農村青少年の作業能に関する研究 (I)

Abstract

This study was chiefly concerned with the analysis of physical work capacity of rural adolescents. The number of subjects, aged from 9 to 18, were 192 for male and 173 for female respectively, but a few subjects could not undergo all the items of the test because of their temporary physical disorders. Analyzing the data from each of the measurements with respect to physique, pulmonary function, and aerobic work capacity, the following results were obtained: 1. Body height and weight were significantly or insignificantly less than the national mean values, but the weight to height in each age and sex was almost equal to the standardized weight to height. 2. At different ages the boys had a little more vital capacity till 13 years of age, but later through the ages of 14 and 15 years the remarkable sex differences appeared to be 87% and 74%. After 16 years the absolute values for boys showed slight increase, but for girls showed hardly any fluctuations. The one-second timed vital capacities also showed the same inclinations as in the case of the vital capacities. Percentages of expired air qualified by the one-second time interval ranged from 85 to 90% in regardless with age and sex. For female subjects maximal breathing capacities decreased gradually after 15 years. 3. For boys the average values of maximal oxygen uptake increased gradually from 1.54 l per minute for 10 year old boys to 2.08 l for the boys of 13 years, and increased sharply to 3.00 l for the boys aged 15 years, when the maximal oxygen uptake reached the plateau. The average values of the girls up to the age of 13 years were 3 to 7% lower than those of the boys of the same age, and as there was no increase later the average values of the girls aged 14 and 15 years were 20 to 28% lower respectively. 4. The highest average values of maximal oxygen uptakes per kg body weight were 58.l ml at the age of 15 years for the boys and 49.6 ml for the girls aged 13 years respectively. And thereafter the average values gradually decreased for both sexes. Pronounced difference between the sexes suddenly appeared at the age of 14 years, and that is, the percentages of the girls to the boys decreased fr0m 88.4% at 13 years to 79.8% at 14 years. 5. In the 9 to 12 years age group the correlations between static dimensions such as body height, weight, body surface area, and vital capacity and functional dimensions such as maximal respiratory volume, maximal oxygen uptakes, and maximal breathing capacity were considerably high for the sexes. The boys in the 12 to 15 years age group had higher correlations than in the younger age group. The correlations for the girls were lower than in the younger age group because in puberty static dimensions did not accompany so functional dimensions as before. The boys in the 15 to 18 years age group showed lower correlations than in the previous age group. This may be partly due to the development of functional dimensions, though not strictly, independent upon static dimensions and partly due to the greater individual differences in the both dimensions. On the other hand the correlations for the girls were much less than in the previous two age groups. This is on the ground that most parts of development of static dimensions appeared as characteristic developments of female and functional dimensions concerning aerobic work capacity were inclined to cease in these ages. 6. The performance of the five-minute run develops up to the age of 15 years for the boys and thereafter no noticeable developments were found. The 13 year old girls showed the best performance and later the girls rather decreased the endurance performance. 7. The correlations of the five-minute run and maximal oxygen uptake decreased with advanced age group for the sexes.