A recently published study in the New England Journal of Medicine, confirmed that the message about the dangers of drinking too much water during athletic competitions, has not been heard.  Researchers looking at the 1100 triathletes competing in the Ironman European Championships between 2005-2013 found that more than 10% drank so much water they diluted the amount of sodium in their bodies to dangerously low levels, which in medical terms is hyponatremia. At its worse, hyponatremia can be life-threatening. 

Part of the problem is that sponsors provide fluid stops all along the event course which sends the message that athletes should drink at every stop. Doing so would surely result in hyponatremia by the end of the event, offers Dr.  Lewis Maharam, chairman of the board of governors for the International Marathon Medical Directors Association.

Source:  HealthDay [Internet]. Health Day; ©2016. For 'Ironman' Athletes, Study Shows Danger of Too Much Water; 2016 Mar 09 [cited 2016 Mar 13]. Available from: https://www.nlm.nih.gov/medlineplus/news/fullstory_157682.html

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Hard as it is for us to believe, drinking large quantities of water is not healthy, and in fact, can be down right hazardous to our health.  Although this is not new information, it is still not registering with some athletes. Excessive water intake dilutes sodium levels in the fluids surrounding the cells causing water to move into the cells, swelling them. The cells in our brains are very sensitive to this and as a result, many of the symptoms of hyponatremia occur because of swollen brain cells.

The symptoms include:

With the weather warming up, if you are a runner, triathlete or biker you are also warming up for another season of your favorite events. But, taking the lead from the information in this week’s article, be careful with how much water you drink during the event. As the International Marathon Medical Director’s Association (2006) recommends below, let thirst be your guide.

Try to drink to thirst. This advice seems way too simple to be true; however, physiologically the new scientific evidence says that thirst will actually protect athletes from the hazards of both over and underdrinking by providing real time feedback on internal fluid balance. If you are not thirsty, try to refrain from drinking. Do not feel compelled to drink at every fluid station nor follow the cues of other runners: their fluid needs are probably very different from your own. If you are “over-thinking” and feel you cannot rely on this new way of thinking, experiment in your training with one of these other ways realizing each has its own cautions as well.”


For more information:

Mayo Clinic - Hyponatremia

American College of Sports Medicine – Exercise and Fluid Replacement


A.D.A.M. Medical Encyclopedia [Internet]. Atlanta (GA): A.D.A.M., Inc.; ©2005. Low sodium level.; [updated 2016 Mar 02; cited 2016 Mar 13]; [about 4 p.]. Available from: https://www.nlm.nih.gov/medlineplus/ency/article/000394.htm


Association of International Marathons and Distance Races, (2006). International Marathon Medical Director’s Association( IMMDA) Revised fluid recommendations for runners and walkers. Available from: http://www.aims-association.org/guidelines_fluid_replacement.htm

Joanna Hayden, PhD, CHES is the principal health education specialist at Associates for Health Education and Behavior in Sparta, a practice focused on improving health through education. For more information please see www.associatesforhealth.com  To contact Dr. Hayden, email her at joanna@associatesforhealth.com