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Oxidative Medicine and Cellular Longevity
Volume 2012 (2012), Article ID 935483, 11 pages
http://dx.doi.org/10.1155/2012/935483
Research Article

Interaction between Overtraining and the Interindividual Variability May (Not) Trigger Muscle Oxidative Stress and Cardiomyocyte Apoptosis in Rats

1Laboratory of Exercise Biochemistry (LABEX), Biology Institute, University of Campinas (UNICAMP), 13083-970 Campinas, SP, Brazil
2Laboratory of Instrumentation for Biomechanics (LIB), Faculty of Physical Education (FEF), University of Campinas (UNICAMP), 13083-970 Campinas, SP, Brazil
3Laboratory of Histology, Biology Institute, University of Campinas (UNICAMP), 13083-970 Campinas, SP, Brazil

Received 9 April 2012; Accepted 16 April 2012

Academic Editor: Michalis G. Nikolaidis

Copyright © 2012 Rodrigo Luiz Perroni Ferraresso et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Severe endurance training (overtraining) may cause underperformance related to muscle oxidative stress and cardiomyocyte alterations. Currently, such relationship has not been empirically established. In this study, Wistar rats () underwent eight weeks of daily exercise sessions followed by three overtraining weeks in which the daily frequency of exercise sessions increased. After the 11th training week, eight rats exhibited a reduction of 38% in performance (nonfunctional overreaching group (NFOR)), whereas eleven rats exhibited an increase of 18% in performance (functional overreaching group (FOR)). The red gastrocnemius of NFOR presented significantly lower citrate synthase activity compared to FOR, but similar to that of the control. The activity of mitochondrial complex IV in NFOR was lower than that of the control and FOR. This impaired mitochondrial adaptation in NFOR was associated with increased antioxidant enzyme activities and increased lipid peroxidation (in muscle and plasma) relative to FOR and control. Cardiomyocyte apoptosis was higher in NFOR. Plasma creatine kinase levels were unchanged. We observed that some rats that presented evidence of muscle oxidative stress are also subject to cardiomyocyte apoptosis under endurance overtraining. Blood lipid peroxides may be a suitable biomarker for muscle oxidative stress that is unrelated to severe muscle damage.