Muscle amino acid arylpeptidases and their serum changes with exercise.

Activities of serum amino acid arylpeptidases were determined in five groups of healthy male adults at rest and after various exercise types using the following substrates: Ala-, Leu-, Phe-, Tyr-, Gly- and Pro-4-Nitroanilide. The exercise-induced changes were compared to the activities of the respective enzymes in resting leg muscles. A regression function was found, showing a close correlation between the mentioned parameters in all groups. The influence of haemoconcentration and intravascular hemolysis on the postexercise measured activities was of no consequence.