Activity changes were studied on electrodermal activity, heart rate, respiratory rate, and the soleus H-reflex during a mental rehearsal of 500 m speed skate sprint. Subjects were 10 speed skate athletes, ranging in age from 18 to 23 years, who had been fully trained by a image training program which including the same mental rehearsal. They were all highly motivated before each experiment. The mental rehearsal was started by a signal gun recorded by a tape recorder, after a rest period (5 min), relaxation (4 min) and a controlor emotion (2.5 min). Skin resistance of the each subject decreased largely during the mental rehearsal of the skating compared with that during relaxation, and increased gradually after completion of the rehearsal. The relative values of the decrease in all subjects were from 25% to 92% (mean of 65%, p<0.01). Heart rate began to increase prior to the rehearsal of the start, and indicated peak values during the rehearsal. The relative values of the increase were from 14% to 40% (mean of 24%, p<0.05). Respiratory rates also increased obviously during the rehearsal. The relative values of the increase were from 14% to 66% (mean of 43%). The patterns of the change of the soleus H-reflex during the mental rehearsal were classified to three groups as follows; a) a group which did not indicate significant change (4/10), b) a group indicated significant decrease of the H-reflex amplitude (4/10), c) a group indicated significant increase of the H-reflex amplitude (2/10). From the above results, it was suggested that the sympathetic nerve was activated in all subjects, when athletes who were intrested in the experiment and had been fully trained by a image training were sellected for the subjects. On the other hand, the individual variation would be existent among subjects whether the motor command from higher center facilitated or inhibited the motor pool of the spinal cord.
Although underwater weighing technique has been employed to obtain the standard values of body composition parameters, this is not practical in field surveys or in population studies.Thus, the development of a simplified method to calculate body volume from height and weight alone was attempted, since body volume is used to get density by means of dividing weight by volume, which is further associated with calculation of percent body fat. According to Du Bois's equation for body surface area, the form of the prediction equation of body volume from height and weight was constructed as V=AH^aW^b, where V, H and W were body volume, height and weight, respectively. Constant of A, and exponents of a and b were calculated by least square method. The prediction equations of body volume were developed for young men who were sedentary in earlier pilot study, physically active in the present study, and both of them,respectively. Estimation errors for these equations were calculated, i.e., the standard errors of estimate were around 500 ml, and the arithmetic mean differences between calculated and measured body volume did not exceed one percent when expressed in percent of total body volume. The validity of each prediction equation of body volume was evaluated especially from the viewpoint of applying body volume in the calculation of body composition parameters, and resulted in being effective to estimate percent body fat with considerable accuracy. Out of these equations, V=1.4267W^<1.0611>/H^<0.1323> was most recommended. This was derived from combined subjects consisting of both sedentary and physically active young men, and was thought to be applicable to many cases in spite of physical activities. Moreover, a diagram to read percent body fat from height and weight was suggested using the above equation. This seemed to be available for an easily obtainable index of obesity or leanness based on fat content unlike other body build indices, such as Rohrer's index and others.
In almost any ball game related to team sports, playing positions are specialized. Therefore it is essential that coaches must put their players in positions appropriate to their abilities. The purpose of this study was to investigate cognitive structures of rugby football positions.They were analysed by multidimensional scaling (INDSCAL: Individual Differences Scaling).The members of the WASEDA university rugby football club (N=107) and the veteran coaches (N=17) served as subjects. The results of INDSCAL analysis (2-dimensional solution) were interpreted as follows: Dimension 1: tactical dicision making, Dimbnsion 2: tolerance for contact play. The 15 rugby football positions were divided into 4 clusters by weights of INDSCAL subject space, applying hierarchical cluster analysis. Dimension 1 was especially important to the scrum half,left side centre, full back and standoff. Dimension 2 was of special importance to the left side prop and right side prop. Both dimensions were found to be equally important to the other positions. These clusters were discussed from the coaching point of view, and it was indicated that positions should not be fixed for all beginners in the early coaching stage.
The experiment was design to investigate the influences of exogenous testosterone administration for the weight and functional profiles of slow (soleus: SOL) and fast (extensor digitorum longus: EDL) skeletal muscles in exercise trained rats. Twenty-eight male Wistar strain rats were divided into four groups (n=7, each group); control (C), testosterone administered control (TC), sprint trained with testosterone administered (TS), and endurance trained with testosterone administered (TE). TS and TE groups were trained using motor-driven treadmill from 4 weeks old. TC, TS, and TE groups were administered the testosterone dissolved in corn-oil every day (20 mg/Kg body weight) from 4 weeks old. At the age of 17 weeks old, SOL and EDL muscles were isolated, and weight and functional profiles were measured. Relative muscle weight of TC, TE, and TE groups were significantly higher (p<0.01) than that of control group in both SOL and EDL muscles. Time to peak tension of twitch contraction in TS and TE groups were significantly shorter (P<0.05) than that of the control group in EDL muscle. The half relaxation time of TC, TS, and TE groups were significantly shorter (TC and TE: p<0.05,TS: p<0.01) than that of the control group in SOL muscle. FG fiber composition of TS group was significantly higher (p<0.01) than those of the control and TC groups. Phosphofructokinase activity of TC and TS groups were significantly higher (TC: p<0.05, TS: p<0.01) than that of TC group in SOL muscle. These results suggest that the exogenous testosterone administration influences weight and functional profiles in slow- and fast-twitch skeletal muscle fibers of exercise trained rats differently. Furthermore these influences appeared remakably in sprint trained rat EDL muscle.
The purpose of this study was to investigate the physiological demands on the referees and their movement patterns during rugby games. With this knowledge, training programmes for referees can be more scientifically prepared to meet the physiological demands of the game. Initially seven Japanese regional referees performed a treadmill running test to determine the maximal oxygen uptake (V^^.O_2 max), heart rate (HR) versus V^^.O_2 max regression line to estimate oxygen uptake (V^^.O_2) during rugby games. Referees were investigated for HR via PE3000 heart rate monitor and were filmed with a video tape recorder to estimate the distance covered on the field according to the type of activity performed during rugby games. The results were as follows; 1) The mean V^^.O_2 max of referees was 3.19 l/min (45.3 ml/kg/min). 2) The mean HR of referees during rugby games was 157.4 beats/min, which corresponded to 82.9% of the maximal HR and 77.2% of V^^.O_2 max. As referees performed approximately 50% of actual playing time at an intensity above 8O% of V^^.O_2 max. 3) The mean HR of referees during the second halves were significantly greater than those during the first halves. As for the same referees, the mean HR when refereeing at the semifinal or final game was significantly greater than that when refereeing at the first round. 4) The mean total distance covered in a 60 minute game for a referee was 4315.4 metres.There was no significant difference in distance covered by the referee comparing the first and second halves of a game. 5) Jogging shared the highest percentage of 43.0% of the total distance covered, followed by walking (28.3%) and running (12.5%). There was a considerable amount of backwards movement required by referees (9.9%). A relatively small percentage of distance covered in a game was by sprinting (2.1%) and sidestep (4.2%). From these results, it was suggested that the aerobic work predominated in refereeing and backwards movement was an important action for referees.
The purpose of this study was to investigate physical activity levels of Chinese students in comparison with Japanese students. First, a questionnaire on exercise habits was distributed among the students of 4 universities in China and 6 national unversities in Japan. Answers were obtained from 1,262 Chinese students (771 males and 491 females) and 1,409 Japanese students (1,282 males and 127 females). Second, eighteen healthy male students (9 Chinese and 9 Japanese) who did not participate in athletic clubs were selected as subjects for the measurement of daily activity levels. The heart rate of the subjects were recorded daily during the daytime by using Heart Rate Memory (TKK Instrument Co.). Measurements were taken both in China and Japan to determine the heart rate levels of each subjects and these were compared to the %V^^.O_2 max of different workload levels determined by a Monark ergometer. The results are summarized as follows: 1. The Chinese students tended to engage in exercise more than Japanese students in that (1) fewer complained about lack of exercise, and (2) a higher percentage of the population exercised habitually. Nevertheless, they did not have sufficient oppotunities for sports activity judging from the facts that (1) they had shorter exercise period (2) a lower rate of the population participated in athletic clubs and (3) fewer had experiented sufficient amount of exercise. 2. Although, in general; the Chinese subjects revealed higher rates of activity level exceeding 7O %V^^.O_2 max than the Japanese subjects, the durations of their exercise periods did not allow them to attain an essential time to improve aerobic power, except for one subject; while none of the Japnnese subjects fulfilled these conditions.