The cold-induced vasodilation (CIVD) was measured of 30 male university students who were daily engaged in three or four kilometers running, a rubdown with a dry towel and sports activities (trained group), and of 20 male university students who were hardly doing any physical exercise (untrained group) . Measurements were made five times in spring, summer and autumn in 1976 and in winter and spring in 1977. The results were summarized below: 1. The mean skin temperature (MST) and the temperature at first rise (TFR) were higher and the time of temperature rise (TTR) was earlier in the trained than in the untrained. This trend of difference between the two groups was particularly remarkable in summer, autumn and winter. MST was high in summer and low in winter, and this seasonal variation of MST was in conformity with that of the previous reports. The variation of the index of MST, TFR and TTR well conformed with that of temperature before water immersion (TBI), supporting the reasonability of Nakamura et al's rating method. 2. The resistance index (RI) was higher in the trained after summer and was significant in winter and spring of the following year. The increase of RI in one year was as significant as 18% in the trained while it was only 2% in the untrained. The seasonal variation of RI showed a two-peak behavior, high in summer and winter and low in spring and autumn. The above differences of CIVD scores between the trained and the untrained indicate that physical training is useful for resistivity against cold.
The purpose of this study was to determine the growth and developmental changes and the sex difference in anthropometric characteristics, muscular strength, and flexibility in 205 junior high school competitive swimmers. Factor analytic technique was applied to three different correlation matrices, each of which consisted of 14, 12, and 15 selected variables in anthropometric characteristics, muscular strength, and flexibility domains, respectively. The main results can be summarized as follows; 1) Among 2 extracted factors representing anthropometric characteristics domain, physique (factor 1) grew gradually as the age increased in both sexes. Amount of the physique growth for boys was, however, greater than that for girls. Physique of boys in the 8th and 9th grades was larger than that of girls. Body fat (factor 2) for girls appeared to be greater than that for boys. 2) Among 3 extracted factors representing muscular strength domain, static strength (factor 1) developed gradually as the age increased in the both sexes. Amount of the development for boys was greater than that for girls, and this ability of boys was greater than that of girls. Muscular endurance in fast muscular exercise (factor 2) for boys became to be greater than that for girls as the age increased. Dynamic strength of shoulder-arm girdle (factor 3) for boys of the 8th and 9th grades was greater than that for girls. 3) Among 6 extracted factors reprsenting flexibility domain, trunk rotation flexibility (factor 2) and ankle extension and mobility flexibility (factor 5) for girls were much greater than those for boys. Trunk extension and flexion flexibility (factor 6) for girls seemed to be greater than that for boys. Development of this ability in accordance age increase was found only in boys. In contrast, no differences between sex were found in trunk lateral flexibility (fator 1) and shoulder flexibility (factor 4) .
Sex difference in enzyme activities of the skeletal muscle were examined in rats aged 10 and 35 weeks. At 10 and 35 weeks of age, animals were anesthetized with ether and weighed. M, gastrocnemius, m.extensor digitorum longus and m.soleus were removed from both legs under pentobarbital anethesia and weighed. These muscles were used for the determination of myosin ATPase activity, phosphofruktokinase (PFK) activity, succinate dehydrogenase (SDH) activity and non-collagenous protein (NCP) content. The results were summarized as follows: 1) Thirty-five week-old rats had heavier body and muscle weights than 10-weekold rats in both sexes and males had significantly heavier body and muscle weights than females at both 10 and 35 weeks of age. 2) Similar tendency was observed with regard to total NCP content. Furthermore, it was found that total NCP content was positively correrated to muscle weight (r=0.871, r=0.909 and r=0.871 in m. gastrocnemius, m.extensor digitorum longus and m.soleus, respectively) . However, no significant difference in NCP content per wet weight was found between both sexes and between different age groups. 3) Myosin ATPase activity tended to be lower at 35 weeks of age than at 10 weeks of age, the tendency being the most prominent in the gastrocnemius muscle of male rat (p<0.05) . However, no significant sex difference in myosin ATPase activity was observed in three muscle examined in both age groups. 4) Although not statistically significant, mean PFK activity was slightly lower in 35-week-old rats than in 10-week-old rats, and there was no sex difference in PFK activity at both weeks of age. 5) SDH activity was significantly lower in 35-week-old rats than in 10-week-old rats except that there was no significant age difference in the gastrocnemius muscle of males. There was no significant sex difference in SDH activity in both age groups with an exception of the extensor digitorum longus muscle from 35-week-old rats, where males had significantly higher SDH activity than females.
The effects of varying time intervals and frequency of preliminary stimulations shown in advance of movements upon the variations in the subsequent responses to exogenous stimulations have been evaluated on the basis of the reaction time. The following results have been obtained. 1. In the cases of simple preliminary reactions, if a time interval between the preliminary stimulations and the actual stimulations was less than 1000 msec, the reaction time was delayed more than the cases of the control reaction to simple stimulations. A relationship of index function was found out between the intervals of stimulations and the time of responses. 2. In the cases of persistent preliminary reactions, the shorter the intervals of stimulations, the shorter became the reaction time than that of the control reaction to the simple stimulation. 3. The so-called flying errors which are the movements induced before the actual stimulations were most frequently developed at an interval of stimulations of 1000 msec. On the basis of the above findings of the reactions, the levels of excitements in the center (CNS) and peripheries could be assessed on the basis of the above findings of the reactions that reactions to a stimulation can be variable according to the other stimulations induced prior to the particular stimulation.
The types of skeletal single muscle fibers were studied with the distribution of myosin light chains (MLC) and tropomyosin (TM) to make clear the biochemical property and the possibility of the transformation of fiber types by physical training. Since soleus (SOL) muscle is widely used as an example of slow-twich muscle and extensor digitorum longus (EDL) muscle is used as one of fast-twitch muscle, single muscle fibers were prepared from SOL and EDL muscles of 5-6 weeks old male mice (strain DDY) . Total myofibrillar proteins of the muscle bundles or single muscle fibers were homogenized and fractionated with the micro two-dimensional isoelectric focusing/sodium dodecyl sulfate polyacrylamide gel electrophoresis (IEF/SDS-PAGE) . The fractionated proteins were visualized with coomassie brilliant blue stain method or highly sensitive silver stain method. We found that there were at least two types of fibers in SOL and EDL muscles. In SOL muscle, one contained only slow form of MLC and the other contained both of fast and slow forms of MLC. In EDL muscle, one contained only fast form of MLC and the other contained both of fast and slow forms of MLC. The fiber containing only one form of MLC was classified into typical slow or fast fiber, and the fiber containing both forms of fast and slow types MLC was classified into intermediate fiber. Both of a form and β form of TM were invariably observed in all fibers of SOL and EDL muscles. Relative ratio of a form of TM to β form of TM was, however, larger in the typical fast fiber containing only the fast form of MLC than others. The ratio was smallest in the typical slow fiber. These results suggest the possibility of the continuous transformation in the phenotype of muscular proteins within a single muscle fiber by physical training.