20 days bed-rest on insulin action in relation with body fat in young subjects.

It is well known that a daily positive physical activity is able to control body fat and to improve insulin action for intaking glucose in the muscles, especially under administration of nutrition in human. Conversely, when exposed prolonged inactive condition such as bed-rest in spite of control of nutrition, the insulin action may be declined due to less glucose intake in the muscles and thus the insulin secretion may be increased to maintain blood glucose level. If it is so, the increased insulin should accelerate intake of neutral fat and to lower fatty acid in the fat tissues. Further, if the prolonged inactivity would decrease plasma epinephrine and norepinephrine secretion, the breakdown of the stored fat should be declined due to declining hormone susceptible lipase secretion, resulting in increase in body fat, which may reflect the changes in lipo-proteins and apoproteins. In the present study, the hypothesis mentioned above were investigated in young persons exposed to prolonged horizontal bed-rest of 20 days.