title: Aging is not a barrier to muscle and redox adaptations: applying the repeated eccentric exercise model.
abstract: Despite the progress of analytic techniques and the refinement of study designs, striking disagreement exists among studies regarding the influence of exercise on muscle function and redox homeostasis in the elderly. The repeated eccentric exercise model was applied to produce long-lasting and extensive changes in redox biomarkers and to reveal more effectively the potential effects of aging on redox homeostasis. Ten young (20.6±0.5 years) and ten elderly men (64.6±1.1 years) underwent an isokinetic eccentric exercise session, which was repeated after three weeks. Muscle function/damage indices (torque, range of movement, muscle soreness and creatine kinase) and redox biomarkers (F2-isoprostanes, protein carbonyls, glutathione, catalase, superoxide dismutase, glutathione peroxidase, glucose-6-phosphate dehydrogenase, uric acid, bilirubin and albumin) were assessed in plasma, erythrocytes or urine pre-exercise, immediately post-exercise and at 2 and 4 days post-exercise. As expected, the elderly group exhibited oxidative stress in baseline compared to the young group. Extensive muscle damage and extensive alterations in redox homeostasis appeared after the first bout of eccentric exercise. Noteworthy, the redox responses were similar between the age groups despite their differences in baseline values. Likewise, both age groups demonstrated blunted alterations in muscle damage and redox homeostasis after the second bout of eccentric exercise indicating adaptations from the first bout of exercise. Elderly individuals seem to be well fitted to participate in demanding physical activities without suffering detrimental effects on skeletal muscle and/or disturbances on redox homeostasis. The repeated eccentric exercise model may be a useful and practical physiological tool to study redox biology in humans.
authors.affiliation: Exercise Physiology and Biochemistry Laboratory, Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62110 Serres, Greece. nikolaidis@auth.gr
authors.forename: Michalis G
authors.initials: MG
authors.lastname: Nikolaidis
authors.forename: Antonios
authors.initials: A
authors.lastname: Kyparos
authors.forename: Chrysa
authors.initials: C
authors.lastname: Spanou
authors.forename: Vassilis
authors.initials: V
authors.lastname: Paschalis
authors.forename: Anastasios A
authors.initials: AA
authors.lastname: Theodorou
authors.forename: George
authors.initials: G
authors.lastname: Panayiotou
authors.forename: Gerasimos V
authors.initials: GV
authors.lastname: Grivas
authors.forename: Andreas
authors.initials: A
authors.lastname: Zafeiridis
authors.forename: Konstantina
authors.initials: K
authors.lastname: Dipla
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Vrabas
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000368:Aged; D000375:Aging / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology; D019415:Torque; D055815:Young Adult
keywords: Adaptation; Aging; Biomarkers; Redox biology; Skeletal muscle