Body Composition Changes and Anabolic Hormone Considerations with Advancing Age and in Persons with Spinal Cord Injury

Advancing age in the able-bodied population is associated with adverse body composition changes. Persons with spinal cord injury share similarities with the elderly with regard to changes in body composition, levels of activity, and predisposition to metabolic abnormalities. Acute paralysis from spinal cord injury causes muscle atrophy and relative adiposity. During the chronic phase of immobilization, a more gradual but persistent loss of muscle occurs at a rate that exceeds the rate of these changes with normal aging. In addition to the obvious physical effects of immobilization, endogenous anabolic hormones (testosterone and growth hormone) may be depressed and may contribute partially to these unfavorable body composition changes and adverse metabolic sequelae. In individuals with depleted lean body tissue mass, Stage 3 or Stage 4 pressure ulcers may not heal in an appropriate manner, resulting in increased morbidity and reduction in function and independence. Although generally appreciated, a pressure ulcer is associated with increased metabolic demands, which may not be met even in the hospital setting. Continued catabolism due to stress or inadequate nutrition will impair wound healing. Strategies must be sought to preserve lean tissue with advancing age or in states of immobilization, as well as reverse losses of muscle mass as a result of intercurrent illness.