Veronique Hauschild, MPH
Injury Prevention Division
Directorate of Clinical Public Health and Epidemiology
U.S. Army Public Health Center
Aberdeen Proving Ground, Maryland

When a Soldier collapsed and later died following training at Fort Benning, Georgia, in July 2016, it demonstrated a rare, but real, health threat: drinking too much water. Physical exertion in high heat conditions and overhydrating can kill you.

The Army reports an annual average of two to three heat-related fatalities and more than 1,000 non-fatal heat-related conditions out of about 2,000 overall armed forces hospitalizations. This sobering fact underscores the need for Army training to ensure awareness of risk factors, prevention tactics, signs and symptoms, and treatment protocols. But the dangers go beyond the most common scenarios and on-duty activities.  
 
The combination of hot weather and strenuous activity in many military tactical and training environments can result in substantial body water and electrolyte losses.  

“There are approximately 6,000 cases of fluid and electrolyte disturbances treated annually in the Army training environment,” said Samuel N. Cheuvront, Ph.D., research physiologist,
U.S. Army Research Institute of Environmental Medicine. “Adherence to water intake doctrine and the proper consumption of rations (garrison dining or MREs) will provide adequate water and electrolyte replacement. Though not common, an imbalance of electrolytes (known as hyponatremia) caused by overhydrating and/or insufficient rations has resulted in military fatalities.”

To minimize the risks of hyponatremia and dehydration, water doctrine recommendations are to not exceed intakes of 1.5 quarts per hour or 12 quarts per 24 hours. However, even these guidelines cannot fully protect against hyponatremia. High-risk situations for hyponatremia include over-drinking (beyond water intake doctrine), hot weather combined with prolonged exertion, early heat season (non-acclimatized) and inadequate food and electrolyte consumption.  

According to Cheuvront, possible means to prevent this severe condition during high-risk situations include:

•    Monitor hydration – use beads, knots or other markings to track amount of bottles/canteens of water consumed to ensure amount does not exceed 1.5 quarts per hour or 12 quarts per 24 hours.
•    Monitor urine – Frequent urination, especially at night, may be a sign of overdrinking during the day.
•    Ensure proper nutrition and rations for the conditions and activities are consumed.
•    Consider substituting 2 quarts of an electrolyte-rich beverage in place of 2 quarts of the daily water. Various commercial products exist, but the product market and formulas change regularly. Most suitable commercial electrolyte products are those with an electrolyte composition closer to sweat (690-1380 mg sodium and 195-390 mg potassium per quart) but which are still palatable.    

Off duty, heat illness can still be a serious life-threatening condition to Soldiers, but there may be an even greater threat to other family members. In the U.S. civilian population, heat illness and related fatalities are highest among infants and young children, athletes (especially in school sports programs), outdoor laborers, the elderly (over 65 years) and those who are obese or with certain health conditions and medications.  

Unlike in a military environment, there is no "buddy system," and others may not be aware of signs and symptoms. Soldiers and family members should be alerted by general heat illness red flags, including high temperatures, direct sun, lack of air conditioning and activities leading to dehydration. Under these conditions, be on the lookout for those at greater risks. The following includes those who are at increased risk for heat illness and activities that can contribute to the problem.

•    Infants and young children and the elderly, whose body systems are not as able to regulate heat as healthy adults, are at risk. Minimize their exposure to high temperatures (such as in parked closed cars, even for a few minutes) and direct sun.
•    Middle school, high school and college athletes or those participating in outdoor activities in hot weather, especially while wearing uniforms. For example, marching band or football training season are high-risk school activities for heat illness.
•    Distance running or racing, especially between April and October.
•    Drinking alcohol while playing sports or other outdoor recreational activity can increase dehydration and lower awareness.
•    Dogs die each year from heat stroke — and not just those left in hot cars. Our furry friends can’t sweat. They can only pant to cool themselves, so they’re are less able to accommodate heat stress from the hot sun or running in even moderate weather than their human.  

Outdoor warm-weather activities can be fun and healthy or dangerous and deadly. Remember, the heat can kill.

For more information and training tools (videos, slides, factsheets), see the U.S. Army Public Health Center Army Injury Prevention webpage at http://phc.amedd.army.mil/topics/discond/hipss/Pages/HeatInjuryPrevention.aspx.