Inter- and Intra-rater Reliability of Measurements of Pressure Threshold and Tolerance on Muscle and Tendon in Healthy Subjects

Background and purpose: Quantitative measurement of clinical muscle pain is essential for documenting the severity and progress of muscle lesions. This investigation evaluates the inter- and intra-rater reliability of measurements of pressure threshold and tolerance of a muscle belly and the tendon taken using a commercially available pressure meter(PM). Methods: Pressure threshold and tolerance on the upper trapezius muscle and supraspinatus tendon were repeatedly measured on both sides of 20 healthy adult volunteers(15 female and 5 male). Two researchers took the measurements. Measurements at different points were made at least two minutes apart. Intra-class correlation coefficients (ICC) were used to quantify the reliability of repeated measurements. Results: The results of this study demonstrated fair to excellent intra-rater reliability both on the upper trapezius muscles (0.86~0.98) and on the supraspinatus tendons (0.68~0.93). The inter-rater reliability (0.48~0.85) of pressure threshold and tolerance measurements on the muscles and tendons was also fair to excellent. Conclusion: These results revealed that PM was moderately to highly reliable when used to measure pressure threshold and tolerance of muscles and tendons by a single or by various examiners. These suggest that PM is a useful tool in clinically diagnosing abnormal tenderness.