To measure the shear wave velocities of proximal limb muscles in healthy people and analyze the related factors.

A total of 88 healthy volunteers recruited from West China Hospital of Sichuan University from 2019 to 2020 were selected, and their gender, age, body mass index (BMI), and exercise habits were recorded. The shear wave velocities of different muscles (triangle, biceps brachialis, rectus femoris, and lateral femoral muscle) on both the left and right sides and in different sections, different positions, and different body positions were measured, and the shear wave velocities of the muscles between different genders, ages, exercise status, and BMIs were compared. Twenty subjects were randomly selected to calculate the inter-observer and intra-observer consistency of shear wave velocity measurements of the triangle and rectus femoris muscles.

There was no significant difference in shear wave velocities between the left and right sides of each muscle in longitudinal section (P＞0.05). The shear wave velocities of all muscles were higher in longitudinal section than in cross section (P＜0.05). The shear wave velocities of the biceps brachii muscles at the extended long axis section were higher on the lateral side than medial side (P＜0.05). The shear wave velocities of the biceps brachii in extensor position were higher than those in flexion position (P＜0.05). The shear wave velocities of lateral femoral muscles were higher in the 18~49 age group than in the 50~70 age group (P＜0.05). The shear wave velocities of the biceps brachii were significantly higher in the BMI＜18.5 kg/m² group and 18.5 kg/m²≤BMI＜24 kg/m² group than in the BMI≥24 kg/m² group (P＜0.05). The shear wave velocities of the triangular muscles was higher in people with regular exercise than in those with less exercise (P＜0.05). The intra-observer and inter-observer consistency of shear wave velocities of the deltoid and rectus femoris muscles was good or excellent (ICC＞0.88).

Shear wave elastography can be used to quantitatively measure the hardness value of muscles in healthy people, and the section and position of the muscle and the body position, gender, age, BMI, and exercise habit of people are factors related to such measurements. Our results provide a basis for the in-depth study of idiopathic inflammatory myopathies.