American Medical Society for Sports Medicine
For Immediate Release Apr 27, 2005

OVERLAND PARK, KANSAS:  An increasing number of marathon runners are at risk for developing dangerously low sodium levels. In an article this month in the New England Journal of Medicine, Dr. Christopher Almond et al. reported on the number of runners who were studied in the 2002 Boston Marathon. Of 488 runners who had their blood analyzed at the end of the race, 13% had hyponatremia, reflecting low sodium blood levels.

Various characteristics of the runners were studied, including age, race, gender, body-mass index, marathon experience, weight, use of anti-inflammatory pain medications, and intake of fluids during the endurance event. Analysis revealed that those individuals who did develop hyponatremia were the ones that tended to gain weight during the race, take longer to finish (4 hrs or more), and be at either extreme of body-mass index. On the basis of this and previously reported data, the authors concluded that excessive consumption of fluids is the single most important factor associated with hyponatremia. During training and endurance events, athletes should be careful not to ingest more fluids than necessary.

AMSSM Member Balu Natarajan, M.D., Associate Medical Director of the Lasalle Bank Chicago Marathon, dispels the myth of having clear urine before endurance events. Having seen a rise in the number of cases of hyponatremia during the last several Chicago Marathons, he recommends moderation in fluid intake prior to and during the race. In an accompanying editorial in the same issue of the Journal, Dr. Benjamin Levine and Dr. Paul Thompson note that the international sports medicine community is developing updated guidelines for fluid intake during exercise. 

The American Medical Society for Sports Medicine (AMSSM) was organized in 1991 by physicians who recognized the need for an organization within the field of sports medicine that approached athletes, exercising individuals, and teams comprehensively with consultative and continuous care of their orthopedic, medical, nutritional, and psychosocial issues. Although sports medicine concepts are often thought of in conjunction with professional and elite athletes, these concepts apply to athletes of all levels including grade school, high school, college and recreational athletes. AMSSM is comprised of over 900 Sports Medicine Physicians whose goal is to provide a link between the rapidly expanding core of knowledge related to sports medicine and its application to patients in a clinical setting.