KINEMATICS OF SOCCER INSTEP KICKING: A COMPARISON OF TWO-DIMENSIONAL AND THREE-DIMENSIONAL ANALYSIS

The influence of two- and three-dimensional filming procedures on the calculation of soccer instep kicking kinematics was examined in this study. The knee angular velocity calculated three-dimensionally was compared with the data obtained from the following two procedures: 1. the angular velocity vector was computed as a perpendicular component to the sagittal plane (2D projection); 2. the angular velocity was computed only from the two-dimensional coordinates (2D standard). A distorted changing pattern was produced by the 2D standard approach which was most likely caused by computing segmental angular velocities from quasi-planar projection. It is suggested that researchers treat with caution any comparisons in the literature between three-dimensional angular kinematics and those computed two-dimensionally

THE EFFECT OF HIP LINEAR MOTION ON LOWER LEG ANGULAR VELOCITY DURING SOCCER INSTEP KICKING

The influence of the hip linear motion on the lower leg kinetics was examined for soccer instep kicking. Five highly skilled club players volunteered and their kicking motion was three-dimensionally captured at 200 Hz. According to the procedure of Putnam (1991), the interactive moment due to the hip linear acceleration (MHLA) acting on the lower leg was extracted. The MHLA exhibited a large positive moment to increase the lower leg angular velocity during the final phase of kicking. This effective action of the MHLA was mostly caused by the upward acceleration of the hip. As the hip motion is exclusively due to the motion of the support leg, it can be assumed that the effective action of the MHLA is most likely due to the support leg motions such as the knee extension motion during kicking

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 (

HIGH-LOADING ABSORPTION CHARACTERISTICS OF NATURAL AND ARTIFICIAL TURFS

The present study was designed to illustrate shock attenuation characteristics of natural turf as a target property for long pile artificial turf (3-g turf) and to compare the property with that of existing 3-g turf systems. A recently proposed new high loading test was conducted to detect the initial state of shock attenuation property of natural turfs with two different bases (sod and sand base) and of 3-g turfs with three different infills (sand, rubber and sand/rubber). Clear differences between these turfs were observed as the natural turfs are having a higher impact damping and a larger hysteresis with plastic surface deformation. Those features would be beneficial in lowering a high load imparted to the human body but might limit player’s performance

INFLUENCE OF BODY WEIGHT ON PULLING FORCE IN HAMMER THROW

In hammer throw it can be considered that the body weight affects the throwing distance because the muscle volume is directly proportional to the body weight. The pulling force of the hammer may also be affected by the body weight. The purpose of this study was to investigate the influence of the body weight on the pulling force during throwing motion in hammer throw

MOTION CHARACTERISTICS IN HIP HOP DANCE UNDERLYING SUBJECTIVE EVALUATION OF THE PERFORMANCE

The purpose of this study was to extract the motion characteristics that are closely related to the subjective evaluation of hip hop dance performance. The subjects were 11 expert, six non-expert and nine novice hip hop dancers. Each dancer performed the “wave“ motion as the experimental task. Movements of upper extremities during the task were captured by a motion capture system and several kinematic parameters including the propagation velocity of the wave (PV) were calculated. We found that the coefficient of variance of the PV was highly correlated with the subjective evaluation by the judges (r=0.770,

MOTION CHARACTERISTICS AFFECT EVALUATION BY JUDGES IN HIP-HOP DANCE: KINEMATIC ANALYSIS OF STEP MOVEMENT

The purpose of this study was to extract motion characteristics closely related to high evaluation by judges, through a comparison of “side-step” movement between eight expert and eight non-expert dancers. Their step motions were captured and the head trajectory relative to the centre of mass, face inclination, and time lags among neck, trunk, hip and knee angles were calculated. As a result, a quarter cycle of phase delay between the neck motion and other body parts were observed for the expert dancers. This delay resulted in a large displacement of the head relative to the centre of mass and a large range of motion of the face inclination. The face inclination was highly correlated with the judging score (r = 0.869). Thus, it is assumed these motion characteristics are the most important element of the side-step movement that induces a better impression of judges

BALL IMPACT KINEMATICS AND DYNAMICS IN SOCCER KICKING

The purpose of this study was to illustrate dynamic behaviours of shank, foot and ball through ball impact phase. A time-frequency filtering approach succeeded in establishing more representative shank kinematics just before, during and just after ball impact whereas other procedures failed to remove noisy oscillation from the baseline, lost the peaks of rapid changes or produced totally distorted movement patterns frequently seen in many previous studies. Likewise, ultrahigh-speed video cameras (5000 Hz) and a mathematical model of ball deformation clearly demonstrated the dynamic interaction between the foot and ball during ball impact. It can be assumed that effectual duration to accelerate the ball corresponds to approximately three fourths of visually determined ball contact time and a longer contact time did not associated with a higher ball velocity

A KINETIC COMPARISON OF THE INSIDE SOCCER KICK BETWEEN HIGH PERFORMANCE PLAYER AND JUNIOR PLAYERS

Kinetic aspect of the inside soccer kick was investigated and comparison was made between those of a high performance player and junior players. One high performance player and five junior players volunteered to participate in this study. Their kicking motions were analyzed through three-dimensional cinematograpgic technique. Joints torques, generated at hip and knee joints, were computed by a three-link kinetic chain composed of thigh, shank, and foot. A marked difference was observed for the hip external rotation torque. All the junior players exhibited hip external rotation torque, and its magnitude was particularly dominant in the latter part of leg swing. Conversely, the magnitude of hip external rotation torque for the professional player was negligible. These results may help to explain differences in kicking techniques between the two levels of players

A COMPARISON OF BASIC RHYTHM MOVEMENT KINEMATICS BETWEEN EXPERT AND NON-EXPERT HIP HOP DANCERS

Common motion characteristics that may be linked to higher judging evaluations of hip hop dance were investigated. A comparison of the rhythmic movement between ten expert and twelve non-expert dancers was undertaken. Trajectory data was captured using a motion capture system at 120 Hz and kinematic parameters including the time lags of occurrence of peak joint angle in neck, trunk, hip and knee joint were calculated. Smaller time lags between neck and other joints were observed in the expert dancers. Furthermore, the neck motion was delayed for approximately a quarter cycle of the basic rhythm compared with the half cycle delay observed in the non-expert group. Timing differences in the coordination of joint angles is the most likely a factor to explain the higher judging evaluations awarded to the expert dancers