Professor Hanson noted that PEPCK-Cmusmice, dubbed "the mighty mice", "are metabolically similar toLance Armstrongbiking up thePyrenees. They utilize mainlyfatty acidsfor energy and produce very littlelactic acid. Without eating or drinking, they can run for four or five hours. They are 10 times more active than ordinary mice in their home cage. They also live longer – up to three years of age – and are reproductively active for almost three years. In short, they are remarkable animals." However, "they eat twice as much ascontrolmice, but they are half the weight, and are very aggressive. Why this is the case, we are not really sure."