When produced in excess, free radicals may promote cellular oxidation, damage in the DNA structure, aging and a variety of diseases [4], impair skeletal muscle function and pain and, thereby affecting exercise performance [5]. In an attempt to minimize the effects of oxidative stress during

physical activity, many athletes and sports professionals are performing supplementation with antioxidant vitamins. However, recent studies raise the assumption that exercise alone could increase the MEK162 solubility dmso oxidative capacity of skeletal muscle and potentiate the action of endogenous VS-4718 nmr antioxidants, which is sufficient to counteract the negative effects of oxidative stress induced by the mechanical stimuli [3, 6–8]. In view of this background, the aim of this commentary was to systematize the results of the last studies published regarding the effects of antioxidant vitamins intake on oxidative stress in exercise in humans. Results and discussion We included 12 studies published in the last years that addressed the supplementation of antioxidant vitamins in trained volunteers (n = 05; Table 1) and in volunteers submitted to endurance exercise (n = 07; Table 2). Table 1 Results of the studies with endurance trained volunteers supplemented with vitamins A, C, and E Study Experimental design Sample Duration Suplementation

protocol Result         Vitamin A Vitamin C Vitamin E Ergogenic Ergolytic Tauler et al. [6] Randomized, double-blind 15 athletes 90 d* 30 mg 1000 mg 500 mg ↔ ↔ (β-caroten) Gauche et al. CP673451 clinical trial [9] Randomized, double-blind 22 athletes 21 d (pre-exercise) + 2 dias (post-exercise) 6 mg 200 mg 32 mg ↑ N/R (β-caroten) Nielsen et al. [10] Randomized, double-blind, cross-over 15 athletes 28 d – 400 mg 180 mg ↔ ↔ Patil et al. [11] Randomized, double-blind 37 athletes 21 d – - 200 mg ↔ ↔ Louis et al. [12] Randomized, double-blind 16 athletes 21 d 17.1 mg 319.2 mg 48 mg ↑ N/R         (β-caroten)         * Vitamin C supplementation occurred only in the last 15 days of the study; ↑ Improved exercise performance; ↔ No results on exercise performance; N/R – not reported. Table 2 Results of

Loperamide the studies with untrained volunteers submitted to endurance exercise and supplemented with vitamins C e E Study Experimental design Sample Duration Supplementation protocol Result   Vitamin C Vitamin E Ergogenic Ergolytic Bloomer et al. [13] Randomized, double-blind 15 trained and e 15 untrained subjects 14 d (pre-exercise) + 2 d (post-exercise) 2000 mg 835 mg ↔ ↔ Gomez-Cabrera et al. [7] Randomized, double-blind 14 untrained subjects e 36 rats 8 weeks 1 g (humans) and 0.24 mg∙cm-2 (rodents) – N/R ↓ Ristow et al. [3] Randomized, double-blind 20 trained and e 20 untrained subjects 4 weeks 1000 mg 440 mg N/R ↓ Yfanti et al. [14] Randomized, double-blind 21 untrained subjects 16 weeks 500 mg 400 IU ↔ ↔ Yfanti et al. [5] Randomized, double-blind 21 untrained subjects 16 weeks 500 mg 400 IU ↔ ↔ Nalbant et al.