Effects of Quercetin Supplementation on Performance and Oxidative Stress Measures in Endurance Runners

To investigate the effects of dietary Q supplementation on oxidative stress, antioxidant activity, and performance measures in trained endurance runners. We hypothesized that quercetin will improve antioxidant status and, thus, increase exercise performance in endurance athletes. During six weeks of supplementation utilizing a double blind, randomized design with a two week washout period, 8 trained (VO sub(2peak) 59.2 + or - 1.4 mL times kg super(-1) times min super(-1 )) young (22.7 + or - 4.1 yrs) male subjects received quercetin (1000 mg/d) or placebo (P) while maintaining their current training schedules. Blood samples were collected at baseline, post VO sub(2peak) test, and post 10K time trial (TT). Following six weeks of supplementation, there was a significant interaction between treatment and time with the variable MDA (Q: -0.69 + or - 0.22 pmol/mg protein vs. P: +0.88 + or - 0.53 pmol/mg protein, interaction p = 0.019, repeated measures ANOVA). There were no significant pretreatment-to-posttreatment changes in TAC, SOD or protein carbonyl (p > 0.05).