高所作業の生理学的研究

Abstract

Work on electric poles commonly seen in electric industry is usually performed in a posture using a safety rope which has special "static" components. Climbing up an electric pole is a kind of heavy work (R.M.R 15∼30) accompanying concentration of density of blood. Optimum climbing speed could de presumed by considering oxygen consumption, pulse rate increase and results of some functional tests. It is proposed to be necessary to take a short rest immediately after climbing up the pole, According to electromyographic study, main muscles contracting in the working posture on poles are abdominal muscles, hip muscles, flexors of the thigh, and flexors and extensors of the lower legs. Special features of the static load by the posture consist in continuous contraction of both flexors and extensors of legs, resulting from the lack of possibility to relax so long as the worker is on the pole. Regarding such a kind of posture, the optimal one can be suggested by electromyographic study namely by determining the parameters of the posture which show the least discharge intensity of leg muscles. Electromyogram of some leg muscles during arm-exchanging work on poles revealed grouping voltage with slowing which suggested the appearance of muscle fatigue. Taking in account the variation of other metabolic and prychological functions during working on poles it is postulated that there must be a maximum permissible limit of duration of working on the pole, since the worker is exposed to continuous danger of accidents. The limit seemed to be within 60 minutes, desirably between 30 and 45 minutes.