the closing and relaxing of a muscle is dependent on the four mineral horseman of function, calcium (Ca), sodium (Na), magnesium (Mg),
and potassium (K). Sodium constricts
and potassium relaxes, with Ca
and Mg initiating each phase of the action. If an individual is low in potassium, it appears that that singular event of low potassium can be sufficient to permit a cramp to occur.