Abstract
Maximum torque and electromyography (EMG) of muscle activity when turning an 18 inch dia. hand wheel valve was measured at 3 different heights to determine the biomechanical loading on a worker's body. Twenty-four electric utility plant mechanics and operators participated in this study. The major independent variables were valve height (overhead, chest, and knee level) and torque direction (right and left). The major dependent variables were maximum torque (ft-lbs) and maximum voluntary contraction (%MVC) of EMG. Subject's exerted an average of 111 ft-lbs counterclockwise torque, which was greater that the mean 104 ft-lbs generated in the clockwise direction. Furthermore, participants exerted 13 to 16% greater torque at the overhead level than at chest level. When turning the valve counterclockwise (left), the %MVC of the left side muscles was greater than the right side muscles and vice versa for turning the valve clockwise (right).
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