Handheld dynamometers are portable devices, simple to use without requiring specific training for the professional performing the test, that allow for the evaluation of muscle strength through the grip strength of the dominant hand (hand grip strength or HGS).1

Low grip strength predicts unfavorable situations in many patients, such as a longer length of stay, functional problems, lower quality of life, and increased mortality, as it is used to assess maximum muscle strength.2 Low levels of maximum muscle strength can indicate the presence of sarcopenia, which influences the evolution of these patients.3

Due to its ease of use, grip strength is routinely used in standard clinical practice. It is important to use a calibrated handheld dynamometer in good condition to obtain interpretable data and compare them with the reference population.

Currently, different models of handheld dynamometers can be found. They can be electric or analog, hydraulic or mechanical, and have different grips. The American Society of Hand Therapists endorses the Jamar® Hydraulic dynamometer as the reference device.4

Several studies have documented the differences between the Jamar dynamometer and other dynamometer models, both analog and electric. To study the reliability and validity of other devices on the market, Orit Shechtman et al. compared the Jamar dynamometer with the Dynx in healthy subjects (20–40 years old) and found significant differences between the grip scores obtained (± 6.222 kg; p = 0.014).5 After examining these results, our study aims to expand the range of compared devices in the current literature. Handheld dynamometers measure muscle strength through the grip strength of the dominant hand. We observed in routine clinical practice the differences in measurements depending on the dynamometer used and thus defined the objective of this study: to compare the Dynx, Saehan, and Smedlay dynamometers with the Jamar dynamometer (reference device) to evaluate the correlation and agreement of their measurements and to check if it is indifferent to use different dynamometers.