According to the past results of Sport Test held in TOCHIGI Prefecture in 1968, it was certainly found that the endurance run test showed the most characteristic regional trend that adolescents born and reared in mountaineous farm villages, which topographically lie from mountain to plain, obtained significantly better performance than those in commercial and residential streets. The main objectives of the present investigation were to know how much difference, if any, is found concerning endurance capacities between the both adolescents and the study was, therefore, designed in the sphere of physical resources of energy to measure the aerobic work capacities of PWC₁₇₀ and Vo₂ max., and it was assumed that commercial streets represenetd urban districts and on the other hand mountaineous farm villages also represented rural districts. The total number of subjects, aged from 9 to 17 years, who performed the PWC₁₇₀ test of submaximal work load as preliminary one, were 732; 159 in male and 157 in female in urban, and 218 in male and 198 in female in rural districts. But the subjects to be tested in Vo₂ max. of maximal work load were further chosen at random from those who received the PWC₁₇₀ test, and the number of them were 559 in all. The apparatus for the determinations of PWC₁₇₀ and Vo₂ max. was MONARK bicycle ergometer. The three points-four minute method was used in the PWC₁₇₀test and the two-minute stepwise method was adopted for measurement of Vo2 max. The pedalling rate was 50 rpm in the both tests. Every step of work load was increased by 150kpm/min. Concomitantly skinfold thicknesses in the four points of upper arm, scapula, wast, and umbilicus were also measured.
The following results were obtained:
1) Urban adolescents had significantly thicker subcutaneous fats than rural ones.
2) No differences were found in PWC₁₇₀ (kpm) in all the ages between urban and rural adolescents for male, but rural adolescents were significantly superior to urban ones after the age of 12 years in PWC₁₇₀ (kpm/kg) . For female urban adolescents were rather better than rural ones before the 11 years, but on the contrary rural adolescents were significantly higher in PWC₁₇₀ (kpm/kg)
3) The regional differences that rural adolescents were superior to urban ones in aerobic work capacities were recognized earlier in age for PWC₁₇₀ (kpm/kg) than for Vo₂max. (ml/kg), and further appeared in younger ages for female than did for male.
4) In the regression equation y=ax+b, in which x was assumed to express body weight (kg) and y mean PWC₁₇₀ (kpm) or Vo₂ max. (1), and the standard deviation from y, δy, was also calculated, the characteristic regional trend was found in urban and rural districts. Then it could be considered that a was the increase rate of aerodic work capacities to body height and δy was the interpersonal variation. In the case of Vo₂ max. (1) for boys, the higher increase rates were consistently found in rural districts and the smaller variations were also identified. It is apparent that this is partly due to the higher occupation of the activating tissues in body weight increaserate and partly due to their better functioning.
5) According to the allometrical expressions concerning aerobic work capacities, y=b×h^a, obtained by the same mathematical procedure as used by Asmussen, PWC₁₇₀ (kpm) for boys had the same body heights in the two critical points of urban and rural districts, and up to these body heights a was considerably higher in rural boys but almost same α were indicated after the points. As for Vo₂ max. (1), the body heights in the critical points differed in urban and rural districts, that is, the body height in rural boys was about 10cm higher than in urban ones.

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In order to investigate the mechanism of activity of motor units, discharges of single human motor units in the m. vastus medialis in voluntary contraction by use of electrodes inserted in the muscles were simultaneously recorded with the tension developed at the knee joint in its extension effort. The results were as follows.
1) The single spike discharges of single motor units were observed at the rate of 54.5-86.2%, the total number of discharges being 100%, when the knee extension effort was gradually increased and was abruptly decreased by the time of spike wave appearance on the Braun tube.
2) When the tension of knee extending force was maintained steadily, the longest consecutive discharge in a single motor unit was observed for more than 90 minutes.
3) The tension of knee extending force at the recruitment in a certain single motor unit recorded in 15 seconds interval was nearly constant within 30-60 minutes tested with certain fixed value for each motor unit except some fluctuation.

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In order to clarify the voluntary strength control mechanism, certain characteristics of motor units were studied after series of recordings were simultaneously made on the discharge of single motor unit in the m. vastus medialis in its voluntary contraction by use of electrodes inserted in the respective muscle and the tension developed when attempting to extend the leg at the knee joint. The results obtained were as follows:
1) When analyzed from the relationship between discharge interval and its standard deviation, unit of other type which may be classified as“intermediate”unit than kinetic and tonic units as previously classified, was found.
2) The mean value of muscular tension was found to be proportionate with value of standard deviation, when tension made by recruitment of motor unit was measured by 15 seconds interval. While the K unit was found to be of low threshold value, T and M units were found to be of high values.
3) No consistent relationship was found between the mean value of relative threshold and the frequency of single spike appearance, while K unit showed a tendency of smaller rate of single spike appearance than T unit.
5) A decreasing tendency was generally observed in the mean value of relative threshold and its standard deviation, by loading isometric muscle tension of 2-10kg for 3-10 minutes. The rate of single spike appearance also deceased by same loading.

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