title: Evaluation of muscle quality reliability and racial differences in body composition of overweight individuals.
abstract: The purpose of this study was to evaluate the reliability of ultrasound measures of muscle cross-sectional area (mCSA) and echo intensity (EI) in overweight subjects. A secondary purpose was to evaluate racial differences in EI, mCSA and body composition. In 33 overweight subjects, mCSA and EI were determined from a panoramic ultrasound scan of the vastus lateralis. Body composition was determined using dual-energy X-ray absorptiometry (DXA). Reliability of mCSA and EI was calculated from the intra-class correlation coefficient (ICC), standard error of the measurement (SEM) and minimal difference (MD). The ICC, SEM and MD for mCSA and EI were 0.87, 2.12, 5.89 and 0.74, 4.58, 12.69, respectively. There were no significant racial differences in body composition (p > 0.05); however, EI was significantly lower for black subjects (p = 0.018). These results suggest ultrasound measures of mCSA and EI are reliable in overweight subjects, and EI may provide additional muscle composition evaluations, beyond DXA measures.
authors.affiliation: Applied Physiology Laboratory, Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Malia N
authors.initials: MN
authors.lastname: Melvin
authors.affiliation: Applied Physiology Laboratory, Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA. Electronic address: Abbsmith@email.unc.edu.
authors.forename: Abbie E
authors.initials: AE
authors.lastname: Smith-Ryan
authors.affiliation: Applied Physiology Laboratory, Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Hailee L
authors.initials: HL
authors.lastname: Wingfield
authors.affiliation: Applied Physiology Laboratory, Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Sarah N
authors.initials: SN
authors.lastname: Fultz
authors.affiliation: Applied Physiology Laboratory, Department of Exercise & Sport Science, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Erica J
authors.initials: EJ
authors.lastname: Roelofs
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D050177:Overweight / Q000000981:diagnostic imaging*; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging*; D044469:Racial Groups / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D014463:Ultrasonography
keywords: Echo intensity; Muscle cross-sectional area; Overweight; Race; Reliability; Ultrasound