However, the studies are highly heterogeneous, which has resulted in contradicting opinions. The aim of this review is to identify similar studies investigating the effects of tocopherol supplementation on exercise performance and oxidative stress and to perform minimally biased qualitative comparisons and meta-analysis.

The literature search and study selection were performed according to Cochrane guidelines. A 2-dimensional study execution process was developed to enable selection of similar and comparable studies.

Twenty relevant studies were identified. The high variability of study designs resulted in final selection of 6 maximally relevant studies. The purpose of this study was to investigate the individual and combined antioxidant effects of menstrual cycle phase-related alterations in blood serum oestradiol concentrations and of dietary vitamin E supplementation on exercise-induced oxidative stress and muscle performance.

Blood samples were taken before and after the exercise, to evaluate haematocrit, plasma lactic acid and malondialdehyde concentrations, erythrocyte antioxidant enzymes superoxide dismutase SOD and glutathione peroxidase GPx activities and apolipoprotein B containing lipoprotein non-high density lipoprotein, HDL, fraction oxidation.

Serum vitamin E, follicle stimulating hormone, luteinizing hormone and oestradiol concentrations were measured in pre-exercise blood samples.

Neither vitamin E supplementation nor oestradiol concentrations influenced SOD and GPx activities or the susceptibility of the non-HDL fraction to oxidation while at rest. Plasma malondialdehyde concentration was unaffected by exercise, however significant reductions in erythrocyte SOD and GPx activities and increased susceptibility of the non-HDL fraction to oxidation were noted after exercise.

Exercise-induced changes were reduced when oestradiol concentration was high in the preovulatory phase, independent of the serum vitamin E concentrations. In conclusion, these findings suggest a better protective role of oestradiol against oxidative injury, compared to vitamin E.

This is a preview of subscription content, log in via an institution to check access. Rent this article via DeepDyve. Institutional subscriptions. Medical School of Uludag University, Department of Sports Medicine, Bursa, Turkey e-mail: hakan uludag. However its effects on isokinetic exercise performance are unknown.

A recent study suggests that vitamin E and α-lipoic acid supplementation may in fact suppress skeletal muscle mitochondrial biogenesis, regardless of training status Some studies have shown the benefits of lipoic acid or vitamin E supplementations in endurance trained horses Nitric oxide NO has been implicated in the improvement of exercise capacity through vascular smooth muscle relaxation in both coronary and skeletal muscle arteries as well as via independent mechanisms.

Endothelial nitric oxide synthase eNOS uses the amino acid L-arginine as a substrate to synthesize nitric oxide NO. On the other hand, antioxidants may prevent nitric oxide inactivation by oxygen free radicals 6. Chen et al.

investigated the effects of L-arginine and antioxidant supplements on exercise performance in elderly male cyclists and reported that this intervention has a potential role in improving exercise performance in the elderly Spirulina is a blue-green alga that seems to exert antioxidant properties, which are attributed to molecules such as phytocyanin, β-carotene, tocopherol, γ-linolenic acid and phenolic compounds; it has also shown a preventive effect against the skeletal damage under exercise induced oxidative stress Anthocyanins e.

chokeberry juice limit the exercise-induced oxidative damage to red blood cells, most probably by enhancing the endogenous antioxidant defense system Superoxide dismutase SOD , a key enzyme that catalyzes the reduction of superoxide anions to less reactive hydrogen peroxide, is found in some plants but has limited use due to the inactivation of the enzyme in the gastrointestinal tract.

Recently an original and modified vegetable formula made from SOD-rich melon extract has been developed as an oral route agent; this product has been investigated and seems to promote antioxidant status in professional rowers without effect on oxidative damage induced by exhaustive exercise The main minerals involved in antioxidant-related functions include copper Cu , zinc Zn , iron Fe , selenium Se and manganese Mn ; their antioxidant effects contribute to the action as co-factors for antioxidant enzymes 6.

Copper and zinc as co-factors for Cu Zn-superoxide dismutase which is responsible for eliminating superoxide radicals. Iron is an essential co-factor in the antioxidant enzyme catalase. Catalase removes hydrogen peroxide from cells 6.

Increasing dietary or supplemental Fe can improve performance and may help prevent decreases in ferritin associated with exercise. Moderate-level supplementation prevented a decrease in serum ferritin in competitive swimmers Selenium Se is a co-factor for the antioxidant enzyme glutathione peroxidase, which is responsible for removing hydrogen peroxide and other organic hydroperoxide from the cell; Results of the study of Akil et al.

indicate that acute swimming exercise in rats increased the lipid peroxidation in the brain tissue of rats, while selenium supplementation prevented the free radical formation by enhancing the antioxidant activity Manganese Mn is co-factor for manganese-superoxide dismutase, which has a role in eliminating of superoxide radicals produced by oxidative phosphorylation 6.

Trials on Magnesium Mg supplementation in athletes have shown different findings. Some studies have reported a considerable reduction in total serum creatin kinase, serum lactate concentration as well as improvement of cardio-respiratory function after Mg supplementation 6.

Current data suggest that Mg supplementation does not affect performance when serum Mg is within the range of normal values, but may improve performance when marginal or clinical Mg deficiency is present Polat et al.

showed that the combined effects of exercise and zinc supplement have a positive effect on the hematological parameters of athletes that may lead to better performance and increased endurance Although a balanced vegetarian diet high in antioxidant-rich foods has been proposed as a dietary recommendation to enhance endogenous antioxidative capacity and attenuate exercise-induced oxidative stress, studies on vegetarian athletes is lacking and there is no sufficient evidence to support this hypothesis Limited investigations have reported effects of antioxidant-rich foods on exercise-induced oxidative stress; consumption of a diet rich in Allium vegetables Allium sativum, Allium cepa, Allium fistulosum or Allium tuberosum before and after exercise training increased the ratio of reduced glutathione to oxidized glutathione in rat models These findings indicate that athletes require higher intake of natural antioxidants especially antioxidant-rich foods It seems that the best recommendation regarding antioxidants and exercise is having a balanced diet rich in natural antioxidants and phytochemicals.

Regular consumption of various fresh fruits and vegetables, whole grains, legumes and beans, sprouts and seeds is an effective and safe way to meet all antioxidants requirements in physically active persons and the athletes. The increase in production of free radicals with intense physical exercise can exceed the capacity of the antioxidant defense systems in the body and induce oxidative conditions; currently however both positive and negative aspects of ROS generation in sport performance are considered.

Despite remarkable evidence of the positive effects of various vitamins and supplements in improvement of unfavorable imbalance between oxidative reactions and antioxidant equilibrium, controversial data are observed in literature; some investigators even believe that supplementation with antioxidants prevent health-promoting effects of physical exercise and may be harmful in humans or may delay muscle recovery; antioxidant supplementations may also block the positive effects of exercise on improved insulin sensitivity.

Overall, there is insufficient data supporting the effectiveness of antioxidant supplements to prevent the probably probable damages of strenuous exercise, particularly the improvement of physical exercise performance.

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