The project will use carbon-13 magnetic resonance spectroscopy to assess whether high glycogen levels in skeletal muscle of patients with Glycogen Storage Diseases is a prelude for muscle damage.

Patients with Glycogen Storage Diseases will be examined using carbon-13 MR-spectroscopy to quantify the glycogen levels in lumbar, thigh and calf-muscles. The pattern of glycogen concentration will be compared to the pattern of muscle atrophy found in the literature.

Inclusion Criteria:

• Subjects with genetically verified neuromuscular disease or healthy control
• Healthy controls needs to be healthy to be included, evaluated by the investigator

Exclusion Criteria:

• Ferrous objects in or around the body
• Pacemaker or other implanted electronic devices
• Claustrophobia
• Inability to understand the purpose of the trial or corporate for the conduction of the experiments.
• Participation in other trials that may interfere with the results.
• Competing conditions at risk of compromising the results of the study, evaluated by the investigator.
• Strenuous exercise in the preceding 2 days before examination
• Pregnancy or breastfeeding

Patients with Pompe or McArdle disease and healthy controls