Comparison Of Quadriceps Femoris Muscle Morphology Using Ultrasonography During Two Different Body Positions

Abstract

PURPOSE: To evaluate the effects of body position on muscle cross-sectional area (mCSA) and echo intensity (EI) of the rectus femoris (RF) muscle in healthy young women. METHODS: Seventeen healthy females (20.88 ± 1.17 yrs.; 167.30 ± 6.43 cm; 71.44 ± 14.81 kg) underwent 6 ultrasound scans (US) of the RF during two different body positions. For the first position, participants were instructed to lie supinated (lying) on a padded plinth for 5 minutes to allow for potential fluid shifts prior to collecting ultrasound images. For the second position, participants were instructed to sit upright (seated) on the edge of the padded plinth with their leg hanging freely and a 90° angle at the knee. During each position, mCSA and EI were assessed in the dominant limb via three panoramic US scans. Each image was scaled and mCSA and EI were quantified using image analysis software. The best image for each position was used for analysis. Repeated measures analyses of variance (ANOVA) were used to analyze mCSA and EI of the RF across the different body positions (lying vs. seated). RESULTS: There was no significant difference in mCSA during the supine (Mean ± 95% CI; 10.71 ± 1.57 cm) versus seated (10.95 ± 1.47 cm) positions (p = 0.166). Furthermore, there was no significant difference in EI during the supine (34.25 ± 3.08 AU) versus seated (33.27 ± 3.28 AU) positions (p = 0.301). CONCLUSIONS: The results indicated that a change in body position from supine to seated had no significant effect on the measurement of rectus femoris mCSA or EI from panoramic US scans. However, during visual inspection, possible changes in the shape of the RF were noted (i.e., flattening and widening of the RF while lying compared to seated). Therefore, future investigations may wish to investigate the effects of body position on ultrasound measurements of RF muscle thickness.