RESUMEN
OBJECTIVE: In the present study, the intra-rater reliability of upper trapezius morphology, its mechanical properties and intramuscular blood circulation in females with myofascial pain syndrome were assessed using ultrasonography. DESIGN: A total of 37 patients (31.05 ± 10 years old) participated in this study. Ultrasonography producer was set up in three stages: a) Gray-scale: to measure muscle thickness, size and area of trigger points; b) Ultrasound elastography: to measure muscle stiffness; and c) Doppler imaging: to assess blood flow indices. RESULTS: According to data analysis, all variables, except End Diastolic Velocity (EDV), had excellent reliability (>0.806). Intra-class Correlation Coefficient (ICC) for EDV was 0.738, which was considered a poor to good reliability. CONCLUSION: The results of this study introduced a reliable method for developing details of upper trapezius features using muscular ultrasonography in female patients. These variables could be used for objective examination and provide guidelines for treatment plans in clinical settings.