What diet/strenghtening is best with metabolic myopathy?

L carnitine: It is not clear what you mean concerning metabolic myopathy. Many conditions affect muscle metabolism. Most common is the use of steroids, then the diabetic state, and then congenital disorders of metabolism. One common condition is carnitine deficiency. Supplemental carnitine may be of value with little side effect. Basic good nutrition and appropriate exercise is also important.