Thirteen studies representing 41 cases of symptomatic EAH that provided comment on drinking plan or motivation for chosen drinking behaviours
| Study (year) | Subjects, age (years old) sex (♂♀) activity | Serum [Na+] mmol/L (initial or range) | Symptomatic EAH with drinking above thirst (comments from report) |
|---|---|---|---|
| Frizzell et al (1986)122 | 24♂/45♂ Ultrarunners | 123/118 | Runners as a group, are taught to “push fluids” Athletes are instructed to drink more than their thirst dictates, since thirst may be an unreliable index of fluid needs during exercise |
| Armstrong et al (1993)84 | 21♂ Lab subject | 122 | Voluntarily consumed this large volume of fluid because he believed that drinking water copiously would decrease his risk of heat illness |
| Herfel et al (1998)41 | 22♂ Football player | 121 | He was diagnosed with muscle cramps secondary to dehydration. Therefore, five liters (L) of 0.45% normal saline in 5% dextrose was administered intravenously along with 3 L of liquids by mouth over a five hour period |
| Reynolds et al (1998)189 | 6* (4♀/2♂) Soldiers | 118–134 | Consuming large volumes of water as “protection against becoming a heat casualty” predisposed these troops to the physical impairment that they intended to avoid |
| Backer et al (1999)73 | 7* (6♀/1♂) Hikers | 109–127 | Most patients diagnosed as having hyponatremia have a distinct history of high fluid intake… Unlike heat exhaustion patients, few of our hyponatremic patients were thirsty when evaluated, perhaps because they drank more fluids and were hyperhydrated |
| Garigan et al (1999)45 | 18♂ Soldier | 121 | Complained of thirst, drank 3 quarts, then vomited…told to drink 1 quart every 30 minutes With encouragement by unit members, he consumed 10 quarts of water during the next 90 minutes |
| Hew et al (2003)61 | 21* (9♀/8♂) Marathon runners | 117–134 | Advice given to runners was “drink until your urine is clear” and “do not wait until you are thirsty to drink” |
| Dimeff (2006)40 | 27♂ Football player | 116 | Complained of feeling ill… encouraged to consume sports drinks Admits to drinking 2–3 gallons water every day because he had been taught that “water is the best replacement fluid” and because that is what he was advised to do growing up in Texas |
| Hew-Butler (2007)8 | 41♂ Ironman triathlete | 132 (nadir) | Subject reports he was never thirsty, but drank to “stay ahead of thirst” |
| Draper (2009)49 | 37♀ Marathon runner | 117 | She followed a strategy (as advised by fellow experienced marathon runners) to begin the race “well-hydrated” (drinking greater volumes than her thirst dictated) Warnings were issued over the public address system at the race start relating to ensuring a high intake of fluids was maintained |
| Rothwell and Rosengren (2008)118 | 43♂ Hiker | 107 | Complained of abdominal pains and leg cramps for 24 hours leading up to collapse On the evening before and day of collapse, fellow trekkers and guides encouraged him to drink large amounts of water |
| Coler et al (2012)151 | 85♂ Hiker | 120 | Subject was encouraged to…“Push fluids” above thirst |
| Rogers (2015)51 | 46♀ Swimmer | 118 | Her intended fluid regimen…was 200 mL of fluid every 20 minutes She reported no sensation of thirst throughout the race Although she did not feel thirsty, she was encouraged to drink by the support staff |
*Case reports involving multiple subjects: total number of subjects (number of female/male subjects).
EAH, exercise-associated hyponatraemia.