The purpose of this study was to compare two methods for determination of the three-dimensional (3 D) segment angular velocity. One is Tang's method (1995), which was calculated by using the relationship of cross products for angular velocity vector and displacement vector with global coordinate system. The other method, reported by small researchers, which calculated the angular velocity by differentiation of unit vectors in three-orthogonal moving coordinate system fixed at the segment. Twenty-four male university baseball players were used as subjects. 3 D coordinates of 15 body segments during the baseball throwing motion were obtained by using the 3 D DLT method. The angular velocities where the upper torso, the upper arm and thigh of throwing arm side were calculated with above two methods. Large differences were found in all segment angular velocities. These results indicated that Tang's method did not consider the angular velocity about the longitudinal axis of segment. Tang's method, however, may be useful for the 3 D motion analysis of the sport activities, except for the motion which observed the rotation about the longitudinal axis of body segment.

This study was designed to clarify the effects of anaerobic and aerobic trainings for on the physical fitness, and blood lactic acid (La) and the form of locomotion activity during a game in soccer players. The subjects were twelve soccer players of amateur top-level in Japan. Measurements of the physical fitness were done for body composition, leg extension power (LegP), maximum anaerobic power (AnPmax), 40-second power (40 secP), maximum blood lactic acid (Lamax) as well as running speed at OBLA (OBLA-V). These measurements were carried out five times during a training period: August and December in 1993, and March, May and August in 1994. Measurements during the game were conducted in August, 1993 and in May, 1994 for the exercise intensity using La and the from of locomotion activity using a video camera. As a result, relative and absolute fatness, and lean body weight improved significantly between August and December in 1993, and between December in 1993 and March in 1994. LegP increased significantly between December in 1993 and March in 1994. AnPmax, 40 secP, Lamax and OBLA-V increased significantly between December in 1993 and March in 1994, and between March and May in 1994. La, dash time and jogging time of the players during the game increased significantly between August in 1993 and May in 1994. But, there weren't significant differences in %Lamax of the players during the game. These results indicates that the improvement of anaerobic and aerobic capacities in soccer players led to positive effects on activity levels of the high intensity during the game.

Although three-dimensional motion analysis recently has become popular in biomechanical study, tow-dimensional analysis based on the images obtained through a single camera is still used in biomechanical research because it costs less in the staff, economic, time and equipment necessary for both experiment and calculation. To obtain two-dimensional coordinate from the human body, two principal methods, 4 point method and DLT (direct linear transformation) method, are regularly used. The purpose of this study was to discuss these two methods applied in different filming condition by esimating standard errors. The results showed that the DLT method has a higher accuracy than the 4 point method in two kinds of photographic angles of look side and look down, but delicate care should be paid for perspective errors when human movement lies out calibration plane in the DLT method.

The present study was designed to identify the abnormal gait of limping from the view of the leg muscle strength whose loss caused kinematic changes of leg motions to carry the body weight. The limping was simulated by muscle fatigue of the quadriceps femoris after repetitive knee extensions in the isometric contraction.

Eighteen healthy male sutudents aged 20.0 ± 2.1 years old performed three different exertions, when the muscle strength of left knee extensor decreased to 60, 40 and 20 % BW (body weight). Their normal and abnormal gait were videotaped to measure the joint angle changes of knees and ankles. In addition, selected kinematic parameters such as left and/or right step lengths were analyzed in a gait cycle.

The most severely fatigued condition of 20 %BW trial showed significantly (p<0.05) different 1) velocities during both left (fatigued leg side) stride and right-to-left step, 2) ranges of knee and ankle angles from those in the normal gaits. On the other hand, the least fatigued 60 %BW trial showed significantly different range of ankle angle, while the intermediately fatigued 40 %BW one in both knee and ankle angles.

The present results suggest that the muscle strength of knee extensors of around 40 to 60 %BW are necessary to perform normal gait, which could be target values to be achieved by patients in a rehabilitation program.

The purpose of this study was to three-dimensionally investigate joint torques and joint torque powers of the lower limbs in sprint hurdles. Male and female hurdlers and multi-event athletes in sprint hurdles were videotaped (200 fps) with two high-speed cameras which were panned. Ground reaction forces during the take-off and touchdown phases were measured with a Kistler force platform (500 Hz). Kinetic analysis procedures were carried out to estimate joint torques and joint torque powers of the lower limbs. The results were summarized as follows: The patterns of the joint torques and the joint torque powers of the lower limbs during the recovery and preparatory phases showed similarities with those of sprinting, for instance, the negative powers of the knee joint just before the touchdown were observed both in the preparatory phase of sprint hurdles and in the recovery phase of sprinting. On the other hand, the patterns of the joint torques and the joint torque powers during the take-off phase and hurdling phase were different from those of sprinting. Finally, it was inferred that the lateral swing of the trail leg appeared in the first half of hurdling was caused by the joint force power and the flexion torque power of the hip joint rather than active abduction-adduction torque of the hip joint.