Hand dynamometry: Does the device used for measurement matter?

Handgrip dynamometers measure muscle strength through the grip strength of the dominant hand. The purpose of this study is to compare the Dynx, Saehan, and Smedlay dynamometers with the Jamar dynamometer (gold standard) by evaluating the correlation and concordance of their measurements to determine if it is indifferent to use different dynamometers.

Cross-sectional study conducted between 2020 and 2021. We evaluated a group of patients (GP) from the Endocrinology and Nutrition consultations and a control group (CG) of health personnel. Dominant hand grip strength was measured with four different dynamometers Jamar, Dynx, Saehan and Smedlay, in random order. Statistical analysis was performed with SPSS using Student's t-test, intraclass correlation coefficient (ICC), and Bland-Altman plots.

A total of 124 subjects were included; 91 GP (60.4% women), mean age 54.9 (SD14.2) years. ICC showed the best correlation for Saehan in GP (0.977 p < 0.001) and in GC (0.960 p < 0.001). Dynx correlated better in GP than in GC (0.967 vs. 0.900, p < 0.001) and Smedlay had the worst correlation in GC (0.812 p < 0.001). The dynamometer with the lowest bias (-0.39, SD 3.11) and better limits of agreement (LOA) in both groups (GP -0.39, GC -0.51) was the Saehan CONCLUSION: Despite good measurement correlation, there is bias and insufficient agreement between different dynamometers, so they should not be used interchangeably.