Isometric pull forces in the sagittal plane

Abstract

This paper investigates the differences in maximal isometric horizontal pull forces in the sagittal plane about a frontal plane work envelope. Eight subjects produced maximal isometric horizontal pulls about 32 positions in the frontal for each of three different postural conditions: free standing, fixed standing and seated. Four horizontal positions (0, 200, 400, 600 mm relative to the mid-line of the body) in the sagittal plane at four vertical heights in two standing postures (1070, 1470, 1610, 2000 mm from the floor) and one sitting posture (220, 620, 760, 1150 mm from a seated reference position) were tested for both the left and right hand under all three postural conditions. Experimental findings reveal that the largest horizontal forces were produced at a height of 1070 mm in the standing postures and 220 mm in the sitting posture and were within 200 mm to the left and right of the mid-line of the body. These findings confirm that work-station designs should position heavy materials near the mid-line of the body, at or about elbow height to take advantage of operator’s force-producing capabilities in the sagittal plane.