[15] Randomized 16 untrained subjects N/R 1000 mg – ↑↓ N/R ↑ Improved exercise performance; ↓ Impaired exercise performance; ↑↓ Partial
result; ↔ No results on exercise performance; IU – International Units; N/R – not reported. In general, it was observed that there are controversial results about antioxidant supplementation during high-intensity exercise. According to two studies evaluated [3, 7], the placebo group presented significant better physical performance, fatigue resistance and antioxidant protection when compared to the supplemented groups. In contrast, Gauche et al. [9] and Louis et al. [12] evaluated Estrogen/progestogen Receptor modulator the effects of vitamin and mineral supplementation on muscle activity of athletes and observed that dietary supplementation provided a slight advantage over the placebo group in maximum voluntary muscle contraction after high-intensity exercise. This small advantage in the supplemented group compared to the placebo group was sufficient for the authors to consider the antioxidant supplementation as an ergogenic aid. Regarding the other studies, no differences were
found between the groups. Sample characteristics The subjects included in the studies presented different metabolic and body composition patterns. It is known that untrained subjects are more responsive to an exercise bout and, consequently, much more susceptible to suffer cellular damage from oxidative stress than trained individuals. For example, muscle damage caused by oxidative stress, in general, is more pronounced in untrained individuals [16]. Another point to Thiamine-diphosphate kinase be considered click here is the sample size of the studies. It was observed that the number of individuals that comprise the groups used in the studies listed in Table 1 is smaller than those in Table 2. This can be partially justified by the difficulty of recruiting athletes to be volunteers. Consequently, the statistical power and the effect size of such data can be compromised and should be carefully interpreted. Dietary control Parallel to vitamin supplementation, it was observed that several studies did not perform dietary control
of the subjects [3] or performed an inadequate control [9–12] to assess the possible interference of diet on the outcome. The dietary control is quite important since some vitamins and minerals may compete in terms of absorption in the gastrointestinal tract. Thus, the absence or inadequate dietary control can be considered a bias of the published studies. Tauler et al. [6] and Yfanti et al. [5, 14] performed dietary control through food records before and after the intervention. Gomez-Cabrera et al. [7] instructed the subjects to YM155 purchase repeat the diet in the day before the exercise test in the pre- and post-supplementation periods. Only in the study of Bloomer et al. [13] dietary control was performed through food records. The variables analyzed were: total caloric value of the meals, amount of proteins, carbohydrates and lipids and of vitamins A, C and E.