Ultrasonic Thickness of Middle Trapezius Muscle in Young Healthy Men

Background and Middle Trapezius Muscle (MTM) is a key muscle in maintaining postural stability of the shoulder but it has received less attention in research. This study aimed to measure the ultrasonic thickness of the MTM in non-athlete healthy young men. Also, inter-rater repeatability in measuring ultrasonic thickness of this muscle was calculated.
A fundamental applied study was carried out by voluntary participation of 60 healthy young men aged 18-28 years. Demographic characteristics of the participants were recorded and ultrasonic thickness of both left and right MTM was measured by two examiners when the muscle was at rest. The measurements were repeated for three times. Data analysis was conducted in SPSS V18 using Intraclass Correlation Coefficients (ICC) between the first and third measurements to assess intra-rater reliability. In addition, Standard Error Measurement (SEM) with a 95% confidence interval (CI=95%) was estimated.
Average ultrasonic thickness of the left and right MTM was 8.03 ± 1.55 and 8.10 ± 1.54 mm, respectively. The ICC between the measurements from the first and second rater was 0.86. Inter tester reliability showed ICC 0.95 and 0.98 for right and left MTM respectively.
Measurement of ultrasonic thickness of MTM at rest, showed a high intra reliability. Further studies are recommended to measure MTM ultrasonic thickness in patients suffering from neck and shoulder dysfunctions.