"Space-based" Dynamic of Mg Loss -- William J. Rowe, MD (gifted cardiologist) has studied this special dynamic of Mg loss in space for ages and he has written extensively on this topic. Enjoy!
http://www.femsinspace.com/articles.htm

A World Record Marathon Runner with Silent Ischemia Without Coronary Atherosclerosis . Rowe, WJ. Chest 99:1306-1308, 1991.