The purpose of this study is to investigate the influence of the heel-gradient, which is the heel-toe drop in shoe-sole, on the dynamic characteristics of the support leg muscles in a constant pace running motion. Two types of indices; such as, muscle contributions to the whole-body CG acceleration, and dynamic conversion ratios of individual muscle to the generation of the whole-body inertial force, are calculated from a dynamics analysis utilizing the equation of the whole-body motion. The results obtained from seven heel strikers' running motion at the speed of 3.3 m/s indicate that (1) increase in rearfoot midsole thickness relative to forefoot one provided i) increase in the contribution of vasti to support caused by the increase of the magnitude of muscle force, ii) increase in the contribution of vasti to braking caused by increase of the dynamic conversion ratio, iii) decreases of muscle force and relative load of gastrocnemius, and iv) decrease in the contribution of gastrocnemius to propulsion, and (2) decrease in the contribution of soleus to support was affected by decrease of magnitude of muscle force, and increase in the contribution of soleus to propulsion was affected by increase of the dynamic conversion ratio.

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The purpose of this study was to know the relationships between subjective evaluations and three dimensional kinetics and kinematics data of running motion. We captured three dimensional kinetics and kinematics data of running motion of 35 average runners. At the same moment, we recorded video pictures of running to apply to subjective evaluation test. We selected 12 persons as evaluators of these pictures. They had enough experience of coaching or had sufficient knowledge of biomechanics. In rating, there were totally 9 descriptions (Pace, Style, Secure, Rhythm, Relax, Dynamic, Smooth, Balance, Total) in the 7-grade evaluation. The results of subjective evaluation of running motion were classified into only 2 parameters ('Dynamic' and 'Secure') by means of factor analysis. For each representative parameter, correlation coefficients with all kinetics and kinematics parameters were calculated and screen out the inessentials. As a result, these parameters were classified into 10 groups by means of multiple regression analysis and we calculated multiple regression equation on these parameters. Finally, we calculated multiple regression equation of 'Total' composed of 'Dynamic' and 'Secure'. The determination coefficient value of equation was 0.84 using a 0.01 level of significances. These results suggested that it was possible to quantify the running motion accurately by subjective evaluations.

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The purpose of this study is to compare the differences of running styles, Rear-foot strike (RFS) and Fore-foot strike (FFS), concerning the parameters of the vertical mathematical model and propose effective running style. The ground reaction forces are measured by force platform under two types of running style with various velocities ranged from 2.23 m/s to 4.46 m/s. A unique set of parameters of the model for each trial is computed by nonlinear programming to minimize the sum of the relative standard error of ground reaction force and the relative error of rebound velocity. The differences of the running styles were considered by using results from parameters of multi-degree of freedom model. The results of this study indicate that although the FFS needs much energy than that of RFS in low speed running, the FFS needs less energy than that of RFS in high speed running because of the impulse as the internal forces that is calculated by a set of parameters of multi-degree of freedom model.

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In this study, the functional role of starting blocks in the sprint start was examined. Participants were 6 sprinters (height: 175.8±5.0 cm; weight: 69.2±4.0 kg; personal best 100 m time: 10.65±0.13 s) who performed two kinds of sprint starts: a crouch start with starting blocks (BS), and a crouch start without starting blocks (CS). During block clearance, two force plates were used to measure the force applied to the front and rear starting blocks (in BS) or to the ground (in CS). The force plates were placed under each block (in BS) or under the participant's feet (in CS). The ground reaction force of the first and second step after block clearance was measured using another two force plates. The sampling frequency for these measurements was 1 kHz, and kinematic data were recorded using four high-speed cameras at 250 frames/s. The horizontal impulse applied to the rear block in BS was greater than that applied by the rear foot in CS; the horizontal impulse applied to both starting blocks in BS was greater than the horizontal impulse in CS. The vertical impulse applied to both starting blocks in BS was lower than the vertical impulse in CS, and the duration of force application to both starting blocks in BS was shorter than the duration of force application in CS. Taken together, starting blocks enable a greater horizontal impulse to be applied in a shorter time during block clearance, compared with no starting blocks. Therefore, the starting block can be regarded as an essential tool for enhancing sprint start performance.

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Shock attenuation property of shoe is especially important in indoor-sports because indoor-shoe users perform a jump and suffer a large landing impact force repeatedly. Moreover foot landing pattern is essentially different between jumping and running in that the forefoot lands first with the rearfoot next in jumping and vice-versa in running. This study firstly developed an evaluation method of shock attenuation in drop jump with accelerometer after the relationship between the acceleration data on the shank and sensory test values of shock attenuation was found. Furthermore, the stress-strain curves of shoe-sole materials under compressive load and also plantar pressure distribution during drop jumps were measured to calculate the stored energy in the forefoot and rearfoot areas of shoe-sole respectively. It was found that the main area attenuating the landing force by its compressive deformation in drop jump was the rearfoot of shoe-sole however the shock attenuation property could be affected by the hardness of the forefoot area if the mechanical conditions of the rearfoot area were the same.

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The purpose of this study is to investigate the shock attenuation properties of long pile synthetic turf filling unit. Two different types of specimens (turf in infill, volume ratio; sand : rubber = 5:5 and 7:3), one type specimen (no turf in infill, volume ratio; sand : rubber = 5:5) and five different areas of test foot were prepared. Multi-intensity multi-area impact tests (20 impact trials with different intensity are performed for each 5 different impact areas) were performed for considering the parameter identification and shock absorbing properties with simulation. As the results, we could not measure in no turf because test foot was buried in infill. But, Stable data were obtained in turf. Adaptation of exponential type nonlinear Voigt model is also possible for the sample of this study. However, identification accuracy was same as the previous study.

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Knee osteoarthritis (OA) is a restriction factor for daily activities of the elderly. The relationship between knee OA and knee adduction moment has been studied however the effect of walking speed on the relationship in the healthy elderly has not been clarified. The purpose of this study is twofold: (1) to investigate the relationship between walking speed and knee adduction moment especially in the elderly, (2) to verify the effect of special-made shoe on knee adduction moment. 77 subjects joined the first experiment and it was found that knee adduction moment increased with the increase of walking speed while there was no significant difference between the elderly and the young. However, the elderly showed significantly lower leg extension power than the young so it is suggested that the load on the knee adduction is relatively larger in the elderly. The special-made shoe had a hard stiffness on the lateral side of the sole and showed small knee adduction moment during walking in two subjects who had relatively large knee adduction moment out of seven subjects.

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In many sports, it is necessary to exert external forces for generating joint torques which accelerate body. Since there is a strong relation between performance and joint torque generation, inverse dynamics problem (IDP) has been used for joint torque estimation. If external forces are dominant in dynamic equations, dynamic terms can be neglected, which leads to force equilibrium. These equations of force equilibrium express geometric mapping between external force and joint torque with Jacobian matrix in statics. The authors examined validity of the equations as a tool for joint torque estimation in comparison to IDP in landing motion experiment. The results showed estimated ankle and knee torque was comparable to that of IDP. The authors theorized and established the benefit to apply equations of force equilibrium for dynamic motion analysis.

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The purpose of this study is to develop an evaluation method for compression properties of foam materials with heterogeneous microstructure. An analytical approach for evaluating compression properties of foam materials by the two-dimensional finite element analysis using homogenization method was described in this paper. First, porosity, mean cell diameter and dispersion of cell diameter were investigated from observation of cross-section structure using one foam material. Those parameters have similar features in any cross sections. We suppose that one cross section represent all other cross sections of foam material. Second, compression properties of foam materials were investigated by conducting a uniaxial compression test. Then, a unit cell model for numerical simulation of microscopic structure was created. Two-dimensional finite element analysis based on a formulation of homogenization theory was performed, and the analysis results were compared with the compression test result. As a result of the comparison, the effect of foam material structure on compression properties was evaluated.

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Highly functionalized polymer materials are demanded to improve performance by computer simulation because of its economical efficiency. Recently, constitutive law including the effect of dumping are needed for modeling such materials. Elasto-viscous models are generally selected in this case as it can represent dumping conveniently, while elasto-plastic models can be an effective option when we consider problems of wide strain range. Based on above, we need to apply proper constitutive law to practical design of commercial products. Therefor we remarked at elastoplastic models for the key step. The aim in this paper is representing yield point of resin materials which depend on temperatures and strain rates by adopting Cowper-Symonds equation. We paid attention to take simple ways so it might be manageable when dealing with some similar analyses.

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Due to excellent properties, high damping, low density and unique stress-strain curve, resin foams have been widely used in various industrial fields. As a midsole the application of the resin foams is dominant, because the plastic foam has many designing parameters such as foaming ratio, matrix resin type, cell size and geometry. In the designing process of midsole material, the prediction of mechanical behavior is very important. In this study the simplified numerical simulation model for EVA(Ethylene-Vinyl Acetate) foam is proposed. This model is constructed by thin shell elements and void is represented by Kelvin's truncated octahedron. The cell wall thickness distribution is considered by the shell elements' thickness control. In order to check the validity of the proposed model, stress-strain relationship under the uni-axial compressive load is compared with experimental one. After the checking, friction effect between rigid plate and foam surface on the mechanical behavior is discussed. Moreover it was confirmed that the model could predict the foaming ratio dependency.

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In this study, a homogenization analysis of foam materials to consider the microscopic structure was conducted. This analysis allows the establishment of a design method for porous polymer for sports equipment. A foam material was defined as a material which has a periodical microscopic structure. Deformation of the microscopic structure was uniform, and microscopic periodicity was kept under finite deformation. The polymer matrix was assumed to have incompressible hyperelasticity, which was represented by the Mooney-Rivlin model. An original 3-dimensional simulation program was developed. Uniaxial tensile tests using foam materials were conducted to investigate the effect of porosity on mechanical characteristics. Specimen porosities were 26%, 61%, 66%, and 76%, and pore shape was nearly spherical under microscope observation. The simulation model also had periodic and equally-sized pores. Uniform deformation and periodic boundary condition were applied to the unit cell. The applicability of the proposed method for foam materials was shown by comparing the numerical simulation with the mechanical loading test results.

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The performance of female players is increasing worldwide. It seems important to be able to kick a fast ball for scoring goals in a high level soccer game. To kick a fast ball, clarifying the leg swing motion mechanism, and conducting training suitable for female which is based on scientific evidence are inevitable. This study was designed to compare the swing motion between female and male soccer players to extract the mechanical and technical characteristics of female players. The motion capture system (250 Hz) were used to compare ball velocity, foot velocity, average peak knee joint torques, angular velocity of thigh and shank, and average energy ratio of female and male soccer players in an attempt to elucidate the mechanical and technical characteristics of female players before ball impact. The ball velocity, foot velocity immediately prior to impact, and average peak knee and hip joint torques, average thigh and shank energy were smaller for the female players than for the male players (p < 0.05). Moreover, the mean thigh-to-shank energy ratio for female players was lower than that of male players. Female and male players' swing motions presumably include energy transfer by means of a kinetic chain technique between the thigh and shank; however, our results suggest that female players may have a lower thigh-to-shank energy ratio than male players. In order for female players to increase ball velocity, effective transfer of energy from thigh-to-shank seems to be vital important.

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In studies dealing with body movement and sports techniques, a method that is commonly used involves analysing joint torque using inverse dynamics based on kinematic data obtained through motion capture systems. On the other hand, another analytic technique that has become increasingly common entails generating movements and performing simulations on the basis of the force data for joint torque and the like; this technique employs forward dynamics to calculate the kinematic data. In general, however, the inverse dynamics and forward dynamics analyses are performed independently, and there have been almost no studies in which analysis is conducted by combining the two analyses. Therefore, in this study, an analytic environment was constructed for analysing the motion of kicking a soccer ball, in which inverse dynamics and forward dynamics were combined; the environment was constructed by using a formula manipulation language based on a simple two-dimensional double pendulum model. The results showed that although the kinematic data obtained from the motion capture system did not completely match the kinematic data obtained from the simulation in which forward dynamics was used, adequate agreement was observed between the two sets of data. In this study, it was considered that the development of an analytic environment that combined inverse dynamics and forward dynamics enabled a more refined analysis of the motion of kicking a ball.

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The purpose of this study was to describe the characteristics of the ball impact in soccer volley kick. Nine experienced male soccer players performed volley kicks. The ball was projected by soccer machine at three speeds (9.0m/s for Low speed condition: 11.5m/s for Middle speed condition: 15.0m/s for High speed condition). The volley kick performances were recorded with three high-speed cameras. Ball velocity after impact had a significant correlation with the foot velocity in each speed condition. Ball-foot speed ratio (= ball speed after impact / foot speed before impact) had a quadratic relation to the impact point of the ball on the foot along the short-axis and it was high when the ball impact point was near the mid-sagittal plane of the foot.

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In recent years, it is seen as FC Barcelona in soccer, team ball retention is high as to leave good results, but the act itself that holds the ball is not mean that the score is provided with a direct factor of victory or defeat it can not be said that. In fact, win or lose, and I wonder there is a relationship-scoring runs and keeping the ball in modern football. In this paper, by which we consider the statistical relevance of the score-runs and victory or defeat and ball retention in three major league in Europe, and discuss the direction of the ball holding tactics in the future. The result, a positive correlation was observed between the outcome and ball retention. It is believed that increasing the retention of the ball as a valid tactic and that holds the ball. Correlation was also observed with respect to scoring, runs, a positive correlation with respect to score, a negative correlation was observed with respect to runs.

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This study examined the impact of different trajectories of a thrown baseball on batting accuracy, and discusses the actions taken by the batter that affected the accuracy of the impact. Seven university baseball players hit baseballs thrown in various trajectories, and four synchronized high-speed video cameras were used to record the hits. The movement of the bat, ball, and batter's body were analyzed by three-dimensional direct linear transformation. The results of the analysis were as follows: 1) The point of impact between the ball and the bat varied according to the ball's trajectory, suggesting that maintaining a constant impact point on the bat is difficult. 2) Batters compensated for changes in ball trajectory mainly by altering the rotation angle of the hips and shoulders. Especially for inside or high trajectories, larger hip and shoulder rotations were necessary, allowing batters to begin the batting motion earlier. 3) Batters needed to actively judge the ball's trajectory, which gave them less time to execute their swing.

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In baseball batting, the horizontal direction to which the batted ball will project is influenced by two factors; (a) the direction to which the impacting surface of the bat is facing at ball impact and (b) the interaction of the inclination angle of the bat in the vertical direction and the position of the ball impact along the short axis of the bat. The purpose of this study was to describe the three-dimensional orientation of baseball bat at ball impact for each direction (same, center, and opposite field) of batted ball. Forty-seven elite baseball players performed 7-36 trials of free-batting. Behavior of the ball impact was recorded with two high-speed cameras (2500 fps). All trials in which the bat collided with the ball, including the foul balls, were used for the analysis. The orientation of bat at ball impact was described as the azimuth angle and the depression angle of the bat's long-axis. Frequency distribution maps were constructed to display the probability of hitting the ball toward the same, center and opposite fields for each combination of azimuth and depression angles of the bat at ball impact. The frequency distribution maps illustrate that a unique zone exists for each direction of the batted ball and that the zones overlap substantially. These results suggest that batters can hit the ball toward the three directions even if the orientation of bat at ball impact was same.

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The purpose of this study was to compare between golfer's putting motion and the physical pendulum. One skilled golfer participated in this study. He executed ten putts as accurately as possible, in order to reach a target distance of 0.5, 1.0, 1.5, 2.0, 2.5m. Movement pattern characteristics were assessed by kinematic analysis. In addition, putt of the same distance were tried using the physics pendulum of firmly fixed putter. It was found that the putter head speed, at the time of impact in the human putt, exceeded that for the physics pendulum putt. The initial velocity of ball at impact of golfer's putting was faster than that of the physics pendulum's except aim distance 0.5m. Therefore, the difference between human putting and the physics pendulum was shown. However, it was understood that successful putts are achieved by having skillful motor control.

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In recent years, bicycles are attracted as lower environmental burden transfer. Then, amateur competitors keep increasing, and they began to indicate data of aerodynamic specification of bicycle components as frames, spokes, helmets and wheels. This study verified the effects of Sub9 produced by Zipp. Zipp argues this wheel "produce forward lift" in a wind angle of 12 to 18 degrees. Therefore, we made 3 kinds of wheels, plain disk, normal disk wheel and Sub9 model. Those were used as a drag force measurement and flow visualization, and investigated in non-rotate conditions and rotate conditions. Drag force of each model was measured with three components load cell. Flow visualization in a smoke wind tunnel was also carried out in a vertical plane. As a result, Sub9 produced little thrust over wind angle of 16 degrees. Plain disk have similar specification to Sub9, and normal disk wheel is the worst wheel in this study. The results of the flow visualization also explain these phenomena well.

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In a long-distance bicycle road game, in order to make the main rider win, an entire team makes a formation and assigns the main rider in an advantageous position for less drag. This study verified the effects from the formation consisted of multiple riders, usually called "train," with replicas aerodynamically. Four replicas were used as a train in drag force measurement and flow visualization. Bicycle replicas were fixed onto a ground plate, and the spacing of each replica was kept constant. Drag force of each replica was measured with three component load cell. Flow visualization in a smoke wind tunnel was also carried out in a horizontal plane at the riders' height. Several train formations expected to reduce drag including crosswinds were attempted. As a result, the least drag on the replica of the main rider was obtained when it was placed at the end of the train in a linear arrangement. The results of the flow visualization also explain these phenomena well.

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Windsurfing is a marine sport that combines elements of surfing and sailing, which started in the 1960s. The rig is connected to the board by a free-rotating universal joint and consists of a mast, boom and sail. A windsurfing sail is made of monofilm (clear polyester film), dacron (woven polyester) and mylar. Cambered sails have battens which help to hold a rigid aerofoil shape in the sail, better for speed and stability. This paper is performing analysis by a Computational Fluid Dynamics (CFD) to grasp the basic characteristic of two-dimensional sail sections. Although various airfoil profiles can be considered in the sail, arc wings are investigated because the wings are the most fundamental profiles. Three type airfoil profiles are analyzed in this paper. There are arc wings, arc wings attached to a mast, and the real sail shapes which are connected smoothly form a mast to an arc wing. Results show that arc wings are obtained the best performance among the three type wings.

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The only energy source of sailboat is wind. Decision making is need in partially observable and unsteady environment. Sailing is a reinforcement learning problem. State and action spaces consist of continuous variables such as appearance wind, target position and sail direction. Some of them are vectors. This paper shows reinforcement learning simulation with particle filter which aims to learn human sailor's knowledge acquisition of predicting and utilizing wind.

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Formula SAER is a student design competition organized by SAE International (formerly Society of Automotive Engineers). The body shapes could have been developed by CFD, but the designs of under bodies have been underdeveloped. This research evaluates the aerodynamic performance of a under tray by CFD and a wind tunnel test using a scale model. The scale model was manufactured by a 3D printer. The aerodynamic performance was measured in a wind tunnel with setting the models in mirror images which considers a ground effect. As a result, the aerodynamic performance of the under body was able to be certainly evaluated compared with the conventional method.

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The purpose of this study was to investigate the difference of joint motion and state of ball-contact between the pitches of fastball and breaking ball. The joint motion of upper limb, trunk and lower limb during baseball pitch were measured by accelerometers and gyro sensors. The state of ball-contact was measured indirectly by eight strain gauges attached to the surface of nail of 2nd and 3rd finger. Four subjects belonged to a college baseball team participated in this study and pitched fastball and breaking ball such as slider, shoot, forkball and curve ball five to ten times. Measuring with the sensors mentioned above, the angular velocities of joint motions and the strain of nail during the ball-contact were obtained directly or calculated. Those were rotation and tilting forward of trunk, rotation of hip, swing of forearm and upper arm, pronation of forearm, internal rotation of shoulder, rotation and swing of both side thighs, and left leg. As the results of analysis of the joint motion and the strain of nails, the following were clarified. The joint motions during the pitches of slider were similar to those during the pitches of fastball. The timing of ball-release of fastball pitches were later than that of slider pitches, and were earlier than that of shoot pitches. The strain of nail during the pitch of fastball was larger at nail tips called 'N' in this study. During the pitch of slider, the strain was larger at radial side of nail called 'W' in this study.

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In baseball pitching, pitcher's trunk has a kinetic role for conveying the kinetic energy from the lower limb to the upper limb. In such context, a term "the stretching of the chest", one of the upper-trunk motions, is often used in coaching. Although several qualitative reports on the term have been published, its biomechanical features and functions are still unclear, due to the lack of quantitative studies. Accordingly, the term is used ambiguously in both coaching and clinic. In order to eliminate such ambiguity, we have been trying to develop a quantitative analysis of the stretching of the chest. First, Fukushima (2011) developed parameter S defined from the relative positions of the reflective markers secured to the skin surface of the thoracic vertebrae for evaluating the curvature of the vertebrae. His preliminary studies using basic motions of the upper limb revealed that the S-value is independent from most of the motion parameters of the upper limb, except its horizontal abduction and adduction affecting the stretching of the chest. In this paper, we applied the parameter to the analysis of baseball pitching in order to clarify 1) time series of S1-value, 2) the relationship between S and the motion parameters of the upper limb, 3) kinetic chain during pitching. Experiments using 12 subjects revealed that parameter S could be a variable capable of evaluating the stretching of the chest, providing us with new kinetic information during pitching and the stretching of the chest could be considered a factor of the kinetic chain.

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Free-throws are one of the important factors for deciding basketball game outcomes. The purposes of this research were to analyze free-throws by measuring plantar pressures during free-throw movements and to explore the potential to construct free-throw training feedback application using plantar pressure sensors. Ground reaction force impulse was tested in a comparison between highly skilled and unskilled subjects. The impulse of skilled subjects was significant smaller than those of unskilled subjects. Skilled subjects also threw the ball using shorter durations and smaller ground reaction forces. In addition, the variability of impulse was much more stable in skilled subjects. The meaning of these results is likely that skilled shooters can throw the ball more efficiently with high level of movement reproducibility.

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This paper describes the hysteresis in the aerodynamic properties of a discus near to its stalling angle. Wind tunnel tests were carried out with a full-size woman's discus. The experimental aerodynamic data D, L and M were obtained from wind tunnel tests as functions of the angle of attack. It was found that the drag, lift and pitching moment coefficients, C_D C_L and C_M, increase with increasing the angle of attack up to a stalling angle of 30°. Beyond the stalling angle, C_L and C_M decrease suddenly and abruptly with increasing angle of attack. On the other hand, recovery from the stall does not occur at the same stalling angle of 30° when the angle of attack decreases from the stall state; recovery actually occurs at 25°. The C_L -α(angle of attack) curve is almost the same when the angle of attack is less than 24°. Therefore, hysteresis occurs near the stalling angle.

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We have already formulated the dynamics-switching three-link and three-joint (an upper body, two thighs, and two lower legs) optimal control model that reproduces human rising movements from a chair, and clarified its effectiveness and the existence of the optimal relation between two factors (input weight and dynamics-switching time) indispensable for sit-to-stand movements. This report clarifies theoretically how the knee- and ankle-joint torques at the seat-off time affect the subsequent rising movement, and examines the possibility to predict the risk of falling caused by miscalculation of these torques. Consequently, the following results are shown: (1) as for the knee- and ankle-joint torques at the seat-off time, there exist effective ranges necessary for the optimal control model to rise successfully from a chair, and the range of the knee-joint torque is smaller than that of the ankle-joint torque; (2) a shortage of the ankle-joint torque at the seat-off time makes the model pratfall; (3) a shortage of the knee-joint torque at the seat-off time makes the model fall forward to its knees, and an overage of the same torque makes the model pratfall. These results suggest that the knee- and ankle-joint torques at the seat-off time can be important factors controlling the success or failure of rising movements from a chair, and that the optimal control model is effective in simulating falling movements as well.

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The objective of long jumping is try and jumping as far as possible by stepping on a take off board and landing in the sand pit. In the long jump landing, athletes are affected by the dynamics of the reaction force of the sand pit that is different from the hard surface reaction force. Therefore, in order to obtain a good landing motion, it is necessary to simultaneously analyze the dynamics of sand and athletes. The aim of this study is to obtain an optimal landing motion in the long jump by Multi-Objective Genetic Algorithm using a long jump model. This model is composed of two elements, which are a musculoskeletal model and landing pit model. The human body model is based on a multi body model containing eight rigid links and nineteen Hill-type muscles. The sand pit is modeled as particles assembly. The particles collision model consists of several forces, including a spring force which forces the particle apart, and a dashpot force which causes damping. Generally, it is very time-consuming to calculate the optimal motion and particle calculation. Here, this paper proposes the floating sand pit model which is suited to optimization of landing motion. Optimization using the proposed model was conducted by coupled simulation of human and sand pit.

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This paper formulates an optimal control model that reproduces human whole-body reaching movements with cooperation between arm and body. The model consists of four links (an arm, an upper body, a thigh, and a lower leg) and four joints (shoulder, hip, knee, and ankle joints), and minimizes the sum of square of torque-change integrated over the movement duration. This paper applies the proposed model to reproducing whole-body movements with cooperation between rising and reaching movements, and clarifies its performance and factors indispensable in reproducing the same whole-body movements as humans. Consequently, the following results are shown: (1) the input weight R_<44> of the model's shoulder joint affects the way of cooperation between the model's arm and body in the optimally-predicted whole-body reaching movements; (2) smaller (or larger) values of R_<44> expand (or narrow) the range of swing back of the model's arm in the optimally-predicted movements; (3) the optimal movement predicted at a large value of R_<44> agrees well with the experimental one; (4) a decrease in the input weight of R_<44> causes a decrease in the magnitude of the model's hip-joint torque. These results suggest that the proposed model is effective in simulating whole-body reaching movements with cooperation between arm and body and that the input weight R_<44> can be a factor involved strongly in the way of cooperation between arm and body.

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Multi-objective optimization of ski jumping flight was carried out, and then the trade-offs between the objective functions could be visualized using Self-Organizing Maps. It was assumed that there are four objective functions and 29 control variables in this case. Three of the four objective functions are concerned with the style point, and the other is the flight distance. It was found that that there is a sweet spot in Pareto-optimal solutions. In the case of the sweet spot, the hip bend angle is almost 50 degrees during the flight.

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We proposed a wireless measurement system of 3-axis stress distribution at a human sole by using small and thin 3-axis force sensors. The sensor chips 2mm square made by using MEMS (Micro Electro Mechanical Systems) technologies were mounted on the flexible printed circuit board, wire-bonded and buried in silicone rubber by injection molding to fabricate 3-axis force sensors. After the calibration for crosstalk compensation, these sensors were placed on the insole at the heel, thenar and hypothenar. The 3-axis stress distribution was measured in going up and down stairs. The output signals from sensors were amplified 100 times with Wheatstone bridges and differential amplifiers, converted to digital signals and wirelessly transmitted to PC with a Bluetooth module on the CPU board. Measured data which comprised pressure, shear stress of front-back direction and shear stress of lateral direction were compared with the data in level walking, and were consistent with the somatic sensation of the human subject.

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Shock attenuation property of sports surfaces is especially important not only for the athlete's performance but also for injury prevention. To evaluate the properties of the sports surfaces, some sports governing bodies often adopt friction tests and shock attenuation tests to determine the horizontal and vertical characteristics, respectively. Although the diagonal impacts are often observed in athletic sports, shock attenuation test treats only the vertical impact test. Therefore we developed a two-dimensional impact test device for examining the two-dimensional cushioning characteristics of sports surfaces in previous studies. To produce a simultaneous two-dimensional force against a test specimen, we incorporated a parallelogram linkage in the measuring system. In this study, two kinds of cushioned and an non-cushioned impact tests were examined to calculate the FR(Force Reduction) values not only in vertical but also in horizontal impact force. And the maximum deformations of impact tests were also acquired by the high-speed video analysis. As the results, both of vertical and horizontal impact forces which varied with initial impact angle and drop height were well represented by quadratic surface. Therefore vertical and horizontal FR value of two kinds of surface were calculated from the experimental maximum force and estimated impact force with the same height and initial angle. Futhermore, the horizontal maximum deformations are strongly related to the initial angle of the impact force because the horizontal impact force increases sharply with increasing the initial angle of the impact.

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To conduct material characterization of soft material that exhibits large deformation against external load, simple tensile, pure shear and equibiaxial tensile tests are considered necessary to conduct. In this study, a novel method to conduct equibiaxial tensile tests using combinations of a universal testing machine and a special fixture was proposed. Simple tensile, pure shear and equibiaxial tensile tests of a silicone rubber were conducted, and stress-strain curves obtained from the tests were then used to identify the parameters of hyperelastic Ogden model of the silicone rubber. Validation was performed by simulating the three tests using hyperelastic Ogden model in a commercial finite element analysis software with the identified parameters. Simulation results were in good agreement with the test results, indicates that the test and the identified parameters were valid. Comparisons to the results of simulations using parameters identified only by simple tensile test result show that it is important to use results of the three different tests in order to obtain better simulation results.

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Shoes are essential for decreasing the amount of impact force at the landing. The impact force generates heat, thus sometimes the temperature in shoes rises more than 40 ℃ in outdoor in summer. Therefore thermal environment in shoes is harsh. However, there are few researches addressing the formation of thermal environment in shoes. In the present study, the authors carried out the experiment with subjects for quantitative evaluation of temperature change during various walking condition, and established energy flow model. The authors measured temperature under various walking condition of walking speed. Through the experiment, the pressure value and contact area of feet, landing, swing time, and feet moving velocity during walking. The authors established energy flow model and carried out the numerical simulation for predicting thermal environment in shoes. In the model, the heat was gained by landing, human metabolic, and ground surface temperature. On the other hand, the heat was lose by feet movement with convection heat transfer. The heat was mainly transferred by conduction within human skin. Some parameters in the simulation were decided by using subject experiments. The result of the numerical simulation for predicting thermal environment in shoes qualitatively agreed with subject experiments by using two-dimensional heat conduction model. However, temperatures in numerical simulation was slightly higher than the experiments. The detailed considerations remain as future works.

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A new design method for designing competitive swimsuits using 3-dimensional stress calculation was investigated in this paper. An anisotropic hyperelastic modeling of swimwear fabric was developed from the results of tensile loading tests. 3-dimensional stress distributions of swimwear in swimming motions were calculated by the anisotropic hyperelastic model. The displacement fields of 3D-CG human model which reproduce swimming motion of human body were applied to stress calculation. For the material modeling, the uniaxial cyclic tensile loading tests were conducted to obtain the mechanical characteristics of competitive swimsuits. From loading test results, the mechanical characteristics of swimwear fabrics show anisotropy and the stiffness of the fabric shows hardening along with stretching. The cyclic tensile loading test results show stiffness reduction which depended on the maximum deformation. To take the anisotropy and stress reduction into account for the material modeling, a stress softening model for anisotropic hyperelastic model using stiffness ratio of warp or weft was proposed. In this paper, 3-dimensional stress distributions of swimwear were calculated by the proposed anisotropic hyperelastic model. A polygonal model of the swimwear was prepared and deformation of swimwear was adapted to the skin of 3D-CG human model in swimming motions. From the calculated results, stress distributions were possible to be visualized on the 3D-CG swimwear model.

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In this study, the effect of microscopic structure on mechanical characteristics of stretch fabric was evaluated to design fabric easier and more reasonable. Stretch fabric has anisotropic and hyperelasticity because of its microstructural effect. In order to obtain the macroscopic mechanical characteristics of the fabric, uniaxial tensile test was conducted. Also, the deformation of the yarn was recorded by the microscope to reveal the effect of microscopic structure on the macroscopic mechanical characteristics. The recorded video was analyzed with motion image analysis software TEMA (Photron Ltd.). From the analysis result, microscopic strain and the angle between warp and weft yarn were obtained. Comparing microscopic strain with macroscopic strain, the microscopic behavior of stretch fabric was clarified.

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The authors have developed the smart suit and the smart suit lite as an assist suit for fatigue reduction. The smart suit has elastic materials and actuators. The elastic materials are sources of assisting force and the actuator can control the assist force by adjusting the length of the elastic materials. On the other hand, the smart suit lite has only elastic materials like supporters. In this study, we apply the smart suit and the smart suit lite to racehorse trainers because their work accompanied by a large burden. In the results, we confirmed large effect of fatigue reduction through field experiments.

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After seven singles players had retired or withdrawn with injuries at Wimbledon 2013, the All England Club issued an extraordinary statement defending the state of its grass. According to the International Tennis Federation, the seven retirements and walkovers in singles were believed to be the most on the same day at a Grand Slam event in the Open era. All of the slipping and injuries led to questions of why. The suggested culprits included the length of the season, the short time to adjust to grass from clay, and the condition of the courts. There have been several significant falls, the most graphic being when Azarenka twisted her right knee during her first-round that left her lying on the court in tears for several minutes. With so many players being asked about court conditions in news conferences and so many news media requests to speak to the groundskeeper, the All England Club issued a statement about the grass."The court preparation has been to exactly the same meticulous standard as in previous years, and we expect them to continue to play to their usual high quality." It is said that different types of tennis injury have been associated with play on different court surfaces and current knowledge of tennis player and court interactions is limited. Some research with tennis injury incidence, player movements and the biomechanics of slips were begun and a new direction for assessing tennis player-surface interactions has discussed for practical use in the future regulation of tennis courts. On the other hand, in sports, moving body parts around a fixed joint is very popular, but it seems to limit one's power, whereas more power can be generated and the strain on the body is lessen by using the entire body without twisting motion and not resorting to just the fixed joint. This paper proposed the approach for realization of robust physical movements in tennis based on distributed control of physical body in humanoid biped robots, which uses only small active power making full use of equilibrium instability as a source of driving force with simple state transition. Making postures simultaneously by using the entire body produces natural movements.

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Press contusion in chest and abdomen is the most serious trauma for crowd accident. However, injury tolerance for this trauma has not been determined in the eyes of biomechanics research. In order to understand criteria for press injury, we conducted animal experiment in thoraco-abdominal stress. Change in animal state on static press obtains from blood gas analysis and vital signs. As a result, physiological situations on experimental animal are compounded by increase of load.

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Thoraco-abdominal injury is the most dangerous trauma from press load is the most dangerous trauma for crowd accident. The purpose of this investigation is to understand criteria of this injury. In order to develop criteria for thoraco-abdominal injury from press load, the present study conducted volunteer experiment that applied mild press load and measured vital signs. As results, experimental condition of chest: 20kg abdomen: 30kg have a baneful influence on dynamic state of aspiration.

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This study investigated the associations between potential early signs and athlete burnout dimensions measured simultaneously, and between potential early signs measured at the beginning of the season and burnout dimensions measured at the end of the season. The sample comprised of 144 collegiate male soccer players (M= 20.0years, SD= ±1.3) from Japan. They completed Japanese version of two quantitative questionnaires: Athlete Burnout Questionnaire (Raedeke & Smith, 2001) to measure burnout dimensions and Potential Early Signs of athlete burnout (Cresswell & Eklund, 2004) to measure five early signs: money hassles, sport-related hassles, social support, competence, and control items. The results exhibited Japanese soccer players scoring significantly higher values in reduced accomplishments compared to previous studies. In addition, significant positive relationship between perceived sport-related hassles and burnout dimensions was indicated, whereas perceived social support, competence and control illustrated negative relationships. Future studies should examine the process of how the perception of potential early signs lead to burnout.

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The Purpose of this study was to examine the perspective of soccer coach from coach's life story, in particular focus on their previous coached experiences. The life stories of 18 soccer coaches using a life story approach were described and interpreted. They also considered the subjects' past experiences in the following processes. Firstly, coach's perspective was effected previous coached experiences. Secondly, coaching experiences and playing experiences also contributed coach's perspective. The findings of this research showed the coach's perspective consists three factors that previous coached experiences, coaching experiences, and playing experiences. The most important thing was that recognition confirmed by coaches themselves from their narratives. The results suggested those narrative data need further more specific analysis and, consideration for put to practical use in the coaching field from now on.

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