The Myths of Dehydration and Heat Illnesses
- The primary cause of hyponatremia in athletes is drinking too much water.
- The incidence of hyponatremia appears to be between 13% and 15% among endurance athletes.
- Gender and the duration of athletic activity appear to be predictors of the incidence of hyponatremia.
- Sodium supplementation has no effect on the occurrence of hyponatremia.
- There seems to not be a single case of death resulting from sports-related dehydration in the medical literature.
Following is a brief review of the literature on exercise-associated hyponatremia. Please see the article based on these studies here.
Hyponatremia among Triathletes in the Ironman European Championship. N Engl J Med. 2016; 374:997-998.
Exercise-associated hyponatremic encephalopathy and exertional heatstroke in a soldier: High rates of fluid intake during exercise caused rather than prevented a fatal outcome. Nolte HW, Hew-Butler T, Noakes TD, Duvenage CS. Phys Sportsmed. 2015 Feb;43(1):93-8.
- Efficacy of oral versus intravenous hypertonic saline in runners with hyponatremia. Owen BE, Rogers IR, Hoffman MD, Stuempfle KJ, Lewis D, Fogard K, Verbalis JG, Hew-Butler T. J Sci Med Sport. 2014 Sep;17(5):457-62.
- Medical complications and deaths in 21 and 56 km road race runners: a 4-year prospective study in 65 865 runners--SAFER study I. Schwabe K, Schwellnus M, Derman W, Swanevelder S, Jordaan E. Br J Sports Med. 2014 Jun;48(11):912-8.
- Sodium Supplementation and Exercise-Associated Hyponatremia during Prolonged Exercise. Hoffman MD, Stuempfle KJ. Med Sci Sports Exerc. 2014 Dec 29.
- Water and sodium intake habits and status of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment: an observational field based study. Costa RJ, Teixeira A, Rama L, Swancott AJ, Hardy LD, Lee B, Camões-Costa V, Gill S, Waterman JP, Freeth EC, Barrett E, Hankey J, Marczak S, Valero-Burgos E, Scheer V, Murray A, Thake CD. Nutr J. 2013 Jan 15;12:13.
- Avoid adding insult to injury - correct management of sick female endurance athletes. Hew-Butler TD, Boulter J, Bhorat R, Noakes TD. S Afr Med J. 2012 Oct 22;102(12):927-30.
- The incidence of exercise-associated hyponatraemia in the London marathon. Kipps C, Sharma S, Pedoe DT. Br J Sports Med. 2011 Jan;45(1):14-9.
- Prevalence of hyponatremia, renal dysfunction, and other electrolyte abnormalities among runners before and after completing a marathon or half marathon. Mohseni M, Silvers S, McNeil R, Diehl N, Vadeboncoeur T, Taylor W, Shapiro S, Roth J, Mahoney S. Sports Health. 2011 Mar;3(2):145-51.
- Acute water intoxication during military urine drug screening. Tilley MA, Cotant CL. Mil Med. 2011 Apr;176(4):451-3.
- An intervention study of oral versus intravenous hypertonic saline administration in ultramarathon runners with exercise-associated hyponatremia: a preliminary randomized trial. Rogers IR, Hook G, Stuempfle KJ, Hoffman MD, Hew-Butler T. Clin J Sport Med. 2011 May;21(3):200-3.
- Do male 100-km ultra-marathoners overdrink? Knechtle B, Knechtle P, Rosemann T. Int J Sports Physiol Perform. 2011 Jun;6(2):195-207.
- Beliefs about hydration and physiology drive drinking behaviours in runners. Winger JM, Dugas JP, Dugas LR. Br J Sports Med. 2011 Jun;45(8):646-9.
- Lack of awareness of fluid needs among participants at a Midwest marathon. Brown S, Chiampas G, Jaworski C, Passe D. Sports Health. 2011 Sep;3(5):451-4.
- Can changes in body mass and total body water accurately predict hyponatremia after a 161-km running race? Lebus DK, Casazza GA, Hoffman MD, Van Loan MD. Clin J Sport Med. 2010 May;20(3):193-9.
- Exercise-associated hyponatremia. Rosner MH. Semin Nephrol. 2009 May;29(3):271-81. doi: 10.1016/j.semnephrol.2009.03.001.
- Exertional dysnatremia in collapsed marathon runners: a critical role for point-of-care testing to guide appropriate therapy. Siegel AJ, d'Hemecourt P, Adner MM, Shirey T, Brown JL, Lewandrowski KB. Am J Clin Pathol. 2009 Sep;132(3):336-40. doi: 10.1309/AJCP30OGLSLWLEIY.
- Risk factors for exercise-associated hyponatremia in non-elite marathon runners. Chorley J, Cianca J, Divine J. Clin J Sport Med. 2007 Nov;17(6):471-7.
- Marathon related death due to brainstem herniation in rehydration-related hyponatraemia: a case report. Petzold A, Keir G, Appleby I. J Med Case Rep. 2007 Dec 28;1:186. doi: 10.1186/1752-1947-1-186. (See Figure.)
- Hyponatremia among runners in the Boston Marathon. Almond CS, Shin AY, Fortescue EB, Mannix RC, Wypij D, Binstadt BA, Duncan CN, Olson DP, Salerno AE, Newburger JW, Greenes DS. N Engl J Med. 2005 Apr 14;352(15):1550-6.
- Death from hyponatremia as a result of acute water intoxication in an Army basic trainee. Garigan TP, Ristedt DE. Mil Med. 1999 Mar;164(3):234-8.