Agreement Between an Isometric and a Pneumatic Device for The Assessment Of Handgrip Strength In Geriatric Inpatients Based On The Conversion Formula By Neumann: Findings From The Sarcopedia Study

Introduction: Handgrip strength (HGS) is a key indicator for sarcopenia. The JAMAR dynamometer (JD) is commonly used to measure HGS as isometric force in kilograms. In older adults the preferred device is the Martin Vigorimeter (MV), which measures compressive force in kilopascals (kPa). To compare results of studies that use just one of the two instruments, a conversion factor has been proposed. However, there is limited data validating this conversion calculation in a geriatric setting.

Objectives: Agreement between JM and MV for the assessment of HGS in the evaluation of probable sarcopenia based on the conversion formula by Neumann.

Methods: Data of a prospective registry study documenting and comparing results of various diagnostic approaches for sarcopenia among geriatric inpatients were used. Among all participants, HGS was quantified by JD with handle at 2^nd position, as well as by MV with size 5 rubber ball. Pearson correlations were used to compare the two measuring methods by choosing the highest HGS value of three attempts on each hand. Bland-Altman plots were used to assess the agreement between the two devices. To control for the measurement difference between the two devices, the conversion calculation established by Neumann was applied [1]. EWGSOP2 cut points were used to differentiate between low and normal HGS.

Results: The correlation between MV and JD was high (r=0.837) among the 93 participants (mean age 82.6 years, 51% male, BMI 25.2 kg/m²). The conversion of MV to kg resulted in a 6% lower strength than the JD measurement, with a mean difference of 1.4 kg (SD 4.1). Converting JD measurements to kPa resulted in 11% lower strength than the MV measurements, with a mean difference of 4.7 kPa (SD 7.4). Using the JD-based and converted EWGSOP2 cut points for both methods, agreement was found in 76% of women and 81% of men. Low HGS was identified more frequently with JD (20% in women, 38% in men) than with MV (9% in women, 32% in men).

Conclusion: Both instruments demonstrate equivalent clinimetric properties. However, the MV appears to be a more sensitive measurement method, as it considers both strength and functionality, making it a potentially more comprehensive tool. Given these differences, it is important to re-evaluate either the conversion formula or the cut-points specific to MV to ensure accurate assessment in this patient setting.

Publication History

Article published online:
25 May 2025

• References

• 1 Neuman S. et al. Comparison of the grip strength using the Martin-Vigorimeter and the JAMAR-Dynamometer: Establishment of normal value. In vivo. 2017