Skeletal muscle loss: cachexia, sarcopenia, and inactivity123

https://doi.org/10.3945/ajcn.2010.28608AGet rights and content
Under an Elsevier user license
open archive

Loss of skeletal muscle mass occurs during aging (sarcopenia), disease (cachexia), or inactivity (atrophy). This article contrasts and compares the metabolic causes of loss of muscle resulting from these conditions. An understanding of the underlying causes of muscle loss is critical for the development of strategies and therapies to preserve muscle mass and function. Loss of skeletal muscle protein results from an imbalance between the rate of muscle protein synthesis and degradation. Cachexia, sarcopenia, and atrophy due to inactivity are characterized by a loss of muscle mass. Each of these conditions results in a metabolic adaptation of increased protein degradation (cachexia), decreased rate of muscle protein synthesis (inactivity), or an alteration in both (sarcopenia). The clinical consequences of bedrest may mimic those of cachexia, including rapid loss of muscle, insulin resistance, and weakness. Prophylaxis against bedrest-induced atrophy includes nutrition support with an emphasis on high-quality protein. Nutritional supplementation alone may not prevent muscle loss secondary to cachexia, but, in combination with the use of an anabolic agent, it may slow or prevent muscle loss.

Cited by (0)

1

From the Division of Geriatrics, Department of Medicine, Duke University Medical Center, Durham NC.

2

Presented at the symposium “Cachexia and Wasting: Recent Breakthroughs in Understanding and Opportunities,” held at Experimental Biology 2009, New Orleans, LA, 18 April 2009.

3

Address correspondence to WJ Evans, Muscle Metabolism Unit, GlaxoSmithKline, MS R&D N2-2204A, 5 Moore Drive, Research Triangle Park, NC 27709. E-mail: [email protected].