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The Physiological Effects Of a Mid-shift feed of sucrose
Abstract
When men work continuously at a moderate (1'0 litres/ min oxygen consumption) or hard rate (1'5 litres/ min oxygen consumption) for 6 hours, the respiratory quotient falls from 0·94 to 0·80. In classical concepts this ind:cates that 68% of the caloric requirement comes from carbohydrate initially and that only 30% comes from that source at the end of the work period. This change in metabolism is associated with an increase in oxygen consumption and heart rate, indicating that the men were being less effective mechanically towards the end of the work period when they were using predominantly fat metabolism. A mid-shift feed of 100 and of 200 g of sucrose in water .caused an immediate rise in RQ and a higher level of RQ than in the fasting men which persisted for the rest of the work period. This was associated with a lower rate of oxygen consumption than in the fasting state. Whife there may be some doubt about the immediate increase in RO being due to a shift towards carbohydrate metabolism after' the ingestion of sucrose, there can be little doubt that this is the case from the end of the first hour onwards, after the ingestion of sucrose. The doubt about whether the rapid increase in RQ after the ingestion of sucrose is due to a change from fat to carbohydrate metabolism or whether it is due to an alteration in blood insulin level following the ingestion of sucrose could be resolved by ingesting HC sucrose and studying the output of HC CO, in expired air. In view of the practical importance to industry of showing whether or not carbohydrate given during a mid-shift feed is actually metabo'ized during the remainder of the shift, a study with HC sucrose appears to be fully justified; its scientific value in solving the above problems is not in doubt.
