Why can acylcarnitine transferase deficiency cause muscle damage during severe exertion?

Acylcarnitine transferase deficiency causes muscle damage during severe exertion because it disrupts the essential shuttle system required to transport free fatty acids into the mitochondria for oxidation.1

Under normal conditions, this enzyme facilitates the attachment of fatty acids to carnitine, forming acylcarnitine, which can then cross the mitochondrial membranes to be oxidized for energy. When this enzyme is deficient, the muscle fibers are unable to effectively utilize fatty acids as a fuel source. During periods of severe exertion, when the demand for energy is high, the inability to process these fats leads to metabolic stress and subsequent muscle damage. Early recognition of this condition is important, as it is considered potentially treatable.1