Glucose Intolerance During Decreased Physical Activity in Man

Impaired glucose tolerance is a well documented consequence of absolute bedrest in man. Previous studies have shown a decrease in forearm glucose uptake during intravenous glucose infusion after fourteen days of bedrest. Bedrest is associated not only with physical inactivity but with a change in gravitational vector. This study was designed to examine the individual contributions of these factors to the glucose intolerance of bedrest. Thus, glucose tolerance tests were carried out in exercising subjects at bedrest and in rhesus monkeys immobilized in the vertical plane. Exercise in man improved glucose tolerance during bedrest, and vertically immobilized monkeys demonstrated significant glucose intolerance. It is concluded that the glucose intolerance of bedrest is a function of the decrease in physical activity.