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Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "
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15.10.2013 |
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Resveratrol reduces effect of interval training
The sun's shining and we're feeling perky. On this beautiful October day we feel like writing on one of our favourite subjects. And no, we're not going to tell you how good plant-based proteins are for you. Today we're on another favourite subject.
Cell and animal studies have shown that resveratrol extends life expectancy. It activates protective enzymes that are also activated through caloric restriction and physical exercise. In rats and mice the life-extending effect is conspicuously absent, but resveratrol does enhance the positive effects of training.
The Danes set up their experiment to see whether resveratrol can also help humans who want to do something to improve their cardiovascular condition. They got about thirty men – average age 65 – to do interval training twice a week on an ergometer. In addition to that, the men trained their whole body once a week using a CrossFit workout, and they also did a 5-km walk once a week.
Half of the men were given a placebo; the other half took 250 mg resveratrol each day.
The Danes discovered that the training improved the men's cardiovascular condition. After eight weeks of training the subjects' vascular cell adhesion protein 1 [VCAM-1] concentration had decreased significantly. VCAM makes it possible for immune cells to attach themselves to the epithelium of the blood vessels. The higher the VCAM-1 level, the worse the hardening of the arteries. Resveratrol supplementation seemed to enhance that effect somewhat, which is a positive sign.
The other effects of resveratrol were not positive, however. In the placebo group the resting heart rate decreased by a significant amount; in the resveratrol group this did not happen. In the placebo group the average blood pressure [MAP] decreased by a significant amount; in the resveratrol group this did not happen. The maximal oxygen uptake [VO2max] – the primary determinant of fitness – rose in both the placebo and the resveratrol group, but the increase was greater in the placebo group. And so on, and so on.
Ergo: resveratrol supplementation undermines the effect of interval training.
The Danes suspect that resveratrol has an antioxidant effect, and that it captures the radicals released by physical exercise. But it's the free radicals that stimulate the cardiovascular system to become healthier. Supplementation with high doses of vitamin C and E has been shown in some studies to reduce the effect of training via the same mechanism.
Of course we're not as clever as the Danes, but we have a different theory – which, by the way, doesn't contradict the Danish hypothesis. Resveratrol inhibits the manufacture of HIF-1-alpha in many cell types. This is shown in the figure below, which we extracted from a study done in 2004. [Clin Cancer Res. 2004 Aug 1;10(15):5253-63.] HIF-1-alpha is a key factor in the positive cardiovascular effects of physical exercise.
Endurance athletes who have used supplements containing both resveratrol and green tea may not recognise the signs mentioned here. They often report positive effects. This may well be the case. The phenols in green tea stimulate the enzyme CYP1B1 in the liver. This enzyme converts resveratrol into piceatannol. And piceatannol stimulates the production of HIF-1-alpha.
What would have happened if the Danes had given their subjects piceatannol instead of resveratrol?
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