Aerobic exercise: a potential therapeutic intervention for patients with liver disease.

Fatigue is a symptom of liver disease. Indirect evidence suggests that this type of fatigue is centrally mediated. Non-alcoholic steatohepatitis (NASH), which may lead to cirrhosis, is associated with insulin resistance. An activated hypothalamic pituitary adrenal axis results in increased secretion of cortisol releasing hormone, cortisol and catecholamines. Prolonged exposure to high levels of cortisol is associated with insulin resistance, as exemplified by the metabolic syndrome. Accumulation in visceral fat is an independent factor associated with insulin resistance. Central (visceral) fat is less sensitive to insulin than the rest of body fat and the central nervous system and not peripheral insulin, appears to regulate lipolysis in visceral fat by, at least in part, adrenergic mechanisms. Aerobic training has documented beneficial effects on mental health and fatigue secondary to chronic illness. In addition, aerobic training increases insulin sensitivity. Thus, aerobic training may decrease fatigue in liver disease and improve NASH.