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Abstract
Background: Quercetin is a bioflavonoid which occurs in many food items. Some previous studies on quercetin showed inconsistent results on exercise performance, muscle damage and body muscle in athletes. The aim of this study was to determine the effects of eight weeks of quercetin supplementation on exercise performance, muscle damage indices and body muscle in badminton players. Methods : This placebo-controlled, double-blind clinical trial was conducted on 26 badminton players for eight weeks. The subjects were randomly assigned to one of two groups to receive quercetin (1000 mg) or placebo (1000 mg dextrose). VO 2 and time to exhaustion (TTE) for measuring performance and body fat percentage (BFP) were measured before and after intervention. Plasma sample swere obtained for the determination of plasma lactate before and after intervention. Results : Lactate concentration, body fat percentage and VO 2 max did not show any significant difference ( P > 0/05) after eight weeks of supplementation with placebo and quercetin between two groups and within one group. There was a significant increase in TTE after intervention in the quercetin group ( P < 0/05) but a significant change was not observed in the placebo group ( P > 0/05). Conclusions : The current study shows that intake of quercetin may improve endurance exercise performance but may not reduce the body fat percentage.