Effects of endurance training on skeletal muscle oxidative capacities with and without selenium supplementation.
ABSTRACT The purpose of this study was to examine the changes induced by endurance training, with or without selenium (Se) supplementation on: 1) mitochondrial activity of succinate dehydrogenase (SDH) and cytochrome c oxidase (Cyt Ox),2) the myosin heavy chain (MHC) expression in muscle fibers and 3) their association with aerobic performance. Twenty-four male students volunteered to participate in this double blind study: selenium (Sel, N = 12) vs placebo (Pla, N = 12). During a 10-wk endurance training program, the Sel group received a daily Se supplementation containing 180 micrograms of organic selenium (selenomethionine), while the Pla group received a placebo. Before (Pre) and after (Post) the program (3 sessions wk-1) an endurance exercise (Capmax) was performed in order to determine the aerobic endurance capacity assessed by the total oxygen uptake during the running test (VO2tot). All parameters of aerobic performance were increased in both groups, concomitantly to a rise in mitochondrial Cyt Ox activity. Two positive relationships were found: 1) between type I MHC and VO2tot increments (r = 0.65, P < 0.05), 2) between training volumes and VO2tot increments (r = 0.53, P < 0.05; N = 23). The training program produced an 8.2% significant increase in type I MHC (P < 0.05) while type II MHC decrease was not significant (-4.4%). Although they were almost non-existent before the program, muscle fibers which co-expressed type I and II MHC displayed a marked increase afterwards (4.9 +/- 5.7 vs 1.1 +/- 2.1%, P < 0.05). Muscle GSH-Px activity, at rest, did not respond to endurance training or Se supplementation. The results suggest that the neuromuscular system is still in an evolutive state after 10 weeks of endurance training, and that selenium supplementation has no effect on endurance training-induced adaptations.
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ABSTRACT: Nutritional adequacy and physical activity are two aspects of a health-promoting lifestyle. Not much is known about antioxidant nutrient requirements for exercising elderly (EE) subjects. The question of whether exercise training alters the status of antioxidant vitamins as well as trace elements in elderly subjects and fails to balance the age-related increase in oxidative stress is addressed in this study. There were 18 EE (68.1+/-3.1 years), 7 sedentary elderly (SE; 70.4+/-5.0 years), 17 exercising young (EY; 31.2+/-7.1 years) and 8 sedentary young (SY; 27.1+/-5.8 years) subjects who completed 7-day food and activity records. Each subject's blood was sampled on Day 8. A similar selenium (Se) status but a higher erythrocyte glutathione peroxidase (GSH-Px) activity were found in EE subjects as compared with EY and SE subjects. Blood oxidized glutathione was higher and plasma total thiol was lower in EE subjects as compared with EY subjects. Mean vitamin C (167 vs. 106 mg/day), vitamin E (11.7 vs. 8.3 mg/day) and beta-carotene (4 vs. 2.4 mg/day) intakes were higher in EE subjects as compared with EY subjects. However, EE subjects exhibited the lowest plasma carotenoid concentrations, especially in beta-carotene, which was not related to intakes. Despite high intakes of antioxidant micronutrients, no adaptive mechanism able to counteract the increased oxidative stress in aging was found in EE subjects. Results on GSH-Px activity illustrate that the nature of the regulation of this biomarker of Se status is different in response to training and aging. These data also strongly suggest specific antioxidant requirements for athletes with advancing age, with a special attention to carotenoids.The Journal of Nutritional Biochemistry 08/2006; 17(7):463-70. · 3.89 Impact Factor
Article: Antioxidant supplementation and tapering exercise improve exercise-induced antioxidant response.[show abstract] [hide abstract]
ABSTRACT: The present controlled-training, double-blind study (supplemented, n = 7; placebo, n = 9) investigated whether taper training (TT) and antioxidant supplementation, i.e., 150 micro g of selenium, 2000 IU of retinol, 120 mg of ascorbic acid and 30 IU of alpha-tocopherol, modulates antioxidant potential, redox status and oxidative damage occurrence both at rest and in response to exercise. Two weeks of TT followed four weeks of overloaded training. Dietary intakes were recorded. Before and after TT, triathletes did a duathlon consisting of 5-km run, 20-km bike and 5-km run. Biological studies were conducted at rest and after exercise. Whatever the nutritional status, TT induced a decrease in resting blood reduced glutathione (GSH) concentration (p < 0.001), erythrocyte superoxide dismutase (SOD) activity (p < 0.0001) and plasma total antioxidant status (TAS) (p < 0.05). Only in the supplemented group (Su) with TT, did plasma glutathione peroxidase (GSH-Px) activity decrease (p < 0.05) and CD4(+) cell concentration increase (p < 0.05). However, antioxidant supplementation increased plasma TAS increase in response to exercise and TT (p < 0.05). After exercise, TT also induced a lower decrease in blood reduced and oxidized (GSSG) glutathione (p < 0.01) in both groups, but TT had no effect on lipoperoxidation as estimated by plasma thiobarbituric reactive substances or on muscular damage occurrence estimated by plasma creatine kinase isoenzyme MB mass. During TT, antioxidant supplementation at nutritional doses reinforces antioxidant status response to exercise, with an effect on exercise-induced oxidative stress, and no effect on oxidative damage.Journal of the American College of Nutrition 04/2003; 22(2):147-56. · 2.29 Impact Factor