Jamie
I don't know if you are doing IHC, but if you are, try using any one of the polyclonal Myosin antibodies. ( I have one polyclonal from one company that does't work).  These usually work well for fibre typing of muscle for most routine pathology applications.  The best results are obtained on frozen sections of muscle, by simply cutting the sections, air dry them for a few minutes, ( do not fix them ) then proceed with your usual HIC procedure.  The chromogen should be DAB however for the best differentiation of type IIa and b fibres. We also counter stain these sections in our H&E eosin solution befor coversliping to demonstrate the type 1 fibers which are not stained by the Myosin antibody.  Parafin sections work well, but show more artifact due to the processing of the tissues, and while satifactory are not as nice.
Kerry Beebe
Kelowna General Hospital
B.C. Canada