Detection of submaximal effort with computer-assisted grip strength measurements.

The purpose of this study was to establish a simple observation to help in distinguishing patients who are giving their maximal effort during computer-assisted grip strength measurements from those who are not. Preliminary observations had suggested that maximal effort with this grip-strength device was characterized by greater force in the radial digits than the ulnar digits and a small variability in force between individual grasps. These observations were then prospectively analyzed in the following groups: (a) 178 assembly workers tested during a routine screening at a computer manufacturing company and during pre-placement physicals; (b) 196 workers with a hand injury or cumulative trauma disorder who were seeking consultation for medical treatment; (c) 55 workers with a hand injury or cumulative trauma disorder being measured to determine their return to work status or impairment rating; and (d) 58 asymptomatic volunteers. The volunteers were instructed to perform the maximal grip in the same fashion as the other groups and then to repeat the test exerting a submaximal effort they estimated to be 50% of their own maximal effort. The results of this study demonstrated that there is a highly significant association, P < 0.001, between the presence of a "total pattern" (radial over ulnar force being less than 1.0, unilateral grip variation greater than 15%, and difference between the left and right grip variation greater than 5%) and the presence of submaximal effort during grip-strength measurements.