The purpose of this study was to elucidate how long it takes to reach peak blood flow after muscle contractions in consideration of the cardiac cycle. Seven healthy female subjects performed two successive dynamic plantar flexions of 1-s duration at 30, 50 and 70% of maximal voluntary contraction (MVC). Based upon the blood flow response after a single contraction, we set up intervals during two successive contractions each corresponding to 10% (10 I), 30% (30 I) and 50% (50 I) of the time required to reach peak blood flow. Upon cessation of contraction, the popliteal artery blood flow (Qpa) increased progressive, beat-by-beat increase and peaked by the 5^th cardiac cycle, for all conditions. The highest peak blood flow among the cardiac cycle was at 3^rd cycle in overall data. Peak Qpa values reached after exercise did not differ among intervals, whereas peak Qpa value attained after exercise was significantly greater in 50 and 70%MVC than 30%MVC (p<0.05). The result indicates that the augmentation of the Qpa after exercise with short duration differed with the exercise intensity but the timing for reaching peak post-exercise value did not differ in terms of the number of cardiac cycles.

The purpose of this study was to clarify the relationship between left ventricular muscle mass, skeletal muscle volume and vessel structures in elderly women (n=15, 76.0±5.4 years). We measured the thigh muscle thickness, and brachial and common carotid arterial diameter using B-mode ultrasound method. Posterior wall thickness, interventricular septal thickness, left ventricular end-diastolic internal diameter, and aorta artery were measured by B-mode echocardiography. No significant relationship was obtained between brachial and common carotid arterial diameters, and aortic diameter. On the other hand, significant correlation coefficients were obtained between cardiac muscle thickness and thigh muscle thickness (r=0.674, p<0.01). A significant correlation coefficient was also obtained between the estimated skeletal muscle volume and left ventricular mass [LVmass](r=0.542, p<0.05). The slope of regression equation between estimated thigh muscle volume and LVmass in elderly women in this study was (y=0.11x+75.65) steeper than in children (y=0.06x+14.02) reported previously. These results indicate that the ventricular muscle (LVmass) is closely related to the skeletal muscle volume in ordinary elderly women and skeletal muscle mass at a given LVmass is smaller in elderly women than children.

The purpose of this study was to prove the hypothesis that the effect of strength training is memorized and reinforced by retraining. Untrained university-age men participated in this training program. The retraining leg was subjected to 5 weeks of isometric training, 17 weeks of detraining and 5 weeks of retraining in knee extension. The contralateral training leg was subjected to 5 weeks of isometric training during the same period as the retraining phase of the retraining leg. Maximal isometric torque of knee extension increased after the 5-week training and remained at the trained level during the 17week detraining period. Torque gain by retraining of the retraining leg was 2.6 times greater than that of the contralateral training leg. These changes in isometric torque corres-ponded with changes in iEMG of the vastus lateralis. The cross-sectional area of the quadriceps femoris muscle did not change with training. Results support the hypothesis that the effect of strength training is memorized and reinforced by retraining. In addition, results show that these adaptations would be explained by recruitment and rate coding of motor units.