The relationship between two power-grip testing devices and their utility in physical capacity evaluations.

This study compared two isometric-grip testing devices and considered the efficacy of combining data from the two as a means of identifying both functional status and consistency of effort for physical capacity evaluations (PCEs). Two groups (26 healthy subjects and 40 patients who had upper-extremity impairments) were used to establish the reliability of applying force on a jamar dynamometer, and on an Isometric Strength Testing Unit (ISTU). Many of the patients had been referred because of inconsistencies between subjective complaint and medical presentation. The results indicate that power-grip force outputs are highly related across the two test devices, which validates their utility as part of a PCE for wrist-hand involvement. A simple index (2-ratio) of functional status and consistency was developed by combining test data from the two devices. The sensitivity of the 2-ratio, in combination with other indices of consistency, is discussed.