The purpose of this study is to investigate histologically the distribution of muscle spindles and the relationship (size, number) between intrafusal and extrafusal fibers. M.tibialis ant. of Wistar-strain rats was chiefly used in this experiment. Alcohol solution of Sudan black B was used to stain the fibers. The results were as follows: (1) Muscle spindles were distributed more at the middle part of the muscle and were observed more in innermost region than in peripheral. (2) Muscle spindle consists of sarcosome rich (red) and sarcosome poor (white) intrafusal fibers. The number of red intrafusal fibers involved in a muscle spindle is more than that of white intrafusal fibers. (3) Development of intrafusal fibers and extrafusal fibers was observed as days passing after birth. The rate of hypertrophy of extrafusal fibers is greater than that of intrafusal fibers while their development occurs.

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This study was made for the purpose of clarifying the extent to which the intrathoracic pressure, especially the snatch pressure, rose when performed sports skills with explosive power in both straining and exhaling states. Seven healthy male adults were used as subjects and Balloon Method was used to record the rise of intrathoracic pressure while performing totally 19 skills, five in track and field and 14 in ball-games. The results were as follows: 1. When the skills were involved in the upper arm which required an impulsive power were performed under straining state, the rise of intrathoracic pressure was most remarkable; it was found that the snatch pressure rose up to above 200mmHg. 2. There were large individual differences in the extent of the rise of intrathoracic pressure when perfumed skills in both straining and exhaling states, but no difference was found between the skilled and the unskilled or between the experienced and the less experienced. 3. When a subject performed the same skill in both exhaling and straining states, the rise of the intrathoracic pressure in the latter state was 1.2-2.4 times higher than that in the former. It may be possible to prevent, to some extent, the excessive rise of the intrathoracic pressure by performing skills while exhaling or shouting when lifting things or executing instant power. 4. The appearance of more than 200mmHg of snatch pressure obtained in this study was unexpectedly high, which may cause faint following acute circulatory collapse or obstruction in the brain circulation.

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According to recent statistics on the school health, the general physique and physical fitness of pupils in the part-time high school (PTHS) are considerably inferior to those in the full-time high school (FTHS). This fact may possibly be due to certain differences of food intake and living situation. The present investigation was attempted to analyze their nutritional status and living situation by time studies on the pupil of several PTHSs in Gifu district in Japan, and their results were compared with those of FTHS in the same district. The subjects consisted of 161 boys and 245 girls, of which 85 pupils from PTHS and 321 from FTHS. The results were summarized as follows: 1) Animal protein intake and the protein score in the food of PTHS-pupils were lower than those of FTHS. 2) Carbohydrate, fat, vitamins and mineral intake in PTHS-pupils tended to be less than the FTHS. 3) Comparing the balance of calorie intake (calculated from the food analysis) with the energy output (rendered by time study analysis) between PTHS and FTHS-pupils, the amount of energy reserve of the FTHS-pupils tends to surpass that of PTHS. 4) The food intake of PTHS-girls tended to decrease with age, while little difference was noted in food intake in boys. 5) It may be considered that the chance of physical training is relatively limited in PTHS-pupils because of the present situation in time and space not sufficient to improve their growth, as well as their handicaps in familial back-ground. Further, in addition to improvements of these situations, increase in high quality of animal protein in take should also be adevisable.

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The research aims at the analysis of the effects resulted from the exercise practice and the suspension of the practice. The infants were given the following seven types of exercises to do once a day: (1) standing on one leg (2) repeated sidesteps (3) standing broad jump (4)running broad jump (5) bending forward (6) repeated jumping on one leg and (7) back muscle. The results were comparatively studied as they were drawn (1) before the infants started practice (2) a month after they started (3) two months after they started (4) before the summer holidays and (5) after the holidays. We have reached the conclusion that remarkable effects of practice in exercises have been observed in respect of the types of exercises that required "skillfulness" and "promptness" but no remarkable effects have been observed in respect of the once that require muscular labor.

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There exists a considerable literature on the peripheral nerve conduction velocity in man by means of evoked electromyography. Some of them have elucidated certain factors that influence conduction velocity. The work of Kato (1960) indicated that conduction velocity was affected by room temperature. It may be assumed that room temperature would affect temperature of tissue surrounding the nerve. On the other hand, Buchthal et al. (1944) and Saltin et al. (1968) showed that the muscle temperature rises during or after muscular exercise. In the present experiment the maximal conduction velocity of ulnar nerve was measured after two minutes of rhythmical contractions of forearm flexors. Fifteen minutes after the work, the mean velocity for 12 cases increased 4.8m/sec. above the initial value. After muscle exercise, skin temperature rose as well as girth of foreran. Conduction velocity was correlated with skin temperature but not with room temperature. The mean residual latency was 1.75±0.06msec (S.D.) for l0 measurements during the rest-period. After exercise the mean latency was shortened to 1.64±0.26msec. Paired "t"-test showed the difference to be significant at O.O1 level.

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Ski-Jump performances were investigated in this study. Most of the difficulties for studies were to get the physical data. And few papers have previously been reported. The times of approaching and flight, and flight distance are measured. The performances of the take-off are taken with 16mm camera and the style points are recorded. Nine excellent Ski-Jumpers expected to be as the Olympic contenders were chose as subjects. In the conclusion, significant relationships were pointed out as follow; Flight distance (X) and Flight time (Y) Y= 0.041X +0.143 r = 0.92^<**> Approach time (X) and Flight time (Y) Y =-0.75X+ 5.52 r = -0.64^* Flight distance (X) and Approach time (Y) Y= -0.023X +5.36 r = -0.60 The importances of timing on take-off, flight direction, muscle power and fighting style should be emphasized from those data.

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Experiments were performed to investigate the muscle strength ratios and the maximum strengths exerted in 6 tests of hip flexion, hip extension, pulling the leg forward, pulling the leg backward, knee extension and plantar flexion. The subjects were 5 healthy males from 20 to 29 years old. The following results were obtained: 1. The maximum voluntary isometric muscle strength varied according to respective angles of all joints. 2. The maximum strength values were obtained when the hip angles were 210° in hip flexion, 90° in hip extension, 240° in pull the leg forward, 120°in pull the leg backward; the knee angles was 100° in knee extension; the ankle angle was 80° in plantar flexion.

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In the present paper the author tried to clarify the structure of volley-ball class from the viewpoints of form and teaching of skills of volley-ball. The data were collected by the use of V.T.R. in volley-ball classes for the first grade at A and B Senior High Schools for 8 school hours. And then they have been arranged by a Series of Time (i.e. Barnes's Motion and Time Study) to make clear (1) What basic elements the structure of volley-ball class consists of, and (2) through what exercises each skill of volley-ball is taught and how each skill is synthetically taught in actual class. The results are as follows : 1) At A High School, skills of volley-ball are analyzed into various basic one, and system-attired. and then synthesized so that students may obtain and develop each skill systematically through 8 school hours On the other hand, at B High School, such basic skills are repeatedly taught and exercised hot separately but organically. 2 ) The ways of the exercises of skills are considerably different in both schools. Especially at A School, skills are taught through the process of concentration and development so that students may master them automatically. 3) Judging from (1) and (2), the ways of the exercises of each skill which may be thought of as a mail object in each class, and the number how many times students play it are different. It is more remarkable that at B School 'toss' and 'attack' are not taught at all through 8 school hours. 4) The game was performed several times as a final part of volley-ball class at the sixth, seventh, all eight periods at both schools. But as a game may be thought of as the place where the students can estimate themselves whether or not they could sufficiently obtain skills of volley-ball, and where teachers themselves can reflect on the method of their teaching and exercises, it is very important for developing the skills of the students to decide when the game should be performed in the unit of volley-ball.

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