title: Diagnostic ultrasound estimates of muscle mass and muscle quality discriminate between women with and without sarcopenia.
abstract: BACKGROUND
  Age-related changes in muscle mass and muscle tissue composition contribute to diminished strength in older adults. The objectives of this study are to examine if an assessment method using mobile diagnostic ultrasound augments well-known determinants of lean body mass (LBM) to aid sarcopenia staging, and if a sonographic measure of muscle quality is associated with muscle performance.
  
  
  METHODS
  Twenty community-dwelling female subjects participated in the study (age = 43.4 ± 20.9 years; BMI: 23.8, interquartile range: 8.5). Dual energy X-ray absorptiometry (DXA) and diagnostic ultrasound morphometry were used to estimate LBM. Muscle tissue quality was estimated via the echogenicity using grayscale histogram analysis. Peak force was measured with grip dynamometry and scaled for body size. Bivariate and multiple regression analyses were used to determine the association of the predictor variables with appendicular lean mass (aLM/ht(2)), and examine the relationship between scaled peak force values and muscle echogenicity. The sarcopenia LBM cut point value of 6.75 kg/m(2) determined participant assignment into the Normal LBM and Low LBM subgroups.
  
  
  RESULTS
  The selected LBM predictor variables were body mass index (BMI), ultrasound morphometry, and age. Although BMI exhibited a significant positive relationship with aLM/ht(2) (adj. R (2) = 0.61, p < 0.001), the strength of association improved with the addition of ultrasound morphometry and age as predictor variables (adj. R (2) = 0.85, p < 0.001). Scaled peak force was associated with age and echogenicity (adj. R (2) = 0.53, p < 0.001), but not LBM. The Low LBM subgroup of women (n = 10) had higher scaled peak force, lower BMI, and lower echogenicity values in comparison to the Normal LBM subgroup (n = 10; p < 0.05).
  
  
  CONCLUSIONS
  Diagnostic ultrasound morphometry values are associated with LBM, and improve the BMI predictive model for aLM/ht(2) in women. In addition, ultrasound proxy measures of muscle quality are more strongly associated with strength than muscle mass within the study sample.
authors.affiliation: Muscle Morphology, Mechanics and Performance Laboratory, Clinical Research Center - Human Performance Research Unit, Veterans Affairs Medical Center Washington, DC, USA ; Department of Medicine, School of Medicine and Health Sciences, The George Washington University Washington, DC, USA.
authors.forename: Catheeja
authors.initials: C
authors.lastname: Ismail
authors.affiliation: Department of Physical Therapy and Health Care Sciences, School of Medicine and Health Sciences, The George Washington University Washington, DC, USA ; Department of Health Sciences, Malek School of Health Professions, Marymount University Arlington, VA, USA.
authors.forename: Johannah
authors.initials: J
authors.lastname: Zabal
authors.affiliation: Muscle Morphology, Mechanics and Performance Laboratory, Clinical Research Center - Human Performance Research Unit, Veterans Affairs Medical Center Washington, DC, USA ; Physical Medicine and Rehabilitation Service, Veterans Affairs Medical Center Washington, DC, USA.
authors.forename: Haniel J
authors.initials: HJ
authors.lastname: Hernandez
authors.affiliation: Muscle Morphology, Mechanics and Performance Laboratory, Clinical Research Center - Human Performance Research Unit, Veterans Affairs Medical Center Washington, DC, USA.
authors.forename: Paula
authors.initials: P
authors.lastname: Woletz
authors.affiliation: Department of Exercise and Nutritional Sciences, Milken Institute School of Public Health, The George Washington University Washington, DC, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Manning
authors.affiliation: Muscle Morphology, Mechanics and Performance Laboratory, Clinical Research Center - Human Performance Research Unit, Veterans Affairs Medical Center Washington, DC, USA ; The School of Kinesiology and Health Studies, Queen's University Kingston, ON, Canada.
authors.forename: Carla
authors.initials: C
authors.lastname: Teixeira
authors.affiliation: Department of Exercise and Nutritional Sciences, Milken Institute School of Public Health, The George Washington University Washington, DC, USA.
authors.forename: Loretta
authors.initials: L
authors.lastname: DiPietro
authors.affiliation: Department of Medicine, School of Medicine and Health Sciences, The George Washington University Washington, DC, USA ; Departments of Biochemistry and Molecular Medicine, School of Medicine and Health Sciences, The George Washington University Washington, DC, USA ; Departments of Medicine and Rehabilitation Medicine, Georgetown University School of Medicine Washington, DC, USA ; The Johns Hopkins University School of Medicine, Johns Hopkins University Baltimore, MD, USA ; Research Service, Veterans Affairs Medical Center Washington, DC, USA.
authors.forename: Marc R
authors.initials: MR
authors.lastname: Blackman
authors.affiliation: Muscle Morphology, Mechanics and Performance Laboratory, Clinical Research Center - Human Performance Research Unit, Veterans Affairs Medical Center Washington, DC, USA ; Department of Exercise and Nutritional Sciences, Milken Institute School of Public Health, The George Washington University Washington, DC, USA ; Research Service, Veterans Affairs Medical Center Washington, DC, USA.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Harris-Love
keywords: body composition; diagnostic ultrasound; dual-energy X-ray absorptiometry; geriatric assessment; muscle performance; muscle strength; myosteatosis; sarcopenia