Foot march related injury and illness awareness is essential to unit readiness and the ability to enable and sustain continuous operations. The following information focuses on injury and illnesses, including musculature and skeletal conditions that relate to injury risk, and injuries most common to foot marches under loads.
Injury Risk Factors
F-1. Leaders screen Soldiers for strength, endurance, and mobility to identify high injury risk Soldiers and provide corrective interventions to address the identified deficiencies. Post screening, leaders conduct reassessment to determine if identified Soldiers are physically prepared to conduct a foot march under load.
Hot Weather Injuries
F-2. Soldiers participating in foot marches often encounter hot weather environments impacting mission accomplishment. Continued exposure to hot environments degrades physical performance capabilities, significantly impacts morale, and eventually causes hot weather injuries. Hot weather conditions impair many aspects of normal military functioning in field environments, which in turn can influence Soldier health and performance.
Dehydration
F-3. Dehydration occurs when the body loses too much fluid. Certain amount of body fluid is lost through normal activity. Normal daily intake of liquids replaces this loss. When individuals are engaged in strenuous activities, fluid is lost through sweating, and loss creates an imbalance of fluids in the body. If this loss is not matched by rehydration, it can contribute to dehydration.
Heat Illness
F-4. While there is a range of adverse effects that can result from the body overheating, the two major kinds of heat illnesses (also called heat injuries) are-heat exhaustion (can be mild or more severe) and heatstroke (most severe form of heat illness and possibly fatal). See ATP 4-25.12 and TC 4-02.1 for additional information on heat illness and first aid. Exertional heat illness refers to a spectrum of disorders resulting from total body heat stress that includes-heat cramps, heat exhaustion, and heatstroke.
Heat Cramps
F-5. Excessive sweating caused by an imbalance of electrolytes in the body leads to cramping. This condition causes the casualty to exhibit—
- Cramping in extremities including arms and legs.
- Abdominal or stomach cramps.
- Excessive sweating.
Heat Exhaustion
F-6. Heat exhaustion is caused by loss of body fluids (dehydration) through sweating without adequate fluid replacement. It can occur in an otherwise fit Soldier who is involved in physical exertion in hot environments especially if the Soldier is not acclimatized. These signs and symptoms are—
- Excessive sweating with pale, moist, and cool skin.
- Headache.
- Weakness.
- Dizziness.
- Loss of appetite.
- Cramping.
- Nausea with or without vomiting.
- Urge to defecate.
- Chills or gooseflesh.
- Rapid breathing.
- Tingling of hands or feet.
- Confusion.
Heatstroke
F-7. Soldiers can suffer from heatstroke due to being exposed to high temperatures (such as direct sunlight), dressed in protective over garments, or perhaps has worn body armor extensively, which causes body temperature to rise. Heatstroke occurs rapidly in Soldiers who engage in work or other physical activity in high-heat environments. Heatstroke is caused by failure of the body’s cooling mechanism, which includes decrease in the body’s ability to produce sweat. The casualty’s skin is red or flushed, hot, and dry. The casualty may experience—
- Weakness.
- Dizziness.
- Confusion.
- Headaches.
- Seizures.
- Nausea.
- Stomach pains or cramps.
- Respiration and pulse may be rapid and weak.
- Unconsciousness and collapse may occur suddenly.
Note. Heatstroke is a medical emergency and can be fatal if not immediately addressed. The casualty must be evacuated to the nearest medical treatment facility as soon as possible.
First Aid
F-8. Heat casualties should be monitored continually for development of conditions that may require performance of necessary basic lifesaving measures. Table F-1 shows common heat injuries along with signs, symptoms, and first aid to apply when heat injuries occur.
Note. Do not use salt solutions in first aid for heat injuries.
Cold Weather Injuries
F-9. Soldiers participating in military training or deployments often encounter cold stress impacting mission accomplishment. Continued exposure to cold environments degrades physical performance capabilities, significantly impacts morale, and eventually causes cold weather injuries. Cold environments include exposure to extremely low temperatures in arctic regions, and cold wet exposures such as rain or water immersion in warmer ambient temperatures. Cold weather conditions impair many aspects of normal military functioning in field environments, which in turn can influence Soldier health and performance.
Signs, Symptoms, and First Aid
F-10. Cold weather injuries can occur anytime while foot marching under load. Table F-2 on page 132 shows common cold weather injuries Soldiers may encounter and the signs, symptoms, and first aid remedies for these types of injuries.
Note. Rewarming a severely hypothermic casualty is extremely dangerous in field environments due to the possibilities of such complications as rewarming, shock, and disturbances in the rhythm of the heartbeat. These conditions require treatment by medical personnel.
Dehydration
F-11. Dehydration is as prevalent in cold regions as it is in hot regions. In hot weather, Soldiers are aware of their bodies losing fluids through sweat. In cold weather, however, it is extremely difficult to realize this condition exists since sweating is not as apparent as in hot environments. In cold climates, sweat evaporates so rapidly or is absorbed so thoroughly by layers of heavy clothing it is rarely visible on the skin. Dehydration occurs during cold weather operations because drinking is inconvenient. Dehydration weakens or incapacitates for several hours, or sometimes several days. Rest is an important part of recovery, and casualties must limit movement during their recuperative period to decrease risks of becoming a cold injury casualty.
Windchill
F-12. Table F-3 shows how wind speeds increase the sensation of cold, known as windchill. Frequent winds in mountain areas cause extremely low windchills. Command emphasis should include countermeasures based on windchill, not on thermometer reading, specifically nutrition, ample fluid intake, and multiple, loose clothing layers.
Injuries Caused by Sunlight
F-13. Solar radiation injuries caused by sunlight are likely at altitude due to increased ultraviolet radiation and reflection from snow and rock surfaces. Solar radiation injuries can be severe and occur with much shorter exposure at higher altitudes. Injuries caused by sunlight include sunburn and snow blindness.
Sunburn
F-14. Sunburn may be likely to occur on partly cloudy or overcast days when Soldiers may be unaware of the threat and do not take appropriate precautions. Use sun block with at least 30 sun protection factors to help prevent sunburns.
Snow Blindness
F-15. Snow blindness occurs when ultraviolet light is absorbed by external parts of the eyes, such as eyelids and cornea. The only warning is a bright, sunburn-like eye damage. Damage can occur in just several hours. Sunglasses or goggles with ultraviolet protection prevent snow blindness. Sunglasses with side protectors are recommended.
High Altitude Illness and Effects
F-16. Decreased availability of oxygen in atmospheric air is an environmental stress unique to high altitudes. It lowers oxygen supply to body tissues that can cause illness at high altitudes and a decline in physical and mental performance.
Note. One meter equals 3.28084 feet, so to calculate the exact altitude in feet, multiply the number of meters times 3.28084.
Hypobaric Hypoxia
F-17. Hypobaric hypoxia can interact with other factors in the environment to increase the likelihood of environment-related injuries, or it can exacerbate preexisting medical conditions. Given its widespread effects, basic understanding of hypobaric hypoxia is essential for medical personnel supporting military units operating in high mountain regions.
F-18. A curvilinear reduction occurs in ambient barometric pressure with increasing altitude. Although oxygen makes up about 21 percent of the atmosphere at all altitudes, a progressive decrease in partial pressure of oxygen means there is less actual oxygen at higher altitudes compared to sea level.
F-19. The relationship of decreased oxygen availability to altitude illness and performance decrease provides classification of altitude exposure based on arterial oxygen content and its physiologic effects. Information presented in figure F-1 is for acclimatized low altitude individuals having ascended rapidly from low altitudes.
Note. Rapid ascent to altitudes above 2,439 meters (8,002 feet) increases individual susceptibility to altitude illness. Primary altitude illnesses are acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), and high-altitude cerebral edema (HACE). Additionally, many individuals develop a sore throat and bronchitis, producing disabling and severe coughing spasms.
Acute Mountain Sickness
F-20. AMS is the most common form of altitude illness. AMS is a short-lived illness, like an alcoholic hangover, normally lasting from 2 to 7 days. AMS symptoms include headache, nausea, fatigue, and lightheadedness. AMS develops within 6 to 24 hours of altitude exposure, and its incidence and severity increase in direct proportion to ascent rate and altitude. (See table F-4 on page 136.)
F-21. Individual AMS susceptibility is currently not predictable from measurements made at low altitudes. However, prior history of AMS is the best predictor of future susceptibility to AMS under similar ascent conditions. For all individuals, sustained physical exertion early in altitude exposure greatly increases AMS incidence and severity.
F-22. Figure F-1 on page 135 shows with ascent to increasing altitudes, risk of developing altitude illness, AMS, and experiencing an aerobic work performance decrement is inversely proportional to resting arterial oxygen saturation. In relationship between arterial partial pressure of oxygen and hemoglobin, significant decreases in resting oxygen saturation do not emerge until altitude exceeds 2,400 meters (7,874 feet).
F-23. Although resting oxygen saturation is well-preserved up to 2,400 meters (7,874 feet) drop in arterial partial pressure of oxygen decreases diffusion of oxygen from the lungs to the blood and from the blood to the cells. This decrease in oxygen diffusion rate becomes apparent during physical activities as an arterial oxygen desaturation at altitudes as low as 1,000 meters (3,281 feet). Thus, physical work performance is decreased at altitudes slightly higher than 1,000 meters (3,281 feet), though resting oxygen saturation is near sea level values.
F-24. The best methods for reducing AMS susceptibility are altitude acclimatization and minimizing physical exertion at high altitudes. If altitude acclimatization is not possible, pharmacologic prophylaxis, which creates 75 percent reduction in symptom severity, is available with acetazolamide, a carbonic anhydrase inhibitor.
Note. Before taking medication consult a doctor.
F-25. Acetazolamide induces mild metabolic acidosis via bicarbonate diuresis, which stimulates breathing and increases arterial oxygen content to ameliorate hypoxemia. Additional benefits include mild diuresis reducing development of edemas, which is the likely basis for all altitude illnesses.
F-26. Adverse side effects of acetazolamide include paresthesia or tingling sensation, potential dehydration, and decreased aerobic endurance performance. Several studies have demonstrated 1,000 micrograms of acetazolamide per day produces about a 25 percent decrease in endurance performance at low and high altitudes.
F-27. Thus, prophylaxis with high doses of acetazolamide impairs prolonged physical performance at all altitudes. Current guidance recommends limiting acetazolamide to individuals with known susceptibility to AMS or using lower doses (250 to 500 micrograms per day) for rapid ascents to altitudes below 4,000 meters (13,123 feet).
Pulmonary Edema
F-28. HAPE is potentially fatal, although an uncommon illness, occurring in usually less than 10 percent of individuals ascending above 3,660 meters (12,008 feet). Individuals making repeated ascents and descents above 3,660 meters (12,008 feet) may have an increased susceptibility to HAPE. Prevention of HAPE is similar to AMS. However, instead of acetazolamide, individuals with prior history of HAPE may take a vasodilator such as nifedipine (20 micrograms sustained release every 8 hours). Sildenafil, tadalafil, and inhaled beta agonists, such as salmeterol, are additional options for the prevention of HAPE.
Cerebral Edema
F-29. HACE is potentially fatal, although an uncommon illness, occurring in usually less than 2 percent of individuals ascending above 3,660 meters (12,008 feet). HACE is an exacerbation of unresolved, severe AMS often occurring in people who have AMS symptoms and continue to ascend. If left untreated, HACE can progress to coma and death in 12 hours or less. Prevention of HACE is the same for AMS.
Effects on the Human Body
F-30. When operating in mountainous terrain, military and civilian personnel often experience a decline in physical and mental performance. Common effects of altitude exposure on the human body include—
- Reduced physical performance.
- Psychological effects.
- Sleep disturbances.
- Dehydration.
- Poor nutrition.
Reduced Physical Performance
F-31. Soldiers cannot maintain the same physical performance at altitude as they can at sea level, regardless of their fitness levels. Countermeasures include ensuring acclimatization, adjusting activity rates and load carriage, planning frequent rests during activities, and planning and performing physical conditioning programs at altitude.
Psychological Effects
F-32. Altitude exposure may result in changes in senses such as vision and taste, mood, and personality. These effects are related directly to altitude and are common at above 3,048 meters (10,000 feet). Some effects occur early and are temporary, while others may persist after acclimatization or for extended periods after descent:
- Vision—
- Is generally the sense most affected by altitude exposure.
- Can be impaired, for dark adaptation is reduced significantly, affecting Soldiers at altitudes as low as 2,438 meters (7,999 feet) and can potentially affect military operations at altitude.
- Mental effects most noticeable at extreme altitudes include decreased perception, memory, judgment, and attention span.
- Changes in mood and personality traits are common during altitude exposures.
Sleep Disturbances
F-33. Altitude exposure may have significant effects on sleep. Most prominent effects are frequent periods of apnea, which is a temporary pause in breathing and fragmented sleep. Reports of being unable to sleep and nighttime restlessness are common and may contribute to mood changes and daytime drowsiness. These effects have been reported at elevations as low as 1,524 meters (5,000 feet) and are common at higher altitudes.
Dehydration
F-34. Dehydration is common in Soldiers at high altitudes. Causes include perspiration, vomiting, increased breathing, and diminished thirst sensation. Dehydration decreases physical performance, increases symptoms of altitude illness, and may increase the risk of developing cold injuries.
Poor Nutrition
F-35. Poor nutrition can severely impact military operations and contribute to illness or injury, decreased performance, and poor morale. At high elevations, dulled taste sensations make food undesirable, and nausea or lack of energy can decrease motivation to prepare or eat meals. Poor eating habits may lead to constipation, aggravation of hemorrhoids, and undesired weight loss.
Products to Avoid
F-36. Products to avoid at high altitudes include tobacco, alcohol, and caffeine. Tobacco smoke interferes with oxygen delivery in the body and increases the amounts of carbon monoxide in close spaces. Irritant effects of tobacco smoke can narrow airways and interfere with breathing. Alcohol impairs judgment and perception, depresses respiration, causes dehydration, and increases susceptibility to cold injury. Caffeine from coffee and other sources may not improve physical and mental performance. Caffeine causes dehydration and should be consumed in moderation.
Acclimatization
F-37. Altitude acclimatization eliminates altitude illness and allows Soldiers to achieve maximum physical work performance possible. Once acquired, acclimatization is maintained if the Soldier remains at altitude. It is lost over several days after returning to lower elevations. Exposure to higher altitudes requires additional acclimatization.
F-38. For most Soldiers at high to very high altitudes, 70 to 80 percent of respiratory component of acclimatization occurs in 7 to 10 days; 80 to 90 percent of overall acclimatization generally occurs in 14 to 30 days; and maximum acclimatization may take months or years. Two methods Soldiers can use to achieve high altitude acclimatization are staged ascent and graded ascent.
Staged Ascent
F-39. Soldiers ascend to moderate altitudes and remain for 4 days or more to acclimatize before ascending higher. When possible, Soldiers should stop at several altitudes to allow a greater degree of acclimatization.
Graded Ascent
F-40. Slow ascents allow partial acclimatization. To reduce risk of altitude illness, have Soldiers spend 1 or 2 nights at moderate altitude 1,200 meters (3,937 feet) to 2,400 meters (7,874 feet). At altitudes above 2,400 meters (7,874 feet), Soldiers should not sleep higher than 300 meters (984 feet) above the previous night’s sleeping altitude.
Note. Combination of staged and graded ascents is the safest and most effective way to prevent altitude illnesses.
Fueling the Body
F-41. In addition to ways described for inducing altitude acclimatization, maintaining adequate hydration levels and primarily consuming carbohydrates can improve physical performance. Fueling the body also decreases altitude illness susceptibility.
Hydration
F-42. Dehydration significantly impairs physical performance and may increase susceptibility to AMS. Physical performance decreases produced by dehydration are likely in addition to impairments produced by hypoxia. Dehydration increases severity of hypoxic symptoms, such as lightheadedness and dizziness. Water requirements may be increased at high altitudes due to increased loss of water through breathing and diuresis produced by hypoxia and acetazolamide.
Carbohydrates
F-43. Carbohydrates are the most efficient fuel for optimizing physical performance at altitude. Recent research has indicated 6 to 12 percent glucose or maltodextrin solution in liquid form (such as, 56 grams in 560 milliliters of water) ingested just before and periodically during moderate to intense physical activity improved endurance performance by 10 to 25 percent at 4,300 meters (14,108 feet).
F-44. Carbohydrate supplementation maintains blood glucose levels and reduces perception of effort. Moreover, consuming it after completing an activity speeds recovery and replenishes muscle glycogen stores. In addition to providing energy to power prolonged and intense activity, consuming carbohydrates in liquid form assures better hydration status by replacing much of fluid volume lost due to sweating and increased ventilation.
F-45. High carbohydrate diets are recommended at altitude as an intervention to alleviate symptoms of AMS. Diets high in carbohydrates at altitude stimulates ventilation and improves blood oxygenation. Since the severity of AMS is linked closely to low blood oxygen levels, increasing blood oxygen content through enhanced carbohydrate metabolism should lessen symptoms of AMS. High carbohydrate diets compared to high fat or protein diets at altitude is typically better palatable, digestible, and acceptable by all individuals.
Note. Certain nutritional supplements are not effective in preventing altitude illness or enhancing physical performance. Ingestion of high doses of antioxidant vitamins or ginkgo biloba does not effectively reduce AMS susceptibility. Furthermore, creatine supplementation (to aid in performance) during short, high-altitude exposures does not improve physical performance.
Musculoskeletal
F-46. Soldiers need strength to be able to withstand the rigors of continuous operations while under load. The goal is to attain the muscular strength required to perform functional movements against resistance. A well-designed strength and conditioning program improves performance and appearance and controls injuries. Injuries are defined as any intentional or unintentional damage to the body resulting from acute or chronic exposure to mechanical, thermal, electrical, or chemical energy, and from the absence of such essentials as heat or oxygen. The following paragraphs focus specifically on musculoskeletal (orthopedic involving musculature and skeleton) conditions as it relates to the type of injury risk most common to foot marches under loads.
Bone Stress Injuries
F-47. Lower extremity stress fractures are common in foot marching. Normally affected areas are the foot, shin, knee, and hip. Stress fractures occur when the rate of stress on the skeletal system exceed the rate of repair and recovery. In addition to overuse, additional risk factors for stress fractures include older age, poor nutrition, and prior physical inactivity or low physical fitness.
Metatarsalgia
F-48. Metatarsalgia is a descriptive term for a nonspecific painful overuse foot injury. Walking with heavy loads may be a predisposing factor for metatarsalgia. This may cause the foot to rotate from front to rear for more prolonged periods resulting in mechanical stress in this area. Treatment is conservative and includes rest, use of ice packs, elevation of the foot, and anti-inflammatory medications. (See table F-5 on page 140.) Metatarsal pads can be used. If symptoms persist, further evaluation for more serious problems such as fractures or tumors is warranted.
Shin Splints
F-49. Shin splints are a common term that may include many diagnoses or causes and is not an actual injury or diagnosis. One of the most common causes is inflammation of the shin bone. Traction forces from the muscles of the lower leg pull on the shin bone causing pain and inflammation. Overuse is the most likely cause; however, many factors can increase the likelihood of this occurring including:
- Repeated marches on hard surfaces.
- Feet with unusually high or low arches.
- Worn-out boots.
- Poor mobility at the ankle.
Knee Pain
F-50. Knee pain is another condition associated with Soldier load. It may result from overuse, improper training, prior injury, or hereditary. Knee pain can be difficult to diagnose. Various disorders include patellofemoral pain syndrome, patellar tendonitis, bursitis, and ligamentous sprain. These conditions can arise from an abrupt increase in road marching mileage or intensity (load) or duration or from climbing hills if Soldiers have not been conditioned for this activity. Treatment includes rest, use of ice packs, and anti-inflammatory medications (see table F-6). Core, quadriceps, and hamstring strengthening and stretching exercises, along with calf stretching, may be important to prevent recurrence.
Meralgia Paresthetica
F-51. Meralgia paresthetica (tingling thigh syndrome) is an abnormal condition characterized by pain, numbness, and tingling sensation in the outer thigh. It is caused by compression of the nerve. For instance, when Soldiers wearing body armor are seated for long periods, the lower edge of the body armor may compress the groin region, resulting in compression of the lateral femoral cutaneous nerve. Symptoms generally subside with removal of the chronic compression. See table F-7 for signs, symptoms, prevention, and treatment.
Rucksack Palsy
F-52. Rucksack palsy is believed to be caused by the shoulder straps of backpacks. It can cause a traction or tension injury of the nerve roots of the neck. Symptoms include numbness, weakness, cramping, shoulder blade winging, and minor pain in the shoulder, elbow, and wrist. Possible risk factors for rucksack palsy include heavy loads, improper load distribution, and longer distances under load. See table F-8 for signs, symptoms, prevention, and treatment of rucksack palsy.
Low-Back Injuries
F-53. Low-back injuries can pose significant problems during Soldier load and foot marches. Low-back injuries are difficult to define. Pain may result from trauma to spinal discs, ligaments connecting vertebral bodies, nerves, or supporting musculature.
F-54. Heavy loads may be risk factors for back injuries. Heavier loads could lead to changes in trunk angle stressing back muscles, discs, and ligaments. The research suggested that new technologies that put weight higher on the shoulders may help reduce back problems. This results in optimal posture and eliminates prolonged bending of the back.
F-55. The double pack method can help reduce the incidence of back problems because it results in optimal posture and eliminates prolonged bending of the back. Thus, better load distribution (front and back) could reduce back injuries. A balanced strengthening and conditioning program involving the core, upper and lower body can assist in performance enhancement and injury prevention. See table F-9 for signs, symptoms, prevention, and treatment of low-back injuries.
Local Discomfort and Fatigue
F-56. Another important aspect of Soldier load, from the individual’s perspective, is discomfort. In Soldiers carrying backpack loads over long distances, local pain and discomfort is often reported in the feet, shoulder, and back areas. Foot pain could be due to blisters and abrasions and pressure on the feet. Shoulder discomfort could be caused by the rucksack straps that place pressure on the shoulders.
F-57. Discomfort varies depending on the pack system design. For backpacks with or without frames, majority of discomfort appears in the neck and shoulder regions. For backpacks with hip belts, which remove pressure from the shoulders, discomfort is localized to mid trunk and upper legs. Overall, when loads are carried primarily on the waist, they create less subjective discomfort compared to shoulder discomfort.
F-58. Local fatigue while carrying loads is common. Muscle groups having the greatest decrements in strength are lower back muscles, hip extensors, and knee flexors. This is often caused by lack of experience carrying loads or lack of training carrying loads. Proper fitting of equipment is important when carrying loads. Leaders should always check their subordinates to ensure equipment is being worn properly. This can create less fatigue during and after missions.
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