Skeletal muscle biopsies from highly trained endurance athletes have been shown to contain an increased percentage of the creatine kinase MB (CK-MB) isoenzyme, which has been attributed to continuous regeneration of the skeletal muscle fibers in response to exercise-induced injury. The purpose of this study was to determine whether myocardium undergoes a similar degenerative-regenerative process as a result of exercise training. Fifteen mongrel dogs underwent a 12-wk period of training (N = 8) or cage confinement (N = 7). The animals were then sacrificed, and samples of left and right ventricular myocardium were analyzed for total CK activity and CK-MB isoenzyme content. Percentages of CK-MB were slightly but insignificantly higher from both ventricles of exercise-trained as compared with cage-confined dogs:left ventricle, 4.6 ± 0.6% vs 3.3 ± 0.6%, respectively (P = 0.15);right ventricle, 4.0 ± 0.4% vs 3.0 ± 0.8%, respectively (P = 0.29). We conclude that chronic exercise training does not induce physiologically important degenerative changes in myocardium.
- Dog (Canine) exercise
- Myocardial degeneration
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation