For many years, physiologists were content to adopt the doctrine of the school of Voit and his followers with respect to the effect of muscular exercise on nitrogenous metabolism. This tended "to displace protein from the position of primacy to which it had been raised by Liebig." Until recently the dominant current view suggested that muscular work does not increase protein metabolism; furthermore, the character of the protein metabolism has been regarded as essentially unchanged by ordinary muscular activity. This is not intended to deny that under unusual conditions, when fat or carbohydrate are not readily available, protein may become the main source of energy in the body.
Cathcart1 of Glasgow has challenged the older contentions. As he presents his claims:
Let it be granted then that the main supply of energy is drawn from non-nitrogenous sources, still the substance of the muscle is rich in nitrogen. It would
METABOLISM DURING PROLONGED REST. JAMA. 1930;95(1):37–38. doi:10.1001/jama.1930.02720010041018