Reliability of Grip Strength Assessment with the Computerized Jamar Dynamometer

The purpose of our study was to determine the reliability of the model PC5030PT computerized Jamar dynamometer (J. A. Preston, Jackson, MI). A test-retest reliability study was conducted in which 33 normal subjects were tested three times over a 6-week period. Standard procedures for assessing grip strength were followed. Both left and right hands were tested. We quantified three characteristics of the force curve: (a) the slope of the rise in force, (b) the maximal or peak force, and (c) the mean sustained force over the last 3 sec of a 5-sec contraction. Reliability was good with intraclass reliability coefficients ranging from .84 to .93. We conclude that the computerized Jamar will yield reliable measurement of grip strength if the instrument is calibrated properly and if standardized procedures for grip strength testing are followed.