Fat and carbohydrate metabolism during exercise in phosphoglucomutase type 1 deficiency

Area of Science:

• Biochemistry
• Exercise Physiology
• Metabolic Myopathies

Background:

• Phosphoglucomutase type 1 (PGM1) deficiency is a rare metabolic myopathy.
• Symptoms of PGM1 deficiency are exercise-induced.

Purpose of the Study:

• To investigate the hypothesis that intravenous (IV) glucose could improve exercise intolerance in a patient with PGM1 deficiency.
• To explore the metabolic effects of glucose infusion during exercise in PGM1 deficiency.

Main Methods:

• Experimental intervention study conducted in an exercise laboratory.
• Involved a patient with PGM1 deficiency and healthy controls.
• Utilized cycle ergometer for peak and submaximal exercise tests with and without IV glucose infusion.

Main Results:

• The patient with PGM1 deficiency showed a 12.5% increase in peak work rate and reported easier exercise with IV glucose.
• Patient's heart rate decreased by 11 beats/min during exercise with glucose infusion.
• Control subjects did not experience improvements; the patient tended towards hypoglycemia during submaximal exercise.

Conclusions:

• PGM1 deficiency presents as a mild metabolic myopathy with exercise-related symptoms, similar to McArdle disease but without a "second wind" phenomenon.
• IV glucose infusion demonstrated potential to alleviate exercise intolerance in PGM1 deficiency.
• The findings suggest PGM1 deficiency clinically resembles other partial defects in glycolysis.