2012 Volume 88 Issue 3 Pages 103-113
Weeding with a bush cutter on slopes, whereby the worker constantly has to deal with the danger of losing balance and falling, is extremely difficult. Such work in fact results in many severe accidents every year in Japan’s agricultural and forestry industries. However, few researches have been conducted with regard to maintaining correct posture and balance when working under these conditions, and currently implemented safety measures against such accidents are insufficient. It seems natural to assume that farmers with considerable experience in working on slopes with bush cutters know how best to maintain an effective working posture so as to prevent a fall. The aim of the present study was to determine ways to reduce severe accidents when working with a bush cutter on slopes. An attempt was made to establish whether full-time farmers adopt a special posture or use particular techniques to avoid falls.
Two experiments were conducted. The electromyographic features when working with a bush cutter on a slope were examined; the relationship between the myoelectric potential of the leg muscles and the centre of gravity position of the body while weeding on a simulated slope were studied by means of a gravicorder. The results suggest that farmers do in fact utilize appropriate muscle strategies to prevent falls. The following two mechanisms may explain the muscle strategy during weeding with a bush cutter on slopes. One is that the swing range of the centre of gravity of position of the body is limited as far as possible by the muscles of the lower limbs, which act to secure the ankle joints on the slope. The other is that the angle between the plantar surface of the left foot and the slope is reduced as much as possible, resulting in increased frictional force.
It is highly likely that workers with considerable experience in weeding with a bush cutter on slopes would have built up knowledge with respect to this kind of working posture. Systematizing findings about such workers appear to increase the safety of both current and future workers and may result in greater information for developing safety devices.