Written by Greg Arnold, DC, CSCS. Those in the quercetin group were able to ride 13.2% longer than the group without quercetin.
Quercetin is one of the most abundant type of antioxidants called flavonoids, present in a wide variety of fruits, vegetables, and berries (1). Flavonoids have been shown to possess a number of healthful properties, most notably as an antioxidant and an anti-inflammatory (2). But research in mice has started to look at flavonoids like quercetin beyond their antioxidant and anti-inflammatory properties to possible benefits affecting the mitochondria, the structure in every cell where energy is made (3).
A small study in humans (4) suggests quercetin may affect endurance and oxygen intake. Twelve volunteers (7 men and 5 women) between the ages of 20 and 26 and considered to be fit but not highly trained participated in the study. They consumed either 500 milligrams of food-grade quercetin powder or a placebo twice daily in sugar-free Tang for 1 week and then completed an exercise test on days 7 and 8. They were then switched over to the other supplement group for 7 days and completed the exercise test again on days 7 and 8.
The exercise test was performed on an exercise bike, pedaling at a resistance that had them breathing at 75% of their maximum oxygen intake (called “VO2max”) until they could no longer pedal at 50 repetitions per minute for 30 seconds. Before beginning the ride, participants were encouraged to give their maximum effort and were instructed on the importance of this performance bout, but no encouragement of any kind was given during the ride. They were also asked not to alter their diet or over-the-counter medications during the course of the study, especially during the 24 hours before exercise testing.
The researchers noted significant improvements in both VO2max and fatigue in the quercetin group compared to the placebo group. Specifically, VO2max in the quercetin group was 3.8% higher than the placebo group (47.7 vs 45.9 milliliter/kilogram/minute, p < 0.05). Ten of the 12 volunteers had higher VO2max after quercetin supplementation, with quercetin improving VO2max by 5.2% from the start of study compared to 1.4% in the placebo group.
Regarding endurance, those in the quercetin group had 13.2% longer riding times compared to the placebo group (105.7 vs. 93.4 minutes, p < 0.05). Eight of the 12 volunteers rode longer after quercetin treatment than with placebo treatment, with quercetin helping improve ride times by 26.2% from the start of the study compared to 12.9% in the placebo group. The researchers attributed part of the improvement in ride times, especially in the placebo group, to familiarity of doing the exercise test, since the same bike was used to calculate VO2max before the study began.
The researchers suggested that quercetin’s powerful role as an antioxidant may have improved endurance by helping maintain healthy levels of calcium in the muscles during the exercise test (5). They concluded that this small, preliminary study showed that “short-term feedings of relatively low doses of the naturally occurring dietary flavonoid quercetin were associated with a modestly higher maximal oxygen consumption, along with a substantially higher endurance capacity in healthy, fit but untrained participants.”
Source: Davis, J. Mark, et al. “The dietary flavonoid quercetin increases VO2max and endurance capacity.” International journal of sport nutrition and exercise metabolism 20.1 (2010): 56-62.
© 2010 Human Kinetics, Inc.
Posted May 9, 2013.
Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY. You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com
References:
- Harwood M. A critical review of the data related to the safety of quercetin and lack of evidence of in vivo toxicity, including lack of genotoxic/carcinogenic properties. Food and Chemical Toxicology 20087; 45: 2179–2205.Hamalainen M. Anti-inflammatory effects of flavonoids: Genistein, kaempferol, quercetin, and daidzein inhibit STAT-1 and NF-kappaB activations, whereas flavone, isorhamnetin, naringenin, and pelargonidin inhibit only NF-kappaB activation along with their inhibitory effect on iNOS expression and NO production in activated macrophages. Mediators of Inflammation 2007; 45673.
- Davis, J.M., Murphy, E.A., Carmichael, M.D., & Davis, B. (2009). Quercetin increases brain and muscle mitochondrial biogenesis and exercise tolerance. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 2009; 296: R1071–R1077.
- Davis JM. The dietary flavonoid quercetin increases VO(2max) and endurance capacity Int J Sport Nutr Exerc Metab 2010 Feb;20(1):56-62.
- Reid MB. Free radicals and muscle fatigue: Of ROS, canaries, and the IOC. Free Radical Biology & Medicine 2009; 44: 169–179.
