In order to observe the development of physical fitness of rural boys and girls, a series of examinations with respect to physique, various physical-strength-tests, maximum O₂ intake and vital capacity were investigated with 541 boys and 436 girls in middle-and high-school in Nakatsugawa district in Gifu prefecture in autumn, 1966. And their result was compared with the value of average Japaness children of the same age. The result obtained was summarized as follows
1) The development of physique, such as body height, body weight, girth of chest and sitting height, did not differ from the average Japanese level.
2) The running ability of rural children was slightly inferior to that of the average Japanese children for the short-distance-running (50m), in which one must give the maximum power within short period of time. On the other hand, it was rather superior to the average Japanese children for the long-distance-running (1500m for boys and 1000 m for girls), in which one must display a full effort for the endurance work for relatively long period of time.
3) The result of neuromuscular test, which was revealed by broad jumping, side step and back strength, indicated that the value of rural girls was lower than the average Japanese, whereas that of rural boys did not show such a difference. An index of respiratory and circulatory system as in the step-test for girls was slightly lower than the average Japanese girls, but no difference was obtained in rural boys.
4) The vital capacity and maximum O₂ intake of rural children were, in general, nearly the same as the average Japanese value. However, among children of middle school who were not able to go on to high school on account of poverty, there were several boys and girls having a lesser pulmonary function.
5) The comparison of these items with those of foreign children indicated that no difference was recognized among them, for example, the indication of physical capacity for long endurance work, the maximum O₂ intake of rural Japanese children was not different from that of the Swedish children reported by P.O. Åstrand,

Three middle-aged men (55-58 years) trained for 50 weeks. Exercise consisted of twelve minutes walking on the motor driven treadmill at the load of 70% of maximum oxygen intake, three times per week.
Evaluations for maximal and submaximal work were made at 5-week intervals using treadmill walking method. Mean maximum oxygen intake improved 29.5% (26.1-39.7 %) over the 50-week period from 1.93 to 2.50 l/min, Mean maximum oxygen intake per body weight improved 24.5% from 34.9 to 43.5 ml/kg.min.
But through the training session, the maximum values of maximum oxygen intake were obtained over the 25-week to 35-week period on each subject. After that period, maximum oxygen intake were unchanged or slightly dropped neverthless the training was continued.
As the linear relationship was found between the oxygen intake and heart rates during exercise, the regression equations were calculated on each maximal test. The regression line might represent the oxygen pulse on each heart rates level during exercise. The oxygen pulse improved clealy also during submaximal work. The improve-ment of oxygen pulse were distinctive to 25-35 week period and after that no change were occured.
In the submaximal test, there was seen clear improvement of efficiency during 20 minutes walking at the load of 70%, 50%, 30% of maximum oxygen intake respectively, even after the period that the increment of maximum oxygen intake could not be caused by training.

In order to study the physical fitness of rural children in Gifu prefecture, a total of 128 rural boys and girls aged 8-14 years old in the Tokuyama-Elementary School and-Middle School, which are in a far rural district from busy civilized urban distriet, were measured for the developmental status, i. e, physique, examination of physical fitness, maximum working capacity, cardiorespiratory function and urinary excretion in summer, 1962, and the comparison was made on the results obtained there with those of the average Japanese children of the same age.
The results obtained were as follows:
1) Little or no difference was found between physical development of rural children and that of average Japanese boys and girls ; i. e, the physique of rural children was not superior nor inferior to the value of the average Japanese children.
2) The record of sprint games, such as 50m-sprint-run, broad jumping, ball throwing, Sargent-jump, grip strength and back strength of rural children was lower than that of the Japanese average. Whereas, the endurance ability measured with a long-distance running (1500m for boys and 1000m for girls) was tended to be higher in the rural children, especially in the girls, than the average Japanese value. However, no significant difference was presented in the flexibility test (forward bending of the upper-body in standing posture) between rural and average Japanese values.
3) The examination of cardiopulmonary function : i.e. E.C.G., blood pressure, heart rate, vital capacity and maximum expiratony flow rate exhibited no abnormal sign. The systolic and diastolic blood pressure tended to increase with age, but the heart rate tended to decrease. The examination of the urinary glucose, protein and occult-blood remained normal, and most of the urine pH of the girls were within the range between 6 and 7, whereas, those of boys were between 5 and 6.
4) The maximum working capacity (maximum oxygen intake, vital capacity) showeda linear increase proportional to age and physique (body height, body weigmt, body surface, etc, ) over the range of the age tested. Sexual difference appeared after 12 years of age.
5) The possibility was suggested that the maximum O₂ intake could be predicted from the vital capacity of the same individual regardless of age, sex and physique, and a theoretical background for that was discussed.