BLOOD SUGAR REGULATION IN EXERCISE

Abstract

Studies on human subjects (principally 2) showed that in easy work in which lactic acid does not accumulate, blood sugar remains near the rest level. If work brings on exhaustion in 10-40 min., blood sugar may be increased 10-66%. Usually a still higher level is reached 5-10 min. after the end of work. Activity which brings on exhaustion in less than 3 min. with energy production chiefly anaerobic is characterized by little change in blood sugar during work and by moderate or small increases in recovery. The following mechanisms are probably involved: In moderate work increased circulation rate and decreased glucose content of blood reaching the liver are accompanied by increased glycogenolysis in the liver. Thus there is no change in arterial blood sugar concn. either in work or in transitory states. While adrenalin may play a part, it is not essential and if secreted the supply is not excessive. In severe work, adrenalin secretion is abundant and the increase in glycogenolysis is greater than the increase in rate of glucose oxidation. Concn. of blood sugar increases considerably in work and still more when fuel consumption declines in recovery. Finally, in anaerobic work the time is too short for the adrenals to come into effective action.