CLASSIFICATION OF OVERARM THROWING MOTION IN JAPANESE ELEMENTARY SCHOOL GIRLS

The purpose of this study was to classify the overarm throwing motion of elementary-aged girls. Throwing motion of forty girls from sixth-grade was analyzed three-dimensionally. The z-score of joint angles was calculated as an index of deviation from a standard motion model and used as a variable for cluster analysis. Based on a distance between the clusters, the throwing motions of the sixth-grade girls were classified into three groups. One group had a throwing motion similar to the standard motion model, resulting in significantly longer throwing distances, while the other groups exhibited throwing motions that differed from the standard motion model, e.g., maximum external rotation of shoulder joint was low. These results indicate the potential effectiveness of the standard motion model as a reference in the evaluation of throwing technique

EFFECT OF THE TRUNK iNCLlNATiON ON, MECHANICAL ENERGY CHANGE PURING GAIT IN ELDERLY ADULTS

The purpose of this study was to investigate effects of the trunk forward lean during gait in elderly people on effectiveness use of mechanical energy (El). The participants were five healthy elderly and ten healthy young people. The participants walked with the trunk leaning forward at their preferred speed. The gait motion was captured with a VlCON system and the ground reaction forces during stance phase were collected with two Kistler force platforms. The El of the elderly subjects was significantly smaller than the young subjects. The results indicated that the elderly subjects did greater mechanical work by the leg joints to walk at a same speed as young subjects. The lower El was related to a remarkable increase in the negative work at the ankle joints

Simultaneous flood risk analysis and its future change among all the 109 class-A river basins in Japan using a large ensemble climate simulation database d4PDF

This study investigated simultaneous flood risk among all the 109 class-A river basins over Japan using the big data of (over 1000 years) annual maximum hourly flow simulated from a large ensemble climate simulation database for policy decision making for future climate change, and proposed a novel approach in its geospatial analysis by applying two informatics techniques: the association rule analysis and graph theory. Frequency analysis of the number of rivers with the annual maximum flow over the flow capacity in the same year (defined as simultaneous flooding here) indicated that simultaneous flood risk will increase in the future climate under 4-degree rise scenarios in Japan, whose increment is larger than the variation of sea surface temperature projections. As the result, the return period of simultaneous flooding in eight river basins (the same number as in a severe storm in western Japan, 2018, causing the second worst economic damage since 1962) is estimated at 400 years in the historical experiment, 25 years in the 4-degree rise experiment. The association rule and graph theory analyses for the big data of annual maximum flows in the future climate scenarios indicated that simultaneous flood occurrence is dominated by spatial distance at a national scale as well as by the spatial relation between mountainous ridges and typhoon courses at a regional scale. Large ensemble climate simulation data combined with the informatics technology is a powerful approach to simultaneous flood risk analysis

COMPARISON OF THE HAND-DRIBBLING MOTION BETWEEN SKILLED AND UNSKILLED SUBJECTS

The purpose of this study was to investigate the differences in the kinematics of skilled and unskilled between the skilled and unskilled dribblers. Ten male university basketball players as the skilled subjects and thirty males as the unskilled ones participated in this study. The three-dimensional coordinate data of reflective markers on the body and a ball were captured with a VICON system operating at 250Hz. The skilled players employed the external-internal rotation and adduction-abduction of the shoulder and the forearm supination-pronation to achieve longer contact time and lower catch and release heights

DEVELOPMENT OF THE OVERARM THROWING MOTION FOR JAPANESE ELEMENTARY SCHOOL GIRLS

The purpose of this study were to investigate characteristics of the overarm throwing motion for Japanese school girls, 2nd, 4th and 6th grades, with a standard motion model of skilled girls. The throwing motions of fifty-one girls were videotaped and seven girls for each grade were selected based on the throwing distance for 3-D motion analysis. Throwing distance, ball velocity and release height were significantly increased with the increase in school grades. The 2nd grade girls threw by a dominant shoulder joint abduction and elbow joint extension, the 4th grade girls indicated a large range of motion of the right upper limb, and the 6th grade girls strode forward with the trunk leaned to the right and used a rapid external-internal rotation of the shoulder joint

COMPARISON OF ANGULAR FACTORS TO DETERMINE QUICKNESS IN SEOI-NAGE BETWEEN ELITE AND COLLEGE JUDO ATHLETES

The purpose of this study was to identify factors to determine the quickness of a Seoi-nage by comparing the kinematic parameters during the Kuzushi and Tsukuri phases between elite and college Judo athletes. Three-dimensional data were collected on seoi-nage performed by three male elite judo athletes and seven male local college athletes using a three-dimensional motion analysis technique. This study found that the angular velocity of the upper limb of elite judo athletes was much faster than that of the college athletes. The elite athletes performed Seoi-nage with a technique in which they rotated lower body first, and then upper body so that the rotation of the upper limb was minimized in the early part of the turning phase. This finding can help teaching of a quick seoi-nage

FRONT-TURN MOVEMENT IN SEOI-NAGE OF ELITE JUDO ATHLETES

The purpose of our work was to investigate the control of the front-turn movement (Mae-mawari sabaki) for seoi-nage of elite judo athletes to obtain findings for effective coaching. Threedimensional data were collected on seoi-nage performed by six elite judo athletes using a three-dimensional motion analysis technique. The most distinguishing feature of the present study results is that the decrease in the trunk inclination angle closely related to the decrease in the moment of inertia of the body in the turning phase. This study found that elite judo athletes performed seoi-nage by turning their body while quickly raising their trunk so that the moment of inertia of the body about the vertical axis was minimized

MUSCLE CONTRIBUTIONS TO BODY MASS CENTER VELOCITY DURING VERTICAL AND FORWARD JUMPING

The purpose of this study was to quantify the horizontal and vertical velocities of the body mass center produced by the lower limb muscles during vertical and forward jumps. Vertical and forward jumps were simulated using a model of the musculoskeletal system consisting of four rigid segments actuated by six leg muscles. It was found that most of the vertical velocity of the body mass center was produced by the soleus and gastrocnemius in both jump conditions. The horizontal velocity at take-off was larger for the forward jump, caused by a larger forward velocity produced by the hamstrings, soleus, and gastrocnemius and a smaller backward velocity produced by the vasti and rectus femoris. The force development patterns were different only in the hamstrings and rectus femoris, indicating that these bi-articular muscles may play an important role in the control of jumping direction

KINETICS OF OVERARM THROWING MOTION FOR SKILLED JAPANESE ELEMENTARY SCHOOL BOYS

The purpose of this study was to investigate the kinetics of overarm throwing for skilled Japanese elementary school boys, in order to gain insight into children’s throwing motion. The throwing motions of 42 boys from the second, fourth, and sixth grade were videotaped using three high-speed cameras; and seven boys from each grade were selected for 3D motion analysis, based on their throwing distance. Although no difference in the elbow extension torque before the release was observed, the angular velocity and the joint torque of the shoulder external/internal rotation tended to be greater for students of higher grades. Thus, the sixth graders tended to depend more on shoulder external/internal rotation with the effective use of a stretch-shortening cycle of the shoulder muscles, while the second graders seemed to depend more on elbow extension

IMPACT PATTERNS IN SOCCER KICK MOTION FOR ELEMENTARY SCHOOL BOYS

The purpose of this study was to investigate impact patterns and kinematics of the kicking motion in Japanese elementary school boys. The school boys were classified into three groups: good-impact, toe-impact, and poor-impact groups. There were large differences in the ball speed, foot speed, and impact ratio between the good-impact group and the other groups. The good-impact group extended the hip joint largely during the back-swing phase. The college students largely inclined the support leg more than the elementary school boys. The elementary school boys should be taught to increase the range of motion of the kicking leg and to contact the ball with the top of the foot near the foot center of mass, which can be induced by angled approach steps