Oxidative Stress of an Endurance Overtraining Animal Model

Abstract

Recently we developed an overtraining animal model to study the mechanisms related to performance decrement. PURPOSE: Seek for overtraining (OT) biomarkers studying the oxidative stress of heart, red gastrocnemius and plasma. METHODS: 27 Wistar rats were submitted to 11 weeks of running: 8 weeks of daily training followed by 3 weeks of incrementally increased training frequency from two to four times daily. Six performance tests were realized. Two groups were detected by the slope (a) of least square fit using tests 4, 5 and 6: Functional Overreaching (FOR, a > -15.05) (N=11) and Nonfunctional Overreaching (NFOR, a < -15.05) (N=7). A control group (CO, N=9) was also analyzed. Catalase (CAT), Superoxide Dismutase (SOD) and Lipid Peroxides (TBARS) were analyzed in heart and muscle and Glutathione Reductase (GR) in heart. Antioxidant Capacity (FRAP) and Lipid Peroxides (MDA) were measured in plasma. RESULTS: Mean±SD, p<0.05. NFOR showed performance (Kg.m) decrement in test 6 compared with test 4 (369.6±93.0 × 528.8±58.6). FOR increased the performance in test 6 compared with test 4 (700.8±73.69 × 550.8±29.2). FRAP (umol eq Trolox/L) was higher in CO (278.44±20.85) than FOR (230.36±21.33) and NFOR (242.17±20.20). Plasma MDA (uM) was higher in NFOR (1.77±0.57) than CO (0.93±0.19) and FOR (1.02±0.25). Heart and Muscle analyzes are shown in Table 1.TABLE 1: Oxidative Stress in Heart and MuscleCONCLUSION: The oxidative stress in NFOR is higher than FOR and CO. However, heart seems to be more protected. The muscle oxidative stress is possibly one of the mechanisms related to performance decrement in OT. Plasma MDA could be a biomarker of the NFOR state. Supported by Fapesp and CNPq