Presence of Creatine Kinase MB Isoenzyme during Marathon Training

Abstract

To the Editor: During last year alone, over 100,000 people ran marathons. Thus it is becoming important to appreciate that rather striking changes may occur in blood chemistry as a consequence of endurance training.^{1 , 2} Specifically, increased activities of creatine kinase isoenzymes may occur in the serum of healthy persons during strenuous, long-term training. The purpose of this report is to describe the persistent elevation of the MB isoenzyme of creatine kinase (MB CK) observed during a four-month period in a runner training for a marathon.The subject was a 178-cm, 68-kg, 27-year-old man who had been a runner for four . . .