Validity, reliability and test-retest study of Grip strength measurement in two positions with two dynamometers: Jamar® Plus and K-Force® Grip.

Our objective was to compare grip strength measurement in two body positions (sitting and standing) with the K-Force® Grip dynamometer and the Jamar® Plus Digital hand dynamometer, and to conduct a test-retest study of the K-Force Grip device. The study was conducted on 50 healthy young adults aged 18-25 years. Maximal grip strength was tested in sitting and standing positions with both devices. After 2 days, a re-test was conducted with the K-Force Grip. The correlation coefficient was high for grip strength measurements in sitting and standing positions with the K-Force Grip and Jamar Plus dynamometers (r > 0.9 for all). K-Force Grip values were similar in sitting and standing positions (p > 0.05). Despite this similarity, K-Force Grip measured significantly lower values than Jamar Plus (p < 0.05). Thus, the K-Force Grip device can be used as an alternative to the Jamar Plus dynamometer, regarded as the gold standard in evaluating grip strength. We believe that the same devices should be used in clinical studies, research, and patient follow-up.