Do you get enough Magnesium in diet ? Frequent muscle spasm ( at night ?) is one of the classic symptoms of Magnesium deficiency. Exercise without proper nutrition could worsen the condition since you 're excreting minerals/Magnesium through sweat.
WHFoods: magnesium
National Academy of Sciences set a tolerable upper limit (UL) on intake of magnesium at 350 milligrams per day ( for supplement ) but the expert at
Magnesium-Deficiency Catastrophe: The Magnesium Web Site recommended 6-10mg/KG if there is no significant renal impairment.