THE EFFECTS OF EXERCISE OF THE PERONEUS LONGUS AND TIBIALIS POSTERIOR MUSCLES ON HEEL RAISE / 体力科学

Objective: This study aimed to clarify changes in planter pressure at the 1, 2, 5 metatarsal head, and muscle activities resulting from exercise of the peroneus longus (PL) or tibialis posterior (TP) muscles. Method: Nine subjects (3 male, 6 female) were recruited. Before and after exercise, planter pressure at the metatarsal heads and the activities of PL, TP, tibialis anterior, and soleus muscles were recorded during heel raising using electromyography and a foot sensor. The first exercise was a maximal isometric contraction of the PL and peroneus brevis (PB). The second was contraction of the TP, and the third was of all three, the PL, PB, and TP. Result: The amount of planter pressure at the first metatarsal head increased after PL exercise. The standard deviation at the second metatarsal head decreased after PL and TP exercise, but showed no change after PL exercise. Conclusion: After PL and TP exercise, heel raises were possible with few perturbations at the metatarsal head. After PL exercise, the amount of planter pressure at the first metatarsal head increased, but there was no change in perturbations. The results show that it is necessary to consider the effect of short time exercise.

RELATIONSHIP BETWEEN HEART RATE VARIABILITY DURING EXERCISE AND VENTILATORY THRESHOLD / 体力科学

The aim of this study was to investigate the relationship between heart rate variability (HRV) during exercise and ventilatory threshold (VT), using the MemCalc system which is superior in spectral analysis. Nine healthy male subjects with no cardiopulmonary disease performed an exercise test to exhaustion to determine VT on a bicycle ergometer. Low frequency (LF : 0.04-0.15 Hz), high frequency (HF : 0.15-0.40Hz) and LF/HF ratio power spectra were calculated by maximum entropy method (MEM) spectral analysis, using the MemCalc system. In each case, when the subject started exercise, the HF component declined rapidly during the first 30 seconds ; and compared to the resting value, it declined to approximately 5 % at VT. The possibility of using this phenomenon as a criterion for setting intensity of exercise is tinder consideration. The LF/HF ratio showed different patterns of variation among the subjects. A significant linear relationship was seen between the declining rate of the HF component and VT (r=0.93, p<0.001), suggesting a corres pondence between the heart's capability of adjusting to maintained exercise and high endurance capacity.