Army Physical Fitness Test (APFT) FM 21-20 / TC 3-22.20 Training Info

TC 3-22.20 Appendix D – Environmental Considerations

Appendix D

Environmental Considerations

Soldiers must be ready to perform physically demanding tasks in hot, cold, and high altitude environments. Acclimatization to these environments during the conduct of PRT and other daily training activities is essential to safely preparing Soldiers for physical success. When gradually exposed to these environments and the intensity and duration of activities are adjusted, Soldiers can safely acclimatize over time.


D-1. Soldiers need to acclimatize properly prior to conducting PRT in extremely hot environments. Heat acclimatization allows for those specific adaptations that aid in the reduction of physiological stress (heart rate, core temperature, and sweat adaptation). It also improves physical work capability in the heat and builds Soldier confidence. In hot environments Soldiers will safely acclimatize to the heat by conducting PRT sessions during the heat of the day at a lower intensity and volume. For example, PRT can be moved from early morning to late morning or from late morning to mid-afternoon. This allows for acclimatization by gradually progressing to a warmer/hotter environment. Consideration must also be given to wear of the IPFU ensemble (Figure D-2).

D-2. Heat acclimatization works on a principle of repeated bouts of heat exposure that are stressful enough to safely elevate core temperature and provoke the sweating mechanism. Limited physical activity accompanied by rest in hot environments will result in only partial acclimatization. Acclimatization requires a minimum daily heat exposure of two hours when combined with endurance and mobility, and strength and mobility training. Research has shown that repeated bouts of shorter duration exercise, like those found in speed running, allow for acclimatization more safely than sustained activity in the heat. Initially, Soldiers will train at a lower intensity and shorter duration, then safely progress, increasing physical exercise intensity, duration, and volume to achieve optimal acclimatization in warm/hot environments. In most cases Soldiers can acclimatize in approximately three weeks. Soldiers will maintain acclimatization for approximately one week with about 75 percent of acclimatization lost within three weeks once the Soldier no longer remains in that environment. Soldiers of low fitness levels or those susceptible to heat injuries may require additional days/weeks to fully acclimatize.

D-3. Soldiers must consume sufficient amounts of water to replace water lost due to sweat. Sweating rates greater than one quart per hour are not uncommon. Acclimatization increases sweating rates, which in turn increase water requirements. A risk to acclimatized Soldiers is dehydrating faster than their water intake. Dehydration reduces thermal regulatory advantages achieved through acclimatization and high levels of physical readiness.


D-4. Soldiers and PRT leaders must be aware of the signs and symptoms of heat injuries and their severities. They must know how to assess Soldiers who may be at risk and be ready to provide appropriate treatment immediately. If any of the below symptoms of heat cramps, heat exhaustion, or heatstroke are experienced, immediately stop physical activity and seek treatment and/or medical attention.


Symptoms: Muscular twitching, cramping, muscular spasms in arms, legs, or abdomen.
Treatment: Monitor Soldier in a cool, shaded area, and give water and/or electrolyte sports drink. Call for
medical attention if situation worsens.


Symptoms: Excessive thirst, fatigue, lack of coordination, increased sweating, cool/wet skin, dizziness, and/or confusion.

Treatment: Monitor Soldier in a cool, shaded area, attempt to cool Soldier’s head and body with cold water and give water and/or electrolyte sports drink and await medical attention.


Symptoms: No sweating, hot/dry skin, rapid pulse, rapid breathing, seizure, dizziness and/or confusion, loss of consciousness.

Treatment: Monitor Soldier in a cool, shaded area, attempt to immediately cool Soldier’s head and body with

cold water or ice blanket and give water and/or electrolyte sports drink while awaiting medical



Symptoms: Confusion, weakness, nausea, and vomiting.

Treatment: Typically misdiagnosed and treated as dehydration. Monitor Soldier and follow treatment for heat

exhaustion. If symptoms persist or become more severe with rehydration, replace salt loss and

transport immediately to medical facility. DO NOT continue to have Soldier drink more water.


D-5. Ensuring that Soldiers are properly hydrated and receive regular, adequate nutrition is a good way to prevent the onset of heat injuries. Water is the preferred hydration fluid before, during, and after physical training activities. Drink 13 to 20 ounces of cool water at least 30 minutes before beginning exercise (approximately 2 glasses of water). After exercise, drink to satisfy thirst, then drink a little more. Also avoid alcoholic beverages and soft drinks because they are not suitable for proper hydration and recovery. Sports drinks may be consumed, but are not required and contain a considerable number of additional calories. It is also possible to drink too much water. Be sure to limit intake to NO MORE THAN 1 ½ quarts per hour (48 oz) during heavy exertion. Remember, hydration is also important in the cold environment. Many times loss of water is not as noticeable when it is cool or cold.

D-6. Good nutrition practices helps ensure Soldiers have the needed vitamins and minerals for safe performance of exercise in hot environments. Sodium, potassium, and B complex vitamins are lost through sweat and exertion in the heat. It is important to replenish calories lost during exercise with foods containing these nutrients. Try to eat within an hour after exercise. This will assist in recovery as the body is still burning calories at an elevated rate.


D-7. During exercise in the cold, the body usually produces enough heat to maintain its normal temperature. As Soldiers become fatigued, however, they slow down and their body produces less heat. Two types of cold injury conditions may occur due to prolonged exposure and/or loss of core temperature. Soldiers and PRT leaders must be aware of the signs and symptoms of cold injuries and their severities to assess Soldiers who may be at risk and to provide appropriate treatment immediately. If any of the following symptoms (frostbite or hypothermia) are experienced, immediately stop physical activity and seek treatment and/or medical attention.


D-8. Soldiers participating in military training or deployments will often encounter cold stress that can impact successful mission accomplishment. Continued exposure in a cold environment degrades physical performance capabilities, significantly impacts morale, and eventually causes cold weather injuries. Cold environments include exposure to extremely low temperatures (Arctic regions), and cold-wet exposures (rain or water immersion) in warmer ambient temperatures. Cold-weather conditions impair many aspects of normal military functioning in the field, which in turn can influence Soldier health and performance.

Frostbite. When skin is exposed to temperatures/wind chill of 20 degrees Fahrenheit or below there is potential for freezing of skin tissue or frostbite (Figure D-1).

Symptoms: A white or grayish-yellow skin area; skin that feels unusually firm or waxy; numbness in body parts exposed to the cold such as the nose, ears, feet, hands, and skin.
Treatment: Keeping susceptible areas covered is the easiest way to prevent frostbite from occurring (Figure D-2). If any of the aforementioned symptoms are experienced, immediately stop physical activity and seek treatment and/or medical attention.

Hypothermia. This condition develops when the body cannot produce heat as fast as it is losing it (Figure D-1). When Soldiers experience prolonged exposure to cold temperatures or become wet or submerged in cool-water temperatures, they are susceptible to hypothermia.

Symptoms: Shivering, loss of judgment, slurred speech, drowsiness, and muscle weakness.

Treatment: Dressing in layers and wearing breathable undergarments that wick away moisture are helpful in preventing hypothermia. If a Soldier has the symptoms listed above, attempt to make him warmer and request medical attention.


D-9. Soldiers may be deployed to theaters of operation that are at altitudes in excess of 3000 feet above sea level. Altitude acclimatization allows Soldiers to decrease their susceptibility to altitude illness and achieve optimal physical and cognitive performance for the altitude to which they are acclimatized. Altitude acclimatization has no negative side effects and will not harm health or physical performance upon return to low altitude. However, Soldiers with good aerobic endurance may acclimatize sooner and perform better than those of low fitness levels. Refer to the following website for more detailed discussion on altitude acclimatization.


D-10. Avoid exercising near heavily traveled streets and highways during peak traffic hours. If possible, avoid exposure to pollutants before and during exercise (including tobacco). In areas of high smog concentrations, train early in the day or later in the evening.


D-11. Use a waterproof or sweat proof sun block (SPF 15 or higher) when exercising in warm weather to avoid sunburn. Follow the instructions on the bottle for proper use.

D-12. For more information related to environmental considerations, see the following websites for more detailed information.

U.S. Army Public Health Command


U.S. Army Research Institute of Environmental Medicine

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