As someone who has had leg cramps since about 12 years old, there is no known "cure" for muscle cramping. Lots of things can help but I really think it is genetic. Just your muscles overriding your brain's instructions to keep working hard. In addition to getting the right minerals to your muscles it also has to have something to do with the blood getting enough oxygen to the muscles to keep working at a high rate.
Along with inventing a rain jacket that really does breath and allows you to stay dry when raining finding a cure for cramping issues will make you a gazillionaire.