THE NATURE OF THE FOODSTUFFS OXIDIZED TO PROVIDE ENERGY IN MUSCULAR EXERCISE

Publisher Website
Google Scholar
Abstract
The experiments were performed on a single well trained dog, which was given the customary standard maintenance diet of about 60% carbohydrate, 25% fat, and 15% protein. The animal was caused to run for 10 min. at about 14.4 miles per hr. on a horizontal treadmill introduced into a closed system for obtaining the gaseous exchange. Employing the term "work" loosely to indicate the mass of the animal moved through horizontal distance, the "work" done was approximately 3,000 horizontal kgm. Experiments during the post-absorptive state, at least 18 hr. after the last food, were alternated with experiments after the ingestion of either fat, glucose or meat. Most of these latter experiments followed the ingestion of fat. The exercise was preceded and followed by periods during which the resting metabolism was obtained, and the excess metabolism of exercise and recovery was calculated upon the difference between the exercise and recovery gaseous exchange, and that of the average of the pre and post-exercise resting periods, as had been done in the previous work. The conclusions are: The specific dynamic action of fat, as well as that of glucose, is abolished during muscular exercise and recovery, i.e., this extra energy, which at rest appears as waste heat, is utilized as free energy in muscular work. This tends to confirm the non-specificity of the oxidative recovery process of muscular contraction. On the other hand both the "calorigenio" action of epinephrine and the specific dynamic action of tyrosine, like that of protein, cannot be used in muscular work. Hence the above mentioned non-specificity is limited, as certain oxidative exothermic reactions will not serve for this purpose. Incidentally, the experiments confirm the conception that the calorigenic action of epinephrine is due neither to muscular work nor to the specific dynamic action of carbohydrate.

This publication has 5 references indexed in Scilit: