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00005768-200705001-0085700005768_2007_39_s38_jamurtas_decreased_5miscellaneous< 16_0_1_0 >Medicine & Science in Sports & Exercise© 2007 American College of Sports MedicineVolume 39(5) SupplementMay 2007p S38Decreased Blood Oxidative Stress After Repeated Eccentric Exercise: 676: May 31 8:15 AM ‐ 8:30 AM[C-17 Free Communication/Slide - Muscle Damage and DOMS: MAY 31, 2007 8:00 AM - 10:00 AM ROOM: 264]Jamurtas, Athanasios Z.; Nikolaidis, Michalis G.; Paschalis, Vassilis; Giakas, Giannis; Fatouros, Ioannis G.; Koutedakis, Yiannis; Kouretas, Dimitris1Univ. of Thessaly, Trikala, Greece2Democritus University of Thrace, Komotini, Greece3Univ. of Thessaly, Larissa, Greece. (Sponsor: Allan Goldfarb, FACSM)Email: ajamurt@pe.uth.gr PURPOSE: To examine the effect of repeated eccentric exercise on the time-course changes in several indices of muscle damage and compare them with changes in blood oxidative stress indices.METHODS: Twelve females underwent an isokinetic exercise session consisting of 75 eccentric knee flexions, which was repeated after three weeks. Isometric torque, range of movement (ROM), delay ed-onset muscle soreness (DOMS), creatine kinase (CK), reduced glutathione (GSH), oxidized glutathione (GSSG), thiobarbituric-acid reactive substances (TBARS), protein carbonyls, catalase, uric acid, bilirubin and total antioxidant capacity (TAC) in blood were measured pre, immediately, 1, 2, 3, 4 and 7 days post-eccentric exercise.RESULTS: All muscle damage indices (torque, ROM, DOMS and CK) changed significantly after exercise. The concentration of all oxidative stress indices changed significantly in a way indicating increased oxidative stress in the blood (GSH and GSH/GSSG decreased while GSSG, TBARS, protein carbonyls, catalase, uric acid, bilirubin and TAC increased) peaking, in all but bilirubin, at 3 days and returned at baseline values after 7 days post-exercise. The repeated bout of eccentric exercise induced significantly less muscle damage and blood oxidative stress than the first bout. In general, from the increasing or decreasing area under the curve calculated for each oxidative stress index, the second bout produced 1.8 to 6.1-fold less changes in oxidative stress than after the first bout.CONCLUSION: A repeated bout of eccentric exercise attenuated muscle damage and blood oxidative stress compared to the first bout. Based on these findings we suggest that muscle-damaging exercise should be viewed as a different challenge compared to non-muscle-damaging exercise with regard to their effects on blood redox status.Decreased Blood Oxidative Stress After Repeated Eccentric Exercise: 676: May 31 8:15 AM ‐ 8:30 AMJamurtas, Athanasios Z.; Nikolaidis, Michalis G.; Paschalis, Vassilis; Giakas, Giannis; Fatouros, Ioannis G.; Koutedakis, Yiannis; Kouretas, DimitrisC-17 Free Communication/Slide - Muscle Damage and DOMS: MAY 31, 2007 8:00 AM - 10:00 AM ROOM: 264539