The primary purposes of this study were 1) to confirm age-related deterioration of physical performance in older adults longitudinally, and 2) to predict future functional status and mortality by initial level of physical performances. The subjects were 517 older adults examined both in 1992 and 1996 in the Tokyo Metropolitan Institute of Gerontology, Longitudinal Interdisciplinary Study on Aging. The same battery consisting of muscle strength, balance, walking, and manual speed was administered to the subjects in the baseline and follow-up examinations. A significant longitudinal decline was observed in all physical performances except for grip strength. The age-related decline accelerated with aging for preferred walking velocity. Inter-subject variability in walking velocity significantly increased for 4 years period. Maximum walking velocity was a common predictor for functional status and mortality. The results suggest that physical performance measures, especially maximum walking velocity, is a valid means for physical therapy to evaluate physical functioning of community-living older persons.
The present study was designed to investigate the nature of motor information processing in the intertrial intervals of a discrete motor task. In Experiment 1, the subjects were given the task of grasping the dynamometer with an intensity yielding a value as close as possible to the target value (40% of the subject’s maximum grasping power). The exercise session consisted of 5 trials without Knowledge of Results (NO-KR phase), and 30 trials with Knowledge of Results (KR phase). In the KR phase, one of the two interpolated tasks, one was a verbal task and the other was a motor task, was given during the KR delay interval or the post-KR delay interval. Performance level in the exercise session was measured by constant error and variable error. In Experiment 2, the degrees of difficulty in the two types of interpolated tasks used in Experiment 1 were measured. The main results of our experiments were as follows; (1) Although the results of Experiment 2 showed that the difficulty of the verbal interpolated task was exceeded that of the motor interpolated task, only variable errors of the groups which had executed the motor interpolated task were increased. If the kinetic sense was changed by executing the motor interpolated task, constant error should have increased. The results of Experiment 1, however, showed no difference in constant error, suggesting that the occurrence of interference by the motor interpolated task is related to the capacity of the motor short term memory space. (2) In the latter period of the KR phase, variable error of the group in which the motor task was interpolated during the KR delay interval was at the same level as that of the control group. Whereas variable error of the group in which the motor task was interpolated during the post-KR delay interval exceeded that of the control group over the whole of the KR phase. These results suggest information processing during the post-KR delay interval has more influence on performance than that during the KR delay interval.
This study was undertaken to evaluate the postural effect on ventilatory responses during both supine and sitting exercise. Seven healthy men performed two exercise tests utilizing the ramp protocol (20 watts/min) with a cycle ergometer in each position. The results were as follows: The oxygen uptake and the oxygen pulse measured at 180 watts and at anaerobic threshold in the sitting were significantly higher compared with those in the supine position. The average of carbon-dioxide output, minute ventilation and tidal volume at lower exercise intensities showed higher values in the sitting compared with those in the supine position, whereas there were no significant differences for respiratory rate. There was significant difference in the slope of the minute ventilation to carbon-dioxide output plot between sitting and supine position. In conclusion, the higher minute ventilation in the sitting position was mainly performed by higher tidal volume which may counteract the effects of an increase in physiological dead space. The lower slope of the minute ventilation to carbon-dioxide output plot which shows more effective ventilation in the supine position may be due to decreased physiological dead space and higher diffusion capacity.
The purpose of this study was to investigate the effects of weight bearing at varying intervals in suppressing the progression of disuse muscle atrophy, while setting the total daily weight bearing time constant. Disuse muscle atrophy was induced by 2-week hindlimb suspension. Thirty male Wistar rats ( weight : 215 ± 8 g ) were divided into 6 groups ( 5 rats/group ) : control (CON), suspension alone (SUS), two sessions of 30-minute weight bearing at intervals of 4, 8, and 12 hours during suspension, and one session of 60-minute weight bearing at intervals of 24 hours during suspension. Weight bearing was done each day during the daytime. Histochemical staining, followed by morphometrical analysis using NIH Image, demonstrated that the cross-sectional area of type I fiber in SUS was 44% of that in CON, while in the weight bearing groups ranged from 62 to 70%. The proportion of type I fibers was lower in SUS and tended to increase as the interval of weight bearing become longer, indicating the effects of weight bearing at intervals of 12 and 24 hours. For both types I and II, the distribution of muscle fiber size indicated that weight bearing at longer intervals was more effective in keeping the cross-sectional areas of muscle fibers closed to that in CON. In conclusion, when suppressing the progression of disuse atrophy of rat soleus muscle by weight bearing of one hour per day, the results suggest that the weight bearing intervals is important factor.
The purpose of this study was to investigate the effects of cervical traction on the soleus H reflex amplitude in stroke patients. Cervical traction with intensity of 3 kgw was performed on six stroke patients. The soleus H reflex was evoked before, during, and after the cervical traction. All subjects showed smaller H reflex amplitudes in the second and third minutes after traction than before the traction. The results suggested that cervical traction with intensity of 3 kgw inhibited the soleus H reflex amplitude several minutes after traction in stroke patients.