Excessive intracellular acidosis of skeletal muscle on exercise in a patient with a post-viral exhaustion/fatigue syndrome. A 31P nuclear magnetic resonance study.

A patient with prolonged post-viral exhaustion and excessive fatigue was examined by 31P nuclear magnetic resonance. During exercise, muscles of the forearm demonstrated abnormally early intracellular acidosis for the exercise performed. This was out of proportion to the associated changes in high-energy phosphates. This may represent excessive lactic acid formation resulting from a disorder of metabolic regulation. The metabolic abnormality in this patient could not have been demonstrated by traditional diagnostic techniques.