I am negative for any muscle involvement as far as autoimmune disorders go. I have the OJ subtype of Antisynthetase and it generally presents without muscle problems.
However, I have experienced a great deal of muscle weakness from lack of oxygen, not being to be as active and also the prednisone causes great muscle weakness in the major muscles of the hips, thighs, and shoulders. I did improve when on lower doses of prednisone but I was weak and shaky and had tremors on doses of 15 mg and above.