Marathon runners, triathletes, and the like may do well to keep their fruit baskets well-stocked— research has discovered that, in addition to potentially aiding recovery, polyphenols from apples and grapes may also boost endurance. Published in Nutrients, the double-blind study recruited 48 active men, ages 25 to 37, to perform three high-intensity cycling tests. For the first test, the men cycled at 70% of their predetermined maximum aerobic power for as long as they could until exhaustion. For the second test, the men were randomly given 500 mg of a supplement with a polyphenol profile similar to that in apples and grapes or a placebo the evening before and one hour prior to a cycling test. During the cycling test, they cycled until exhaustion at 70% of their maximum power. For the third test a week later, the men swapped treatments and again cycled until exhaustion at 70% of their maximum power. During all three tests, researchers timed how long the men took to reach exhaustion, as well as physical parameters such as blood pressure, heart rate, breathing rate, and oxygen use. In addition, the men used a scale to report on their perceived level of exertion every four minutes while cycling. Researchers found that:
Compared with the placebo, the men cycled an average of 9.7% longer after receiving the polyphenol supplement.
Taking the polyphenol supplement was also associated with a 12.8% average increase in time to reach their maximum perceived level of exertion.
None of the physical parameters measured during exercise were affected by the polyphenol supplement, but supplement use was associated with a longer respiratory recovery time, which may have been due to the longer exercise time.
These findings suggest polyphenols from apples and grapes may help endurance athletes up their game. It’s important to note, however, that this research was funded by the manufacturer of the polyphenol supplement used in the study; therefore, unaffiliated research is needed to confirm these results. In the meantime, while polyphenols from eating fruit are different from polyphenol supplements because your body may absorb them differently, apples and grapes do make great snacks and are an excellent pre-exercise choice to give you extra fuel. And you may not have to eat an extraordinary amount to get a lot of polyphenols: depending on the variety, an apple has about 136 mg of polyphenols, and around 2/3 of a cup of blue-black grapes has about 169 mg of polyphenols.