Resistance exercise defined as muscle movement against a resistance such as weight is a potent anabolic stimulus. Endurance exercise however does not preserve lean mass. The mechanism remains unclear but is likely the result of local muscle effects and an overall systemic response. When initiated in the catabolic state, resistance exercise diminishes the degree of protein loss. Increasing lean body mass in the elderly and chronically ill population by this approach can markedly decrease disability. Large-muscle exercise should be given priority, because this training can significantly reduce muscle loss and accelerate gain. In a burn injury or wound patient population in whom catabolism is pronounced, an aggressive, early program of resistance exercise that continues through the recovery phase is of major importance as an additional anabolic stimulus.

In turn, lack of resistance exercise as occurs with bed rest, a fixed splint or general inactivity will lead to muscle atrophy (net catabolism) in addition to that caused by the burn.

VII. CURRENT EVIDENCE ON ANABOLIC AGENTS AND BURNS

Malayappa Jeevanandam, PhD, Lois Ramias, BS, Raymond F. Shamos, MD, FRCS, FACS, and William R. Schiller, MD, FACS

Background: Human growth hormone (hGH) is a potent anabolic agents, which has profound effects on protein, carbohydrate, and lipid metabolism. The role of this primarily anabolic hormone in the severe catabolic state of trauma is not known.

Results: A decreased hGH level was noted in the hyperglycemic and hypercatabolic injured state, particularly in victims of trauma who were young and not obese, compared to respective volunteers. A significant (p = 0.025) inverse relationship was observed between age and plasma hGH levels in this group of patients who had experienced trauma. Nutritional therapy improved the protein and fat metabolism but could not reverse to the normal state. In young patients who had experienced trauma and who were not obese, the hGH levels were significantly improved because of dietary intake, whereas in elderly patients or patients who were obese no changed was noted.

Conclusion: These results are consistent with less lipid mobilization and inefficient utilization of fatty acids in the elderly patients or patients who were obese who had abundant fat sources to spare. Elevation of hGH level by exogenous administration may improve the nitrogen economy and lipid mobilization, particularly so in the elderly patients or patients who were overweight. Our study supports the view that provision of adequate nutrition with daily administration of human hGH in the first week after trauma would enhance the metabolic status of the patient, resulting in reduced morbidity and earlier discharge from the hospital. (Surgery 1992; 111:495-502.)

A prospective study of growth hormone, insulin-like growth factor (IGF-1) and cortisol secretion was undertaken in six adults with burn injury. Serum concentrations of growth hormone and IGF-1 were low in all patients during the first 2 weeks of hospitalization. The mean growth hormone level was 4.35± 0.83 m /L on day 1 and 1.70± 0.50 m g/L on day 13. The mean serum concentration of IGF-1, which reflects overall growth hormone secretion, was 0.43± 0.09 U/ml on day 1 and 0.61± 0.11 U/ml on day 13; these values are distinctly low. After 3 to 4 weeks, IGF-1 concentrations increased to the mid-normal range, whereas growth hormone values did not change. Morning plasma cortisol concentrations were modestly elevated; however, urine free cortisol concentrations, which reflect total cortisol secretion, were elevated 2 to 28 times above normal values at the time of admission (mean, 443.5± 323.7 nmol/L).