In this report the roentgenograms of the corpus vertebrae, the disci intervertebrales of those having the good flexibility and poor flexibility were observed. Particularly the actions of the connected muscles, when the maximum trunk-flexion and extension were taken, were compared between two groups, and the factors that were supposed to have produced the difference of the trunk flexibility between the individuals were discussed.
Results are in summary as follows ;
The shrinking and extension appear in the disci intervertebrales when the maximum flexion and extension were taken. For the trunk flexion in then rear side of the disci intervertebrales, for the trunke xtension in the front side, for the left side-ward bend in the right side, and for the right side-ward bend in the left side of one, that is, in the extension of the disci intervertebrales at the opposite side to bending the differences were observed. Moreover they were appeared in the disci intervertebrales of the vertebrae lumbales remarkably, and in the group of poor flexibillty the extension of the disci intervertebrales was appeared less than in the group of good flexibility.

It is studied in this paper whether the current physical growth rate over four seasons parallels the physical growth rate over four seasons as observed in previous studies. For these purposes, some physical growth traits influenced by urbanization among rural school children were investigated in comparison with urban school children using the longitudinal method.
The results obtained were as follows:
1) Fathers whose only job was farming in the rural sample, were decreasing; conversely farmers having other jobs were increasing. Number of siblings were two in average and families with both parents working increased in rural sample, thus the rural school children were observed being influenced by urbanization remarkably.
2) As for the physical growth rate, the tendency to show remarkable growth in spring was observed to be decreasing, because the season of maximum growth was dispersed among the four seasons, the season depending on age. This is, significantly different physical growth rates were observed in all seasons in addition to spring; therefore growth rate seems to be averaging over seasons as a whole.
3) The change of periodicity in one year was observed in both samples in the process of physical growth on height.
4) But on the other hand, study of the percentage of school children showing maximum growth by seasons revealed that the percentage of those with maximum growth in summer and spring was highest, and those with maximum growth in autumn and winter was lowest. This same seasonal growth was observed in both samples.
5) The two results mentioned at 2) and 4) obtained between the physical growth rate and the percentages of school children showed a possible point of disagreement regarding the maximum growth rate. It should be understood that most of the school children showed maximum growth rate in summer and spring, but the difference of growth rate between these two seasons and the other ones was decreasing.

The first object of this study was to investigate the constituent factor of physical flexibility. The second purpose was to reconsider if the measures of physical flexibility which have been customarily used are valid, and choose those measures which have high validity. To investigate this the method of factor analysis was used.
The following results were obtained:
1) It has been recognized that there are eight constituent factors (F1-F8) of physical flexibility. Of those factors, the first concerns the flexibility of the trunk.
2) To choose the measurement items, it is valid to choose those items which showed a high factor loading to each factor. In this study, seven items (trunk flexion, upperarm raising, sideward neck bending, instep flexion and extension, wrist pronation and supination) were chosen.
3) From the results written above, it can be seen that it is inappropriate and insufficient to measure only the flexibility of the trunk. But to simplify the measurement method, physical flexibility can be estimated by measuring trunk flexion and sidewards bending.

This study was to examine the relationship between bone maturation scores and the nutrition indexes, and to consider the estimated range for the evaluation of bone maturation scores. This study investigated the relationship between the bone maturation scores and the nutrition indexes of compound variables of height, body weight and sitting height, by the correlation coefficients in eleven items and used them as raw data for analysis.
The obtained results were as follows
1. The correlation coefficients between the nutrition indexes and bone maturation scores (Middle Phalanges) showed that in the second sexual period boys were significance at the level 0.05 in all the Rohrer, Kaup and Kawahata indexes. Each of them were as follows : Rohrer index 0.325, Kaup index 0.415, Kawahata index 0.485. In the girls also the correlation coefficients showed significance between the Rohrer, Kaup, and Kawahata indexes of all three phalanges scores, especially in correlation with the Middle Phalanges scores : Rohrer index 0.458, Kaup index 0.540, Kawahata index 0.424.
2. If the bone maturation scores are evaluated by the three nutrition indexes, it may be estimated that the bone maturation scores are evaluated by the Middle Phalanges scores for both boys and girls.
Regression Equations and the Standard Error (SE.) of estimate are as follows
Rohrer Index ; Boys : Y=12.42+0.75X, S.E.=±0.15
Girls : Y=10.00+1.55X, S.E.=±0.38
Kaup Index ; Boys : Y=10.48+0.62X, S.E.=±0.21
Girls : Y=8.23+1.13X, S.E.=±0.35
Kawahata Index ; Boys : Y=10.47+1.82X, S.E.=±0.21
Girls : Y=12.08+2.66X, S.E.=±0.29
note : X (nutrition indexes) Y (bone maturation scores)
3. The S.E, of estimated scores in bone maturation scores which were obtained by using each the nutrition index scores of the estimate equations were very small and the results of t-Test in the means of estimated scores and the means of actual measurement showed hardly any significant difference at the level 0.01. According to these results the estimate equations used here were considered to be of higher reliability.
4. The bone maturation scores were compared with the two groups, good and poor, classified by the nutrition indexes. In the case of the boys there was no significant difference in the Rohrer index.
But according to the Kaup and Kawahata indexes there were significant differences in each part of the bone except for the Proximal Phalanges scores. In the girls there were equally significant differences in all three nutrition indexes of the good-poor groups.
From the results found in this study, the nutrition indexes may by considered as an index to estimate the bone maturation scores, at least, of junior high school students in growing period.

The effect of isokinetic training was investigated for the strength development in the thigh muscles under various training conditions. Thirty one males from healthy high-school students served as subjects of this study. Training was performed using a Cybex II machine with two kinds of repeated load conditions (number of repetitions, cf. Table 1 & Fig. 1) at to different rotational speeds (30 degrees and 180 degrees per second) . The training was done three times per week for nine weeks. The effects of training were evaluated on the basis of the amount of increase in the strength during knee flexion and extension.
The results were summarized as follows :
1) The effect of training became apparent most swiftly under the rotational speed of 180 degrees per second and light load of repetitions, respectively.
2) The largest increase in the muscluar strength was observed for the group with training speed of 180 degrees per second and hevey load of repetitions, respectively.
3) The strength increased periodically every four or five week for all conditions.