Abstract
The purpose of this study was to investigate the effect of increasing the intensity of exercise on serum enzyme levels in untrained males. Subjects exercised on a treadmill at one of four inclines for 15 minutes, and serum enzyme determinations were made before and after exercise. Results showed a greater increase in mean serum enzyme levels after strenuous exercise than after either mild or moderate exercise. Variations in serum enzyme concentrations between subjects, as well as differences in the relative increases of enzymes, were shown to exist.