SEAL Physical Training Manual

Chapter 13 Physical Training in Special Environments
Physical training in extreme environments is extremely challenging and requires high physical fitness.Extreme environments refer to special environments such as high temperature and heat, low temperature and severe cold, and high altitude.Even very good athletes, if they do not make sufficient preparations in advance, or ignore the signs of disease, they will also have various symptoms of discomfort.For a variety of reasons, many extreme environments are currently uninhabited and inaccessible.Therefore, before the trainees enter the extreme environment, in order to ensure safety and improve the training effect, they must formulate a physical fitness plan and make preparations.

Environmental adaptability is the process and ability to adapt to a new environment. Specifically, it refers to the physiological and biochemical changes that occur in the body when the human body is continuously or repeatedly exposed to high temperature, severe heat, low temperature and severe cold, high altitude or other new environments to adapt to the environment. Variety.Therefore, environmental adaptability refers to the various changes that gradually occur when the human body adapts to a new environment.This chapter focuses on physical training for these extreme environments and physical training in enclosed spaces.

Section [-] Physical training in high temperature environment

Physical training in a hot and humid environment is a great challenge to the human body.The human body closely controls changes in body temperature through different metabolic systems.When the body temperature rises and the heat dissipation pressure of the human body is high (for example, after strenuous exercise, wearing protective clothing for high-temperature work, etc.), the skin sweat gland system is the first to play a role in reducing body temperature by evaporating sweat.Relative humidity is an important factor affecting sweat evaporation. When the humidity is high, sweat evaporation is severely inhibited and the speed is slow.

The human skin is like the radiator of a car. When the body temperature rises, the blood circulation accelerates, and the skin sweats. The sweat absorbs the heat in the blood, and the heat is released from the body with evaporation, and the body temperature drops.Only evaporated sweat can effectively lower body temperature, while dripping and lost sweat has no cooling effect.The human body speeds up the operation of the sweat gland system through the following two ways:

Increase heart rate: Increase the heart rate, promote blood circulation, thereby increasing the blood pumping volume of the skin, and can transfer more heat from the body to sweat.

Increase sweat volume: Stimulate sweat glands to produce more sweat and promote sweat evaporation, thereby lowering body temperature.

How high the temperature is considered high temperature?Risk ratings for heat training are usually based on wet bulb temperature (WB-GT).When the wet bulb temperature exceeds 35°C, that is, when the temperature is higher than 35°C and the relative humidity is greater than or equal to 60%, it is not suitable for physical training; if it must be done, please exercise with caution.

1.Factors that prevent the body from cooling down
Humidity Heat: As humidity increases, the air becomes saturated with water and the rate at which sweat evaporates slows.

Skin disorders: Deep burns, sunburns, rashes and other skin problems can prevent sweat from evaporating.

Clothing: Poorly breathable clothing can prevent sweat from evaporating.

2.high temperature adaptability

The human body usually can adapt to the high temperature environment after 1-3 weeks.For healthy individuals, 75% of acclimatization to high temperature occurs in the first week.It is more difficult to do physical exercise at this time, and you will feel tired if you exercise a little.Adaptability has two aspects:
Cardiovascular and cerebrovascular adaptation: After cardiovascular adaptation to the high temperature environment, the heart rate of a specific exercise intensity can be gradually reduced.It is the fastest-changing item in adaptation.

Sweat gland metabolism adaptation: It occurs earlier, the sweat gland metabolism function is strengthened, and the duration is longer; after the sweat gland metabolism adapts to the high temperature environment, it will reduce sweating, thereby reducing water volatilization and accumulating physical energy.

1) How to speed up the adaptation to high temperature

stick to aerobic training
Before entering a high-temperature environment, one should have a good endurance quality. This solid foundation can reduce the pressure on cardiovascular adaptability.The intensity of endurance training in the pre-adaptation stage must be strong, which can increase the core temperature of the human body, lay a solid foundation for future high-temperature adaptation, and speed up high-temperature adaptation.After the people with stronger aerobic metabolism ability withdraw from the high temperature environment, they have a stronger ability to maintain high temperature adaptation, and the loss of high temperature adaptation function is slower.Remember: Although aerobic training can speed up heat acclimatization, it cannot replace it.

Training in hot environments
Any form of physical activity can speed up acclimatization to heat, but at a lower intensity than usual.Seek guidance from your local sports medicine professional.If the environment permits, the intensity can be gradually increased until the training standard is reached.

stay well hydrated
With the strengthening of sweat gland metabolism, the human body will consume a large amount of carbon, thus requiring more water.Trainers who have adapted to the high temperature can produce up to 8 to 10 liters of sweat per day.Thirst cannot be used to judge whether the human body is dehydrated.When training in a high-temperature environment, you need to drink 9.5-11.5 liters of water per day, but not more than 5 cups per hour. "Less" and more frequent water intake can reduce the risk of heat stroke. In a high-temperature environment, heat stroke can sometimes be fatal.

2) How to maintain high temperature adaptability
High temperature adaptability must be achieved through repeated and continuous exposure to high temperature environments.However, high temperature acclimatization may not be maintained even with frequent exposure to high temperatures.There are many factors that can trigger a reduction in fitness, as follows:
Lack of sleep
Drinking
Dehydration
Salt depletion
stop training
It has not yet been determined how long it takes to completely lose high temperature adaptability, but generally speaking, the physical fitness achieved by 2 weeks of high temperature training will be completely reduced after 3-4 weeks of stopping training.

3.High temperature damage

There are many types and subtypes of heat damage.However, the overall can be divided into three categories:
Hyperthermia muscle cramps: Refers to muscle twitches caused by high-intensity training at high temperatures, accompanied by severe pain.It usually occurs in those trainees who have not acclimatized to the heat. The specific reason is not clear (it may be caused by electrolyte depletion), but when the trainer acclimatizes to the heat environment, the injury will gradually disappear.

Hyperthermia Exhaustion: Severe injury caused by dehydration and electrolyte depletion.Patients experience dizziness, light-headedness, fatigue, nausea and vomiting, and sometimes headaches.After discovery, the patient should be carried to a cool and ventilated place immediately, filled with water or injected with saline intravenously.

High temperature heatstroke: When the body temperature exceeds 40°C, the sore body cannot effectively control the body temperature.Heat stroke is a very dangerous patient, if not treated in time, it will be life-threatening.Many reasons can lead to heat stroke, even if the trainers with sufficient water, if the symptoms listed in Table 11-1 are ignored, heat stroke will occur.

Prompt medical attention can save lives.Master the basic essentials of first aid and check the pulse, respiration and heartbeat of the heatstroke sufferer.Immediately transfer the patient to a cool and ventilated place, remove clothing, smear the whole body with warm or cold water, and fan to speed up cooling.If ice cubes are available, apply cold compresses to the neck, underarms, and groin.Medical personnel should give intravenous injection and oxygen infusion immediately, and it is best to transfer the heat stroke victim to a nearby medical center for treatment.

There are many drugs and chemicals that can reduce the ability to adapt to high temperatures. In high temperature environments, contact with these substances should be avoided to improve high temperature combat capabilities.Table 11-2 summarizes drugs and chemicals that should be avoided in high temperature environments.

High temperature training summary
Be well prepared, perform aerobic training, and improve your aerobic capacity—very effective during sudden heat combat missions and can promote heat acclimatization.

Avoid training during the hottest part of the day.

Go to a professional sports medical center for consultation and get the best training plan.

The training intensity should be appropriately reduced in the first 2 weeks.

Keep your body well hydrated.

Take care to avoid any illness (dysentery, vomiting, fever) that could lead to dehydration.

Pay attention to observe your body and be alert to the aura symptoms of various high temperature diseases.Once such symptoms are observed, training should be slowed down or terminated; isolate the patient.

Avoid exposure to medicines and substances that may cause dehydration or other heat illness.

Section [-] Physical training in low temperature environment

The severe cold is the most dangerous training environment, which may threaten the lives of SEALs.In the absence of any protective measures, the human body is damaged faster by low temperature than by high temperature.In cold climates, the body's metabolic mechanism will keep itself warm, and SEALs can also improve their cold adaptability through exercise:
Increased Metabolic Thermogenesis: Human cells can burn energy (carbohydrates, fats, proteins) to produce heat.Passive muscle contraction can increase the body's metabolic capacity by 5 to 6 times.

Peripheral vasoconstriction: The vasoconstriction on the surface of the skin can organize blood and dissipate body heat outward.

Behavioral adaptation: In a severe cold environment, human beings know to add clothes to keep out the cold or seek shelter from the cold.It is also possible to increase metabolism through strenuous exercise to generate heat and keep warm; the maximum heat emitted by strenuous exercise is 10 times that produced by resting metabolism.

How low is a cold environment?Like hot environments, temperature is not the only indicator.Temperature and humidity are the two criteria for judging a high-temperature environment; in a low-temperature environment, cold wind will reduce human comfort.When the temperature is low, the human body can dissipate heat to keep warm, forming a small "insulation environment" around the body; however, the cold wind blowing from time to time will blow away the warm air, thereby increasing the heat loss of the human body.A low temperature environment refers to an environment where the temperature is lower than 9.4°C and the wind speed is greater than 40 km/h.There are potential risks for the human body to be exposed to this environment.

1.Factors that reduce adaptability to low temperature
Insufficient energy intake: Reduces the body's metabolic heat production capacity.

Injury or poor physical condition: Reduced exercise capacity and exercise thermogenesis.

Dehydration: Increase heart pressure and accelerate human fatigue.

Low body fat: Subcutaneous fat acts as an insulator, which is a problem for SEALs because they tend to have low body fat.

Excessive perspiration: Wear breathable underwear to avoid excessive perspiration.On the one hand, wet clothes will reduce the function of keeping out the cold, and on the other hand, it will also lower the body temperature, resulting in freezing.

Drinking alcohol: Accelerate blood circulation, cause the body to emit more heat, and accelerate the drop of body temperature.

2.low temperature adaptability

Unlike high temperature adaptability, the human body does not undergo significant physiological changes when adapting to low temperature environments.Studies have shown that exposing hands to low temperature for 30 minutes a day can increase blood circulation in the terminal and improve the body's ability to resist cold.However, this approach will increase the body's heat loss.

3.hypothermia injury

Many low temperature injuries can occur when training in low temperature environments, but these injuries can be avoided as long as you dress appropriately and be alert to various warning signs of injury.

1) Hypothermia

Hypothermia is a common temperature injury in Navy SEALs.The core body temperature of players often drops below 35°C. Compared with other low temperature injuries, mild hypothermia is easier to treat.Symptoms of lower core body temperature include the following aspects, and you must be careful about these symptoms when training in a low-temperature environment.

Trembling uncontrollably;
slurred speech;

sluggishness;

slow thinking;

If the shivering stops but other symptoms persist, it should be severe hypothermia.

Once any of the above symptoms appear, please take rescue measures immediately, otherwise the injury will be aggravated and even life-threatening.Care should be exercised when treating a hypothermic patient, and caution should not be exercised to elevate the patient's body temperature through strenuous exercise, which can cause cardiac arrest.Damp clothing should be removed, placed in a dry blanket or sleeping bag, and kept warm by two dry, normal body temperature teammates.Do not immerse or partially immerse the casualty in hot/warm water as this will cause cardiac arrest.Mildly hypothermic injuries can be allowed to gradually warm up on their own, but this treatment is not suitable for severe injuries.

Gradual warming is the safest way to return to normal body temperature.

2) frostbite

The most common parts of chilblains are the hands and feet, however, if other parts of the body are not properly protected, chilblains can also develop.Chilblains are often accompanied by three processes: initially feeling cold, followed by numbness, and finally, after the body temperature returns, there is obvious pain.The skin at the site of chilblains may appear normal or whitish.After frostbite is found, do not warm the frozen part immediately; it should be confirmed that there will be no further frostbite before implementing rescue measures.If the feet are frostbitten and the injured must walk to the medical site by themselves, do not warm the feet until they arrive.The process of warming your feet will be accompanied by severe pain, and it is easy to aggravate the condition.Any type of frostbite should be treated professionally.

Here are a few ways to effectively prevent frostbite:

Pay attention to keep warm and keep hands and feet dry;
Do not touch iron with bare hands or with bare skin.Hand wraps can reduce the risk of frostbite;
Goggles should be worn in environments with high wind speed.Such as taking snow vehicles, helicopters and skiing;

Teammates check each other for exposed body parts.

3) foot soak disease
Also known as "trench foot".Although no freezing occurs, long-term placement of feet in wet and cold (0°C to 10°C) boots can lead to muscle tissue and nerve necrosis.Keeping feet dry and avoiding wearing tight boots can prevent the disease.

4.nutritional needs

In a low temperature environment, we must pay attention to a nutritious diet.When exercising in a low-temperature environment, the energy consumption of the human body will be doubled several times; in order to maintain body temperature, a large amount of calories in the body will be consumed, and the glycogen reserves in the body will decrease sharply.Carbohydrates are a good source of energy and replenish glycogen stores.For more details, refer to the SEAL Men's Guide to Training.

Summary of physical training in low temperature environment
Dress appropriately according to the weather conditions;
Before training, fully carry out warm-up activities;

Avoid excessive perspiration;

During endurance training, replenish energy (carbohydrate) in time;
keep your body well hydrated;

Avoid exposure to drugs and substances that can cause dehydration, such as caffeine and alcohol;
When treating a hypothermic victim, pay attention to the "gradual warming" approach.

Section [-] Physical Training in High Altitude Environment
After suddenly entering a high altitude area, the athlete's competitive level will drop sharply.There are a number of reasons for this, but the main one is hypoxia — the amount of oxygen in the air drops as altitude increases.Living at high altitude for a long time, the human body will undergo many adaptive changes; most of the changes occur in the first 2-3 weeks.The main adaptive changes that affect exercise capacity include:
Increased blood oxygen carrying capacity;
Increased blood supply to muscles;
Increased muscle oxygen-carrying capacity;

Breathing rate increases.

With less oxygen at high altitudes, athletes' maximal aerobic capacity is reduced.When the altitude is higher than 1500 meters, the maximum aerobic capacity of athletes decreases by 100% to 1% for every 2 meters of altitude increase.Therefore, in an environment at an altitude of 3000 meters, the maximum aerobic capacity of elite endurance athletes is only 65% ​​to 85% of that at sea level.However, the performance of anaerobic athletes was not much different.For example, a sprinter or weightlifter who can sustain 2-3 minutes of extreme exercise at low altitudes can perform similarly at high altitudes because their muscle tissue does not need to work at maximum capacity during anaerobic exercise. Continuous oxygen supply.

1.altitude sickness (AMS)

Altitude sickness is a natural physiological reaction produced by the body to adapt to the changes in air pressure, low oxygen, and dry climate caused by altitude after reaching a certain altitude plateau.Common symptoms include: headache, nausea and vomiting, fatigue, loss of appetite, etc.After a few days, these symptoms will ease and disappear.Trainers who experience altitude sickness can go to lower altitudes for a few days to reduce discomfort.There are two types of life-threatening altitude sickness: high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE).When these two diseases occur, they must be transported to lower altitudes immediately.Oral acetazolamide 24-48 hours before entering the plateau can reduce altitude sickness.This drug is a prescription drug, which needs to be purchased and taken under the guidance of a doctor, 2 mg twice a day, for a total of 125 days.

When training at high altitudes, seek medical attention immediately if you notice the following symptoms:
Cough, short-term exacerbation of breathing;
Coughing up bloody or frothy sputum;

increased headache;

confusion, difficulty thinking;
blurred vision;

Insufficient urination for more than 8 hours;

Persistent difficulty breathing.

2.Other Factors Affecting High Altitude Adaptation
1) Lower temperature

Generally speaking, every time the altitude rises vertically by 1000 meters, the temperature will drop by 6.5°C. Under the combined influence of hypoxia and low temperature, it may make it extremely difficult for the human body to perform aerobic exercise.

2) Air dry

As altitude increases, the relative humidity of the air decreases.The high air ventilation rate at high altitudes can lead to moisture loss in the respiratory tract, while the low temperature can increase the frequency of urination, both of which lead to excessive water loss in the body, which can lead to rapid dehydration.Trainers should keep replenishing water, and they cannot wait to drink water when they are thirsty.

3) Weight loss

After most people reach an altitude of 4000 meters (or higher altitudes), they lose 2% to 3% of their body weight in the first 5 weeks, including a decrease in muscle volume and shortening of individual muscle fibers.Reasons for weight loss include the following:

increased physical exertion;
Hypoxia directly leads to loss of appetite and sense of taste.Please refer to the "Navy SEAL Men's Training Guide" for a reasonable diet;
body water loss;

Altitude sickness.

3.high altitude adaptability

Long-term activities in high-altitude areas will cause a series of physiological changes in the human body to adapt to the new environment, thereby improving the exercise capacity under the limit.When the altitude exceeds 3000 meters, the maximum aerobic capacity of the human body decreases.However, this phenomenon appeared after 2 weeks, so excellent endurance athletes will feel slight changes at first, and as time goes by, athletes will obviously feel their performance level decline.

Section [-] Physical Training in Confined Spaces
Military deployment or extended training often interferes with the daily schedule of physical training.Stopping training altogether can lead to a drastic decline in qualities such as strength and endurance (see Chapter 12); especially on submarines and assault craft, these problems are more likely to occur.In this case, the main problem faced by the team members is not lack of time to train, but how to overcome the difficulty of lack of fitness equipment and formulate a balanced physical training plan.Here is a brief introduction to the readers of physical training items commonly used in confined spaces:

Aerobics

pull-ups, dips
ball grip training
Lightweight resistance exercise machines (such as a swim simulator)

Lightweight resistance exercise machines - elastic resistance training bands to maintain the strength quality of major muscle groups
rope skipping
Step training (although boring, it does not require the use of fitness equipment, so it can be regarded as an effective form of aerobic training)
medicine ball plyometrics
free weight training
Run in place

If the space is large, you can add the following fitness equipment training to improve your strength quality:

climbing machine

exercise bike

rowing machine

walking machine

Treadmill

ski machine

upper arm strength trainer

At a minimum, the sub should have an exercise bike, rowing machine, and free weights.

Exercise bikes and rowing machines are equipped with electronic detectors, which can display time, distance and other functions, and can detect changes in various physical indicators during exercise.However, in confined spaces such as submarines, team members should conduct physical fitness competitions and establish a physical training log for each team member. This will not only help to summarize the training effect, but also increase each other's fighting spirit, promote training, and maintain physical fitness.

Section [-] Suspension of training and physical decline
If the trainer cannot maintain physical training, or must suspend physical training due to other reasons, physical fitness will decline rapidly.Many survey reports have studied the impact of stopping training on cardiopulmonary function. The results show that within 2 weeks of stopping training, exercise capacity will decline significantly; %.In addition, type II muscle fibers lose weight and become smaller; in contrast, maximum muscular strength appears to increase during this phase.Decreased maximal aerobic capacity simply means that it is more strenuous to complete a certain movement than before, but it does not mean that a certain movement cannot be performed.please remember:

The function of physical training is short-lived and reversible.

While maximal aerobic capacity can only be maintained through training, there are other factors that contribute to a decrease in aerobic capacity and ultimately reduced exercise capacity.These factors mainly include the following aspects:
Increasing age
high altitude

Dehydration
lean body mass loss
(End of this chapter)