Serum enzymes activities at rest and after a marathon race.

With the purpose of determining the long and short term changes in serum enzyme activities after a marathon race, a survey involving nine healthy male runners was carried out. A basal blood sample was extracted from each 24 hours prior to the race and three further extractions were made immediately after the race, as well as at 1 and a final 24 h after the end of the race. In the enzymes of preferably hepatic origin--alkaline phosphatase (AP), ganna-glutamyltransferase (GGT) and alanine aminotransferase (ALT)--scanty modifications were found and these could be related to the changes observed in the plasma volume. Enzymes such as aspartate aminotransferase (AST) and lactate dehydrogenase (LDH), which are widely distributed in the tissues, were found to have undergone more marked variations and these could not be related to the changes in the volume of the plasma, while in enzymes of muscular origin such as aldolase (ALD), creatine kinase (CK) and its cardiac isoenzyme (CK-MB), notable increases were observed due to the muscular injury suffered. The greatest example of this was the increase found in total CK 24 h after the end of the marathon (414.6%). The high serum percentages found in CK-MB in these endurance-trained runners in relation to total CK activity should be carefully assessed in order to avoid false diagnosis of acute myocardial infarction.