It has been observed that the premotion silent period (p. s. p.) appears just before a rapid voluntary movement. This phenomenon is believed to be caused by one of the inhibitory discharge from the central nervous system. In the present study, the effect of p. s. p. appearance was investigated by comparing the advanced informations of the fast reactive movement (Fast condition) and the powerful reactive movement (Powerful condition) . Six healthy males aged 19-21 years were subjected to a series of experiment in which they were asked to exert their muscle strength of 15-20% of their maximum elbow extension strength. They were requested to extend their elbow joint responding to a flashing lamp as quickly as possible on the fast condition. On the powerful condition, they exerted their elbow extensor strength as greatly as possible. The EMG activities of triceps brachii and biceps brachii were recorded by bipolar surface electrodes. Mechanical response was simultaneously recorded using a resistance strain gauge transducer, and the mechanogram was analyzed on the following items: A) premotor time (the time from the signal to the onset of the force curve), B) rate of tension rise (the maximum rate of tension rise in the force-time curve) . The following results were obtained from this experiment.
1) The rate of appearance in p. s. p. on the powerful condition (21%) was significantly higher than the fast condition (9%) .
2) The premotor time on the powerful condition (180msec) was significantly later than the fast condition (160 msec) .
3) The rate of tension rise on the powerful condition (258 kg/sec) was significantly greater than the fast condition (177 kg/sec) .
It was suggested from these results that the frequency of appearance in p. s. p. on the fast condition decreased in comparison with the powerful condition. It was also considered that the appearance in p. s. p. produced the increase of the rate of tension rise.

An electromyographic silent period appears prior to initiation of a reaction movement. In order to estimate the mechanism of the silence, the statistical properties of the EMG before the onset of the phasic discharge were investigated. The EMG activity was processed as a stochastic process, and the statistical properties were analyzed. It was found that the mean of the rectified EMG decreased from 100 ms before the onset of the phasic discharge. As to the relationship between the silence and the depression of the EMG activity, it was estimated that the depressing influence was so remarkable that the silent period was observed.

An electromyographic silent period can be observed preceding a rapid voluntary movement following the sustained contraction. This phenomenon has been called the “premotion silent period”, (p. s. p.) .
In the present study, relationship between frequency of the p. s, p. appearance and joint angle in the preparatory phase was examined. An elbow joint extension to visual stimulus was chosen fo the rapid voluntary movement. It was found that the p, s, p, appeared frequently at the elbow joint angle less than 80 degrees, and no noticeable change of the frequency was seen in this range. The frequency of the p, s. p. appearance exceeding 80 degrees had a tendency to decrease. The authors discussed the possibility of correlation between the p, s. p, appearance and activity of the muscle spindle.

The aim of this study was to clarify the influence of buoyancy on physiological responses during treadmill walking. Six subjects participated in this experiment. The water level was adjusted to the greater trochanter. Normal water (NW) and 1.135 kg/l of specific gravity (high buoyancy ; HB) were set. Oxygen uptake (VO₂), heart rate (HR), and rating of perceived exertion were measured during exercise. VO₂ in HB at all walking speeds were higher than those in NW significantly. HR enhanced in HB over the walking speed of 70 m/min significantly. It was clear that the workload of walking in HB increased remarkably over the walking speed of 70 m/min. This suggested that the water resistance acted on the phenomenon of increase of the workload in HB. Furthermore, it was suggested that walking in HB was useful for rehabilitation and therapeutic exercise in the low-speed and for physical training in the high-speed.

The Cobb's and Ferguson's methods are widely used in order to measure scoliotic angle using the X-ray photograph. Since the scoliotic angle is detected on the bases of the positions of only two and three spines, the measured value includes various kinds of errors. Thus, the present study was designed to examine accuracy and reliability of the Cobb's and Ferguson's methods. The scoliotic angle corresponding to the Cobb's and Ferguson's method were computed using the least square approximating curve that was obtained on the basis of the positions of spines from thoracic to lumbar vertebrae.
As a result, it was found that the scoliotic angle by means of the clinical Cobb's method was closely correlated to that by the least square method with positive correlation coefficient of 0.98. On the other hands, the Ferguson's method showed less relation to the least square method. Thus, it was confirmed that the Cobb's method was more reliable for diagonsis of the scoliosis.