title: Decreased blood oxidative stress after repeated muscle-damaging exercise.
abstract: OBJECTIVE
  To examine the effect of repeated muscle-damaging exercise on the time-course changes in several indices of muscle damage, and to compare them with changes in blood oxidative stress indices.
  
  
  METHODS
  Twelve females underwent an isokinetic exercise session consisting of 75 lengthening knee flexions, which was repeated after 3 wk. Isometric torque, range of movement (ROM), delayed-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 before, immediately after, and 1, 2, 3, 4, and 7 d after lengthening contractions.
  
  
  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, whereas GSSG, TBARS, protein carbonyls, catalase, uric acid, bilirubin, and TAC increased), peaking in all but bilirubin at 3 d and returning to baseline values by 7 d after exercise. The repeated bout of lengthening contractions induced significantly less changes in indices of 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.
  
  
  CONCLUSIONS
  A repeated bout of lengthening contractions attenuated muscle damage and blood oxidative stress compared with the first bout.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Michalis G
authors.initials: MG
authors.lastname: Nikolaidis
authors.forename: Vassilis
authors.initials: V
authors.lastname: Paschalis
authors.forename: Giannis
authors.initials: G
authors.lastname: Giakas
authors.forename: Ioannis G
authors.initials: IG
authors.lastname: Fatouros
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Koutedakis
authors.forename: Dimitris
authors.initials: D
authors.lastname: Kouretas
authors.forename: Athanasios Z
authors.initials: AZ
authors.lastname: Jamurtas
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001663:Bilirubin / Q000032:analysis / Q000097:blood; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005260:Female; D005978:Glutathione / Q000032:analysis / Q000097:blood; D006115:Greece; D006801:Humans; D007866:Leg / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000276:immunology / Q000293:injuries*; D018384:Oxidative Stress / Q000276:immunology* / Q000502:physiology; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014527:Uric Acid / Q000032:analysis / Q000652:urine
chemical_list: D015415:Biomarkers; D017392:Thiobarbituric Acid Reactive Substances; D014527:Uric Acid; D005978:Glutathione; D001663:Bilirubin