To record the displacement of the trunk during gait easily, we placed a portable accelerometer on the subject's back. We examined the reproducibility of the testing and compared it with the measurement of the ground reaction forces with the force plates and our simple motion analysis system using three laser pointers and a video camera. Subjects were five healthy adults and one paraplegic patient. The paraplegic patient whose functional level was T10-11 can walk independently with Lofstrand crutches and a hip-knee-ankle-foot orthosis system with a medial single hip joint (Walkabout^®). The subjects_ who were equipped with the accelerometer at the back of the trunk were directed to walk twice on the force plates at a comfortable speed. The test-retest cross-correlation coefficients ranged from 0.46 to 0.94. The cross-correlation coefficients between the accelerograms from the accelerometer placed on the back and the ground reaction forces ranged from 0.73 to 0.93. With the paraplegic patient, we measured the displacement of the trunk during walking with our motion analysis system. When we added the functional electrical stimulation (FES) to the Walkabout^® system, he could walk faster and the displacement of the trunk in the horizontal plane significantly decreased. The peak-to-peak amplitudes of the accelerographs in the horizontal plane did not differ with or without FES. These results suggest that the gait analysis using a portable accelerometer placed on the back and our motion analysis were valid for clinical use.

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Heart rate variabilities (HRV) during antigravitational posture test and lower body negative pressure test were measured in 21 bedridden patients with severe multiple disabilities and 18 normal persons to investigate their autonomic activity in cardiovascular regulation. After a control period of 5min of supine, each subject underwent an orthostatic sitting test or a lower body negative pressure test of -20mmHg for 5min. From the power spectral density of the HRV, the sympathetic and parasympathetic activities were assessed by the ratio of low frequency power in 0.02 to 0.15Hz to high frequency power in 0.15 to 0.5Hz, and the normalized high frequency power by total power in 0.02 to 0.5Hz, respectively. The results suggest that the autonomic inactivity in cardiovascular regulation for the disabled persons appears to be caused not only by a decrease in total blood volume but also by dysfunction of baroreflex probably due to the prolonged recumbency. Furthermore the deconditioning of their autonomic function seems to be associated more with parasympathetic deterioration. The degree of the orthostatic intolerance may also be linked to their lack of daily exposure to the gravitational forces being provided even by passive sitting posture.

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Two non-invasive methods of measuring muscle fiber conduction velocity (MFCV), minimal voluntary contraction and transcutaneous electrical muscle stimulation, were compared before and after strenuous isometric contraction. Ten healthy male volunteers participated in this study. The methods were performed on the left biceps brachii muscle of each subject. The mean value of MFCV with each method was 3.31±0.33 and 3.97±0.59m/s, respectively, and the values were significantly correlated (r=0.69). Muscles that have fast type I fiber MFCV appear to have faster type II fiber MFCV because minimal contraction generates firing of type I fibers, whereas electrical stimulation excites both of type I and II fibers. The MFCV of both types of muscle fibers seems to decrease to the same extent after strenuous isometric contraction. These findings support the hypothesis that the MFCV of both types of muscle fibers decreases after fatigue when present in the same working muscle.

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