Animals dubbed the “mighty mice” at the University of Pennsylvania Medical School have shown that their muscles heal quickly after an injury; and don’t show the normal signs of aging.

Their muscle mass can be 15 percent to 45 percent greater than that of normal mice.

And it’s because of a gene manipulation that, if it translates to humans, could keep muscles toned and strong well into old age, and slow the progression of diseases such as muscular dystrophy.

More about this reseach here