LINK TO RESEARCH
Am J Clin Nutr
Matthew J Delmonico 1 ,
Tamara B Harris,
Seok Won Park,
Molly B Conroy,
Todd M Manini,
Anne B Newman,
Bret H Goodpaster,
Health, Aging, and Body
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.
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