This study examines the effects of several operator- and task-related variables, defining the operator hand-tool system at the workplace, on peak volitional torque exertion capabilities of males and females with common nonpowered handtools. Maximum volitional torque was measured on 55 adult subjects (30 male, 25 female) in 540 treatment combinations (5 Tools x 2 Postures x 3 Heights x 3 Reach Distances x 6 Angles). Results of the study indicated that peak torque exertion capabilities of females average 66% of the male torques. Means for height and angle, although statistically different, had little practical difference. The major differences were in type of hand tool (30 kg-cm for screwdrivers versus 246 kg-cm for wrenches), posture (140 kg-cm for sitting versus 175kg-cm for standing), and reach distance (185 kg-cm at a distance of 33 cm versus 131 kg-cm at a distance of about 71 cm). Some of the task variable interactions were also significant. Among the various isometric strength and anthropometric variables, isometric shoulder strength was most important and appeared to limit the torque exertion capability of individuals. Peak torque profiles of males and females using common nonpowered handtools are presented.
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