Bed rest and myopathies.
OBJECTIVE
The loss of skeletal muscle with injury or critical illness can be dramatic. This review emphasizes the importance of skeletal muscle as a metabolic reserve. Changes in protein metabolism with bed rest alone and during physiological stress are discussed. Nutritional and hormonal interventions that ameliorate the loss of skeletal muscle are highlighted.


RESULTS
The loss of skeletal muscle that occurs with inactivity alone can be prevented by nutritional supplementation with an essential amino acid formula. Bed rest with accompanying hypercortisolemia produces a threefold greater loss of skeletal muscle than bed rest alone. Essential amino acids stimulate muscle anabolism during acute hypercortisolemia; however, their effects during chronic hypercortisolemia must be explored.


CONCLUSIONS
Skeletal muscle loss with trauma or critical illness is due in great part to the interaction of bed rest (muscular inactivity) and stress (hypercortisolemia). Younger individuals respond to nutritional and pharmacological interventions during bed rest alone. Given a lower relative lean mass in the elderly and the importance of skeletal muscle as a metabolic reserve during stress, it is understandable that clinical outcomes are worse in older patients. Countermeasures to the loss of skeletal muscle, especially in the stressed patient, must be developed.
Ferrando
Arny A
AA
Department of Surgery, University of Texas Medical Branch, Shrine Hospital for Children, Galveston, Texas 77550, USA. aferrand@utmb.edu
Paddon-Jones
Douglas
D
Wolfe
Robert R
RR
D001510:Bed Rest / Q000009:adverse effects*; D016638:Critical Illness; D004734:Energy Metabolism / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000473:pathology*; D009135:Muscular Diseases / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D014947:Wounds and Injuries / Q000150:complications
D009124:Muscle Proteins; D006854:Hydrocortisone