Acute Intake of Grape and Apple Polyphenols Improves Endurance Performance

by | Jul 17, 2018 | 2017, Fitness and Exercise, Polyphenols

Written by Angeline A. De Leon. In a randomized, crossover, double-blind, controlled study, a proprietary blend of 250 mg of grape and apple polyphenols (VinitronTM) significantly enhanced the endurance capacity and delayed exhaustion in the 48 participating subjects.

fruit and vegetablesAlthough oxidative stress is generally associated with negative health outcomes, in small amounts, it may be beneficial, as in the case of exercise. All forms of physical exercise cause some degree of oxidative stress which, after the recovery process, actually bolsters the body’s antioxidant capacity, supporting cellular health and promoting resistance to further oxidative stress (in preparation of future stressors) 1. In fact, the capacity of moderate exercise to produce healthy amounts of oxidative stress has led to its being referred to as an antioxidant 2. However, in the case of endurance exercise, the sustained generation of free radicals causes a significant imbalance between the production of reactive oxygen species (ROS) and the body’s antioxidant defense system 3. To protect against this mechanism, studies have examined the efficacy of polyphenol supplementation to support endurance performance 4. Polyphenols (plant-based micronutrients with potent antioxidant capabilities) are known for their ability to increase nitric oxide (NO), which plays a key role in blood flow and mitochondrial respiration 5. NO, therefore, is highly beneficial not only for increasing muscle strength 6, but also supporting recovery following intense exercise 7. Recent reviews indicate that chronic consumption of different types of polyphenols can have varying effects on physical performance 8, ranging from potentially harmful to beneficial. To better understand the effects of polyphenols on exercise endurance, a study published in Nutrients (2017) investigated the impact of acute polyphenol intake (sourced from apples and grapes) on performance on a high-intensity cycling exercise.

Using a randomized, crossover, double-blind, controlled study design, researchers recruited a total of 48 healthy, physically active males (average age = 31 years) reporting 3-6 hours of exercise weekly. Subjects performed two separate sessions (separated by a 7-day washout period) of endurance exercise using an incremental cycling test. Intensity corresponded to 70% of their maximal aerobic power until exhaustion and pedaling rate was kept constant throughout the test. Time to exhaustion was measured, as well as respiratory and muscle pain (measured 48 hours post-test) parameters. The evening prior and one hour immediately before the first endurance test, participants were randomly assigned to ingest either two capsules of 250 mg of polyphenols (purified extract containing specific profile polyphenols from grape and apple) or matching placebo. Participants alternatively received either polyphenols or placebo in the second test session of the study.

Mean endurance test duration was about 28.0 minutes for the polyphenol group and about 25.5 minutes for placebo. Findings revealed that, relative to placebo, men in the polyphenol group had a significant increase of time to exhaustion during the endurance test (+9.7 +/- 6.0%, p < 0.05). In addition, maximal perceived exertion was reached 2.7 minutes later with polyphenols (+12.8% +/- 6.8%, p < 0.05) vs. placebo. No significant between-group differences were detected in heart rate, ventilation, or blood pressure parameters nor in perception of muscle pain.

Based on findings, the current study appears to validate the positive effects of polyphenols on endurance performance, suggesting that supplementation with polyphenols may increase time to exhaustion while delaying fatigue. Contrary to prior evidence of polyphenols’ vasodilatory benefits for exercise recovery, however, the study also reports a significantly longer VO2 max (maximum rate of oxygen consumption) recovery time for the polyphenol group vs. placebo (+8.5 +/- 11.4 s, p < 0.05). Therefore, follow-up studies are needed to confirm whether the longer recovery time observed here is due to a prolonging of the endurance exercise itself (achieved through polyphenol intake) or whether it is directly linked to the vasodilation effects of polyphenols. Replication of findings using different classes of polyphenols would also be valuable.

Source: Deley G, Guillemet D, Allaert F, et al. An acute dose of specific grape and apple polyphenols improves endurance performance: a randomized, crossover, double-blind versus placebo-controlled study. Nutrients. 2017; 9(8): 917. DOI: 10.3390/nu9080917.

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

Posted July 17, 2018.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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