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Old 09-14-2009, 04:46 AM   #3
Greg Davis
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Join Date: Dec 2006
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Effect of vitamin C supplementation on lipid peroxidation, muscle damage and inflammation after 30-min exercise at 75% VO2max.

1: J Sports Med Phys Fitness. 2008 Jun;48(2):217-24.Links

AIM: Hypothetically, supplementation with the antioxidant vitamins C could alleviate exercise-induced lipid peroxidation. The purpose of this study was to evaluate the effect of vitamin C supplementation on exercise-induced lipid peroxidation, muscle damage and inflammation. METHODS: Sixteen healthy untrained male volunteers participated in a 30-min exercise at 75% Vo2max. Subjects were randomly assigned to one of two groups: 1) placebo and 2) vitamin C (VC: 1 000 mg vitamin C). Blood samples were obtained prior to supplementation (baseline), 2 h after supplementation (immediately pre-exercise), post-exercise, 2 and 24 h after exercise. Plasma levels of VC, total antioxidant capacity (TAC), creatine kinase (CK), malondealdehyde (MDA), total leukocytes, neutrophils, lymphocytes, interleukin-6 (IL-6) and cortisol were measured. RESULTS: Plasma vitamin C concentrations increased significantly in the VC in response to supplementation and exercise (P<0.05). TAC decreased significantly in Placebo group 24 h after exercise compared to pre-exercise (P<0.05). Although MDA levels were similar between groups at baseline, it increased significantly 2 h after exercise only in the Placebo group (P<0.05). CK increased immediately and 2 h after exercise in both groups and 24 h after exercise only in placebo group compared to pre-exercise (P<0.05). Markers of inflammation (total leukocyte counts, neutrophil counts and IL-6) were increased significantly in response to the exercise (P<0.05). In VC group, there was significant increase in lymphocyte counts immediately after exercise compared with pre-exercise (P<0.05). Serum cortisol concentrations significantly declined after supplementation compared with baseline (P<0.05) as well as declined 2 and 24 h after exercise compared with immediately after exercise in VC group (P<0.05). CONCLUSION: VC supplementation prevented endurance exercise-induced lipid peroxidation and muscle damage but had no effect on inflammatory markers.

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The effects of acute vitamin C supplementation on cortisol, interleukin-6, and neutrophil responses to prolonged cycling exercise


Published in: European Journal of Sport Science, Volume 7, Issue 1 March 2007 , pages 15 - 25
Subject: Sport & Exercise Science;

Abstract
The depression of immune cell function that is typically observed after prolonged exercise is thought to be largely mediated by increased concentrations of stress hormones and cytokines as well as, possibly, oxidative stress. The aim of this study was to measure immunoendocrine responses, with acute vitamin C or placebo ingestion, before and during prolonged exercise. In a single-blind, randomized, counterbalanced/crossover design, eight healthy males ingested a bolus of 500 mg and 1000 mg vitamin C 2 h and 14 h pre-exercise respectively, then cycled for 2 h at approximately 60% maximal oxygen uptake (VO2max). They also consumed either placebo or vitamin C (1500 mg l-1) beverages (2.5 ml kg-1 body mass) every 15 min during exercise. Compared with the placebo trial, resting and post-exercise plasma vitamin C concentration and antioxidant capacity were higher and post-exercise oxidative stress markers were lower in the vitamin C trial. There was no difference between trials in the magnitude of post-exercise increases in circulating neutrophil numbers, plasma cortisol and interleukin (IL)-6 concentrations. There was a significant (2-way ANOVA) main effect of trial (P=0.039) and trialtime interaction (P=0.008) for PMA (phorbol-12-myristate-13-acetate)-stimulated chemiluminescence per neutrophil, with the post-exercise values significantly higher in the vitamin C trial (P<0.05). The results suggest that acute vitamin C supplementation may improve post-exercise neutrophil oxidative burst capacity. Given that there was no effect on cortisol, IL-6, and the circulating neutrophil count, a likely explanation is that acute vitamin C ingestion reduced (auto)oxidative “damage” to neutrophils, which could result in less impairment of their functional capacity after exercise.
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