Using two complementary mouse models-the "marathon mouse
" and the "couch potato mouse"-to make, researchers discovered that microRNAs link the two defining characteristics of fit muscles: the ability to burn sugar and fat and the ability to switch between slow- and fast-twitch muscle fibers.
Building on research that produced a genetically altered "marathon mouse
" in 2004, scientists have shown that a drug called AICAR can boost the running endurance of mice by about 45 percent--exercise not required.
"You're taking a couch potato mouse, treating them with a drug and converting them into a marathon mouse
, if you will," My Fox Houston.com quoted Narkar as saying.
"This change produced the 'marathon mouse
,' able to run twice the distance of its normal littermate" Evans says.