Sensitivity of the Jamar Dynamometer in detecting submaximal grip effort.

Twenty-two people with no extremity disability were tested in a standard fashion using the Jamar Dynamometer to establish their maximum grip strength. Each participant was asked to grip first right-handed then left-handed three consecutive times. The directions were reexplained so that each participant would give a consistent, less than optimal effort; three trials right and three trials left were recorded. The standard deviations of each set of these trials were calculated for both right and left hands. These standard deviations were then tabulated as scores for 44 trials of 22 patients, both hands, for maximal and submaximal efforts. These scores were then compared, maximal versus submaximal, using a paired t-test. We found no statistical difference in the two groups in comparing the variability of results. Therefore, the current protocol for Jamar testing can allow a patient to make a consistently submaximal effort, resulting in a false apparent loss of grip strength.