BIOMECHANICAL ANALYSIS OF TAEKWONDO ROUNDHOUSE KICK FOCUSED ON PHASE BEFORE TOE OFF

The purpose of this study was to clarify the biomechanical taekwondo roundhouse kick (RHK) mechanism of the lower half of the body in the phase before toe off the floor (READY phase) focusing especially on techniques for producing faster kicking speed and shortened time of kicking. The results were summarized as follows: i) motion of hip joint in support leg had relation to the flow of mechanical energy to pelvis, ii) extension of hip joint in support leg produced the translational velocity of pelvis, and iii) players accomplished motion of hip joint extension by providing the torque of hip joint extension in support leg at early time. Taken together, our data suggests that coaches should pay greater attention to support leg and READY phase in order to improve the players’ kicking technique for kicking fast and quick

A BIOMECHANICAL ANALYSIS OF THE RELATIONSHIP BETWEEN TENNIS SERVICE MOTION AND BALL SPIN

The purpose of this study was to investigate the relationship between the service motion and the ball spin. Ten male university tennis players were participated in this study. Three-dimensional coordinates data of the players performing flat, kick and slice services were collected using an 10-camera Vicon MX system. In a similar way, the three-dimensional coordinates data of the reflective markers on the ball were collected. The ball spin is controlled by swing direction of the racquet without changing swing speed. When players put a spin on the ball, they changed swing direction rightward to avoid a head-on collision of the ball and racquet. Moreover, the swing direction was mainly controlled by not change of arm swing motion but change of upper body posture

BIOMECHANICAL ANALYSIS OF ROTATION STRATEGY OF BACKWARD SOMERSAULT IN ARTISTIC GYMNASTICS

The purpose of this study was to examine the rotation strategy used by gymnasts to successfully land after a backward somersault. Nine male university gymnasts (1.66 ± 0.03 m, 61.2 ± 0.75 kg) performed a backward-tucked somersault from a box (0.3 m height). Three-dimensional coordinate data was collected by a Vicon MX+ system. We compared the trials in which the landing succeeded and trials in which the landing failed. There was a difference in the moment of inertia during the airborne phase and the phase time. The results of this study suggest that changing the moment of inertia during the airborne phase has a significant effect on the body rotation. In particular, it is considered that the timing at which the phase is switched by changing the moment of inertia determined the body rotation

TENNIS ONE-HANDED BACKHAND STROKE AT DIFFERENT IMPACT HEIGHTS

The purpose of this study was to compare the kinematic differences of the racket during a one-handed backhand stroke at different impact heights. Five male collegiate tennis players were instructed to stroke the incoming balls from different heights to a crosscourt target area. The impact heights were classified as High, Middle, and Low. Significant differences were observed at 3 heights for racket angles (p \u3c 0.05). The decrease of the angular velocity of upper trunk right-lateral rotation at High might be the main element that resulted in a decrease in the resultant velocity of the racket at impact. The greater moment of inertia of the dominant arm and racket about shoulder horizontal abduction-adduction axis at High made arm difficult to be accelerated. It might influence the velocity and control of the one-handed backhand stroke at high impact point

A COMPARISON OF HAMSTRING MUSCULOTENDON DYNAMICS DURING HIGH-SPEED RUNNING BEFORE AND AFTER A FATIGUE EXERCISE

The purpose of this study was to compare the musculotendon dynamics of individual hamstring muscles between before and after a soccer-specific fatigue exercise during the late swing phase of high-speed running. Eight male soccer players performed three sprintings before and after the fatigue exercise. Whole-body kinematic data and ground reaction forces of the support leg were recorded using a three-dimensional motion analysis system and force platform. A three-dimensional musculoskeletal model with 43 Hill-type musculotendon models was used to estimate the musculotendon dynamics. The results of this study showed that there were no significant differences in the peak values of musculotendon force, power, length, and elongation velocity in the hamstring muscles before and after the fatigue exercise

KINEMATIC STUDY ON SEOI-NAGE, TECHNIQUE COMPARISON OF PLAYERS WITH OR WITHOUT ELBOW JOINT INJURIES

The purpose of this study is to clarify how to apply Seoi-nage to reduce the occurrence of injuries in elbow joints. Five participators were male college judo athletes, one as the Uke (receiver) and other four as Tori(Thrower), two of them with pain in elbow and other two without pain. The result shows that the players without pain in elbow flexed the elbow joints greatly and lifts the Uke by not bend the hip joint too much. Two considerations about the players(Tori) with pain in elbow. 1) The movement of Nagekomi in elbow joints was different from the Uchikomi. Therefore, it assumed that great load put on his elbow joints. 2) Hip joint bends after contacting with Uke and the upper body bends and throw with the power of the arm. In conclusion, the player who uses less strength of the lower extremities instead of the strength of upper body, which might cause injury

BIOMECHANICAL STUDY OF SEOI-NAGE IN JUDO - INFLUENCE OF ELBOW\u27S PAIN ON MOTION -

The aim of this study is to clarify Seoi-nage technique for reducing injuries in elbow joints. Uchikomi and Nagekomi were used as the trials. Two judo athletes with pain in elbow and three athletes without pain in elbow were instructed to perform the Seoi-nage as Tori. Strain gauge sensors were set in a judo cloth to measure the force applied by Tsurite (hand grasping the Eri). The results were observed as the follows: i) The athletes without pain applied a large force towards the throwing direction by the internal-rotation of shoulder. ii)In athlete with pain, the force direction was not towards throwing direction, but towards the left rotating side. The group without pain had an ideal movement of applyingSeoi-nage. On the other hand, thegroup with pain did not apply kuzushi, but generate force to throw the Uke by putting flexing the trunk with external-rotation position of the shoulder

THE ANALYSIS OF KINEMATICAL CHARACTERISTICS IN TAEKWONDO ROUNDHOUSE KICK

The purpose of this study was to analyze the kinematical characteristics of lower torso and kicking leg in Taekwondo roundhouse kick (RHK), which was characterized by kicking speed and continuous kicking. The results were summarized as follows: 1) The kicking speed pattern was similar between the two subjects at 90% time of RHK. 2) One subject produced kicking speed mainly by the movements of hip joint and knee joint, while the other by the movements of lower torso and knee joint. 3) The movement of lower torso for the latter subject had a larger range of motion than the other, which had the disadvantage for the continuous kicking. Thus, RHK techniques for both kicking speed and continuous kicking are influenced by the presence of whipping like motion which is characterized by the limited lower torso movement and the faster movement of lower limb joints

KICKING MOTION DIFFERENCE BETWEEN AFFECTED ARM POSITION

This study analysed the difference of motion between affected arm position in Para-Taekwondo roundhouse kick (right leg kick with right affected rear arm/P-TKD-R and left leg kick with right affected frontal arm/P-TKD-L) compared with a Taekwondo roundhouse kick (TKD). The results were summarized as follows: i) Distribution of using arm for helping upper torso and pelvis rotation was depending on unaffected arm; ii) P-TKD-L (affected frontal arm) firstly generate upper torso rotation; and iii) As for kicking speed, P-TKD-R (affected rear arm) was the same as TKD with whip-like-motion. Considered together, our data suggests that affected arm position affected mechanisms of upper torso and pelvis rotation and generating kicking speed. However, Para-subject could control his asymmetry arm for executing roundhouse kick

HOW TO DEAL WITH ROTATION IN PARA-TAEKWONDO

This study analysed the techniques of dealing with rotational motion in Para-Taekwondo roundhouse kicks (right leg kick with right affected rear arm/P-TKD-R and left leg kick with right affected frontal arm/P-TKD-L) compared with a Taekwondo roundhouse kick (TKD). The results were summarized as follows: i) Kicking speed patterns were different between TKD and P-TKD-L; and ii) Amount of frontal arm angular momentum around the X- and Z-axes were different during three conditions (TKD/P-TKD-R/L) because of compensatory motion. Considered together, our data suggests that the affected arm position, in turn, might affect the roundhouse kick mechanism. However the frontal position of the unaffected arm might be a minor effect of the asymmetry arm because the frontal arm can control the rotation of the upper torso