According to a study conducted by the Institute of Genetics and Molecular and Cellular Biology, mice given oral doses of resveratrol were able to run 100% farther than mice not given the resveratrol. The resveratrol dosed mice also displayed a reduced heart rate and energy charged muscles - physical characteristics associated with highly trained athletes. According to the study's lead scientist, Johan Auwerx, "Resveratrol makes you look like a trained athlete without the training".

Will these results translate in to humans?
According to Mr. Auwerx, the same reaction will likely occur in humans based on his analysis of the gene that is influenced by resveratrol in a group of Finnish subjects.
 

So how does resveratrol extend life in certain organisms?
The exact answer is not known but a widely asserted theory is that Resveratrol activates an enzyme that is present in the bodies of many living organism called sirtuin 2 (or SIR2). SIR2 is believed to extend cell life by 'coercing' cells to repair themselves (i.e. repair their DNA while increasing the production of protective antioxidants) as opposed to dying. In essence, it is believed resveratrol extends the lives of individual cells and the lives of the 'host' organisms are extended as a result. 
 

What could be causing the increased endurance?
According to Mr. Auwerx, resveratrol alters muscle fibers to make them more like muscle fibers of a trained athlete. 

Another exciting result from the study!
Resveratrol significantly increased the number of mitochondria in the muscles cells of the mice (mitochondria are responsible for generating cells' energy). The increased mitochondria allowed the mice to burn more calories and thus avoid weight gain. The mice also did not experience decreased sensitivity to insulin (a symptom of being overweight and a cause of diabetes). 

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