title: The creatine kinase system in the serum of runners following a doubling of training mileage.
abstract: This study examined the response of the serum creatine kinase (CK) isoenzyme/isoform system following the stress of successive weeks of increased training. Four highly-trained male long-distance runners doubled their training mileage [45.0 (SD 3.5) to 81.2 (4.7) miles] for 3 weeks. Venous blood samples were obtained prior to the start of the increased training period and at the end of each week, days 7, 14, and 21, 12 h after a training run. All runners experienced a significant increase in training perception difficulty, which correlated with the significant increase in training mileage. While total CK activities did not become significantly elevated until day 14, the tissue isoform CK-MM3, as well as the ratio of CK-MM3 to MM1 (final CK-MM degradation isoform) became significantly elevated at day 7 and remained elevated throughout day 21. These findings demonstrate that an increase in training mileage caused a significant and continuous release of tissue CK activity from skeletal muscle into the circulation.
authors.affiliation: Clinical Laboratories, Hennepin County Medical Center, University of Minnesota School of Medicine, Minneapolis 55415.
authors.forename: F S
authors.initials: FS
authors.lastname: Apple
mesh_terms: D000328:Adult; D003402:Creatine Kinase / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D007536:Isomerism; D008297:Male; D009132:Muscles / Q000201:enzymology; D012044:Regression Analysis; D012420:Running; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase