Validity and Reliability of the InGrip^® Load-Cell Handgrip Dynamometer Compared With the Takei Handgrip Dynamometer...

To validate the InGrip^® load-cell handgrip dynamometer by comparing its performance with the Takei handgrip dynamometer in measuring handgrip strength (HGS) among healthy adults and patients with stroke.

This is a cross-sectional study conducted in community and outpatient clinics, involving 260 healthy adults aged ≥ 50 years and 50 patients with stroke (N = 310). HGS was assessed using the Takei and InGrip^® dynamometers following a standardized protocol. Correlation, agreement, and test-retest reliability were evaluated using Pearson's correlation coefficient, Bland-Altman plots, intraclass correlation coefficient (ICC), standard error of measurement (SEM), and smallest real difference (SRD).

No significant differences in HGS measurements were observed between the two dynamometers in any group. The correlation coefficients between the Takei and InGrip^® were strong for healthy adults (r = 0.944) and patients with stroke (r = 0.967). Bland-Altman plots demonstrated good agreement, with mean biases of -0.14 kg (healthy adults) and -0.87 kg (patients with stroke). The InGrip^® exhibited excellent test-retest reliability, with ICC values exceeding 0.9, SEM below 10%, and SRD under 30% across all groups.

The InGrip^® load-cell dynamometer demonstrated a high correlation, strong agreement, and excellent test-retest reliability when compared to the Takei dynamometer in both healthy adults and patients with stroke. The InGrip^® dynamometer is a valid and reliable instrument for HGS assessment. Further research should explore its applicability across broader clinical and population-based settings.