Bad beef will have a sheen to it, like slime coating that is iridescent in the light. And a very pungent odor! If you had to get yoru nose very close it it to smell anything, it's just fine. Go ahead and use it. BTW: aged beef is refrigerated for 30 days at least after slaughter.
High CPK levels are an indicator of a variety of muscle diseases and problems, not just Rhabdo. The 'normal' CPK levels are between 25 and 170. Over this number, and you have muscle cell damage happening. You can have high(er) CPK levels and not have Rhabdomyolysis. You can have muscle cell death happening, and never get to Rhabdomyolosis. You have to have -enough- cell death and -enough- myoglobin and other toxic dead cell byproducts to overwheml the system.
Muscle atrophy is the loss or wasting of muscle tissue throughout the body. There are two basic ways in which this disease can form. The most severe form of this disease is neurogenic atrophy, a disease caused when an injury or disease harms the nerve which attaches to the muscle. This damage can occur quite suddenly.