Acute Effects of Polyphenol-Rich Fruit Juice on Exercise Capacity and Vessels Dilatation in Healthy Humans: A Randomized, Controlled, Crossover Study

This study examined the acute effects of polyphenol (PP)-rich fruit juice supplementation on the exercise capacity of healthy humans. Thirty-five healthy, sedentary volunteers participated in this randomized, controlled, crossover study. They performed a 6 min walk test two hours after consuming 200 mL of a PP-rich fruit juice (fruit juice) or a PP-poor control juice (apple), separated by a one-week washout. In addition to monitoring the heart rate during exercise, we determined the reactive hyperemia index (RHI), an indicator of vascular dilatation that contributes to exercise capacity. The distance walked during the 6 min test tended to be greater after the consumption of the PP-rich juice, compared to the PP-poor juice (588 ± 15 vs. 561 ± 14 m, respectively). The increase in heart rate was similar in both situations. The RHI increases were similar after both juices’ intake at 1 h, but after 2 h, the RHI increase was significant only after the PP-rich juice intake (from 6.78 ± 0.46 to 8.47 ± 0.47, p < 0.001). In conclusion, acute consumption of PP-rich juice increases vessel dilatation and tends to improve exercise capacity. These data support further studies to determine whether greater consumption of PP-rich fruit juices could improve exercise capacity in healthy subjects.