Twice the mice is twice as nice.
Case Western Reserve University researchers have bred a line of "mighty mice" (PEPCK-Cmus mice) that have the capability of running five to six kilometers at a speed of 20 meters per minute on a treadmill for up to six hours before stopping.
"They are metabolically similar to Lance Armstrong biking up the Pyrenees; they utilize mainly fatty acids for energy and produce very little lactic acid," said Richard W. Hanson, the Leonard and Jean Skeggs Professor of Biochemistry at Case Western Reserve and the senior author of the cover article that appeared in the Journal of Biological Chemistry, entitled "Over Expression of the Cytosolic Form of Phosphoenolpyruvate Carboxykinase (GTP) in Skeletal Muscle Repatterns Energy Metabolism in the Mouse."
The term you want to keep in mind is "PEPCK-C Enzyme". Remember it because you'll be (no doubt illegally) injecting the stuff same day real soon now.
If the youtube embed doesn't work for you, there's a quicktime version. God help us all.