The relationship between serum enzyme activities and delayed muscular soreness following varying workload

Untrained subjects performed contractions with the quadriceps muscles at 90% of 10RM to establish a time course for post-exercise serum enzyme activities and delayed muscular soreness. It was established that the highest serum enzyme activity occurred 8-24 hours post-exercise, while muscular soreness was greatest 48 hours post-exercise. Intensity and duration of exercise was varied by changing percentage of 10RM lifted and number of contractions performed. Venous blood was sampled and muscular soreness determined, 24 and 48 hours post-exercise. Serum activity of LDH, GOT and CPK and free HYP concentration were determined. Low intensity and short duration exercise produced no changes in post-exercise serum enzyme activities and no muscular soreness. Increased intensity and duration resulted in significant elevations in serum enzyme activities and muscular soreness. High intensity exercise resulted in significantly greater serum enzyme activity and muscular soreness than long duration exercise when total work performed was equal. Serum HYP levels were unchanged by any workload. The major portion of the total post-exercise serum LDH elevation was due to LDH-5 isozyme. Subjects exhibiting higher degrees of delayed muscular soreness were unable to raise resistances of 90% of 1RM, 48 hours post-exercise. These findings indicate that (a) the highest post-exercise serum enzyme activities occurred 24 hours prior to the greatest muscular soreness; (b) high intensity exercise was of greater importance in increasing post-exercise serum enzyme activity and muscular soreness than long duration exercise; (c) delayed muscular soreness is correlated with elevated serum enzyme activity; and (d) serum HYP level is not altered by this type of exercise. (Abstract shortened by UMI.).