Inflammation and weakening of voluntary muscle is know as?

Myositis. Myositis refers to any condition causing inflammation in muscles. Weakness, swelling, and pain are the most common myositis symptoms. Myositis causes include infection, injury, autoimmune conditions, and drug side effects. Treatment of myositis varies according to the cause.

Myomalacia- for severe damage. Myopathy for degerative disease