JOINT MOTION AND STIFFNESS REGULATION OF THE KNEE JOINT IN CHOICE REACTION SIDESTEP CUT TASKS

The purpose of this study was to identify the difference of the neuromuscular motor control of the knee joint for sidestep cut performance under two different conditions. A VICON motion analysis system using 12 cameras (250Hz) and a force plate (1kHz) were used to determine the knee joint kinematics and kinetics of 6 subjects during sidestep cut performed under the choice reaction tasks. The reaction signal was displayed 1.8m before the force plate centre (B1.8M) or 0.9m before FP centre (B0.9M). In the accelerating phase, knee extension positive power tended to be greater under B1.8M than B0.9M. The results of this study suggested that the greater stiffness during the decelerating phase in the B1.8M condition causes the greater knee extension power during acceleration

EFFECT OF TRAINING FOR NEUROMUSCULAR CONTROL ON PERFORMANCE OF CHOICE REACTION SIDESTEP CUT

The purpose of this study was to identify the effect of neuromuscular control training on a performance of the sidestep cut with a choice reaction task. Three stages were set in this study. The first one was an experimental session before training (PRE). This was followed by an 8-week training period, and finally an experimental session (POST) after the completion of training. Mean foot contact time in the POST was significantly shorter than in the PRE. The average rectified value (ARV) ratio of electromyography (mean ARV value for 100 ms before foot contact divided by mean ARV value for 100 ms after foot contact) of the rectus femoris was significantly greater in the POST than in the PRE. These results suggest that the postural adjustments for sidestep cut were performed in a shorter time with the aid of neuromuscular control training

EFFECT OF CHANGING TURN ANGLE AND RUNNING SPEED ON CUTTING MOVEMENT DURING SIDESTEP CUTTING

INTRODUCTION: In many ball game sports such as soccer, players often change their direction of movement in the game. A sidestep or open-step cutting, in which the ongoing path proceeds away from the support leg side, is an effective way to retain to fast speed after changing direction (Ohtsuki et al., 1988). Changing direction during running requires appropriate adjustment of posture and movement. The purposes of this study were to investigate the effect of turn angle and running speed during sidestep cutting on the cutting movement, and to get a basic knowledge of the skillful motion

Spontaneous Oxidization of an Amorphous Zr_<70>Au_<30> Alloy in Air

An amorphous Zr_Au_ alloy prepared by the melt-quenching technique was found to possess an extremely high oxidization tendency in air even at room temperature, even though the other Zr-based amorphous alloys remain unchanged in the same environment. Upon oxidization, the amorphous structure changes into a duplex crystalline structure consisting of a monoclinic ZrO_2 matrix including fcc Au particles with a size as fine as about 2 nm at an inter-particle spacing of about 4 nm. The oxidization tendency depends strongly on the humidity in air and becomes remarkable with increasing humidity. Furthermore, the oxidization causes a spontaneous pulverization of the ribbon into fine powders consisting of ZrO_2 and Au. The reason for the exceptionally high oxidization only for the Zr_Au amorphous alloy was inferred to be due to a combination effect of a weak attractive bonding nature between Zr and Au and a great catalytic ability of Au