片手で保持して操作する道具の重量と作業強度(人間環境学)

実験室において測量用のポールを立木に見立て, 床から40cm, 120cm, 200cmのところにそれぞれ枝があるものと想定し, 被験者に, 鉈および鋸を用いて枝打ち模擬動作を行わせ, その際の呼気を分析し, 心拍数を測定した。片手で扱う道具として, 重い鉈を用いる方が軽い鋸の場合より, 酸素摂取量が有意に大きく, したがって作業強度の高いことが明らかとなった。また, 吸気量, 呼気二酸化炭素濃度, ならびに二酸化炭素呼出量においても有意差が存したが, 心拍数には有意差がなかった。また, 測定した11項目を変量とする, 鉈と鋸による作業を判別するための線形判別関数を求め, これを用いてもとの鉈, 鋸を用いる作業に関する各12,計24個のデータについて, 判別得点を求めた。正しく判別されたデータの割合は, 鉈, 鋸いずれについても83.3%で, おおむね正しく判別がなされた。この判別に比較的大きく寄与すると考えられる変量は, RQ, 酸素摂取量, 二酸化炭素呼出量, 吸気量で, これらはいずれも作業強度の差異を反映する測定項目であった。To investigate the difference of work intensity with a hatchet from a saw, 4 male subjects performed sham pruning in the laboratory. A surveying pole was supposed to be a tree with branches at the height of 40,120,and 200cm. At each work, expired gas was analyzed and heart rate was measured. The oxygen uptake of the work with a hatchet was significantly higher than that of the work with a saw. Moreover, between the works with 2 kinds of tools, significant differences were observed on the inspired gas volume, the fraction of expired CO_2,and the volume of expired CO_2. To discriminate the data with hatchet and saw, linear discriminant function with 11 variables was obtained which were correspond to measured 11 items on sham pruning. The variables which contributed largely to discrimination were RQ, O_2 uptake, expired CO_2 volume, and inspired gas volume; these were the items which reflected work intensity

同一作業を床の上とはしご上で行う場合の強度差(人間環境学)

To investigate the difference of work intensity of same work on the floor and ladder, 8 male subjects performed sham pruning in the laboratory with a hatched whose weight was 650g and length was 35cm. A measuring pole 4.5cm in diameter was supposed to be a tree with branches at a height of 120 and 170cm. The height of the subject on the ladder from the floor was 52 and 83cm at the left and right foot, respectively. Oxygen uptake and heart rate of 6 levels were measured i.e. while standing still holding a hatched with a hand, exercising at a branch height of 120,and 170cm, respectively, both on the floor and ladder. Concerning oxygen uptake, both while standing still and in activity, significant difference was observed between the positions on the floor and ladder. The correlation of oxygen uptake and heart rate was significant at p<0.001 about the whole data of all subjects. But according to paired-sample t test, the differences of heart rate between the positions on the floor and ladder were not significant both while standing still and in activity, dissimilar to the case of oxygen uptake

水平面と斜面上における作業の形態別強度差と呼気による判別(人間環境学)

To investigate the difference of work intensity based on work form at plane and slope, 5 subjects performed sham weeding with a scythe and a weeding machine of gasoline engine in a laboratory. Expired gas was then analyzed and energy expenditure was calculated. Both at plane and slope of 20°, energy expenditure of the scythe work was significantly higher than that of weeding machine. And energy expenditure of the work with the scythe at slope was significantly higher than at plane, but concerning the weeding machine significant difference was not observed between plane and slope work. From this result, it was concluded that work intensity at slope was higher than at plane when the work was performed with legs actively, and work intensity did not differ when legs were used only to maintain standing position. At the same time it was revealed that the work with a scythe could be discriminated clearly from that with a weeding machine by means of a linear discriminant function constructed with 6 variables i. e. VE, ETO_2,FEO_2,ETCO_2,FECO_2,and VCO_2