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Abstract

We examined the influence of 3 consecutive days of high-intensity cycling on blood and urinary markers of oxidative stress. Eight highly-trained male cyclists (VO2 max 76 ± 4 mL·kg–1·min–1; mean ± SD) completed an interval session (9 exercise bouts lasting 30 s each, at 150% peak power output) on day 1, followed by 2 laboratory-simulated 30 km time trials on days 2 and 3. The cyclists also completed a submaximal exercise trial matched to the interval session for oxygen consumption. Blood was collected pre- and post-exercise for the determination of malondialdehyde (MDA), total antioxidant status (TAS), vitamin E, and the antioxidant enzyme activity of superoxide dismutase and glutathione peroxidase, while urine was collected for the determination of allantoin. There were significant increases in plasma MDA concentrations (p < 0.01), plasma TAS (p < 0.01), and urinary allantoin excretion (p < 0.01) following the high-intensity interval session on day 1, whereas plasma vitamin E concentration significantly decreased (p = 0.028). Post-exercise changes in plasma MDA (p = 0.036), TAS concentrations (p = 0.039), and urinary allantoin excretion (p = 0.031) were all significantly attenuated over the 3 consecutive days of exercise, whereas resting plasma TAS concentration was elevated. There were no significant changes in plasma MDA, TAS, or allantoin excretion following submaximal exercise and there were no significant changes in antioxidant enzyme activity over consecutive days of exercise or following submaximal exercise. Consecutive days of high-intensity exercise enhanced resting plasma TAS concentration and reduced the post-exercise increase in plasma MDA concentrations.

Item Type:	Article
Authors/Creators:	Shing, C and Peake, JM and Ahern, SM and Strobel, NA and Wilson, G and Jenkins, DG and Coombes, JS
Keywords:	cycling, malondialdehyde, total antioxidant status. Key words: cycling, malondialdehyde, total antioxidant status.
Journal or Publication Title:	Applied Physiology Nutrition and Metabolism
Publisher:	National Research Council of Canada
ISSN:	1715-5312
DOI / ID Number:	https://doi.org/10.1139/H07-051
Additional Information:	Copyright 2007. National Research Council. Please refer to the journal link for access to the definitive, published version. Under the Canadian Copyright Act, individuals may download or print single copies of articles for personal research or study. Any person may reproduce short excerpts from articles in the journals for any purpose that respects the moral rights of authors, provided that the source is fully acknowledged. As a courtesy, the consent of authors of such material should be obtained directly from the author.
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