If the method of improving endurance in mice found by these researchers actually works in the way they think that it works, then it should also increase mouse life span:
The drug candidate, SR9009, is one of a pair of compounds [described] as reducing obesity in animal models. The compounds affect the core biological clock, which synchronizes the rhythm of the body's activity with the 24-hour cycle of day and night. The compounds work by binding to one of the body's natural molecules called Rev-erbα, which influences lipid and glucose metabolism in the liver, the production of fat-storing cells and the response of macrophages (cells that remove dying or dead cells) during inflammation.
In the new study, [researchers] demonstrated that mice lacking Rev-erbα had decreased skeletal muscle metabolic activity and running capacity. [They] showed that activation of Rev-erbα with SR9009 led to increased metabolic activity in skeletal muscle in both culture and in mice. The treated mice had a 50 percent increase in running capacity, measured by both time and distance. "The animals actually get muscles like an athlete who has been training. The pattern of gene expression after treatment with SR9009 is that of an oxidative-type muscle - again, just like an athlete."
The authors of the new study suggest that Rev-erbα affects muscle cells by promoting both the creation of new mitochondria (often referred to as the "power plants" of the cell) and the clearance of those mitochondria that are defective.