Reliability of Ultrasound Measures of M. Gastrocnemius Pennation Angle

There are currently few studies in the literature concerning the reliability and validity of the quantification of parameters of muscle architecture using the technique of ultrasound. The aim of this study is to apply the technique of ultrasound imaging to quantify pennation angle of gastrocnemius muscle (medial and lateral) and to determine the reliability and reproducibility of these measures. Two images of each gastrocnemius of 19 young healthy subjects were acquired using B-mode ultrasound equipment (7.5 MHz), in two visits. Pennation angle was measured five times on each image using image analysis software. The reliability of the total of 380 measurements was determined through coefficients of variation, intraclass correlation coefficients and typical errors of measurement. No significant differences were found between images and between days for any of the parameters (p> 0.05). The coefficients of variation of measures ranged from 3.8 to 11.62%. All intraclass correlation coefficients were within the range of high reliability, with the exception of the pennation angle value within days of the medial gastrocnemius (0.67). The results showed that the methodology used to measure pennation angle in ultrasound images presents high reliability.