magnesium malate first as its bound to malic acid which helps ATP.

or magnesium citrate.

I never had much success with any of them until I tried the magnesium oil. I spray it onto my skin and it absorbs better. I had red cell magnesium tests which were very very low and never improved until I tried the oil. You can buy it from http://www.betteryou.uk.com/

or I think you can get it on Amazon. Its definately worth a try.