Hi Leo, Thanks for posting in HCM. I understand your concern. Leg cramps can occur due to the following reasons: 1. Magnesium deficiency. 2. Electrolyte imbalance. 3. Calcium deficiency. 4. Lactic acid accumulation. 5. Deep vein thrombosis. In your case it appears to de due to magnesium and associated deficiencies. Kindly continue with magnesium intake. Along with it you can take calcium supplementation and electrolyte or oral rehydration salts dissolved in water. Drink excess fluids and citrus fruit juice so that it can flush out accumulated lactic acid. In case the symptoms continue to persist, you need to undergo Doppler studies of the blood vessels in the legs and consult Vascular Surgeon with report for appropriate evaluation and management. Hope the information provided would be helpful. All the best.