Effects of handle size and shape on measured grip strength

Abstract The Jamar handle dynamometer is the most commonly used instrument for measuring grip strength. However, the grip strength applied on a cylindrical handle may not exhibit the same handle size relationship as that observed with the Jamar handle. Direct comparison studies are required to clearly identify the major differences between the two dynamometer styles. This study utilized a recent grip dynamometer design along with the Jamar dynamometer to further examine these relationships. The objective of this study was to compare how changes in grip size affects grip strength measured with each dynamometer style. Results confirm that handle size significantly affects the applied grip strength measured with both types of grip dynamometer. The handle size effect is more pronounced with the Jamar handle, especially at the small handle diameter/span. The highest grip force components observed with the cylindrical handles were found at the fingertips. The Jamar grip dynamometer may not adequately reflect the fingertip forces at the low and middle spans because the fingertips are not applied in the force measurement plane of the Jamar handle. Therefore, the Jamar dynamometer may not adequately capture changes in the fingertip forces under different grip spans. Relevance to Industry: It is important to properly characterize grip strength used in occupational settings in order to optimize tool and machine handle designs. The Jamar dynamometer may not be appropriate for assessing cylindrical or near-cylindrical handles that are found on the majority of tools and machines. The grip strength measured with the cylindrical dynamometer used in this study can be used to help optimize handle designs.