i've been getting horrible calf and foot cramps too, usually ones that wake me up in the night. i figured it was because i don't always stretch after my workouts, but now i wonder if i should be taking a magnesium supplement. i've heard that also helps for, ahem, constipation too, so that would also be helpful. i do take a multivitamin that contains magnesium (50g?) and calcium (?) but the doses are probably too low. should i be taking both magnesium and calcium for the cramps/constipation? or will just magnesium do the trick?