Carbohydrate metabolism and muscular exercise

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Abstract
During rest after prolonged muscular work of moderate severity in 2 human subjects when there was a persistent low R.Q. and ketonuria, there was a reduction of glucose tolerance which seemed to be the same as that found without preceding exercise simply as a result of the combustion of a low-carbohydrate, high-fat diet. It was not accompanied by any significant difference in the response to insulin injected intraven. in either case. In the resting subject the temporary fall of blood-sugar conc. caused by intraven. inj. of insulin was accompanied by a rise of the R.Q. which appeared to signify an increase of carbohydrate metabolism. There was no accumulation of excess lactic acid in the blood, and the effects on the O2 consumption were slight and inconstant. Subcut. inj. of adrenaline caused an increase in the O2 consumption. The R.Q. showed a characteristic change which could be explained by the accumulation and disappearance of excess lactic acid which accompanies the hyper-glycaemia, without postulating any alteration in the oxidation of carbohydrate. After the simultaneous inj. of insulin and adrenaline the changes in blood-sugar conc. were diminished, but the changes of lactic acid conc. in the blood and of the R.Q. were practically identical with those after adrenaline alone. The bearing of these expts. on the question of the possible significance of insulin and adrenaline secretion during muscular work was discussed.