Many studies have been conducted on the monosynaptic reflex (H-reflex) changes which occur before a voluntary movement in man. Especially, it has been shown that there were the changes of H-reflex prior to the rapid plantarflexion movement which was called the premotor inhibition. In the present study, the changes in soleus H-reflex prior to a choice reaction time (RT) were studied, giving the special attention to the possible functional difference of motor patterns to generate the premotor inhibition during a period when the physiological mechanisms involved in the movement. The changes of H-reflex were measured in choice RT experiment in 9 and 6 male subjects under the different two conditions : (a) selection of the response sides (left or right plantarflexion) -the movement pattern was known before the presentation of a response signal ; and (b) selection of the movement patterns (plantar or dorsiflexion) -the responce side was known before. The premotor inhibition was observed only in case of (a), and was dependent on a prerequisite for movement patterns. Moreover, the physiological significance of this phenomenon was indeed related to a presynaptic inhibition, and was related to a modulation of alpha-motoneurone excitability by the pyramidal system. Thus, the premotor inhibition might be related to central motor preprogram controlling presynaptic inhibition on the reflex pathways.
This study was undertaken to examine the mechanical efficiency of stepping exercise on the relations with physical characteristics such as body height, lower limb length, leg length and body weight, and the efficiency was used to estimate the energy metabolism during the stepping exercise. Thirty healthy male students, whose heights ranged from 157.6 cm to 189.0 cm, performed the stepping exercise using a platform from 10 cm to 50 cm. The stepping rate of vertical lifts per minute was fixed to 25 ascents/min., and the height of the platform was increased progressively by 10 cm on every 3 minutes. Oxygen intake during the stepping exercise was measured for the last 1 minute on every stage. Gross, net, work, and delta efficiencies were compited. The results were summarized as follows: 1. It was suggested that there was slightly exponential relationship between energy metabolism and work rate, which was ascribed to the decrease of work and delta efficiencies with increments in work of the stepping exercise. 2. The correlation coefficients between the net efficiency and each physical characteristic were not signifficant for all heights of the platform. This result suggests that the physical characteristics have little or no effect on the mechanical efficiency of the stepping exercise. 3. The mean value and the standard deviation of the net efficiency for heights of the platform above 30 cm were 14.3 and respectively. By using this mean value, energy metabolism during the stepping exercise can be calculated from the equation : Y=0.0163×weight (kg) ×stepping rate (ascents/min.) ×height of the platform (m) +resting energy metabolism (kcal/min.) . The standard error of estimation was ±0.52 kcal. This value was lesser than that calculated from the regression equation between heart rate and oxygen intake during the stepping exercise.
Eighty healthy males aged from 26 to 34 years were studied to evaluate the effects of regular physical training on body composition, respiratory functions, circulatory functions, blood constituents, and physical fitness. The physical training consisted of jogging, volleyball, handball, socker, judo, fencing, and others. The combination of these sports were assigned to all the subjects to be performed for 130 minutes every week-day from April, 1979 to January, 1980. 1) The subjects had, on the average, 518 g of carbohydrate, 125 g of protein including 74 g of animal protein, and 85 g of fat summing up to 3300 kcal a day. These nutrients intake was 30% to 50% excess over the normal value for male Japanese of the corresponding age. Body weight, however, did not change and body fat decreased in spite of large excess food intake. Serum HDL-cholesterol increased and atherogenic index decreased. These facts lead to a conclusion that the noxious effects of overeating can be cancelled by physical activity. 2) Pulse wave velocity of the aorta which reflects the elasticity of the aortic wall decreased. This means that changes in the physical property of the aorta due to aging process can be reversed through physical training. Decrease in pulse wave velocity dose not always mean the regression of atherosclerosis, but the additional findings such as decrease in body fat and in atherogenic index and increase in HDL-cholesterol support the possibility of regression of aterosclerosis by physical activity. 3) The results of physical fitness test indicated marked improvement of physical abilities which reflect muscular strength, muscular power, muscular endurance, body flexibility, agility, anaerobic power, and aerobic power.