Intra-Rater Reliability of the Shore Durometer in the Assessment of Upper Trapezius Muscle Hardness

Background/ Objectives: This study aims to measure the reliability of the Shore durometer in assessing the hardness of the upper trapezius, providing the basis for muscle hardness measurement. Methods/Statistical analysis: The subjects of this study were 30 healthy adult males. After typing for 20 minutes, the subjects’ trapezius muscle hardness was measured while they were in a supine position. This process was repeated for six days. Their muscle hardness was measured three times per day, and the average value of the three measurements was used for analysis. To assess the reliability of the measured results, intra-class correlation coefficients were calculated. Findings: The result was that the intra-rater reliabilities of the left upper trapezius and of the right upper trapezius were 0.827 and 0.816, respectively. The Shore durometer has a high level of intra-rater reliability in measuring upper trapezius muscle hardness. Improvements/Applications: The Shore durometer can provide reproducible results of the upper trapezius muscle’s hardness when repetitively measured by the same measurer.