Effects of Bed Rest on Glucose, Lipid and Amino Acid Metabolisms in the Aged, with Particular Reference to the Effects on Glucose Metabolic Phase

Abstract

The effects of decreased physiologic activity (ie, bed rest) on metabolisms, especially those on the metabolic phase chiefly of glucose, were comparatively studied in a group of the aged and a group of the youth. The fasting blood sugar and insulin remained stable during the first one to two weeks of bed rest, but tended to increase in three or four weeks. The blood sugar curve on OGTT showed a rise week after week during the bed rest, causing the appearance of its peak to delay, and the blood insulin also proved very responsive. These abnormal behaviors of the blood sugar and insulin were more striking in the group of the aged than in the group of the youth. The insulin tolerance test proved the bed rest to reduce the hypoglycemic effect. This reduction in the hypoglycemic effect was more prominent in the group of the aged. During the prolonged bed rest, the blood insulin and triglycerides were distinctly increased in the group of the aged, there being a positive correlation between these two parameters. The serum free amino acids increased with the bed rest; these increases were larger in the group of the youth than in the group of the aged, and the increases in the glucogenic and branched chain amino acids were particularly striking. These findings suggested that glucose metabolic abnormalities at bed rest would be a metabolic phase derived from changes in the peripheral cells, and become more striking with ageing.