Although skeletal muscle mass decreases with aging, its decrease rate may differ among parts of the body. There have been few studies examining the differences in the muscle mass decrease rate between proximal and distal parts of the limbs or between the left and right legs in a large population. Bioelectrical impedance (BI) index, calculated as the ratio of the square of segment length to impedance, is linearly correlated with the muscle mass calculated by MRI (r=0.902-0.976, p<0.05, Miyatani et al., 2001) in the limb segments. The purpose of this study was to examine differences in the decrease rate of muscle mass between the proximal and distal parts of the limbs and between the upper and lower limbs in healthy Japanese. The BI index was measured in the bilateral thighs, lower legs, upper arms, and forearms of 1006 healthy Japanese men and women (aged 15-97 years). While the BI index decreased with aging in all examined parts of the body, the decrease rate was larger in the lower limb than in the upper limb, and in the thigh than in the lower leg. The percentage of people who showed a difference of more than 10 % in the BI index between the left and right lower limbs was significantly higher in the elderly than in young subjects. These differences in the decrease rate of muscle mass between limbs may be associated with decreases in physical functions in the elderly.

Gait analysis was conducted on 7 healthy pregnant women (pregnant group) and 6 non-pregnant women (pseudo-pregnant group) using a 3-D motion analysis system (VICON 460) and two forceplates (Kistlar 9286A). The data was collected at 8-9 months of gestation (pregnant condition) and 4-8 months postpartum (non-pregnant condition) in the pregnant group. In the pseudo-pregnant group, the participants walked with a 5kg-load on their belly (pregnant condition) and without any load (non-pregnant condition). Comparisons using two-way ANOVAs with repeated measures were conducted. Interaction of group × condition was not observed in the measured gait parameters except the angle of the maximum hip adduction. Main effect in the condition and the group was found in some parameters. In the pregnant condition, gait velocity was slower (pregnant group 68.7±8.6 m/min pseudo-pregnant group 63.8±4.8 m/min) than in the non-pregnant condition (pregnant group 75.5±3.2 m/min pseudo-pregnant group 69.8±8.7 m/min). The second vertical peak ground reaction force was smaller in the pregnant condition (pregnant group 105.4±4.8 % pseudo-pregnant group 108.4±6.3 % of body-weight) than in the non-pregnant condition (pregnant group 114.3±7.4 % pseudo-pregnant group 113.5±4.2 % of body-weight). These results demonstrated that pregnant condition changed kinetic and kinematic characteristics of the gait.

The aim of this study was to investigate the relationship between changes in swimming velocity (SV), stroke rate (SR), stroke length (SL) and muscle activities during a 4×50m swimming test to simulate a 200m freestyle race. A total of 20 male collegiate swimmers participated in this study. The electromyography (EMG) signals of 11 muscles, 7 muscles in the upper half of the body and 4 muscles in the lower half, were recorded with surface electrodes. SV, SR and SL were analyzed for each 50m (S1, S2, S3 and S4) from side view recordings of swimmers taken with an underwater camera.SV and SR for S1 were significantly higher than for S2 and S3. SL for S1 was significantly longer than for S3. The averaged EMGs (aEMGs) for S1 were significantly higher than for S2 or for S3 in 5 muscles (flexor carpi ulnaris, biceps brachii, triceps brachii, deltoideus posterior and rectus femoris). There were no significant changes between S3 and S4 in SV, SR, SL and aEMG of all muscles except pectoralis major which showed the highest aEMG in S4. Significant correlations were observed between changes of (Δ) aEMG and ΔSV, especially in upper half muscles (r=0.485-0.939, p<0.05).These results suggested that decline in muscle activities of the five muscles mentioned earlier caused a decrease in SV from S1 to S3; and an increase in muscle activity of the pectoralis major led preventing a decline in SV by maintaining the SR in S4.

The purposes of this study were as follows: 1) to classify competitive swimmers on the basis of their stroke rate (SR) and stroke length (SL) by applying a factor analysis and a cluster analysis, 2) to derive discriminant functions by applying a multiple discriminant analysis of the stroke characteristics, and 3) to compare the race patterns of groups classified according to the results of the cluster analysis. 94 male swimmers who had participated in 100-m freestyle events held at the All Japan Swimming Championship from 2000 to 2004 were selected as subjects. The average value of their swimming velocity, SR, and SL in four swimming phases (15-25 m, 25-45 m, 57.5-75 m, and 75-95 m) were measured from videos captured. The subjects were classified according to their SR and SL by applying a factor analysis and a cluster analysis. Results showed that the competitive swimmers could be classified into Type1-4. Type1 showed high values of SR throughout the race, Type2 showed high values of SR in the first half and high values of SL in the second half, Type3 showed high values of SL in the first half and high values of SR in the second half, and Type4 showed high values of SL throughout the race. Although there was no difference in swimming records among the four groups, each group had different race patterns. These results suggest that the knowledge of race patterns might be useful to swimmers or coaches for planning race strategies.

Left-ventricular dysfunction is diagnosed when the heart rate performance curve (HRPC) of patients deflects upwards during incremental exercise. The aim of this study was to investigate the effect of exercise training on the upward deflection of the HRPC in patients with cardiovascular disease.This study comprised 11 patients who had cardiovascular disease and showed an upward deflection of the HRPC. The patients underwent exercise training (aerobic training, AT intensity: 30-40 minutes, 2-3 sessions/week, and 3-month follow-up). The HRPC of the patients was measured before and after exercise training. We used a method described by Pokan for evaluating the HRPC; the performance curve (PC) index ([PC1 - PC2] × [1 + PC1 × PC2]^-1) was calculated from PC1 and PC2. PC1 and PC2 refer to the heart rate response before and after the O₂ pulse deflection point, respectively. The PC index indicates the following: PC > 0.1, downward deflection; -0.1 ≤ PC ≤ 0.1, linear time course; PC < -0.1, upward deflection.The PC index significantly increased after exercise training (from -0.22 ± 0.09 to -0.14 ± 0.07; p < 0.05). In addition, the HRPC of 4 patients (37%) changed in linear time course.These results suggest that an upward deflection of the HRPC in patients with cardiovascular disease may shift to a linear time course after exercise training.