Oxidative Stress and Exercise
Oxidative stress may be cumulative in intense exercise and hypoxia exposure. Heavy exercise increases ox-LDL-induced monocyte reactive oxygen species production, possibly by decreasing SOD activity and GSH content in monocytes. Athletes regularly participating in up to 40 min of acute high-intensity exercise may require higher intakes of exogenous antioxidants to defend against increased oxidative stress during exercise. They also show that the ROS production is proportional to the maximal aerobic power and inversely related to the consumption of plasma antioxidants.
About Exercise
While the benefits of mild to moderate exercise are well documented, concerns have been raised about the health risks associated with higher-intensity exercise. Numerous studies have shown a correlation between vigorous exercise and increased oxidative stress.
The Studies
Effects of exercise and training in hypoxia on antioxidant/pro-oxidant balance.
Pialoux V, Mounier R, Ponsot E, Rock E, Mazur A, Dufour S, Richard R, Richalet JP, Coudert J, Fellmann N. Eur J Clin Nutr. 2006 Jun 21; [Epub ahead of print]
Objective: The aim was to investigate the effects of acute exercise under hypoxic condition and the repetition of such exercise in a 'living low-training high' training on the antioxidant/prooxidant balance.Design:Randomized, repeated measures design.Setting:Faculte de Medecine, Clermont-Ferrand, France.Subjects:Fourteen runners were randomly divided into two groups. A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training.Intervention:A 6-week endurance training protocol integrated two running sessions per week at the second ventilatory threshold into the usual training. The first hypoxic group (HG, n=8) carried out these sessions under hypoxia (3000 m simulated altitude) and the second normoxic group (NG, n=6) in normoxia. In control period, the runners were submitted to two incremental cycling tests performed in normoxia and under hypoxia (simulated altitude of 3000 m). Plasma levels of advanced oxidation protein products (AOPP), malondialdehydes (MDA) and lipid oxidizability, ferric-reducing antioxidant power (FRAP), lipid-soluble antioxidants (alpha-tocopherol and beta-carotene) normalized for triacyglycerols and cholesterol were measured before and after the two incremental tests and at rest before and after training. Results: No significant changes of MDA and AOPP level were observed after normoxic exercise, whereas hypoxic exercise induced a 56% rise of MDA and a 44% rise of AOPP. Plasma level of MDA and arterial oxygen hemoglobin desaturations after the acute both exercises were highly correlated (r=0.73). Alpha-Tocopherol normalized for cholesterol and triacyglycerols increased only after hypoxic exercise (10-12%, P<0.01). After training, FRAP resting values (-21%, P<0.05) and alpha-tocopherol/triacyglycerols ratio (-24%, P<0.05) were diminished for HG, whereas NG values remained unchanged. Conclusions: Intense exercise and hypoxia exposure may have a cumulative effect on oxidative stress. As a consequence, the repetition of such exercise characterizing the 'living low-training high' model has weakened the antioxidant capacities of the athletes. Sponsorship: International Olympic Committee and the Direction Regionale de la Jeunesse et des Sports de la Region Auvergne. European Journal of Clinical Nutrition advance online publication, 21 June 2006; doi:10.1038/sj.ejcn.1602462.
The effect of 2 weeks vitamin C supplementation on immunoendocrine responses to 2.5h cycling exercise in man.
Davison G, Gleeson M. Eur J Appl Physiol. 2006 May 10; [Epub ahead of print]
An increased systemic concentration of stress hormones (of the hypothalamic-pituitary adrenal axis) and some cytokines may contribute to the depression of immune cell function typically observed after prolonged exercise. The aim of the present study was to