Effects of body segment inertia parameters (BSP) on biomechanical interpretation were investigated through the biomechanical analysis of walking at four speed levels.

Two subjects were asked to perform 15 walks at each speed level. The 15 walking trials in each speed level were measured using an automatic coordinate acquisition system and a force platform. Kinematic and kinetic variables were computed using five sets of BSP; 1) BSP 0: Average value for young adult athletes reported by Ae et al. (1992), 2) BSP 1: Average value for the elderly male reported by Okada et al. (1996), 3) BSP 2: Average value for the elderly female reported by Okada et al. (1996), 4) BSP 3: Average value for the aged cadavers reported by Chandler et al. (1975), 5) BSP 4: Average value for three-year-old children reported by Yokoi et al. (1986).

The significant differences of mechanical variables of walking movement appeared among BSP sets and among speed levels. However, the tendencies of differences in the mechanical variables among BSP sets were similar in all speed levels. Also, changes in the variables due to the increase in speed level were observed to have similar tendencies in five BSP sets. Therefore, as far as we apply one BSP to a certain subject and focus on relative characteristics of mechanical variables calculated by using a BSP set, the use of inappropriate BSP values may have little effect on the results and their interpretation obtained through the biomechanical analysis of human movement.

Critical swimming velocity (Vcri) is recognized to be the swimming speed corresponding to the maximal lactate steady state, and is expressed as the slope of a regression line between swimming distances and their sustained times. In order to determine Vcri, the conventional practical test requires a swimmer to swim a distance of 200 m and 400 m twice. The purpose of this study was to find a simpler method for the determination of Vcri. Eight sprinters (50 m and 100 m freestyle) and eight distance swimmers (400 m and 1,500 m freestyle) performed 50 m, 100 m, 200 m, 300 m, 400 m and 1,500 m at maximal effort in a 25 m-swimming pool. The obtained Vcri were 1.409 ± 0.064 m/sec for sprinters and 1.482 ± 0.026 m/sec for distance swimmers. Then, so as to find the simpler method, the relationships between Vcri and swimming velocities at each swimming distance (V 50 m, V 100 m, V 200 m, V 300 m, V 400 m and V 1,500 m) were investigated. As a result, both sprinters and distance swimmers showed significant relationships between Vcri and swimming velocities at distances over 200 m. From the viewpoint of the aerobic energy supply system to muscle, however, V 300 m was the most appropriate swimming velocity to estimate Vcri as an endurance index from the shortest swimming distance. In order to make sure that Vcri shows the maximal lactate steady state, the subjects were instructed to swim 2,500 m at the three constant velocities (98.5%, 100%, and 101.5% of Vcri). As a result, 100% of Vcri showed a higher steady state than 98.5% of Vcri, but 101.5% of Vcri did not show the steady state. Thus, we recognized that 100% of Vcri was at the highest steady state level. In conclusion, one timed 300 m maximal effort swimming test is believed to be a simpler, more rational method to determine Vcri for both sprinters and distance swimmers.

The purpose of this study was to investigate characteristics of the race pace for elite long distance speed skaters. Male speed skaters who participated in the 5000 m race at the Nagano Winter Olympic Games were videotaped with two VTR cameras (60 fields/s), and twenty elite male skaters were selected for analysis. Average skating speed and cycle frequency in every lap were measured in the straight and curved lanes. The ratio of decline (%) in skating speed was calculated as (1- (average speed from 2600 m to 5000 m/average speed from 200 m to 2600 m)) x 100.

The 20 selected skaters were divided into the top and second groups, ten subjects in each group and each group based on the rank of the races. Skating speed of the race for the top group was significantly higher than that of the second group (p < 0.05~0.001). Although there was no significant relationship between the goal time and the ratio of decline, the skaters in the top group could maintain their skating speed during the final phase of the race, keeping the high cycle frequency in the curves during the same phase. In addition, two races of thirteen skaters who participated in both the Nagano Winter Olympic Games and the World Speed Skating Championships Single Distance 2000 were selected for intra-individual comparison. The race of the better record was referred to as the best race, and the other, as the second best race. In the best race, the skating speed in the first half and the cycle frequency of the curves were higher than those of the second best race. These results indicated that the elite skaters could maintain their higher speed longer, keeping the high cycle frequency in the curves throughout the race.