Energy utilization in intermittent exercise of supramaximal intensity.

MARCARIA, K., R. II. OLIVA, P. E. DI PRAMPERO, AND Pm CERRETELLI. Energy utili<ation in intermittent exercise of supamaximal intensity. J. Appl. Physiol. 26(6) : 752-756. 1969.~In supramaximal exercise the extra energy which is not met by oxidation is drawn from splitting of high-energy phosphate, and only when this source is exhausted is energy drawn from the other anaerobic source, the splitting of acid. In strenuous intermittent exercise, no lactic acid is formed if the oxygen debt contracted during the working period can be met completely by the alactic phosphagen-splitting mechanism; the oxygen debt contracted during the working period must then be completely paid during the rest period. If these conditions are met, very heavy intermittent exercise can be carried out indefinitely, leading to a total amount of work much greater than would have been possible were the exercise protracted continuously until exhaustion. The payment of the alactic oxygen debt fraction is confirmed to be a fast process, the halfreaction time being about 20-25 set; the capacity of this mechanism in young fit nonathletic subjects is about 20 ml/kg body wt.