Sarcopenia and increased adipose tissue infiltration of muscle in elderly African American women

Background: Aging is associated with metabolic, physiologic, and functional impairments, in part through age-related changes in body composition. During the later adult years, skeletal muscle mass decreases and body fat becomes centralized. Objective: The goal of the study was to investigate body composition over time ((x) over bar +/- SD: 2.04 +/- 0.6 y) in healthy, ambulatory, elderly African American women. The hypothesis that a reduction in total-body skeletal muscle (SM) and increases in visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and intermuscular adipose tissue (IMAT) are ongoing in healthy, weight-stable elderly was tested. Design: The study was a longitudinal evaluation of 26 women (age at baseline: 75.5 +/- 5.1 y) with a body mass index (in kg/m(2)) of 27.0 +/- 4.0. Body composition was measured by using whole-body magnetic resonance imaging for the quantification of SM, total adipose tissue (TAT), VAT, SAT, and IMAT. Results: SM (P < 0.001) and bone (P < 0.05) masses decreased, and regional analyses showed a decrease in dual-energy X-ray absorptiometry-derived leg SM (P < 0.05). VAT (P = 0.011) and IMAT (P < 0.001) increased. No changes occurred in TAT (P = 0.45), SAT (P = 0.96), physical function, or food intake. Conclusion: These data show an age-related remodeling of body composition with reductions in SM and corresponding increases in VAT and IMAT. Changes in the previously unstudied depot of IMAT may be involved in the deterioration of metabolic values frequently observed during aging.