The Available Glycogen in Man and the Connection between Rate of Oxygen Intake and Carbohydrate Usage.

Summary. The type of work was ski running at a constant speed on a 750 m circular track set up on level ground. Four well trained male subjects performed this work to the point of exhaustion. During 150–160 min three of the subjects were able to run at a work intensity which corresponded to an oxygen intake of 3.6‐4.1 l/min. (The oxygen intake for the fourth subject was 3.4‐3.9 l/min during 120 min.) The total energy expenditure during this time was 2,000–3,000 Cal; the pulmonary ventilation rose to a mean of 90 l/min and the heart rate was 160–190 beats/min. By determination of the respiratory metabolism the quantity of oxidized carbohydrates was calculated. The RQ values remained during the whole run at a practically constant level. One subject, who had reduced his glycogen depot by 445 g, continued to get 55 % of his calorie need from carbohydrates, although hypoglycemic symptoms were present. The blood lactic acid concentrations at the end of these long periods of work were slightly increased (20 mg %).