Environmental Considerations - Heat Injuries and Symptoms

The following are common types of heat injuries and their symptoms.
• Heat cramps-muscles cramps of the abdomen, legs, or arms.
• Heat exhaustion-headache, excessive sweating, dizziness, nausea, clammy skin.
• Heat stroke-hot, dry skin, cessation of sweating, rapid pulse, mental confusion, unconsciousness.
To prevent heat injuries while exercising, trainers must adjust the intensity to fit the temperature and humidity. They must ensure that soldiers drink enough water before and during the exercise session. Body weight is a good gauge of hydration. If rapid weight loss occurs, dehydration should be suspected. Plain water is the best replacement fluid to use. Highly concentrated liquids such as soft drinks and those with a high sugar content may hurt the soldier’s performance because they slow the absorption of water from the stomach.
To prevent heat injuries, the following hydration guidelines should be used:
• Type of drink: cool water (45 to 55 degrees F).
• Before the activity: drink 13 to 20 ounces at least 30 minutes before.
• During the activity: drink 3 to 6 ounces at 15 to 30 minute intervals.
• After the activity: drink to satisfy thirst, then drink a little more.

Acclimation to Hot, Humid Environments
Adapting to differing environmental conditions is called acclimatization. Soldiers who are newly introduced to a hot, humid climate and are moderately active in it can acclimatize in 8 to 14 days. Soldiers who are sedentary take much longer. Until they are acclimatized, soldiers are much more likely to develop heat injuries.
A soldier’s ability to perform effectively in hot, humid conditions depends on both his acclimatization and level of fitness. The degree of heat stress directly depends on the relative workload. When two soldiers do the same task, the heat stress is less for the soldier who is in better physical condition, and his performance is likely to be better. Therefore, it is important to maintain high levels of fitness.
Increased temperatures and humidity cause increased heart rates. Consequently, it takes much less effort to elevate the heart rate into the training zone, but the training effect is the same. These facts underscore the need to use combat-development running and to monitor heart rates when running, especially in hot, humid conditions.
Some important changes occur as a result of acclimatization to a hot climate. The following physical adaptations help the body cope with a hot environment
• Sweating occurs at a lower body temperature.
• Sweat production is increased.
• Blood volume is increased.
• Heart rate is less at any given work rate.