Adequate Hydration

Hydration is essential to tactical effectiveness.

Adequate Hydration
By: Eugene Nielsen

Replacing body fluids is the single most import thing you can do to manage heat stress and maximize performance. Adequate water intake reduces strain on the cardiovascular system and reduces heat-related stresses and injuries. Dehydration is one of the most common causes of premature fatigue. By reducing the body’s capacity for heat loss, dehydration often contributes to hyperthermia. Dehydration is the primary cause of heat illness. Dehydration will also increase the chances of going into severe shock if injured.

The frequency of accidents and injuries is higher in hot environments than in moderate environmental conditions. Even low levels of dehydration can significantly impair performance. Without adequate water intake, muscle endurance is reduced in less than one hour under hot and humid weather conditions. So too, is alertness and metal capacity.

The importance of adequate hydration cannot be stressed enough. Water makes up 90 percent of the molecules in the human body. It accounts for about 60 percent of body weight in a man and 50 percent of body weight in a woman. Water is the medium in which all of the body’s metabolic reactions take place.

The body water content must be kept within a relatively narrow range for proper functioning. A loss of just 2 percent of body weight due to dehydration will significantly reduce mental acuity and physical performance. A 5 percent loss of body weight due to dehydration causes heat exhaustion. A 7 to 10 percent loss of body weight due to dehydration can result in heat stroke and death.

Even at rest in a temperate climate, the body loses a minimum of three pints of water every 24 hours through perspiration, from the lungs into the air as water vapor, and in the production of urine and feces to rid the body of waste products. The amount of water that is lost through perspiration is dependent on the level of physical activity and the external temperature. The amount of water that is lost through urine is largely dependent on the amount of water that is consumed as well as any excessive substance dissolved in the blood.

In cool climates, people tend to drink more than enough water than is required. The excess water is lost in urine. However, in hot climates or during periods of high exertion, large amounts of water are lost in sweat, requiring an increase in fluid intake to avoid dehydration. Heavy exercise-induced sweating can cause even trained individuals to lose more than three quarts of water an hour.

Just satisfying thirst requirements may not be sufficient to prevent the onset of dehydration.  While thirst generally encourages the consumption of enough water to prevent dehydration under moderate conditions, this mechanism isn’t always a reliable gauge of water needs. The thirst mechanism may fail of because of high losses of water from the body.

Water that is required to prevent heat casualties can be significant. The amount of water necessary will vary based on metabolism, age, weight and physical condition, activity, weather conditions and altitude. Even in temperate conditions, the body may need one pint of water per hour or more during physical activity. Winter operations can also require an increase in water intake because of sweat and water loss from breathing cold, dry air.

The U.S. Army Research Institute of Environmental Medicine conducted research into fluid replacement during hot weather training. Proper fluid replacement guidelines were developed utilizing computer simulations and physiological studies. The Fluid Replacement Guidelines for Hot Weather Training provides the appropriate hourly work time and fluid intake for hot weather training average acclimated soldiers in hot weather.  

Tactical operators cannot control the climatic conditions under which they have to operate. They also cannot always control the amount of physical exertion that is required to accomplish the mission. However, operators can control the replenishment of body water. Tactical armor, while necessary, increases the body’s heat stress. This will increase water requirements. Operators may also be increased risk of heat injuries while in armored vehicles.

Although the nature and duration of the typical SWAT operation makes the supply of water less of a logistical problem than is the case with military operations, adequate water remains essential to mission effectiveness. Consider a SWAT sniper who is in position all day. While the amount of water they will lose during that amount of time probably won’t result in serious dehydration, sufficient dehydration to degrade fine motor skills and mental alertness may occur if the body’s water is not adequately replenished.

The advent of hands-free hydration systems has made getting adequate water while on operations and while training a whole lot easier. The concept of the hands-free hydration system was originated by Michael Edison, a former paramedic. Edison attached medical tubing to an I.V. bag, stuffed the bag into a sock, and sewed the sock onto the back of a T-shirt. Edison subsequently founded CamelBak.

Hands-free hydration systems have evolved considerably since Edison’s expedient contraption.   Today, there are a variety of products from which to choose. BLACKHAWK! HydraStorm and CamelBak Maximum Gear hydration systems are among the best known. There are some significant differences in the construction and design features of the competing product lines.  Compare before buying. Obviously, there is a significant difference between the needs of recreational users and the needs of the tactical operator.

All of the hydration systems utilize FDA-approved polyurethane water reservoirs (bladders).  The reservoirs slip into a variety of backpacks and load-bearing vests. The reservoirs are available in different sizes, the largest reservoirs being capable of holding up to 100 ounces of water. Water is supplied to the operator via a drinking tube that’s equipped with a hands-free bite valve.

Although prolonged sweating can result in a sufficient loss of electrolytes (salts) to cause medical problems, salt tablets are no longer recommended on a routine basis. A single salt tablet increases the body’s water requirements by one pint. Normal salt loss is easily replaced by eating a balanced diet. However, additional salt should be added to the diet when engaging in prolonged exertion. Many experts recommend the eating of salty snack foods to replace salt loss from heavy sweating and prevent hyponatremia,

Hyponatremia is an electrolyte disturbance in which the serum sodium level is lower than normal. A single-serving size bag of salted potato chips contains more than enough salt to

prevent hyponatremia. Hyponatremia has been found to be common in many marathon runners during races. Early stages of hyponatremia may mimic dehydration.  

Dehydration is a silent killer. Even moderate dehydration is a serious threat. Lack of adequate water can greatly reduce tactical effectiveness and put the entire team at risk. Thirst cannot be counted on to ensure adequate water intake. With today’s hydration systems, there’s absolutely no excuse for the lack of adequate hydration for the individual operator. Water may mean the difference between life and death and the success or failure of a mission. 


Simple Tips to Prevent Dehydration

1. Always have adequate water available.

2. Always drink water before, during and after physical exertion to replace body fluids.

3. Anticipate conditions that will increase the need for water. These include elevated temperatures, humidity, protective clothing, and the level of exertion.

4. Recognize that you are already dehydrated by the time that you are thirsty. Drink sufficient water to keep your urine copious and pale.

5. At least five to eight ounces of water should be consumed every 15 to 20 minutes to ensure proper hydration and maintain a safe body core temperature. It’s easier for the body to handle small amounts of water spread out over the day, than larger amounts at one time.

6. Do not exceed 1 ½ quarts of water per hour. Daily fluid intake should not exceed 12 quarts.

7. Avoid diuretics, such as coffee, tea, or soda, all of which act to further deplete the body of fluid.

8. If water is in short supply, eat at a minimum to reduce water loss since water is required for digestion. Avoid fatty foods since they require more water for digestion.

9. Keep cool, clean water within easy reach at all times. Cool water is absorbed more quickly by the body than warm or very cold fluids.

Eugene Nielsen provides investigative and tactical consulting services and is a former officer. He may be reached at

Published in Tactical Response, Jul/Aug 2013

Rating : Not Yet Rated



No Comments

Close ...