RELATIONSHIP BETWEEN 100 M RACE TIMES AND START, STROKE, TURN, FINISH PHASES AT THE FREESTYLE JAPANESE SWIMMERS

The purpose of this study was to examine the relationships between the race performance and elapsed time in each phase composing the race. The races of Japanese top 113 male and 117 female swimmers in the 100 m freestyle event were analysed. For analysis, races were divided into four phases: start, turn, finish, and first and second half of stroke phases. Statistically significant correlations between the total race time and the times of the four phases were obtained (

KINEMATIC CHARACTERISTICS OF KICK START FOR ELITE COMPETITIVE JAPANESE MALE SPRINT SWIMMERS

The purpose of this study was to compare the kinematic characteristics of the kick start technique at the start phase demonstrated by male elite competitive sprint swimmers and male collegiate swimmers in consideration of the performance enhancement. An elite competitive sprint swimmer and eleven collegiate male swimmers performed maximal effort during competitive swimming at the start followed by 25 m crawl swim during experimental trials. The trials were recorded using three synchronized video cameras shooting at 60 fps. Two-dimensional video analysis was performed in the sagittal plane. Calculated variables at take-off were horizontal velocity, speed, attitude angle, angle of projection, whereas those at entry were entry angle, attitude angle, angle of attack. In addition, block time horizontal coordinates for start position and 15 m time were calculated. Based on the results of this study, the kick start technique for the top competitive sprint swimmer was characterized as having shorter block time and higher horizontal velocity at take-off

ROLES OF THE EXTREMITIES DURING KICK START IN COMPETITIVE SWIMMING

This study was aimed at examining the role of the hands and feet at takeoff by measuring the forces applied to the starting block by the right/left hands and feet. A small, waterproof force plate and a three-axis force sensor (operating at 500 Hz) were placed at the front and back of a custom-made starting block with an inclination angle of 10�� and on the right and left sides of the front of the starting block, respectively, to measure the force exerted on the starting block. Five male collegiate competitive swimmers were requested to perform kick starts from the starting block. The rear and front feet had the greatest contribution to the horizontal and vertical velocities, respectively, at kick start. In addition, the hand and foot exerted downward and upward forces, respectively, to the vertical velocity at kick start, revealing bilateral differences in the horizontal and vertical velocities of the hand

EVALUATION OF ARM STROKE TECHNIQUE IN FRONT CRAWL SWIMMING

The purpose of the present study was to evaluate the high elbow technique in arm stroke motion, and to investigate the relationship between the technique and the swimming performance in front crawl swimming. Subjects were fourteen skilled male swimmers and five unskilled male swimmers. The arm stroke motions of subjects were captured threedimensionally (3-D) at 60 Hz during 25 m front crawl swimming. A new index of the high elbow arm stroke technique (high elbow index) was developed. The index was defined by the 3-D coordinates of the three joints (shoulder, elbow and wrist). As the result, the arm stroke technique of the skilled swimmers was different compared with the unskilled swimmers. Moreover, a significant correlation was obtained between the index and the swimming velocity. The results indicated that the index was effective to evaluate the arm stroke technique and the high elbow technique was effective for improvement of the swimming performance in front crawl swimming

Numerical Simulation of a Flow Induced by a Pumping-up Facilities in a Lake

The purpose of this research is solving the flow in a lake which caused by a fan who rotates at the low speed set on the water surface for the purpose of water quality purification of a lake. Although it is shown clearly by various experiments that the water quality in a lake improved by operation of this kind of equipment, the mechanism of the flow was not fully understood. In this research simulation of the flow which was caused by this equipment was carried out numerically, and the aspect of the flow corresponding to various conditions or the form of a lake was investigated