design approaches and tools. This paper discusses the issues and implications of sustainable design of sporting goods. As sporting goods represent one of the most widespread product groups in the world today, they also pose potentially the highest impact to the environment. How does the sporting goods industry cope with the challenge of sustainability, and how can this industry sector develop environmentally sustainable products that will still provide the performance consumers want?

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Comfort is one of the most important factors for runners in choosing running shoes. However, it is difficult for runners to find comfortable shoes, because variation in the shoe size is limited. Morphological fit of the shoe can be improved by using insoles, because insoles can be easily customized. In order to improve the fit by this way, it is necessary to know the relationship between the shape of insoles and the perception of the fit. The purpose of this study is to investigate the relationship between the shape of insoles, pressure sensation, and pressure distribution during running. Subjects were 15 student athletes. 7 insoles conditions (control and 2 arch pad height in 3 different locations) were compared. The location of the arch pad was determined based on the location of navicular bone for each subject. Each subject evaluated the comfort by Visual Analog Scales. Foot pressure was measured by an F-scan system. Pressure sensation at the plantar arch was related to the contact area and pressure. The pressure sensation was different in 3 location of arch pad. The pressure sensation was related to the contact area when the arch pad is located anterior to the navicular bone, to contact area and pressure when it is located at the navicular bone, and to the pressure when it is located posterior to the navicular bone.

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It has been generally said that much functions, such as cushioning, stability, and grip properties, are required of tennis shoes. Above all, in the grip property on omni court, the requirement is so complicated. In otherwise, both the moderate sliding and braking properties are required at the same time. It is very difficult to satisfy these opposite functions simultaneously. Moreover, the evaluation methods of these properties have not been established yet. In this study, the appropriate evaluation method of sliding and braking properties based on a lateral step motion on the omni court is proposed. In order to check the validity of the proposed evaluation method, the evaluation results are compared with the sensual testing results obtained from many players. Moreover, the application of the proposed method to the practical sidestroke motion is also discussed.

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The purpose of this study is to discuss the aerodynamic characteristics of athletic spike shoes using wind tunnel test and computer fluid dynamics (CFD). Wind tunnel tests with the full size athletic spike shoes with upper cover and that without upper cover were carried out to measure the aerodynamic forces (drag, lift and side force). It was found that the drag force of the upper covered athletic spike shoe in the case of attacking angle to be 0 deg. was 1.24N, that of attacking angle to be 35 deg. was 2.51 N, that of attacking angle to be 90 deg. was 3.50 N and that of un-upper covered athletic spike shoe in the case of attacking angle to be 0 deg. was 1.04 N, that of attacking angle to be 35 deg. was 2.23 N, that of attacking angle to be 90 deg. was 3.28 N. An incompressible steady-state analysis was performed using the finite volume method based on fully unstructured meshes with a commercial CFD code (FLUENT6.1, Fluent Inc.). It was also found that the drag force of the upper covered athletic spike model was smaller than that of the un-upper covered athletic spike model. These results suggest that the drag force of the upper covered athletic spike shoe is about 10 percent smaller than that of the un-upper covered athletic spike shoe.

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In order to increase the durability of spikes with resin stud, it is a very important key to select stud material with the higher wear resistant property. However, the quantitative evaluation method of the resin wear resistant property has not been established. In this study, an original evaluation method is proposed. The validity of this method is checked by a comparison with resin wear volume after practical running under the perfect constant condition Moreover, the influences of resin mechanical properties and injection molding condition on wear resistant property are also discussed

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One of the required parameters for running shoes is the impact absorption performance. Impact absorption has an important role to protect a runner from stress and impact. The impact absorption performances of 3 types of shoes were examined by the drop-weight impact test. Furthermore, motion of runner was classified into two, one was that related to the landing and other was related to the taking off, by the EMG and the knee's acceleration sensor. This research led us to decide that the impact absorption of shoe sole especially affected EMG in landing motion, thus the relationship between impact absorption of shoe sole and human's EMG of landing motion was studied.

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Stability which controls the excessive foot motion is one of the important requirement property for running shoes. It is effective for designing the stability to control the torsional deformation of sole at the midfoot region. However the direct structural design is so difficult, because sole torsional deformation is affected by the three-dimensional sole geometry. In this study the optimized designing method based on the homogenization method is applied to sole stability designing. At first, torsional stiffness evaluation base on eigenvibration mode obtained from eigenfrequency analysis is proposed. Then topological optimized designing method in which object function is maximum of eigenfrequency is carried out to design the midfoot region. Finally the validity of the above method is checked by the comparison with the experiment result.

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Fitting comfort is one of the most important factors for runners in choosing suitable shoes. However, it is not always true that runners choose the best shoes from anatomical point of view, because fitting comfort is affected significantly by the preference and the habituation. For example, a runner with wide feet tends to prefer a tight shoe. This suggests that the true fitting comfort may not be realized by conventional research methods in which fitting comfort is evaluated by sensory evaluation. In this paper, we discussed a possibility of an objective assessment of the fitting comfort. Tight and loose fitting shoes were selected for a subject based on the morphology, and the mechanical interactions between the foot and shoe when worn by him were measured. As physical measurements representing the mechanical interactions, the skin temperature was measured using by a thermistor-thermometer at 3 locations of the foot during the treadmill running, and the relative displacement between the foot and shoe was measured at 2 locations of the foot using a high-speed camera. Using these physical measurements, the risk caused by the morphological misfit was examined. The results suggested risks of the blood flow disturbance and loss of power transmission, and a possibility to estimated the objective fitting comfort.

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The objective of this study was to assess the kinematic and kinetic effects of wearing a lateral wedged insole on the knee joint moment during gait, specifically in the frontal plane, in individuals with unstable ankles. Motion analyses were conducted with (1) a three-dimensional motion analysis system and (2) a ground reaction force analysis using force platforms when subjects walked under two different conditions: no wedge and a wedge with a 6-degree lateral angle. The 6-degree lateral wedge significantly reduced knee joint varus moment and increased subtalar joint valgus moment. This finding was correlated with a greater moment arm of the subtalar joint valgus moment with the 6-degree lateral wedge. These results indicate that, under gait conditions, the individuals with unstable ankles wearing lateral wedged insoles had both changes of moments at the subtalar and knee joints via the more laterally shifted location of the center of pressure.

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Because of the differentiation procedure and coodinate transformation, video analized has the problem that calculation of joint torque is inaccuracy. In this study we calculated lower limbs joint torque at knee using gyroscope and accelerometers in runnig. This measurement system is consist of one dual axis accelerometer and one piezoelectric gyroscope, which detects angular velocity and tangential acceleration of the shank of right leg in the sagittal plane. The resuls showed that the knee joint torque from gyroscope and accelerometer are very clearness when subject running 50m. And we found that changing peak joint torque for many steps in sprint running.

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In this paper, the effect of the kinesio taping on the muscle fatigue of the lower extremity is investigated. To this end, a subject performs usual gate motion after load motion using the muscle force measuring and training machine. Some characteristic quantities from the kinematical sense during gate motion are measured and compared between the cases with and without taping. As a result, in the case of gate motion, it was shown that the muscle fatigue in the case of gate motion with taping is less than the one without taping. The load of gate motion is, however, little, so that it was noted that the lower extremity may exert more power to resist the taping. The other hand, in the case of load motion, no significant differences of the characteristic quantities can be observed between the cases with and without taping. It was considered that the taping has not much effect on muscle fatigue in the case of load motion.

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Phenomena of tennis ball impact on a string are formulated through the application of Duhamel's integral. The equations formulated are solved numerically. The effects of initial tension and Young's modulus of the string are investigated.

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The purpose of this research is that clarifies and improves the vibration characteristic by experiment and calculation in order to do the countermeasure of the vibration problem by predicting in the design development and to shorten the development time. This study compares and examines the vibration in the case in which the ball was struck actually and was dropped with the experimental mode analysis using familiarly used tennis racket. It was proven that the second mode appeared, when it struck it by excluding sweet spot. Future schedule carries out the structural optimization of model tennis racket using the anti-resonance point transfer theory.

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Players often say that some strings provide a better grip and more spin than others, but ball spin did not depend on string type, gauge or tension in the past laboratory experiment. There was no research work on the spin to uncover what is really happening during actual tennis impact owing to difficult experiment. This study made clear the mechanism of top spin and its improvement by lubrication of strings according to the previous paper with high speed video analysis of the authors. As the main strings stretch and slide side ways more, the ball is given more spin when the main strings spring back and the ball is released from the strings. This paper provided the detailed explanations that the more spin produce longer contact time between ball and strings, resulting in the reduction of shock vibrations of the wrist joint during impact This paper.

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Currently, the terms used in describing the performance of a tennis racket are still based on the feel of an experienced tester or a player. However, the optimum racket depends on the physical and technical levels of each user. Accordingly, there are a number of unknowns regarding the relationship between the performance estimated by a player and the physical properties of a tennis racket. The lightweight racket with head-heavy configuration is recent tendency of high-tech rackets, increasing power with an increasing racket swing speed. Racket frames as light as 200 grams have appeared in the market. However, the predicted results showed that the lightest racket at present in the market has advantageous for racket head speed, but disadvantageous for coefficient of restitution, rebound power, and post-impact velocity for ground stroke, and it has also large shock vibrations at the racket handle compared to the ordinary super-light weight racket. This means a limit to the weight lightening of tennis racket from the viewpoint of performance. The engineers and racket designers at the racket companies seem to be under intense pressure to keep pumping out new and better technologies every year. This paper investigated the physical properties of new type of rackets appeared in the market with wheels or with clamped strings by contraries replacing conventional grommets on the sides, predicting racket performance in terms of the coefficient of restitution, the rebound power coefficient, and the post-impact ball velocity relevant to the power of the racket. It is based on the experimental identification of the racket dynamics and the simple nonlinear impact analysis. The predicted results could explain the difference in mechanism of performance between the two new type rackets. Although the racket with clamped strings provides higher coefficient of restitution around the center of strings face than the racket with wheels on the sides, there is no big difference in the performance relevant to the power. The shock vibrations at the wrist joint relevant to the comfort or feel will be reported in a separate paper.

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The lightweight racket with head-heavy configuration is recent tendency of high-tech rackets, increasing power with an increasing racket swing speed. Racket frames as light as 200 grams have appeared in the market. However, the predicted results showed that the lightest racket at present in the market has advantageous for racket head speed, but disadvantageous for coefficient of restitution, rebound power, and post-impact velocity for ground stroke, and it has also large shock vibrations at the racket handle compared to the ordinary super-light weight racket. This means a limit to the weight lightening of tennis racket from the viewpoint of performance. The engineers and racket designers at the racket companies seem to be under intense pressure to keep pumping out new and better technologies every year. This paper investigated the physical properties of new type of rackets appeared in the market with wheels or with clamped strings by contraries replacing conventional grommets on the sides, predicting racket performance in terms of the impact shock vibrations of player's wrist joint, which might be related to the feel. It is based on the experimental identification of the racket-arm dynamics and the simple nonlinear impact analysis. The result showed that the shock vibrations at the handle and the wrist joint using the racket with clamped strings are larger than those using the racket with wheels, though the racket with clamped strings provides higher coefficient of restitution around the center of strings face than the racket with wheels on the sides.

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Tennis players need to learn perceptual skills in watching the hitting motion executed by opponent. In skilled perception, visual information of skinning (i.e. body shape and color shading) should have strong effect. This study was aimed to investigate the perceptual effect of the visual information with skinning in tennis serve. Fourteen collegiate tennis players watched the tennis serve motion developed with computer graphic animations of three models (skin, shadow, stick), which were modulated at a certain joint of the racket arm, and required to answer the joint modulated. Results showed the skin model tended to be less correctly answered. As tennis serve motion, which is usually considered as a rapid motion, it is suggested that abstracted motion, e.g. stick model, give effective information for perception.

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It is expected to make use of computer graphics (CG) technology for the studies on anticipation skills in sports. The purpose of this study was to clarify the differences in the characteristics of the anticipation skills when presenting the tennis serve motion with CG animations by comparing with VTR movie. On the bases of the coordinate data of the human body, CG animations were made by a CG modeling software. In the assessment of the CG, we examined anticipation skills when twelve expert tennis players anticipated serve direction during the observation of projected serve motion. Although our results showed that the anticipation accuracy and judgment timing for the presentation of CG animations were similar to that of VTR movie, the searching strategies were different. Therefore it is suggested that the difference of searching strategies is yielded by the smaller amount of information in CG animations than in VTR movie.

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Impact problem between a bat and a ball was studied using vibration modal analysis. Initial kinetic energy of the ball and the bat before the collision is transmitted to their vibration energies and their rigid body kinetic energies. The rebound speed of the ball is theoretically calculated and was measured in the experiments for slow speed impact condition. There was a good agreement between the calculation and experiment. The rebound speed of the ball was also calculated for the high speed impact condition. When the bat hits the ball with relatively high speed, higher order vibration modes appear. Therefore it is possible to increase the rebound speed of the ball by changing the design of the bat, such that the higher order modes are suppressed.

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It is desirable for the design of a baseball bat to analyze exactly the phenomena of the impact between baseball and bat. In order to establish powerful analytical tool for the baseball-bat impact, the numerical analysis programs based on 3-dimensional finite element method are developed. After the calibration of developed programs due to the comparison between calculated and experimental results, the impact characteristics of an aluminum bat for rubber-ball baseball are investigated precisely. It is found that the COR value decreases as the impact velocity increase and it is deeply affected by the hoop rigidity of the cylindrical shell structure in bat.

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In the baseball as popular sports, there are many impact damage accidents by the ball. However, until now there are very few examples which the impact loads and its influence at the time of a ball collision are analyzed. This research clarifies the influence of a ball crash against a living body. In order to create the FEM analysis model of a ball, the material testing of a ball is performed and the material constants are presumed. An impact experiment of the ball with target using the pitching machine and the impact simulation using the dynamic FEM are performed. From the results, the impact force, the contact time and the deformation behavior of ball are obtained.

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To develop position specific baseball gloves, pressure distributions on fingers and palm during the catching motion were measured by using Glove Scan system. As a result, it is found that the pressure distribution is different in each position. For example, the pressure distribution of second baseman shows high pressure in the tip of each finger. On the other hand, the pressure distribution of third baseman shows high pressure in the whole area of middle, ring, and little fingers. The force transmission was improved when we reinforce the part of the glove based on pressure distribution data.

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This study examined two factors that are important for baseball batting, (1) swing speed and (2) ability to repeat the same swing (repeatability). Twenty male subjects participated in the study; eight beginners, five active players from a university baseball club (players), and another seven who played baseball at a high school or university but are not active now (experienced). Each subject hit a ball on a batting tee fifteen times. Swing speed was measured by a custom-made machine using laser position detectors. The motion of the bat head was also recorded by a high speed video camera (250 flames/s). Swing speed was 82.6km/h, 108.2km/h, and 97.2km/h, for the beginner, player, and experienced groups, respectively. Repeatability of the swing was evaluated by utilizing the standard deviation (SD) of the bat head position in the vertical plane when it hit the ball. The SD was 2.1cm for the beginners and 1.1 cm for the player and experienced groups. There were significant differences in both swing speed and repeatability between the beginners and the player or experienced groups. These data suggest that both swing speed and repeatability improve with practice.

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The most common commercial pitching machines are the "two roller" type and also the "arm" type. These machines tend to have certain limitations. In particular it is very difficult to simultaneously change both ball speed and direction. Also some types of pitches, such as the curve or sinking ball, are not easily achieved. In this study we will explain the hardware and software design of a new "intelligent" pitching machine which is able to pitch repeatably with selectable speed, direction and ball rotation. The machine we built had three rollers and the motion of each was independantly controlled by a heirarchical neural network. This network accepted ball speed, direction and rotation as inputs and produced detailed motion control of the three rollers as output.

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In this study, upper extremity of overhand throwing motion was modeled as the link segment system including three segments (humerus, forearm and hand) and 7 degrees of freedom of joint motions. Throwing motions of 3 subjects were filmed from 5 high-speed cameras and joint torques were calculated using the inverse dynamics. The relationships between the joint torques and the velocity of distal end point of upper extremity were analyzed. The results showed that shoulder internal rotation torque (IR) contributed greatly to production of ball velocity and shoulder horizontal adduction torque (HAD) contributed production of elbow velocity. Because of the interaction of IR and HAD, proximal to distal sequential motion of throwing arm was occurred.

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The propelling force in swimming is mainly generated by a hand, although the ratio of the propelling force is not certain whether from the hand or from the whole part of forearm. Replicas of a hand and an arm were produced from a same excellent swimmer. Those characteristic of lift-drag forces and propelling force ratio were taken out by wind tunnel tests based on angle of attack and sweepback angle (horizontal driving angle). As a result, it turned out that the propelling force of the whole arm was set about from 3 to 4 times larger than that of only a palm in the catch and the finish phase of S-shaped pull, and that it was about 1.8 times larger at the pull phase of S-shaped and drag pull swimming.

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The word, "power" is used both in engineering and in human daily life. The definitions or meanings are, however, different from each other. Think a tug of war in deadlock as an example. Power is zero in engineering, even man gets tired. Since sport engineering aims at applying engineering (in most cases mechanics) to human behavior, the definition of power, inner product of force and velocity, is not appropriate. Another definition of power, "physiological power", was proposed to bridge the gap between two meanings of "power". This definition accounts for the above-stated case; a tug of war in deadlock. Its examples to swimming were also included, and the differences between "mechanical power" and "physiological power" are investigated.

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The purpose of present study was to estimate the arm joint angles in front crawl swimming using the accelerometer. The subjects were four well-trained swimmers. The acceleration of the swimmer's wrist was measured using the tri-axial accelerometer, which was attached to swimmer's forearm. The arm motion under water was expressed by the arm motion model, which had three degree of freedom. Each angle of arm joints was formulated as exponential functions. The angles of swimmer's shoulder extension and elbow extension/flexion were estimated using the acceleration data of swimmer's wrist and the arm motion model of front crawl swimming. The results showed the estimated shoulder extension angle was similar to the angle calculated from videography, although it was difficult to estimate all parameters of shoulder extension and elbow extension/flexion angles. It was concluded that the measurement of swimming motion by accelerometer had the possibility to be applied as suitable method to the training of swimming.

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A viscoelastic split Hopkinson bar (SHB) technique is successfully applied to study dynamic behavior of a two-piece golf ball. Strain histories of the incident, reflected and transmitted waves on the input and output bars, resulting from SHB tests on cylindrical specimens of cover and core materials of the two-piece golf ball, are resolved into frequency components by Fourier transformation. Then, in frequency domain waveforms at measurement points are corrected to those at the interfaces between a specimen and bars. The complex compliance of each material is determined by calculating strain-stress ratio in the frequency domain, and 3-element viscoelastic models are subsequently identified based on variations of the complex compliances.

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In the present study, the shape optimization of a golf club is investigated. The optimization of thickness distribution of a clubface is studied for maximizing the release velocity of the ball under the constraint of a constant amount of the clubhead weight The basis vector method, which is an approximate method for the optimization problems, is employed because the sensitivity cannot be derived analytically. The basis vector represents the fundamental change of the shape, and it is preferable for obtaining effective results that the basis vectors are independent mutually. The eigenmodes is used to create the basis vectors in a 3-dimensional problem. The theory of impedance matching is comfirmed numerically by a 2-dimensional example. A 3-dimensional example is given to show that this approach is effective to optimal design of golf clubhead.

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In this paper, we investigate the gripping force in golf swing, which is considered to have close relationship with performance and feeling of the club. The sensor grip using the force sensor chip was developed which can detect the gripping force in radial direction (Fz), tangential direction (Fx). and axial direction (Fy). The sensor grip was attached on the shaft of the test club and the dynamic: gripping force on some part of finger and palm in swing action was examined. Some remarkable results of change in radial and frictional force were obtained as follows. (1) Using a parallel structure plates, we were able to manufacture the reliable sensor chip. Which detects forces in radial direction, tangential direction, and axial direction. (2) In golf swing, the force changes in five periods at swing start, down swing, rist release, impact, and after impact. (3) On the left hand, large axial force is applied as a drawing force for the swing. In the right hand, large tangential force appeared as a force to control of the head face direction. (4) Near the impact, the reduction of the axial force in the left little appeared which may cause the head move straight.

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No one can know how players exert forces and moments on the grip handle from the swing motion. Because the club is manipulated by the hands during swing motion, the upper limbs and the club make a closed multiple-segment loop. This paper proposed a calibration method of the instrumented club under several axial-load conditions for the purpose of studying various tensile-force conditions. The relationship between the sensor output voltage and the applied bending moment at each sensor showed very good linearity and showed little crosstalk in terms of the moments acting about other axes. However, as the tensile loads affected the relationship, the gradients of linearity were calculated by using interpolating functions with respect to the tensile loads. As for the axial forces, the sensor output voltages also showed good linearity with respect to the applied loads, but cross-talking occurred between the tensile forces and the applied bending moments measured at the sensor points. Therefore, the interferences terms were approximated by using polynomial functions and substituted by them. A skilled golf player volunteered to participate in this study as subject. He performed shots using sand wedge club. From the results obtained by this study, the validity of the proposed method was clarified.

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本発表では,粒子シミュレーション手法の1つである粒子要素法を用いて構築した,バンカーショット解析モデルにおいて,実際のサンドウェッジをモデル化し,そのクラブヘッドの形状特性を評価した結果を報告する.粒子要素法は粉体を構成する粒子間の相互作用の総体として,粉体現象をシミュレートする手法であり,バンカーショット解析モデルは,クラブヘッド,ボール,バンカー砂粒子群によって構成される.シミュレーション結果と,実際のショットとの比較を行い,モデルの再現性を検証した.また,ソール部分に溝加工を施したサンドウェッジと通常のサンドウェッジの,ショット条件の違いによる挙動を解析し,形状特性の評価を行った.

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The possibility that elastic supported plate might impact more speed ball than rigid face has been the subject of conjecture in recent years. This impact phenomena was called the effect of trampoline. However the mechanism of the effect of trampoline has not been clarify explained. This sheet proposes to clarify the mechanism of the effect of trampoline by means of computer simulation. As the results of numerical analysis, coefficient of restitution increases when the period of elastic supported plate and duration of contact time of ball coincided with each other. Next, impact characteristics of non-linear support system calculated. As the results, the effect of trampoline is bigger linear support system.

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Many researchers have studied the impact phenomenon in ball games, such as golf, tennis, baseball, soccer and so on. Although it is very important to understand the dynamic characteristics of a ball on the impact phenomenon, the sufficient theoretical understanding of the characteristics has not been obtained. In this paper, normal impact of hollow balls on flat surfaces is theoretically analysed and the dynamic deformation of hollow balls is derived as an axisymmetric motion of an elastic spherical shell by using modal expansion method, where variation of contact area is took into account. Numerical calculation has conducted and the dynamic characteristics are discussed.

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In the golf, the flying distance and direction of ball just after impact is influenced by various motions of the golfer's rotation and translation, the sidespin and initial velocity of the ball, the motion club head and so on. Since the cock motion is done in the near point of contact of the body and the club. It is noticed as the position which transmits the energy stored in the rotation of the body to the club. In this paper, we proposed the measurement method and it's system for using the gyro sensor in order to measure this motion. Although the method was developed for cock motion measurement in the golf swing, it can be applied to baseball, tennis and so on.

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The authors developed a golf swing skill evaluation system using 3-axis piezoresistive accelerometers. Three different kinds of 3-axis piezoresistive accelerometers were attached on the golfer's hip, left wrist and the golf club head. The acceleration time series from these sensors and the synchronized video images were measured during the golfer's driver swing motion. In this study, we focused on both the sway motion of the golfer's trunk and the uncock timing during the down swing phase. This application enables golfers to understand their skill characteristics and improve their technique right after their trials.

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This paper aims at addressing the dynamic simulation capability of the three different types of the two dimensional double pendulum models for the golf swing. In the studies on the golf swing motion, there is no discussion about the dynamic simulation capability of the model. Comparing with the simulation results for the four intermediate level golfers and three advanced level golfers by using the three models, the influence of the difference of the simulation models on the required torques of the neck and wrist joints are discussed here. The results show the same dynamic simulation capability of the three models. The difference of the golfer's level can be evaluated by the time variation of the distance between the neck and wrist joints during the downswing.

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In this study, we perceived the important leg, in order that people might move. Purpose of our study is to suggest the optimum running method by explaining change of a reaction force and a speed in case of grand differences. We calculated the reaction force and the running speed using the four-link model of the leg. As a result, compared with the case of running on the asphalt and the case of running on the sand, the running speed decreases 15.8% in running on the sand. So we carry out the simulation using Particle Element Method (PEM) in order to restrain decrease of the speed in running on the sand, and suggest the optimum running method.

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The purpose of this study was to calculate an equivalent stiffness matrix with respect to ground reaction force during running motion. Eight Subjects' 2-D images for the motion analysis and ground reaction forces were recorded by using a high speed camera and two forceplatforms. The angular velocities which contribute to vertical direction movement were extracted from joint angular velocities using Jacobian Matrix. Joint stiffness of each joint was calculated from a joint torque and the angular velocity. An equivalent stiffness matrix on center of pressure was transformed from the joint stiffnesses. At comparison of heel striker with forefoot striker, differences were observed at the equivalent stiffness matrix. The results of this study suggest that the equivalent stiffness matrix has a potential to quantify the characteristics of runners and running forms.

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The purpose of this study is to understand the effect of skull local shape on the peak stress and stress distribution. A skull-brain finite element model of the human head was constructed by the CT anatomy images. This model includes inner and outer tables (cortical bones), diploe (a cancellous bone), brain and celebral-spinal fluid (CSF) layer. The mechanical properties were obtained by the aid of the published data. The model was validated by using the three types of the published test data from cadaver experiments. In order to know the local shape effect, the present model was compared with the H-head model under impact. The load was applied to a freely supported head on the frontal bone in the midsagittal plane. The Von Mieses stress distributions of the cortical and the cancellous bone were different from each other. A head model with the shape of high fidelity is necessary in order to detect the possibility of the fracture of skull.

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The purpose of this study is to develop the gait support machine that is possible to do rehabilitation. The gait support machine judges a patient's condition automatically and the person can do rehabilitation which suits the person safely without care worker's instruction. The brakes are attached in the machine and are possible to apply load. In this paper, floor reaction forces and joint angles (an ankle, a knee, waist joints) are measured during a normal gait of a healthy person and a gait of using the prototype machine. And the results are compared and it is considered the effect of the prototype machine on a gait operation.

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