Question: How can I prevent muscle spasm or leg cramps?

Dr. Hibberd's Answer:
In younger people, muscle cramps in the legs are usually a sign of fatigue, overuse, or dehydration. Pre-hydrating before vigorous exertion often will help. Water is fine — you do not need fancy electrolyte mixtures. Sometimes underlying disorders such as diabetes and thyroid disorders produce this symptom, while other times electrolyte abnormalities (such as sodium, potassium, calcium, and magnesium) or anemia (low hemoglobin) may be responsible. Often medications, including supplements, are to blame, so examine what you have changed lately.
As we age, circulation disorders become more common, and various other causes of cramps need to be evaluated. Regard the cramps you are getting as a yellow flag suggesting your go to your doctor for a complete evaluation.
I do not advise you seek comfort by using quinine. Though still available for purchase at unregulated Internet sites, this product was removed from the over-the-counter market in all pharmacies in the United States by the FDA because its unregulated use for leg cramps was felt to be hazardous to the public.
Your doctor will check your CBC, blood glucose, electrolytes, and calcium /phosphorus balance as well as evaluate you for underlying precipitating disorders and vascular disease.