Hyponatremia Study

A free-access, online study published by The Proceedings of the National Academy of Sciences of the United States of America (PNAS) is available at:

http://www.pnas.org/cgi/content/full/102/51/18550

and is entitled, ""Three Independent Biological Mechanisms Cause Exercise-Associated Hyponatremia: Evidence from 2,135 Weighed Competitive Athletic Performances," T.D., Noakes, K. Sharwood, D. Speedy, T. Hew, S. Reid, J. Dugas, C. Almond, P. Wharam, and L. Weschler, PNAS, December 20, 2005, vol. 102, no. 51, 18550-18555.

Exercise-associated hyponatremia, which results when the serum concentration of sodium (Na+) is abnormally low, has been the topic of heated discussions in recent years, since prior to the early 1980s, the phenomenon was virtually non-existent.

What accounts for this? The study states, "There are no reports of EAH before 1981 when athletes were advised to avoid drinking during exercise." Incidentally, I remember being told by Marine Corps drill instructors in the late 80s to drink to the point of nausea to prevent dehydration. My platoon still suffered casualties during extremely long forced marches, even in mild temperatures. Dehydration? Or hyponatremia? We'll probably never know.

Not only has the U.S. Military repositioned its stance on the efficacy of drinking while exercising, this PNAS study makes the same recommendation.

What do you think? Do you agree or disagree with this study? Let us know at World Ultra News. We'd love to hear your comments.

(The World Ultra News Team takes no position with respect to this study's results and posts study links for the sole purpose of informing the public and hearing your opinions).

--Constance Karras