Total-body skeletal muscle mass: estimation by a new dual-energy X-ray absorptiometry method123

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ABSTRACT

Background:

Skeletal muscle (SM) is an important body-composition component that remains difficult and impractical to quantify by most investigators outside of specialized research centers. A large proportion of total-body SM is found in the extremities, and a large proportion of extremity lean soft tissue is SM. A strong link should thus exist between appendicular lean soft tissue (ALST) mass and total-body SM mass.

Objective:

The objective was to develop prediction models linking ALST estimated by dual-energy X-ray absorptiometry (DXA) with total-body SM quantified by multislice magnetic resonance imaging in healthy adults.

Design:

ALST and total-body SM were evaluated with a cross-sectional design in adults [body mass index (in kg/m2) < 35] with an SM-prediction model developed and validated in model-development and model-validation groups, respectively. The model-development and model-validation groups included 321 and 93 ethnically diverse adults, respectively.

Results:

ALST alone was highly correlated with total-body SM (model 1: R2 = 0.96, SEE = 1.63 kg, P < 0.001), although multiple regression analyses showed 2 additional predictor variables: age (model 2: 2-variable combined R2 = 0.96, SEE = 1.58 kg, P < 0.001) and sex (model 3: 3-variable combined R2 = 0.96, SEE = 1.58 kg, P < 0.001). All 3 models performed well in the validation group. An SM-prediction model based on the SM-ALST ratio was also developed, although this model had limitations when it was applied across all subjects.

Conclusion:

Total-body SM can be accurately predicted from DXA-estimated ALST, thus affording a practical means of quantifying the large and clinically important SM compartment.

KEY WORDS

Body composition
nutritional assessment
skeletal muscle mass
magnetic resonance imaging
dual-energy X-ray absorptiometry

Cited by (0)

1

From the Obesity Research Center, St Luke’s–Roosevelt Hospital and the Institute of Human Nutrition, Columbia University, College of Physicians and Surgeons, New York (JK, ZW, SBH, and DG); the Department of Biobehavioral Sciences, Teachers College, Columbia University, New York (JK); and the Department of Internal Medicine, School of Medicine, University of New Mexico, Albuquerque (RNB).

2

Supported by National Institutes of Health grants R29-AG14715 and PO1-DK 42618.

3

Reprints not available. Address correspondence to D Gallagher, Obesity Research Center, 1090 Amsterdam Avenue, New York, NY 10025. E-mail: [email protected].