Vitamin C supplementation affects oxidative-stress blood markers in response to a 30-minute run at 75% VO2max.
ABSTRACT Vitamin C supplementation (VC) (either 500 or 1000 mg/d for 2 wk) was compared to a placebo treatment (P) to ascertain if VC could influence oxidative stress. Twelve healthy males (25 +/- 1.4 y) were randomly assigned in a counter-balanced design with a 2-wk period between treatments. Data were analyzed using repeated measures ANOVA. Exercise intensity measures (VO(2), RER, RPE, HR, lactate) were similar across treatments. Resting blood oxidative-stress markers were unaffected by treatment. Exercise decreased total blood glutathione (TGSH) and reduced glutathione (GSH) and increased oxidized glutathione (GSSG) (P < 0.01) independent of treatment. Protein carbonyls (PC) increased 3.8 fold in the P (P < 0.01). VC attenuated the PC exercise response in a dose-dependent manner ( P < 0.01). Thiobarbituric acid reactive substances (TBARS) was not influenced by exercise (P = 0.68) or VC. These data suggest that VC supplementation can attenuate exercise-induced protein oxidation in a dose-dependent manner with no effect on lipid peroxidation and glutathione status.
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ABSTRACT: To assess the effects of different exercise intensities and antioxidant supplementation on plasma protein modification. Trained men (n = 41) from a homogenous population were randomly assigned to perform cycle ergometer exercise either at 70% or 80% of individual .VO2max. Each intensity group was randomly assigned to receive either juice powder concentrate (JPC 70%, n = 11; JPC 80%, n = 10) or placebo (Plac 70%, n = 10; Plac 80%, n = 10) capsules for 28 wk. Four controlled exercise bouts and blood collections were conducted at baseline and study weeks 4, 16, and 28. Blood samples were drawn before (BE), immediately after (IE), and 30 min (30M) and 30 h (30H) postexercise. These samples were analyzed to estimate concentrations of carbonyl groups on plasma proteins (CP) and the redox state of human serum albumin (HSA). In the Plac group, CP concentrations increased at 80% of .VO2max IE and 30M, returning to preexercise concentrations by 30H (P < 0.05). At both 16 and 28 wk, the Plac groups had significantly higher BE and 30H CP concentrations than the JPC groups (P < 0.05). The reduced fraction of HSA, human mercaptalbumin (HMA), decreased at all four exercise tests at both exercise intensities IE and 30M, returning to preexercise values by 30H (P < 0.05). Supplementation had no influence on HSA. These results indicate that CP concentrations increase with 80% .VO2max intensity. The JPC group had lower baseline CP levels after 16 and 28 wk and no exercise-induced CP increase. HSA is reversibly shifted to a more oxidized state by recent intense exercise.Medicine and science in sports and exercise 12/2008; 41(1):155-63. · 3.71 Impact Factor
Article: Oxidative stress biomarkers response to high intensity interval training and relation to performance in competitive swimmers.[show abstract] [hide abstract]
ABSTRACT: Aim of the study is to investigate the modulations of oxidative stress biomarkers and some antioxidants induced by high intensity interval training bout and its relation to swimming performance. Ten swimmers performed a set of 8 maximal swims along 100 m by style of their specialty, with 10 minute for a rest. The concentration of blood lactate ([Lac]) was determined after each swim. The lactate tolerance index (LTI) was determined by the ratio between [Lac] and the respective times of execution of the 8 swims. The time to complete first 100 m swim at maximum effort (P100) and the international point score (IPS) reached in a specific competition were considered performance parameters. Venous blood was collected before and after the anaerobic training effort. Mean blood lactate concentration in the eight swims was 10.9 ± 1.2 mM. Significant increases were observed for TBARS (pre: 4.1±0.7 ?mol/L; post: 4.9±1.1. ?mol/L), CK (pre: 206.4±170.7 U/L; post: 244.4±176.9. U/L), GSH (pre: 0.52±0.06; post: 0.62±0.05. mM), and ascorbic acid (pre: 0.06±0.02; post: 0.11±0.03. mg/dL) after the anaerobic training bout compared to the values obtained before it. In addition, significant correlations (P < 0.05) were detected between LTI and P100 (r = -0.87) and IPS (r = 0.64) and between variation of ascorbic acid and P100 (r = -0.60). Anaerobic training bout proposed induces oxidative stress and cell muscle damage markers as well as modulates some antioxidants of competitive swimmers. The modulation of ascorbic acid seems to play an important role in the performance of these athletes.The Journal of sports medicine and physical fitness 09/2010; 50(3):356-62. · 0.85 Impact Factor
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ABSTRACT: High levels of reactive oxygen species (ROS) produced in skeletal muscle during exercise have been associated with muscle damage and impaired muscle function. Supporting endogenous defence systems with additional oral doses of antioxidants has received much attention as a noninvasive strategy to prevent or reduce oxidative stress, decrease muscle damage and improve exercise performance. Over 150 articles have been published on this topic, with almost all of these being small-scale, low-quality studies. The consistent finding is that antioxidant supplementation attenuates exercise-induced oxidative stress. However, any physiological implications of this have yet to be consistently demonstrated, with most studies reporting no effects on exercise-induced muscle damage and performance. Moreover, a growing body of evidence indicates detrimental effects of antioxidant supplementation on the health and performance benefits of exercise training. Indeed, although ROS are associated with harmful biological events, they are also essential to the development and optimal function of every cell. The aim of this review is to present and discuss 23 studies that have shown that antioxidant supplementation interferes with exercise training-induced adaptations. The main findings of these studies are that, in certain situations, loading the cell with high doses of antioxidants leads to a blunting of the positive effects of exercise training and interferes with important ROS-mediated physiological processes, such as vasodilation and insulin signalling. More research is needed to produce evidence-based guidelines regarding the use of antioxidant supplementation during exercise training. We recommend that an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain the optimal antioxidant status in exercising individuals.Sports Medicine 12/2011; 41(12):1043-69. · 5.16 Impact Factor