This study examined the effects of a single dose of purple grape juice on physical performance, oxidative stress, inflammation and muscle damage in runners. 14 recreational runners performed to running tests until exhaustion at 80% VO2max, 2 hours after the ingestion of purple grape juice or placebo drink (10 mL/kg).

Results showed an increase in performance, highlighted by a longer run until exhaustion after the grape juice (68.4 ± 29.7 min) in comparison to placebo (59.2 ± 27.8 min, p = 0.008). An increase in total antioxidant capacity has also been highlighted with grape juice. Nevertheless, no effect of the juice was noted on inflammatory and muscle damage markers.

Therefore, a single dose of purple grape juice can improve physical performance in recreational runners. The mechanism of action remains however to be clarified.

de Lima Tavares Toscano L, Silva AS, de França ACL, de Sousa BRV, de Almeida Filho EJB, da Silveira Costa M, Marques ATB, da Silva DF, de Farias Sena K, Cerqueira GS, da Conceição Rodrigues Gonçalves M. A single dose of purple grape juice improves physical performance and antioxidant activity in runners: a randomized, crossover, double-blind, placebo study. Eur J Nutr. 2019 Nov 15.