Table 2

Summary of inherited metabolic causes of exertional rhabdomyolysis

Metabolic pathway	Trigger	Baseline CK	Baseline weakness	Examples
Glycogen metabolism	Early onset after intense exercise	Often high	May develop in later life	McArdle’s disease (second wind phenomenon) Tarui’s syndrome (↑exercise tolerance when fasting, compensated haemolysis) Lactate dehydrogenase-A deficiency (photosensitive rash)
Fatty acid metabolism	Later onset after prolonged exercise or illness/fasting	Normal	Unusual	Carnitine palmitoyltransferase (diffuse exertional weakness, respiratory failure)
Mitochondrial metabolism	Early or late onset, prominent fatigue	Normal or high	Possible	Coenzyme Q10 (encephalopathy, ataxia, convulsions) Cytochrome B/C (onset after mild exercise)