Evaluation of exercise intensity indicated by serum lactate dehydrogenase activity in healthy adults

Noting relationship between exercise and serum LDH and alpha-HBD activities, we prescribed 3 exercise regimens of various intensities for 22 healthy adult subjects over predetermined periods. Variations in the serum enzyme activities were determined in relation to these exercise programs. We studied whether these enzyme levels may serve as new indices to evaluate the amount of exercise. The test subjects were divided into 3 groups to perform 3 types of exercise (30%, 50%, 70% of VO2max) for 6 weeks. The serum enzyme activities at the start and completion of the experiment were determined and compared. The results obtained were as follows: A rise in the serum LDH activity was noted in association with exercise. The mean increases for these groups were 10.2%, 7.5% and 23.5%. A statistically significant decrease in the serum alpha-HBD activity was noted in association with exercise. It has been suggested that by observing variations in these enzyme levels in normal individuals for an extended period, change in the intensity of physical exertion within the range of daily activities can be estimated.