In resistance training, it has been empirically accepted that muscle hypertrophy is developed by low intensity and high volume training, while muscle strength and power are developed by high intensity and low volume training. The purpose of the present study was to investigate the influence of two different modes of resistance training on isokinetic strength and muscle cross-sectional area (CSA) in females. Eleven females, who had no experience in resistance training, participated in this study and were randomly divided into two groups. The former consisted of 4-5 sets of 15-20 RM (repetition maximum) with sufficient rest between sets (Group H), while the latter consisted of 8-9 sets of 4-6R M with 90 s of rest between sets (Group S). The former was assumed to be appropriate for muscle hypertrophy and the latter muscle strength, respectively. All subjects completed isotonic knee extension exercise three times a week for 8 weeks. Measurements were made on quadriceps muscle cross-sectional area (CSA) and isokinetic torques at 0, 60, 180, and approximately 300 degrees before training, at the fifth week and the end of training period. Muscle CSA was defined as the sum of CSA measured at 30, 50 and 70% of femur length. After training, muscle CSA had significantly increased in both groups: 3.3 +/- 0.7% (p < .05) for group H and 3.6 +/- 1.1% (p < .05) for group S, respectively. While the changes in isokinetic torque were 43.4 +/- 47.5% (p < .05) for group H and 27.4 +/- 31.3% (p < .05) for group S, respectively. In both groups the percentage changes of the isokinetic strength were significantly higher than those of the CSA. No significant difference in these variables were found between the two groups. These results suggest that during the early phase of resistance training two different modes of resistance training may have similar effects on muscle CSA and isokinetic strength in untrained females.

An axial pump which is used to pump water out of a river often sucks in solid bodies such as leaves and branches. These foreign substances may clog the passage and lead to dangerous conditions such as a decline in the performance of the pump. In this investigation, we conducted the clogging experiments by putting polyester strings in an axial drain pump which has two types of impellers, a radial blade impeller and a swept back blade impeller. By visualizing behavior of the strings in the pump using a high-speed video camera, we compared the anti-clogging performance between the two impellers and investigated the mechanism of clogging. The results of these experiments showed that the pass rate of the strings that flowed into the swept back blade impeller was higher than that in the radial blade impeller. It is because strings that are caught in the leading edge of the swept back blade tend to move to the tip side and be pulled towards the suction surface. In addition to the experiments, we carried out the simulations of these experiments using a CFD-DEM (Discrete Element Method) coupling analysis. The results were in good agreement with the experiments qualitatively.