Which disorder presents with muscle cramping, fatigue, and myoglobinuria with exercise?

The disorder characterized by muscle cramping, fatigue, and myoglobinuria during exercise is McArdle's disease, also known as glycogen storage disease type V. This condition is caused by a deficiency of the enzyme muscle phosphorylase, which is crucial for the breakdown of glycogen into glucose in skeletal muscle.

In McArdle's disease, the inability to mobilize glycogen effectively during periods of exertion leads to symptoms such as muscle cramping and fatigue due to the lack of readily available glucose for energy. Furthermore, the intense exercise can lead to muscle damage, resulting in the release of myoglobin into the bloodstream, which manifests as myoglobinuria – the presence of myoglobin in the urine, often causing it to appear dark or reddish-brown.

In contrast, the other disorders listed involve different metabolic pathways or tissues which do not primarily present with these specific symptoms during exercise. For example, Pompe's disease affects lysosomal glycogen breakdown and presents primarily with cardiomyopathy and progressive muscle weakness rather than exercise-induced muscle symptoms. Cori's disease (Glycogen storage disease type III) involves a deficiency in debranching enzyme and leads to issues with both liver and muscle; however, it does not typically present