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17.07.2010


Animal study: quercetin enhances stamina after you stopped taking it

A dose of quercetin [structural formula shown below] increases the number of mitochondria in cells. And that means more stamina, physiologists at the University of South Caroline discovered when they did an animal study.

Quercetin is a flavonoid, but not one that we get much of in its pure form. Sugared analogues on the other hand are found in tea, apples and onions, and a wide range of herbs, fruit and vegetables. After the downfall of the antioxidant theory interest in quercetin pepped up when researchers discovered that the compound activates the longevity enzyme SIRT1 in cells. That means that quercetin, like resveratrol, may imitate the positive effects of caloric restriction.

Quercetin
In experiments with fat cells quercetin, mostly combined with substances like resveratrol or adrenalin, stimulates the release of fatty acids into the bloodstream. In animal experiments, quercetin raises energy expenditure a little temporarily. In experiments with untrained students, sports scientists managed to raise their endurance capacity by 3 percent a small but significant effect.

In this animal study male mice were given 25 mg quercetin/kg in their food every day for 8 weeks. [Human equivalent: 150-300 mg/day.] There was an exercise mill in their cage and the researchers recorded how often and how intensively the mice used it. In the figure below the curves with the white circles represent the mice that did not get quercetin, and the curves with the black circles the experimental group.


Animal study: quercetin enhances stamina


The quercetin was given for one week. What's interesting in this study is that the ergogenic effects only became clear afterwards.

As you see in the figure below, the flavonoid activated molecules like PGC1alpha and SIRT1 in the cells, thus increasing the number of mitochondria. The graphs show the quantity of mitochondrial DNA in brain and muscle cells.


Animal study: quercetin enhances stamina


In human studies the performance enhancing effect of quercetin is modest. Some researchers conclude that it doesn't exist at all. [J Appl Physiol. 2009 Oct; 107(4): 1095-104.] Maybe this mouse study shows how you should use quercetin: you take it for a week and then stop and only then does the quercetin start to do its work.

The researchers work for the American army, which is looking for nutritional interventions that will help soldiers to perform better in a healthy way.

Source:
Am J Physiol Regul Integr Comp Physiol. 2009 Apr; 296 (4): R1071-7.

More:
Stamina improves with one gram quercetin daily 17.12.2009
Course of quercetin raises metabolism 18.08.2009