Reliability of Semitendinosus and Biceps Femoris Aponeurosis Thickness Using B-Mode Ultrasound

Abstract

Objectives: The aim of the present study was to assess the reliability of aponeurosis and muscle thickness of the hamstrings using ultrasound (US).

Methods: US images were captured from the semitendinosus (ST) and biceps femoris long head (BFlh) of 30 individuals (15 females), undergoing two testing sessions with a 24-hour interval. Measurements were taken at six sites along the thigh at two knee angles (0° = full extension and 90°) in prone position. Aponeurosis and muscle thickness across the entire length of ST and BFlh were evaluated using computational image segmentation which generated ~360 data points per participant.

Results: The intraclass correlation coefficients ranged from 0.937 to 0.998 while the standard error of measurement varied from 0.88 to 2.72% for superficial aponeurosis, from 1.41 to 2.29% for deep aponeurosis, and from 1.50 to 4.22% for muscle thickness. The minimal detectable change ranged from 2.44 to 7.56% for the superficial aponeurosis, from 3.57 to 6.27% for deep aponeurosis, and from 4.17 to 11.70% for BF and ST muscle thickness.

Conclusions: Evaluation of hamstring aponeurosis and muscle thickness measurements at rest displayed very high reliability and, hence, such measurements can be used to diagnose changes in thickness due to injury or exercise interventions.

Keywords: aponeurosis; biceps femoris; hamstrings; muscle thickness; reliability; ultrasound.

Figure 1

Representative examples of a series of static images obtained at the different measurement sites along the thigh length for the Biceps Femoris and Semitendinosus.

Figure 2

Example of ultrasound (US) image of Semitendinosus muscle indicating region of interest as well as the placement of the landmarks to measure muscle and aponeurosis thickness. The fit provided set of landmarks, comprising x‐ and y‐coordinates of 60 evenly spaced pixel points spanning the entire width of the region of interest. The white vertical lines represent thickness measures recorded in Semitendinosus muscle and aponeurosis thickness.

Figure 3

Test (light blue) and retest (dark blue) group mean and SD values for the superficial aponeurosis thickness of the BFlh (A and C) and Semitendinosus (B and D), normalized to muscle length at full extension (A and B) and 90° knee flexion (C and D). The 0% of muscle is proximate to the knee joint, whereas the 100% is closer to the hip joint. The thick lines represent the mean values, while the thin lines, filled with color, indicate the SD.

Figure 4

Test (light blue) and retest (dark blue) group mean and SD values for the deep aponeurosis thickness of the BFlh (A and C) and Semitendinosus (B and D), normalized to muscle length at full extension (A and B) and 90° knee flexion (C and D). The 0% of muscle is proximate to the knee joint, whereas the 100% is closer to the hip joint. The thick lines represent the mean values, while the thin lines, filled with color, indicate the SD.

Figure 5

Test (light blue) and retest (dark blue) group mean and SD values for the muscle thickness of the BFlh (A and C) and Semitendinosus (B and D), normalized to muscle length at full extension (A and B) and 90° knee flexion (C and D). The 0% of muscle is proximate to the knee joint, whereas the 100% is closer to the hip joint. The thick lines represent the mean values, while the thin lines, filled with color, indicate the SD.