title: Interaction between overtraining and the interindividual variability may (not) trigger muscle oxidative stress and cardiomyocyte apoptosis in rats.
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 (n = 19) 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.
authors: Laboratory of Exercise Biochemistry, Biology Institute, University of Campinas, 13083-970 Campinas, SP, Brazil.
authors: Rodrigo Luiz Perroni
authors: RL
authors: Ferraresso
authors: Renato  Buscariolli
authors: R
authors: de Oliveira
authors: Denise Vaz
authors: DV
authors: Macedo
authors: Lázaro Alessandro Soares
authors: LA
authors: Nunes
authors: René
authors: R
authors: Brenzikofer
authors: Danilo
authors: D
authors: Damas
authors: Rodrigo
authors: R
authors: Hohl
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis; D015415:Biomarkers / Q000097:blood; D002374:Catalase / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000378:metabolism; D003402:Creatine Kinase / Q000097:blood; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006352:Heart Ventricles / Q000473:pathology; D008054:Lipid Peroxides / Q000097:blood; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000473:pathology*; D009206:Myocardium / Q000473:pathology; D032383:Myocytes, Cardiac / Q000201:enzymology / Q000473:pathology*; D018384:Oxidative Stress; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D045222:Electron Transport Chain Complex Proteins; D008054:Lipid Peroxides; D017392:Thiobarbituric Acid Reactive Substances; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D002950:Citrate (si)-Synthase; D003402:Creatine Kinase