PUTTING BIOMECHANICAL INFORMATION INTO PRACTICAL USE

In this keynote lecture, activities of the biomechanics research project of The Japan Association of Athletic Federations are first introduced with examples of speed and motion analyses of elite sprinters in world level competitions. The speaker explain various feedback processes of biomechanical information to athletes and coaches, and propose a procedure to bridge the gap between theory and practice. For effective use of biomechanical data in practice, we have to install two kinds of analysis abilities : a qualitative and quantitative analysis abilities. Without one of two abilities we will be unable to be a good sport biomechanist. A sensible quantitative analysis is derived from a sensitive qualitative analysis and the latter is improved by the former

A BIOMECHANICAL METHOD FOR THE EVALUATION OF SPORTS TECHNIQUES BY STANDARD MOTION, MOTION VARIABILITY AND MOTION DEVIATION

ABSTRACT The essential but most difficult steps in an optimization loop of sports techniques are the evaluation and diagnosis of the techniques of students and/or athletes, and the identification of their technical faults and limiting factors. This process is frequently referred to as technique analysis in sport biomechanics but the concept of technical analysis is less well developed. Teachers and coaches frequently adopt a model technique or a template of model performance approach in which sequential pictures and figures of an outstanding athlete or skilled performer are used as a motion pattern model. This paper proposes a biomechanical method for the evaluation of sports techniques in which an averaged motion pattern of skilled performers is used as a standard motion, and motion variability and motion deviation are employed as indices to identify critical technical points and faults of an athlete

THE NEXT STEPS FOR EXPANDING AND DEEPENING SPORT BIOMECHANICS

Starting with introduction of the activities of biomechanics research projects of JAAF in which I was involved, how we conducted feedback of sport biomechanics data to athletes and coaches will be described. I will share ideas to find solutions to some long-standing questions in sport biomechanics and in the field, and to further expand and deepen sport biomechanics. Topics are learning from skilled athletes, exchanging basic and practical biomechanics, i.e. sport biomechanics，expanding sport biomechanics to practice in the field

ANALYSIS OF RELATIONSHIP BETWEEN HAMMER HEAD VELOCITY AND RADIUS OF CURVATURE

INTRODUCTION: In many research papers, the relationship between the hammer head velocity and the radius of curvature of hammer was discussed. The purpose of this study was to re-examine the relationship between the hammer head velocity and change in the radius of curvature with the 2-D computer simulation

COMPARISON OF KINETICS OF THE LEG JOINTS IN SEOI-NAGE BETWEEN ELITE AND COLLEGE JUDO ATHLETES

The purpose of the present study was to identify biomechanical factors that could be used for the evaluation of seoi-nage technique by comparing the techniques of elite and college-level judo athletes. The motion data of the seoi-nage were collected on three male elite judo athletes and nine male student judo athletes using a three-dimensional motion analysis technique and qualitatively compared. This study found that the peaks of the knee flexion torque, knee negative power, hip extension torque and hip positive/negative power on the swing leg of elite athletes was much greater than those of the college athletes. These indicated that the knee and hip joint contributed to the mechanical energy absorption of the tori’s body in the early phase and generated the positive power in the throwing phase

THREE-DIMENSlONAL ANALYSIS OF THE TAKE-OFF PREPARATORY MOTION IN THE LONG JUMP

The purpose of this study was to investigate three-dimensionally how long jumpers move during the take-off preparatory phase and what causes the lateral lean of the body of the touchdown. The subjects were six male university long jumpers. Three-dimensional coordinates and ground reaction forces (GRF) were collected by Vicon cameras and a force platform. The long jumpers placed support foot in the lateral position at L2on and Llon. The take-off foot nearly under the center of mass (COM) in the take-off phase resulted in the inward lean of the take-off leg and the outward lean of the trunk at the instant of touchdown of take-off foot. The lateral lean of the body helped to lower the COM at the touchdown of take-off foot and to use the hip abductors during the t a k e 4 phase

CHANGES IN THE RUNNING MOTION WITH FATIGUE DURING MIDDLE-DISTANCE RUNNING

The purpose of this study was to investigate the changes in the running motion with fatigue during middle-distance running and get the knowledge about how to maintain the running velocity under fatigued condition by comparing the running motion with fatigue to it with no fatigue. The step length at the fatigued was shorter than the non-fatigued, on the other hand the step frequency was larger than the non-fatigue. The peak ankle joint plantar flexion torque and positive torque power of the support leg at the fatigued were smaller than the non-fatigued, as well as the peak and averaged vertical GRFs. The hip joint torque and power of the recovery leg at the fatigued were significantly larger than the non-fatigued. It is appropriate for maintaining the running velocity to move the recovery leg quickly and increase the step frequency under fatigued condition

THREE-DIMENSIONAL ANALYSIS OF THE TAKEOFF MOTION IN THE LONG JUMP

The purposes of this study were to investigate why long jumpers laterally leaned at the touchdown of the takeoff using the three-dimensional kinetics analysis and to obtain suggestions for long jumpers’ training. The subjects were twelve male university long jumpers. Three-dimentional coordinates and ground reaction forces (GRF) were collected by Vicon cameras and a force platform. The results in this study were revealed that the hip joint of the takeoff leg exerted the large abduction torque during the takeoff as well as hip extension torque (peak hip abduction torque, 4.24±3.28 Nm/kg). The hip abductors seemed to help to bear the body against the GRF and to contribute to obtain the vertical CG velocity. These imply why the long jumpers laterally leaned the body at the touchdown of the takeoff

A COMPARISON OF THE SKATING TECHNIQUE IN THE CURVE FOR ELITE AND JUNIOR SPRINT SPEED SKATERS

The purpose of this study was to investigate the technical factors in the curve by comparing the skating techniques for elite (n=1) and junior (n=5) sprint speed skaters. They were videotaped with two VTR cameras at the mid portion of the inner second curve in the 500 m races. Three dimensional coordinates of the skaters were collected to calculate some kinematic parameters using a panning DLT technique. The onset of the push-off in the elite skater (left stroke; 44.0 %, right stroke; 42.0 %) was earlier than that of the junior skaters (53.6±2.5 %, 68.4±6.4 %, respectively). In the left stroke, the ankle of the free leg (right ankle) at the onset of the stroke for the elite skater placed more forward than that of the junior skaters. In addition, the elite skater pulled the free leg forward rapidly during the first half of the left stroke. These results indicate that hastening the timing of the skating movement is very important for skating in the curve lane under high skating velocity

BIOMECHANICAL FACTORS OF EFFECTIVE SEOI-NAGE IN JUDO

The purpose of this study was to compare the seoi-nage techniques between the elite and non-elite judo athletes. The information obtained helps to increase our knowledge on biomechanical factors to determine the effectiveness of seoi-nage. The motion data of the seoi-nage were collected on three male elite judo athletes and seven male student athletes using a three-dimensional motion analysis technique. The velocity generated by the hikite and hip were greater and the angles of pulling and hitting were smaller in the elite judo athletes than the student judo athletes. The comparison of the effects of the velocity and angles of pulling and hitting on the generation of the angular momentum of uke implied that these variables could be indices for coaches to evaluate the effectiveness of the seoi-nage