title: Passive smoking reduces and vitamin C increases exercise-induced oxidative stress: does this make passive smoking an anti-oxidant and vitamin C a pro-oxidant stimulus?
abstract: The current interpretative framework states that, for a certain experimental treatment (usually a chemical substance) to be classified as "anti-oxidant", it must possess the property of reducing (or even nullifying) exercise-induced oxidative stress. The aim of the study was to compare side by side, in the same experimental setup, redox biomarkers responses to an identical acute eccentric exercise session, before and after chronic passive smoking (considered a pro-oxidant stimulus) or vitamin C supplementation (considered an anti-oxidant stimulus). Twenty men were randomly assigned into either passive smoking or vitamin C group. All participants performed two acute eccentric exercise sessions, one before and one after either exposure to passive smoking or vitamin C supplementation for 12 days. Vitamin C, oxidant biomarkers (F2-isoprostanes and protein carbonyls) and the non-enzymatic antioxidant (glutathione) were measured, before and after passive smoking, vitamin C supplementation or exercise. It was found that chronic exposure to passive smoking increased the level of F2-isoprostanes and decreased the level of glutathione at rest, resulting in minimal increase or absence of oxidative stress after exercise. Conversely, chronic supplementation with vitamin C decreased the level of F2-isoprostanes and increased the level of glutathione at rest, resulting in marked exercise-induced oxidative stress. Contrary to the current scientific consensus, our results show that, when a pro-oxidant stimulus is chronically delivered, it is more likely that oxidative stress induced by subsequent exercise is decreased and not increased. Reversely, it is more likely to find greater exercise-induced oxidative stress after previous exposure to an anti-oxidant stimulus. We believe that the proposed framework will be a useful tool to reach more pragmatic explanations of redox biology phenomena.
authors.affiliation: Department of Health Sciences, European University Cyprus, Nicosia, Cyprus.
authors.forename: Anastasios A
authors.initials: AA
authors.lastname: Theodorou
authors.affiliation: Department of Health Sciences, European University Cyprus, Nicosia, Cyprus; School of Physical Education and Sport Science, University of Thessaly, Trikala, Greece.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Paschalis
authors.affiliation: School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece.
authors.forename: Antonios
authors.initials: A
authors.lastname: Kyparos
authors.affiliation: Department of Health Sciences, European University Cyprus, Nicosia, Cyprus.
authors.forename: George
authors.initials: G
authors.lastname: Panayiotou
authors.affiliation: School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece. Electronic address: nikolaidis@auth.gr.
authors.forename: Michalis G
authors.initials: MG
authors.lastname: Nikolaidis
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000009:adverse effects / Q000494:pharmacology*; D015415:Biomarkers / Q000378:metabolism; D003402:Creatine Kinase / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D028441:F2-Isoprostanes / Q000378:metabolism; D006801:Humans; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000187:drug effects / Q000293:injuries / Q000502:physiology; D016877:Oxidants / Q000009:adverse effects / Q000494:pharmacology; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D012146:Rest / Q000502:physiology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects; D055815:Young Adult
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D028441:F2-Isoprostanes; D016877:Oxidants; D014028:Tobacco Smoke Pollution; D003402:Creatine Kinase; D001205:Ascorbic Acid
keywords: Antioxidants; Eccentric exercise; F(2)-isoprostanes; Glutathione; Prooxidants; Protein carbonyls