(13-12-09) Longitudinal study of muscle strength, quality, and adipose tissue infiltration1,2,3

Matthew J Delmonico, Tamara B Harris, Marjolein Visser, Seok Won Park, Molly B Conroy, Pedro Velasquez-Mieyer, Robert Boudreau, Todd M Manini, Michael Nevitt, Anne B Newman and Bret H Goodpaster

1 From the Departments of Epidemiology (MJD, MBC, RB, and ABN) and Medicine (MBC, BHG, and ABN), University of Pittsburgh, Pittsburgh, PA; the Department of Kinesiology, University of Rhode Island, Kingston, RI (MJD); the Laboratory for Epidemiology, Demography and Biometry, National Institute on Aging, Bethesda, MD (TBH); the Institute of Health Sciences, VU University and EMGO Institute, VU Medical Center, Amsterdam, Netherlands (MV); the Department of Internal Medicine, Pochon CHA University, Pochon, Korea (SWP); the Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN (PV-M); the Department of Aging and Geriatric Research, University of Florida, Gainesville, FL (TMM); and the Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, CA (MN).
2 Supported by National Institute on Aging contracts N01-AG-6?2101, N01-AG-6?2103, and N01-AG-6?2106 and in part by the Intramural Research Program of the NIH, National Institute on Aging.
3 Address correspondence to MJ Delmonico, MPH Department of Kinesiology, 25 West Independence Way, Room 214, University of Rhode Island, Kingston, RI 02881. E-mail: [email protected] .
for the Health AgingBody Composition Study
Background: Sarcopenia is thought to be accompanied by increased muscle fat infiltration. However, no longitudinal studies have examined concomitant changes in muscle mass, strength, or fat infiltration in older adults.
Objective: We present longitudinal data on age-related changes in leg composition, strength, and muscle quality (MQ) in ambulatory, well-functioning men and women. We hypothesized that muscle cross-sectional area (CSA) and strength would decrease and muscular fat infiltration would increase over 5 y.
Design: Midthigh muscle, subcutaneous fat (SF), and intermuscular fat (IMF) CSAs and isokinetic leg muscle torque (MT) and MQ (MT/quadriceps CSA) were examined over 5 y in the Health, Aging, and Body Composition study cohort (n = 1678).
Results: Men experienced a 16.1% loss of MT, whereas women experienced a 13.4% loss. Adjusted annualized decreases in MT were 2?5 times greater than the loss of muscle CSA in those who lost weight and in those who remained weight-stable. Weight gain did not prevent the loss of MT, despite a small increase in muscle CSA. Only those who gained weight had an increase in SF (P < 0.001), whereas those who lost weight also lost SF (P < 0.001). There was an age-related increase in IMF in men and women (P < 0.001), and IMF increased in those who lost weight, gained weight, or remained weight-stable (all P < 0.001).
Conclusions: Loss of leg MT in older adults is greater than muscle CSA loss, which suggests a decrease in MQ. Additionally, aging is associated with an increase in IMF regardless of changes in weight or SF.

Source: American Journal of Clinical Nutrition, doi:10.3945/ajcn.2009.28047
Vol. 90, No. 6, 1579-1585, December 2009

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