THE ECONOMY OF MUSCULAR EXERCISE

Abstract

In this account arbitrary limits have been set to moderate work, hard work and maximal work. In the first category the amt. of energy transformed is small, the effects of the physical environment almost negligible, and if fatigue occurs it is of remote rather than of direct interest to the physiologist. With work approaching the limit of capacity, environmental conditions become more important. Fatigue appears to depend on the ratio of the work done to the capacity for work. In maximal work a temporary steady state may be attained, but a breakdown eventually occurs for which any one of several functions may be responsible. The most intense work is chiefly anaerobic and here no steady state is reached. Fatigue increases with the rapld depletion of energy reserves and the accumulation of unoxidized end-products.