There are ball control skills in soccer; dribbling, kick, heading, etc.. Trapping, in particular inside trapping, is also one of the important and often-used skills in soccer. In spite of important skill, few reports are available on trapping ball so far. Asai (1981) has suggested that trapping is regarded as a form of the collision of the ball against the foot, and the velocity of ball just after impact is depended on the reduced mass of leg and the relative velocity of the foot and the ball just before impact. Therefore the ill-effect of miss-judgment of the foot velocity may be reduced in trapping when the reduced mass of leg decreases. However, the relationship between the reduced mass of leg and performance level on trapping has not been clarified. The purpose of this research was to explore the performance level on trapping involved in the reduced mass of leg of High-Performance group (HP) by comparison with Low-Performance group (LP). There is a significant difference between HP and LP on trials which ball velocity just before impact was not less than 8.00 m/s. This result implicated the possibility players who the reduced mass of leg is lower can trap high speed ball.

There has not been any studies which focus on the contact between the kicking foot and the ground at the time of that the ball is being kicked. The purpose of this study is to analyze contact between the kicking foot and the ground in movement of the ground while kicking a ball at rest, so that we can get tips on how to design soccer shoes. Ten subjects made straight kick and top spin curve kick with placing a ball on the Force plate. We took some images, which show the contact between the kicking foot and the ground, by high-speed camera in order to get to know how the amount of momentum has been changed. As a result of that images which we recorded, in case the ten subjects made a straight kick, seven out of ten subjects kicked the ball with making contact the ground by near the tip of the thumb. The average value of the impulse of the straight kick were that the x-axis component was 1.1 Ns, the y-axis component was 10.9 Ns, and z-axis component was -21.6 Ns. As a result of that images which we recorded, in case the ten subjects made top spin curve kick, two out of ten subjects kicked the ball with making contact the ground by near the thenar. The average value of the impulse of the top spin curve kick were that the x-axis component was 2.7 Ns, the y-axis component was 5.1 Ns, and z-axis component was -8.7 Ns. In conclusion, this contact between the kicking foot and the ground may occur while swinging the kicking foot of kicking a ball.

The kick skill is very important in Soccer. So, many study of motion analysis about kick skill were exist. The ball velocity is used for assessment of kick performance. Furthermore, repulsion ratio or point of where kick impact occur are used for assessment of kick impact performance. To assess kick impact performance, it is considered that three dimensional quantification of impact point is necessary. However, capturing impact point is difficult. Because it is hidden by ball and foot when it is in impact. To detect impact point by using optical three dimensional motion capture system and virtual impact model is aim of this study. The virtual impact model was made as a surface of invisible area composed of virtual markers using coordinate value of captured real markers. As the result, the mean coordinate values of impact point on each trial were below; straight (Horizontal:-24.0±5.6 mm, Frontal:152.7±8.4 mm, Vertical:52.3±4.0 mm), curve (Horizontal:-35.6±4.8 mm, Frontal:151.6±13.7 mm, Vertical:47.5±5.2 mm), knuckle (Horizontal:-33.3±9.0 mm, Frontal:140.8±10.7 mm, Vertical:52.1±2.7 mm). According to comparison of coordinate value of each trial, mean point of straight was nearer the center line of foot on instep, mean point of curve was located in lower than others on inside of foot, mean point of knuckle was nearer the foot joint. We revealed significant difference of coordinate value of impact point using virtual impact model.

The purpose of this study was to derive a dynamic equation which quantifies dynamical roles of joint torque inputs considering mechanical elements of racket such as strings, frame, shaft and grip handle during badminton smash motion. The racket shaft was divided into a set of rigid segments connecting to its adjacent segments via virtual joints with rotational springs. The deformation of racket shaft was approximated by using a 2nd order polynomial function from measured data during swing motion. The string is modelled as an elastic cord intersecting with each other. Displacements of the cross points of the cord with forced displacement input was calculated by using an equation which simulates the deformation of the cord. Grip firmness is modelled by setting spring and damper between racket-grip handle and hand. Combining all equation regarding racket deformation and human dynamics, a recurrent formula of expanded generalized velocity vector consisting of generalized velocity vector of system, grip displacement and shaft deformation was derived.

The purpose of this study was to clarify factors that affect shuttlecock flight behavior immediately after impact and propose a method to quantify the degree of contribution. The shuttlecock was modeled as a linked segment model. External force acting on the shuttlecock was applied to each of the feather and the cork. The equation of motion of the shuttlecock was derived by simultaneous establishment of cork and feather constraint formula. In order to verify the accuracy of behavior prediction by simulation, the impact test of a shuttlecock was carried out. The launch machine consists of a rotary arm and a racquet head. The shuttlecock was fixed to cord with foam material. For the simulation model, the stiffness obtained by measurement was used. The results showed that 1) although the center of gravity velocity contained error between simulation and experimental, the trend of change was consistent. 2)both the simulation and experimental angular velocity of the shuttlecock increased immediately after its impact and decreased after reaching the peak. From these results, the validity of the proposed model was shown to predict the behavior of the shuttlecock immediately after the impact. The future task is to design an artificial shuttlecock that is similar to natural one by utilizing these results.

Nowadays, various ball games are amused in the world. Among them, in badminton, a unique type of ball which called shuttlecock is used. It's known that Shuttlecock is the fastest compared to various balls which used in sports. Furthermore, shuttlecock has high slowdown properties due to its special shapes. In sports, applying fluid mechanic in ball movement is very important in the development of sports. Thus, many researches on the aerodynamic characteristics of ball have been done. However, the effects of badminton shuttlecock to the aerodynamic characteristics are still unknown. Particularly, which shuttlecock's slot influence a drag coefficient are unknown. In this paper, the effect of the standard shuttlecock and shuttlecock without the slot on the aerodynamic characteristics are investigated by using wind tunnel experiment. Influence of the shuttlecock's three slots a drag coefficient are investigated by using wind tunnel experiment. In addition, verification experiment of flight trajectory in indoor facility were carried out. From the results, the drag coefficient was differ from the standard shuttlecock and shuttlecock without the slot. The drag coefficient of the standard shuttlecock was about 0.3 higher than shuttlecock without the slot. The drag coefficient of shuttlecock with the slot1 and slot2 was about 0.15 higher than shuttlecock without the slot. But, shuttlecock with the slot2 is about a little higher than shuttlecock with the slot1. In the shuttlecock's flight trajectory experiment results of confirmed that right rotation power increase as initial velocity become higher.

Badminton is one of the popular sports around the world and is the sport having the fastest initial velocity of a batted ball in all ball games. The initial velocity of the badminton shuttlecock reaches up to 408 km/h (113 m/s) at maximum. A shuttlecock has high deceleration characteristics as an airborne projectile and is extremely aerodynamically stable for the flip movement just after impact. These features of the shuttlecock have been the subject of research from the point of view of aerodynamics. In our previous study, it was confirmed that the air flows through the gaps in the shuttlecock skirt was strongly related to high aerodynamic drag. The purpose of this study is to investigate the effect of spin on aerodynamic characteristics of a badminton shuttlecock. The aerodynamic forces were measured for the shuttlecock with spin at several rotational speeds using a force balance in a wind tunnel test. The drag of the shuttlecock with spin increases with increasing rotational speed because the expansion of the skirt diameter is promoted due to a large centrifugal force given by the high rotational speed of the shuttlecock, and the drag force generation is not affected by the spin itself.

In this research, four types of volleyballs used in modern day competitions were targeted to clarify the aerodynamic and trajectory characteristics through wind tunnel experiments and a hitting robot. We confirmed, in particular, that the critical Reynolds number (Recr) changed depending on the ball type and panel orientation (i.e., side A and side B). Recr for a conventional panel-type volleyball Mizuno volley ball was determined to be ~2.8 × 10⁵ (Drag coefficient; C_d = 0.16) on panel side A and 2.0 × 10⁵ (C_d = 0.20) on panel side B. On the other hand, Recr for the Olympic Official Mikasa ball was 2.9 × 10⁵ (C_d = 0.16) in the panel orientation A and 3.3 × 10⁵ (C_d = 0.15) in panel orientation B. Moreover, we found that the landing position of all volleyballs varied depending on the ball type and the orientation of the panel. In particular, the Molten ball has a longer flight distance than other balls and its landing point was biased toward the left side. On the other hand, the Mikasa ball had a relatively short flight trajectory and its landing point was biased to the right. Therefore, it can be hypothesized that during a float serve, the flight trajectory will change depending on the panel orientation and type of volleyball.

In Volleyball, the phenomena that the orbit changes unpredictably without rotation, attract attention. The investigation of these phenomena is important because of the score in game. Many studies have been carried out to clarify the aerodynamics characteristics of volleyballs and the mechanism of orbit changed irregularly. The aim of this study this study is to make clear the relationship between irregular orbit change and the ball speed, and the flight stare of the volleyballs. Firstly, the ball speed when the orbit change irregularly is measured by using 2 high speed cameras. A ball slightly turned when the orbit of the ball changed irregularly. Secondly, the drag coefficient and side force coefficient of balls are measured by wind tunnel experiment. As a result of that, the irregular orbital change was found to be seen in an area of critical region. We confirm a change of the side force coefficient in this area.

We investigate the accuracy of an estimating method for aerodynamic coefficients of balls in flight by using its trajectory data. The error in estimating the aerodynamic coefficients includes measurement and truncation errors: The latter arises in approximating the velocity and acceleration from the trajectory. The motion equation of two-dimensional projectile motion with drag and lift is written in simple expression by introducing complex number form. The relative error of the aerodynamic coefficients is obtained as a function of time interval for interpolation, and it is shown that the error has the minimal value. This fact means that the estimation error remains in principle and never vanishes even in the infinitesimal limit of time interval, and there exists the optimal value of the interpolation interval given according to the terminal velocity and measurement error. Moreover, we apply the result of the present analysis to measured trajectory data of table tennis balls without spinning. In particular, the estimation error in the drag coefficient is clarified from the two-dimensional data of the flight trajectories. As the results, the error is less than about 2% with the optimal interpolation interval at each measured position, and the range of the error in the drag coefficient becomes narrower and also its value tends to decrease gradually as coming closer to the optimal value of the interpolation interval.

Aerodynamics forces acting on a baseball and its effect on a pitch trajectory of a baseball are numerically investigated. Unsteady computational fluid dynamics is used to obtain the aerodynamic forces acting on the baseball. The pitch trajectory is predicted by solving the equations of the baseball motion with 6 DoF, and the effect of the aerodynamic forces is taken into account by using it as the input to the equations of motion. Two coupling methods are performed in this study. One is “1-way method” which conducts the trajectory simulation after the aerodynamics simulation, the other is “2-way method” which conducts the aerodynamics simulation and the trajectory simulation simultaneously. That is, “2-way method” can consider the interaction between the aerodynamics and the pitch trajectory. “1-way method” simulations are conducted to investigate the effect of back spin speed rotational speed of the baseball on the lift force and drop. The results indicate that the higher rotational speed, the larger lift force and the smaller falling. Concerning the result of “2-way method” simulation, it indicates that the interaction of the motion of the baseball and the aerodynamic drag acting on the baseball affect the velocity change for the direction of flight.

For this study, functional electrical stimulation cycles (FES cycling device) of three kinds were developed for people with disabilities: Four-wheel type, Upright type, and Recumbent type. Each cycling apparatus consists of an FES cycling device unit and a wheelchair, from which the unit attaches and releases easily. The three FES cycling devices have different crankshaft height (crank shaft is the mechanical parts connected to both pedals). Using the apparatus, a pedal sensor, and a three-dimensional motion analysis system (Vicon Motion Systems) to assess voluntary and FES motion, this study evaluated the crankshaft height effects on lower limb joint moments of eight normal subjects. Moreover, using the electromyography setup, the effects of crankshaft height on the EMG values of lower limb muscle were evaluated during voluntary motion. Results indicate that, to realize the cycling motion during voluntary motion, the Four-wheel type and Recumbent type devices needed a greater hip moment and knee moment than the Upright type FES apparatus. However, the Upright type needs less power to realize these motions. Moreover, in FES motion, a somewhat similar tendency to that of voluntary motion was observed. The effect of the crankshaft on the EMG value and EMG timing is considerably large. Especially, EMG timing was found to be affected by subject's pedaling skills.

In this study, we suggested a stimulation pattern estimation system using a neural network as a method of determining electrical stimulation pattern during FES cycling. Generally, stimulation pattern decided from crank angle read from encoder. Therefore, the bicycle not attached encoder is not able to FES cycling. However, if stimulation pattern estimation is performed by a neural network, it is possible to perform FES cycling without remodeling the bicycle. Therefore, backpropagation was performed on the input signal using the data of the inertial sensor and the teaching signal using the encoder angle, and the weight and the threshold value were determined. The obtained weights and threshold values were reflected in the system and the stimulation timing was estimated. As a result, stimulation pattern estimation system was possible to estimate the stimulation pattern equivalent to that when using the encoder.

In this study, I evaluated drive performance of the wheelchair which can drive straight on ahead by one-hand operation under two strengths (normal and hard driving) and driving two locations (driving on the gymnasium and bike roller). For evaluation dive performance, I measured upper limb myoelectric and torque generated on the transmission axis during driving. As measurement results, driving on gymnasium measured bigger values of iEMG than driving on the bike roller and significant differences are observed. However, under both strengths, values of torque driving on the bike roller is bigger than driving on the gymnasium. I think these results imply driving on the gymnasium, we operate rolling wheels. For that reason, we generate driving force and power to stop wheels. Thus, values of iEMG driving on the bike roller is smaller than driving on gymnasium. The other hand, values of torque driving on the bike roller is bigger than driving on the gymnasium. Driving on the bike roller, wheels rotation is stationary every one drive. For that reason, I think transmission axis of the wheelchair receives greater load than driving on the gymnasium. From the results, the wheelchair driving on the bike roller cannot be valid currently but we need to continue consideration.

The objective of this study was to evaluate an optimum structure for a rugby wheelchair by estimating the muscle force during straight-ahead operation of the wheelchair using a musculoskeletal simulation analysis. The simulation model was represented by restraining the contact area between the frame and seat of wheelchair and the body model. Muscle force during operation was estimated by an inverse dynamics analysis. In this study, three kinds of body model were constructed with different degree of disability, targeting the most player numbers class 2.0, which was set from the sum of scores based on degrees of the disability of upper limbs and trunks. Wheelchair models were also constructed by varying the range of camber angle (4-grade, 2°intervals), wheel diameter (3-grade, 25mm intervals) and axle positions (5-grade, 50mm intervals up/down and fore/rear), respectively. Effects of design parameters for the wheelchair on the muscle force were investigated, and the combination of parameters able to decrease the muscle force was identified. As a result, the axle position has the strongest effect on muscle force of upper limbs, and it is effective to lower the axle position for reducing the muscle force. This represents that the adjustment of axle position leads to a reduction in risk of injury occurrence.

This study was conducted to clarify relationship between putter head motions of golf, and ball hitting direction, distance with use of statistical techniques. Measurement was carried out by measuring systems for golf putting. The measuring systems composed of 3D gyro sensor and two infrared sensors which is able to measure rotation angle of the putter shaft, distance between the grip end and trunk and initial angle of the putter shaft. From the measurement data, 27 parameters related to putting were selected. From the 27 parameters, 10 parameters related to hitting direction and distance were selected by analysis of variance. 10 parameters were applied principal component analysis to eliminate data redundancy. Using the first to fourth principal components obtained by principal component analysis, the hitting direction and distance were learned and identified by neural network. In addition, from the result of principal component analysis, it was shown that "angle of putter head at the impact", "length of the follow through", “swing speed” and “maximum and minimum rotation around the putter shaft” are main elements representing putting.

Aerodynamics of spinning golf balls were investigated by Wind Tunnel Test and Computational Fluid Dynamics at the wind speed of 25 and 40 m/s. For CFD analysis, turbulence model (k-ω SST) with transition γ-model was applied. As for both methods, a golf ball with shallower dimples has higher C_L at U=40m/s while drastic reduction in C_L was confirmed at U=25 m/s and Sp =0.1. The increase in C_D as with the decrease in Sp was also confirmed at this C_L reduction phase. It seems that the flow around golf ball changes from turbulent to laminar as with the decrease in Sp. Visualization of CFD results indicates that the separation point of the shallower ball upper side shifts forward for the condition of U=25m/s and Sp =0.1 compared with the other conditions.

In our previous studies, club shaft movement during a golf swing was simulated via a finite element method (FEM) model with shaft flexibility. However, the influence of grip acceleration on the club head during the swing was not investigated with this model. Therefore, we made a simulation model in consideration of the torque taking account of the combination of grip acceleration and the position of the centroid of club head. Moreover, the influence of position of center of rotation of club during the golf swing was added to the simulation model. In order to investigate the influence of the torque generated by grip acceleration, shaft deflection during the golf swing and club head kinematics (HS, Path, BA, and FA) at ball impact were measured with a motion capture system (Vicon Blade). The sampling frequency was 500 Hz and markers were attached to the shaft. Examinees were one average golfer, and measurements were taken 10 times. Taking into account the torque and the influence of the position of rotation center, we compared the measured and simulated results. There was no significant influence of the torque and position of rotation center for HS and Path. However, it was found that BA, FA and shaft deflection were close to the measured values. As a result of this study, we improved the accuracy of simulating ability.

Techniques called ”Fitting” , which considers the individual swing characteristics and suggests a golf club optimal for the player, have attracted attention.In the system developed by the authors so far, we can find optimally designed the golf clubs for the individual swing by swinging nine clubs of different characteristics. In this study, the response of the swing data change for the change of club characteristics was described as a function by using system identification. By performing swing change prediction based on the function, we succeeded in achieving high-precision optimal design from three of the above nine clubs.

Ease-of-Swing of golf club deeply related to the speed of golf club head at impact. It is said at the golf industry, golf club weight and golf club balance are considered as the influential parameters for the speed of golf club head at impact. Also, moment of inertia of golf club around grip end is sometimes considered as the same. However, those considerations are not well grounded. In this study, the golfer's arm and club were modelled with the double pendulum model. And, the effects of club parameters for the speed of golf club head at impact were investigated with the theoretical modal analysis, numerical simulation, and experiment. It was found, as a result, that the moment of inertia around shoulder when the arm and golf club are on a straight line have more influential to the speed of golf club head than golf club weight, golf club balance, and moment of inertia of golf club around grip end.

To improve alpine ski racer's turn skill, it is important to make turns smaller in radius of curvature. For realizing this issue, slap ski which could be heel-freed has been developed. In this study, the motions of expert and beginner skiers have been measured by using wearable motion capture system during skiing with slap ski or conventional ski. In case of using slap ski, the slap plate angle has also been measured to confirm the heel-freed level during turns. Furthermore, the results of the experiment have been discussed.

Since kinematic Global Navigation Satellite System (GNSS) has highly accurate positioning ability, it has been used for sports kinesiology such as 3D movement measurement and analysis. Unlike camcorders, GNSS loggers must be attached to measuring subjects, most of which are bodies of athletes and their tools. Therefore we have developed a compact and lightweight GNSS logger named AT-H-02 with post-processed kinematic mode. The purpose of this report is to analyze the motion of a high-level cross country skier. By using the AT-H-02, we measured positioning data of Mr. Petter Eliassen who won the 1st prize at Reistadlopet 50km cross country ski race held in northern Norway at 3rd April 2017. From the motion analysis, we obtained many interesting implication such as slope angle vs. velocity relation.

It is investigated that the side curve and ski deflection are situated on each circular cone surface during the carved turn. From this investigation, the radius of the side curve of the ski had better be increased as the ski deflection increases with the increase of edging angle during the turn. On the base of this investigation, a side curve variable ski was designed and fabricated. Link mechanism was adopted to the shrink of ski width. From a test skiing by some ski athletes, positive comments were obtained.

Ski jumping competition is a sport that competes at the total point of "Distance Point" that digitizes the flight distance and "Judges Point" that digitizes the beauty of flight attitude and landing, and ski jumpers attempt to fly as far as possible. In competition, many provisions for fairness are established. In the rules for ski jumping competition, suit fabric must show the air permeability of a minimum of 40 liters per m2/sec under 10 mm water pressure. However, the effect of air permeability of suit fabric on aerodynamic characteristics has not been fully clarified yet. The purpose of this study is to investigate the effect of air permeability of suit fabric on aerodynamic characteristics. Four types of fabric with different air permeability are used and the wind tunnel experiments were carried out using the fabric clothed elliptic cylinder. The maximum lift coefficient indicates the highest value for no air permeability case among the all cases. The drag coefficient decreases with increasing the air permeability. Also, the stall delay occurs for the fabric with high air permeability, and the lift to drag ratio at the high angle of attack can be improved. By increasing the air permeability, it was found that the flow enters the inside of the fabric, and it flows out from the surface of the fabric, thereby causing a difference in the stall characteristics.

Many studies have performed simulations of skiing and snowboarding which consider the reaction force between a board and the snow surface by linear springs. Actually, the snowboards run while they cut snow and push the snow. In these studies, complicated behavior snow is not taken into consideration. In this study, we develop a simulation of model considering the contact state between a board and snow surface by reproducing snow behavior. The simulation model examines a relation between a geometric shape of board and dynamic behavior of snowboard by this simulation model. In the simulation, snow is reproduced by the Distinct Element Method (DEM). Three boards which are different in the side curve radius examine turn characteristics. As a result of simulation, it is confirmed that the turn becomes larger as the side curve radius is smaller. It is known that snowboard perform turns along side curve. These simulation results agreed with the generally theory of snowboard turn.

Plyometric training is training aimed at improving muscle power to exert muscular strength under high speed. This training may be expected to raise performance specific to the competition through jumping actions and the like. However, in order to prevent injuries in plyometric training and improve the effectiveness of the training, it is indispensable to acquire appropriate exercise techniques. Therefore, in this research, the athlete who was instructed using plyometric training focused on the process of mastering exercise technique, and carried out performance measurement and analysis during training. First of all, 10 college student athletes participating in the experiment were given explanations about plyometric training exercises (Tiff ankle hop, jump to box, side to side push off), and asked to perform each exercise 10 times. Participants were asked to wear a suit with motion sensors fixed at all 10 body parts, and the rotation angle of each sensor was measured using motion capture. Next, the participants were asked to watch a 12-minute video recording the state of the expert's guidance on the plyometric training. After that, we exercised using plyometric training again, and similarly we measured motion using motion capture. After the experiment, we conducted an interview survey with each participant and asked about performance changes and the strengths and weaknesses of each exercise. When the measured rotation angle was compared before and after the video, a significant difference was observed in the rotation angle of the motion sensors attached to the shoulder, chest, and both feet according to the exercise. Based on the result of motion measurement and the answers obtained from the interview survey, we examined the effects of training guidance on athlete performance.

In recent years, the importance of exercising habitually began to be recognized, then the number of people riding a bicycle is increasing. In such a situation, cycle trainers are popular as Equipment to ride a bicycle indoors for training. Cycle trainers that fix both wheels are widely used. Also, as cycle trainers that can ride with confidence and feel realism, front wheel fixed type have been developed. Developers are pursuing realism based on trial and error in consideration of experience about fixing method of front wheel fixed type. The design of the fixing method affects the movement of the bicycle and the human motion and is directly connected with the evaluation of the cycle trainer. Therefore it has significance that understands the relationship between the human motion and the sensibility which changes according to the fixing method of the cycle trainer. Furthermore, it is difficult to realize optimal design for each person to consider human diversity. In order to establish design guidelines on realism at the time of riding, it is necessary to understand the factors that users are evaluating and to consider the evaluation factors of cycle trainers in the design. An evaluation grid method is used to understand the user's evaluation factor. This design method is aiming at extracting the part related to evaluation from the cognitive structure of a person by the subject's own words. Questionnaires of Evaluation grid method was performed for three kinds of cycle trainers with different functions. As a result conglomerate evaluation tree was gotten.

This research is targeted to the junior high school student team that I am teaching.I examined whether day-to-day training will change the appearance of the game.As a research method, we compared the game aspects in the early training training (Pre-traininng Game) and the game in the late training (Post-traininng Game) that divided the training time period.In addition, in order to visualize changes in daily training, we conducted a quantitative analysis of the ball control test once every two months and training of the ball once a week (4 vs 4 + 2 Freeman).Regarding the daily coaching activities, I authored and analyzed the author's own introspective as an object to be analyzed.Considering from the data of the ball position, although the present is still ongoing, the number of times of play is increasing as a whole. This positively coached the players to proceed favorably to the game by dominating the balls, as a result of individuals actively participating in the ball to hold the ball, also lost the ball Parts trying to participate in play to take back the ball can also be considered. Also, as a concept early in training, in order to make a lot of people involved in the ball, the player receiving the ball (the recipient) gave the pass to the third-party player, not the player who issued the pass It made me conscious that to let it go out. As a result, the number of athletes involved in the ball increases, resulting in an increase in the number of players.

The present study considers human body as a multi-degree-of-freedom complex system, and applied slackline (a balance training using flat belt fixed and tensioned between two anchor points) to young healthy subjects to improve the Dynamic Embodied Adaptability (an ability to stabilize and organize system itself quickly and flexibly coordinating its components against dynamic changes of its environment or itself). Although some previous studies investigated the effect of slacklining training, they applied only static measures such as trajectory length of the center of pressure (COP). In the current preliminary study, four subjects participated in our preliminary experiment consisted of once-a-week balance training (two 20 minutes sessions) with slackline for four weeks. The postural balance ability was evaluated by static and dynamic measures (COP trajectory length and DFA scaling exponent, a nonlinear time series analysis method quantifying flexibility/adaptability of biological system). As a result, our hypothesis, that DFA scaling exponent would approach to 1 (i.e., flexibility/adaptability of COP dynamics would increase), was not supported nor any common tendency among subjects were not observed. We should reconsider our experimental design, training program and balance indexes and collect more data to examine our hypothesis statistically in the future study.

Top-level coaches often have a high level of experience as soccer players. In the research into coaches the formation of guidance view and the teaching philosophy are clarified. Specifically, it is reported that player professional experience at the professional level and guidance experience received from the coach at the professional level have an influence on the current teaching philosophy. Meanwhile, there is no professional level experience, but there are also football coaches who are active as J. League coaches. Therefore, the purpose of this research was to focus on the director of the J.League who has no player experience in the domestic top league and aimed to clarify the learning of the football coach as an example. The subjects were two football leaders who acquired the Japan Football Association official class S Coaches license and overseas soccer coach license. We conducted semi-structured interviews with the subjects of the study and conducted qualitative data analysis. As a result, learning early in the beginning of soccer guidance, learning at the time of acquiring overseas coach license, learning of coach and coach was clarified by case.

It increases in the symptom as cervical spondylosis every year. According to the report, more than 85% of more than 60 years of age has the cervical spondylosis. There are several remedies of the cervical spondylosis. The expansive open-door laminoplasty is one of several remedies of the cervical spondylosis. The expansive open-door laminoplasty progress is a part cutting, making slit, bending. It isn't being considered dynamically quantitatively of the operation procedure about the expansive open-door laminoplasty. Therefore, our goal of the research is the quantitative dynamic consideration of the operation procedure about the expansive open-door laminoplasty. One of our progress is to make the 3D model of the cervical vertebra from the computed tomographic, to make the mesh model, to do computer simulations of the expansive open-door laminoplasty. Now I cloud find to create the finite element model of cortical bone of the fifth cervical spine. But I cloud not find to create the finite element model of cancellous bone of the fifth cervical spine. So I’m going to create the easier model. I think I have to change to create ROI of cancellous bone and make the model cervical spine more smooth.

Working environments and products under considering the physical property of users are desired under an aging society with a declining birth-rate. Previously, computer human models which duplicate the properties and the functions of human have been developed. A musculoskeletal model which can evaluate muscle activities is one of computer human models. Conventional musculoskeletal model uses the energy minimum optimization to estimate muscle forces. However, the energy minimum optimization unfortunately usually cannot estimate the functions of antagonistic muscles which act in opposite direction to the prime motion or for restriction of rotational joint motion. Therefore, this study proposes a musculoskeletal model considering the functions of antagonistic muscles. In this proposed model, it is assumed that muscles connecting to the joint act as spring. Joint torque is represented by summation of the torques of the active muscles and the antagonistic muscles. Each muscle force can be estimated to keep balance among the torques generated by muscles. The experiment was conducted to validate the proposed method to estimate muscle forces. Surface electromyograms (sEMG) were measured to compare with the estimated muscle forces. The experimental results showed that the estimated muscle forces had a good agreement with the sEMG of muscles.

In this research, we focused on mechanomyogram (MMG) to evaluate muscle activities. In previous researches, low frequency MMG ranged 10 to 100 Hz were mainly measured. On the other hands, we focused on MMG ranged higher than 100 Hz which is considered to be related to the resonance of muscle fibers. To measure high frequency components of MMG, we use wideband acoustic emission sensor and measured the MMG of the biceps brachii muscle of multiple subjects. As a result, it was confirmed that each subject included the frequency components of 100 Hz to 10 kHz in the MMG. In particular, it was found that as the force exerted by the muscles becomes larger, the MMG of 1 kHz to 10 kHz becomes larger.

In this study, I evaluated drive performance of the wheelchair for competitions for the wheelchair for the sporting event that had the camber angle to the wheel, it can drive straight on ahead by the one-hand drive that had joint mechanism to transmit driving force from one side wheel to other side wheel. The subjects were 5 adult health men, all of them right-handed. Measurement was made for 20 m straight for a short time. For evaluation of performance to drive, I measured upper limb myoelectric and the seat pressure. The seat pressure was measured with a body pressure distribution device. In the analysis I used the center point of the seat pressure which is center of gravity. As a measurement result, hard driving was high iEMG compared with normal driving. Both-handed driving was high iEMG in all the muscles compared with one-hand driving in hard driving. But This result is different from the result of high iEMG in all the muscles in one-handed running of the previous study. This is because measurement conditions are different. Also, it was confirmed that center point of the seat pressure moves greatly in one-hand driving compared with both-hands driving.

Baseballs have high rigidity because they are made of cork, rubber, wool, and cowhide. However, it is safer for children and adults to play baseball with a rubber ball than a baseball because the rubber ball is a hollow two-layer ball made of rubber. Therefore, it is very important to analyze the characteristics of a rubber baseball to suggest safety measures while using the ball. In addition, it is very important to analyze the restitution and impact performance of a rubber ball in developing bat. In this study, the impact performance of A-, B-, and M-ball on a rigid wall was examined, and the restitution and impact performance of each ball were compared. The results of the experiment demonstrated that the M-ball had the lowest coefficient of restitution at a velocity of 5-10 m/s. Moreover, from 30 to 50 m/s, the coefficient of restitution for the M-ball was the same as that for the A-ball and that for the B-ball was lower. The M-ball had the highest impact load and impact pressure. However, there was little difference.

The objective of this study was to construct a finite element (FE) model for a rubber baseball bat which can accurately simulate the behavior of baseball impact, and to investigate the effect of mechanical properties of the hitting area on the rebound of a ball, by conducting FE analysis. FE models of an aluminum bat and a bat which is composed of urethane for hitting area were constructed. The material model for urethane with non-linearity was expressed based on the result of the static tensile and compression tests and a drop weight impact test to represent the strain rate dependency and energy absorption characteristics. The simulation results for the rebound velocity of the ball, which were calculated from impact analyses between the urethane plate and the ball with hyperelasticity, qualitatively agreed well with the experimental results. FE analyses were conducted with the ball model and the bat models which introduced the material models with different forming rate of urethane to the hitting area. From these results, the rebound velocity of the ball tends to depend on the ball impact velocity as well as the forming rate of urethane. The tendency suggests that the ball rebound velocity is involved in the deformation behavior of the ball, especially the deformation velocity to restore the ball deformation.

Much remains unclear regarding the relationship between the length of a baseball bat and the outcome of the hit. This study therefore aimed to clarify how length in a baseball bat affects the batter's hitting of a ball approaching from the front. The participants were four male members of a university baseball club (height: 1.72±1.2 m, weight: 68.3±4.2 kg, baseball career: 13.7±2.5 years) who hit a ball launched from a pitching machine located ahead of them. Participants attempted 10 swings using an experimental baseball bat. Changing the length of the baseball bat affected the rotational motion and the linear motion of bat. The swing changed by the length of a baseball bat. Results indicate that the position of the impact and timing of ball impact changed by changing the length of the baseball bat. This shows that the length of bat affects the impact position of the bat and timing of impact upon a hit.

In this research, the collisional properties of a bat and ball was investigated experimentally for the purpose of hitting performance improvement of the rubber-ball baseball bat which is one of the popular sports in Japan. First, three marketed bats for the rubber-ball baseball of the typical materials were chosen and investigated the coefficient of restitution by the ball collision test based upon ASTM F 2219, as a result, the tendency that coefficient of restitution was increased in the collision position of the ball was near a grip with all bats. Next, it was assumed the influence of the diameter of the collision position as a factor that coefficient of restitution increased on the grip side of the bat and the ball collision test by the cylinder rigid iron of various diameters was examined. As a result, it was confirmed that coefficient of the restitution increases under the condition of small diameter. A similar result was shown for the numerical simulation by FEM and some useful knowledge was obtained for the design of high-performance rubber-ball baseball bat.

Rubber baseball game using a rubber-ball (made of two types a rubber) is an original and a popular sport in Japan. When the rubber-ball is hit with a baseball bat, the ball is greatly deformed compared to an official baseball ball, and the flying distance of the batted ball decreases due to the energy loss to obtain the ball. In this study, it was elucidated that these phenomena occurring in the rubber-ball during the hitting period using finite element analysis models of ball and bat for a rubber baseball. Also, the validity of the conventional restitution performance evaluation test for the baseball bat was evaluated. The evaluation test is different from the actual baseball game in that the used ball has no spin and the rotation center of bat at the swing. From the hitting simulations, it was found that the influences of the ball spin and the rotation center of the bat on the batted ball speed are not very large. Regarding the batted ball speed, the validity of the conventional evaluation test for baseball bat was confirmed.

The number of congestive heart failure (CHF) death has increased by 35 percent in the past quarter century. Heart failure is usually characterized as reduced contraction of heart muscle and dilatation of the chambers. Progressive dilatation and reduced contractility of the heart (= cardiac remodeling) are the common process in progression of heart failure. Prevention of cardiac remodeling is the main target for heart failure treatment. The authors have developed patient-specific cardiac support device (CSD), which is a net covering the patient's heart to prevent cardiac dilation. In this study, the contact pressure distribution between the knitted net CSD and the human heart model was analyzed in a stationary position.

Our previous study proposed a biomechanical model in bathing postures. Methods to support upper body including trunk and head of bather were expected to affect physical relax and biomechanical state, such as joint torque or reaction force from bathtub, in bathing. This hypothesis was verified using the biomechanical model in bathing. Bathing postures and reaction forces from the bathtub to a human were measured for seven healthy male participants in two bathing posture conditions (posture with head supported and unsupported). A three-dimensional motion analysis system and 3D force plates were used to measure the experimental data. A biomechanical model in which a human body is represented as a link of body segments was constructed. Significant increases in joint angles of the lumbar, neck and significant decrease in the hip joint were found when bathing in posture with head supported than unsupported. In addition, in the horizontal direction, sum of reaction forces was reduced due to posture with head supported. This reduction of reaction force result in relief of biomechanical loads on ankle, knee, lumbar and neck. These results suggest that method to support upper body affects biomechanical loads on lower body as well as upper body since reduction of reaction force propagate from upper body to lower body.

Since competitive fin swimming using bi-fin is a relatively new sport, there are no research about swimming motion considering the characteristic of the fin. Therefore players determine their swimming motion based on their own sense and experience. In this research, a simulation model to assess the swimming motion was constructed by extending the swimming human simulation model SWUM. In this model, the fin was modeled as a series of five rigid plates. These plates were connected by virtual springs and dampers, by which forces according to relative distance and velocity acted.

Fin's elasticity was also represented by springs and dampers, by which torques according to relative angle and angular velocity acted. The fin parameters such as the shape, the rigidity, and the hydrodynamic coefficients, were determined by comparing the experimental results of the deformation and the force measurement with the results simulated in the same condition. Fin swimming was simulated in a standard crawl motion. It was found that the body was unstable.

For the competitive swimmers with physical disability, the optimized stroke of crawl swimming has not been clarified yet, and may be different from that of able-bodied swimmers. The objectives of this study was to solve computationally the arm stroke of the crawl swimming that maximized the swimming speed for swimmers with bilateral transfemoral amputation, and to investigate the features of the optimized stroke. The optimized stroke was obtained by the optimization method with Particle Swarm Optimization (PSO) algorithm and the swimming human simulation model. In this method, the design variables were the upper limb joint angles, represented by five degrees-of-freedom (three at the shoulder joint and two at the elbow joint), and the fastest stroke was obtained as the optimized stroke. When the stroke cycle was 1.0 s and the palmar flexion angle at the catch phase was 35 degrees, the swimming speed became fastest. In the short stroke cycles, the optimized stroke was the motion pulling and pushing the water near the trunk with the elbow bending. In the long stroke cycles, the optimized stroke was the motion pushing the water towards the outside of the body. These strokes were thought to reduce the moment which raises the body, by pushing the water shallowly.

We analyzed the movement of Stöckli on a pommel horse based on the data acquired with a motion capture system. The following results were obtained from the analysis. (1) The center of gravity moves around in a wider range in Stöckli than a double-leg circle. (2) Upper body muscles working in the performance of Stöckli are almost the same as a double-leg circle. However the activity level of muscles differs with each other in Triceps Brachii Caput Laterale which shows frequent steep peak in the performance of Stöckli . (3) An evaluation method using the Lissajous diagram generated by two harmonic oscillations of the body rotation and the hip rotation is useful for Stöckli.

A gymnastic technique on the pommel horse, called the double-leg circle, was modeled in the horizontal plane by using a rigid-body segment and variable-length arms. The model has three degrees of freedom, and two control inputs in the single support phase or three control inputs in the double support phase. The inter-joint coordination during the circle was modeled as a virtual constraint with respect to the center-of-mass position and the body orientation, and controlled by the feedback linearization. The result showed that the model has a periodic solution partially similar to the horizontal motion of the circle performed by gymnasts.

We investigate the eight subjects of the double-leg circle on the pommel horse, and perform the kinematic analysis of the whole body. There was a strong positive correlation between the cycle of double-leg circle and the height / weight of the subject. We clarify the transition from the time series data about the controlling of the upper trunk and lower body. We analyze the motion of the skilled subjects and discuss their characteristics. Based on the analysis results, it was suggested that the flank out motion of the legs on the pommel are important for realizing fast circle motion.

The purpose of this study was to quantify the pole bending mechanism in pole vaulting. Pole was modeled as a series of ten rigid segments connecting its adjacent segment via joint with rotational spring component. The stiffeness of the spring was identified from the measured deflection under loaded condition of pole. A male pole vaulter participated in the experiment. A motion capture system was used to measure the 3-D coordinate data of 47 and 20 reflective markers attached to the whole-body and the pole, respectively. Force and moment exerted on grip center were calculated with a force/moment equilibrium equation, and then kinetics were decomposed into the kinetics of each hand by assuming a force-distribution ratio along the longtudinal direction of the pole. The joint torques of the vaulter were calculated via inverse dynamics with use of the estimated kinetics of the hand. The result obtained in this study show that the right shoulder flextion torque and the left sholder extension torque exerted in the first half of pole bending phase.

Several theories about the friction on snow and ice have been suggested. The frictional melting theory was proposed by Bowden and Hughes has widely been borne out. However, there are some phenomena that are difficult to explain by this theory. In contrast, the adhesion theory related to shearing force of snow or adhesion force in real contact area was proposed by Tusima and Takeda et. al. The major difference of two theories depends on existence of melted water by friction. In this study, we have measured the coefficient of friction statically/dynamically on snow surface. The influence of grain size of snow, temperature, material of slider, and contact time/velocity has been investigated experimentally. In comparison of the results, the mechanism of low friction on snow has been considered. It suggested the possibility that kinetic friction is the same mechanism as static one.

Our attempting to clarify mechanism of snow friction in Skiing has been conducting. There are mainly two theories, that is the friction melting theory and the adhesion theory, to explain why friction on ice is so low. The difference of the theories depends whether water melted by friction as lubricant exists or not. Although the former is widely borne out, it might be difficult to explain the cause why snow is slippery in very low temperature such as in the Antarctica. The latter is same as the concept for general materials and depends on real contact area on snow surface. In this study, owing to evaluate the real contact area on snow surface, a method by dielectric properties of snow with a comb-shaped electrode has been proposed. A finite element analysis of electromagnetic field has been conducted simply as the first step to examine possibility of the method.

Movement of a curling stone was studied with high precision by use of digital image analysis in order to obtain the relationship between curl ratio and both translational and angular velocities, using sequential images taken with a camera located on the ceiling. Calibrations to remove lens aberration were done prior to the experiment. Defining the line segment for movement of the curling stone in the time range of 0.5 sec, transition of curl ratio was measured in relation to a change of translational velocities in the movement of the curling stone. It was shown that the curl ratio is not uniform and has fluctuations in the change of the translational velocities.