Back
WARNING: Any unauthorized duplication or publication of the material contained in this section is prohibited. Contact me (justinpeterson23@gmail.com) if you need to reproduce this.
Exercise Physiology for Pilots
Most pilots are aware of the fact that exercise is good for them. But, they don’t always know what is going on inside their bodies by maintaining fitness. Moreover, many are acutely aware of the dangers of not exercising. Especially
as pilots get older, they see the need for proper nutrition and
exercise as they talk with their Aviation Medical Examiner. More and
more in our society, pilots and people in general are leading sedentary
lifestyles. It is an American epidemic. Our bodies change to suit their physiological needs and environment. If we don’t use our muscles to their full extent, they atrophy. If we don’t use our cardiovascular system enough to put a real strain on it, it will respond by changing resting pulse rate. Our bodies adapt to us using the elevator instead of the stairs. This is an important concept in studying how exercise affects pilots in the flight environment.
There are advantages to being physically fit. Blood profiles change, sleeping patterns improve, bones become denser, blood sugar levels stabilize, longevity increases, even psychological problems can be fixed. The physically fit pilot will contrast in many ways against the sedentary pilot. I will show these comparisons to emphasize the importance of exercise as well as the disadvantages of being in poor physical shape. Being physically fit is important to pilots in the flight environment and on the ground because it improves performance and enhances safety.
Pilots are being lured into a sedentary lifestyle and it is showing at medical examinations. Currently (2003), 3,640 pilots have been waived by the FAA to get their medicals back from Coronary Artery Disease. 3,682 pilots have had their medicals waived from a Myocardial Infarction. 35,131 pilots have had their medicals waived for Hypertension (www.leftseat.com/sistats.htm). Many more have lost their medicals and not reinstated them. These medical conditions are the result of many factors including heredity, diet, exercise, and stress. Exercise has shown to play one of the largest factors in maintaining cardiovascular health.
Exercise does many things to alter our body’s chemistry and composition. After regular exercise, our muscle mass increases. The muscle tissues get stretched and torn. The body’s response is to repair the tissue to a greater level than before. The metabolic rate increases as the lean body mass increases.
The human body seems to adapt to whatever treatment it receives. If
you are a long distance runner, your body will increase red muscle
strength and produce more fat disassembling enzymes to meet the
tremendous calorie requirements. If you are a weightlifter, your body will increase white muscle strength and produce more glucose disassembling enzymes. If
you are a high altitude runner, your lungs will increase in capacity
and blood will increase the number of red blood cells to carry more
oxygen.
Muscles are basically biochemical motors. They convert chemical energy into mechanical energy and heat. Muscle tissue needs three things to function properly. It needs oxygen and fuel (glycogen) to produce ATP. ATP, or adenosine tri-phosphate, is a muscle chemical known as the “energy currency” of the muscle cells. Second, it needs to be able to get rid of metabolic waste products, such as carbon dioxide and lactic acid. Lastly, it needs to have adequate cooling so it does not overheat (Freudenrich, 1999).
The
growth of muscle tissue can only happen if we allow enough time in
between strenuous activity so that our muscles can fully restore
themselves. During exercise, the glycogen inside the muscle cells is depleted. The body needs either carbohydrates or protein to make glycogen. It also needs a considerable amount of time for this process. As we get older, this process takes longer.
Utilizing glucose or fatty acids for energy has two stages of extracting energy from the bonds. The first stage is anaerobic, meaning it requires no oxygen. This is when either the glucose or the fatty acids are turned into pyruvic acid. The second stage is aerobic, meaning it requires oxygen. This is when the pyruvic acid is combined with oxygen to produce ATP, carbon dioxide, and water. If your muscles are not getting enough oxygen, the pyruvic acid builds up and turns into lactic acid. Lactic acid is slightly toxic and burns the muscles. Lactic acid needs oxygen to get converted back to pyruvic acid. After that it needs more oxygen to get converted to ATP, carbon dioxide, and water (Bailey, 1991). When you exercise too hard, the body can make a lot of lactic acid and the body will be in oxygen ‘debt.’ The body needs its oxygen! The point is that muscles need oxygen and fuel to carry out metabolism.
Insulin plays a large role in where the glucose goes. Muscles that have been allowed to get out of shape resist the action of insulin. This is called insulin insensitivity. After an unfit person eats a large meal, there is much glucose in the blood. The pancreas then sends insulin into the bloodstream to open muscle cells to let the glucose inside so that it can make glycogen. But in the unfit person, the glycogen requirement is small and the insulin doesn’t work as well. This causes the blood sugar level to go to “stratospheric” heights. This high concentration causes glucose to enter fat cells (more like forced into fat cells) and be converted into glycerol, the building block of triglycerides (Bailey, 1991). The unfit person has elevated blood sugar levels and for longer periods of time than a fit person after eating. Obviously, pilots need to have a stabilized blood sugar level to perform best.
Once
a person has realized that they have gained weight over time, there are
different factors that determine how fast they can lose that extra fat,
such as exercise, diet, past history, and genetics. Exercise and fat storage are inversely related, of course. The more we exercise, the less we store fat and vice versa. Calorie intake directly affects what rate fat is stored. If a person eats less calories that they use, they will lose fat (and possibly muscle mass). If someone eats more calories than is necessary, they will store fat. Past history of one’s body greatly affects the ability to lose extra fat. People who have never exercised before have a harder time losing fat than “ex-jocks.” If one’s family history includes a preponderance of obesity, he or she will be more resistant to fat loss.
Strength is the greatest amount of force that a muscle can exert in a single effort (Willis & Campbell, 1992, p1). Adequate strength is always an asset to a pilot. Pilots in corporate or cargo jobs may be required to load all of the baggage/cargo themselves. They need to have the strength to handle the loading and still have energy left over for the flight without being exhausted. In flight, there are various scenarios that would require ultimate strength. If a trim control system were to malfunction, great strength would be required to control the airplane. Some airplanes, like the Cessna 310, have cowl flaps that are very hard to open or close while in flight. Also,
in the event of an engine failure in a light twin, if inadequate
opposing forces are not applied, the airplane may roll and yaw out of
control. Moving a general aviation airplane with a tow bar up an incline can require hundreds of pounds of force. In
today’s society, it is advantageous for the pilots to be strong so that
they fend off terrorists from hijacking airplanes for destructive
purposes.
Decompression
sickness, or DCS, is a condition where nitrogen changes from its
dissolved state in a liquid to a gas while inside the body. Pilots that have a higher body fat percentage are at a disadvantage when subjected to conditions that cause DCS. DCS is prevented by outgassing excess nitrogen through the lungs. The blood is responsible for rounding up the nitrogen from all over the body. The blood supply to fat tissue is less than the blood supply to the rest of the body. This means that it takes longer for nitrogen to exit the body from fat. Nitrogen
is likely to remain in high concentrations in the fat and blood coming
from fat, meaning it is more likely to become supersaturated with
nitrogen, causing it to come out of solution. DCS damage can be irreversible, so it is important to adequately protect oneself by keeping body fat percentages low.
In
strenuous exercise, just about every system in your body either focuses
it efforts on helping the muscles do their work, or it shuts down. The heart beats faster so that it can supply more blood to the muscles. The stomach shuts down so that it does not waste needed energy. There are many processes that occur simultaneously to aid the body while exercising. In a fit individual, these processes occur later after starting exercise. This means that the fit person has a wider “envelope” of physical performance.
There is an orchestra of techniques the body uses to respond to exercise. They include the heart, blood vessels, nervous system, lungs, and skin. As a person exercises, their blood vessels dilate to adjust for greater blood flow. This can be compared to a garden hose running into a fire hose. The body has the ability to divert blood to the most essential organs and systems. This is where the infamous adage “don’t swim for thirty minutes after eating” comes from. The body’s circulation system is actually very complex. The hypothalamus, a primordial part of the brain that controls visceral functions, increases the rate and depth of breathing. The heart increases four or five times in output compared to rest. When the heart is pumping at full force, the cardiac output is about 20-25 liters per minute. As a person exercises, there is an increased unloading of oxygen to the muscles from the blood protein hemoglobin. Exercise lowers the pH of the blood because of localized concentrations of lactic acid (and partly because of hydrogen ions). The oxygen is not as attracted to the hemoglobin (chemically speaking, of course) when the pH is low. This means that the muscles can take in oxygen more easily (Freudenrich, 1999).
The skin plays a large role in exercise. The skin helps keep the body cool because it has a large surface area and can radiate and evaporate. All of the metabolic processes would make the body overheat without it. The hypothalamus controls the temperature of the body by controlling the amount of sweat released for cooling. Evaporative
cooling is a very efficient way to cool the body, but it requires much
more water than the metabolic processes create. Thus, it is important to plan for fluid intake while exercising. When the body can no longer maintain a constant temperature, a heat stroke can set in.
Many pilots get headaches while flying. This can be the result of a number of causes. Insufficient oxygen uptake can cause headaches, as well as other symptoms. People who are fit have a larger lung capacity and can get more oxygen out of each breath. Also, a recent study at the
Many doctors commonly use exercise as a low cost, low risk alternative treatment for health problems. Obesity, anxiety, insomnia, hypertension, and a variety of psychological disorders can be mitigated by exercise. The cost of medicine may skyrocket in the near future, but the cost of exercise is free. People that make the decision to exercise are reducing the staggeringly high cost of medical treatments. They are not only alleviating any illness they have, but are also preventing any other type of illness in the future.
Mental disorders are a major health concern today. In the small pilot population, these people with severe mental disorders are weeded out through medical examinations. Pilots may, however, have minor mental problems. Depression, stress, anxiety, and symptoms of affective disorder can hit any pilot at any time. Exercise has been shown to have a profound effect on various psychological processes. Exercise actually alters the chemistry of the brain and has the effect of leveling, or stabilizing, the ups and downs of some chemicals, while steadily decreasing or increasing others. The most common psychological benefits that are linked to exercise are improved confidence, well-being, sexual satisfaction, reduced anxiety, improved intellectual
functioning, and alleviation of depressed moods (Willis & Campbell, 1992, p41). The
issues have been researched and exercise is linked to all of them, but
we are not completely sure of how and what the specifics are.
A measurable amount of positive effects from exercise can be seen in the general population. These effects would help a pilot just as well. Long-term
rigorous activity decreases absenteeism at work, alcohol abuse,
confusion, headaches, stress response, and work errors. This is good news for the fit pilots. They will have better concentration in the cockpit and can reduce the amount of errors. Type A behavior is considered hazardous for long-term health. Type
A behavior is associated with impatience, aggressive/competitive
behavior, and an unrelenting urge for recognition or power. This will also decrease with long term exercise. This is one of the many “normalizing” effects of exercise.
The mind and body are closely intertwined. In fact, the mind has been shown to have substantial effects on the body. Placebos can actually fix an illness because the brain is tricked into its destiny of better health. The human brain is a master pharmaceutical center. It can produce more chemicals than one can imagine. Physical activity has quite a number of effects on human emotions. Exercise is an activity of the body, which affects the brain, which again will affect the body. It is all just an interrelated cycle. It is hard to substantiate such immeasurable aspects of exercise such as emotional benefits. However, the general consensus is that there is a decided emotional advantage to proper exercise. When a person exercises regularly, they experience more joy, satisfaction, and enthusiasm. This makes them keep exercising, which makes them experience these emotions. It is like a positive physiological and psychological cycle. If someone only concentrates only on the physical aspect of exercise, they
are likely to lose motivation and not reap the full benefits of psychological health. Enjoying the exercise is the most important part of keeping it a long-term habit. Too many people sign up for a membership to a gym, only to quit after a few weeks or months. This is because they were only focusing on building muscle or losing weight. If the exercise is highly enjoyable, one is more likely to enjoy the full benefits of exercise on the mind and body. In
other words, a person who enjoys exercise will be healthier than a
person who does the same amount of exercise, but does not enjoy it.
Many physicians (most in fact) prescribe exercise for depression. Although
it is now common knowledge that exercise can alleviate nonpsychotic
depression, we are not sure of how the body actually does it. Some hypotheses, as explained by Willis and Campbell (1992), are:
1. The increased blood flow and oxygenation accompanying exercise may have a beneficial effect on the central nervous system. 2. Exercise is known to increase norepinephrine while low levels of norepinephrine are associated with depression.
3. The development of a sense of mastery and self-control through regular exercise may help patients improve depressed states. 4.
Improvements in body image and self-concept often associated with
exercise are believed to be factors in preventing or ameliorating
depression.
Exercise is just the physical actions of the body. Muscles are really just biochemical motors. Exercise is an important part of a large biological energy cycle. The sun gives plants the ability to construct large chains of hydrocarbons which contain energy when broken down. We eat the energy that comes from plants either directly or indirectly. We use these chains of hydrocarbons,
or polysaccharides, to make ATP, the chemical that directly provides
energy for muscle cells so that work can be done.
There are many aspects of human physiology that pilots need to be aware about and exercise is one of them. Pilots need to be educated on the benefits of maintaining a high level of physical fitness. The trend current trends of the American lifestyle are threatening the overall health of the pilot workforce. If these trends can be reversed, pilots will discover that they feel better, look better, and perform better in the cockpit. They will have a higher margin of safety against the more inhospitable places of the atmosphere. They will respond more quickly to changes in the environment. Their body chemistry will be improved. They will have a higher mental acuity. They will sleep better and be further rested than before. They will enjoy life the way that it is meant to be enjoyed. That is what exercise is all about.
Works Cited
Svoboda, M., Thomas, M., Bergmann, D., Rochat, G. (1985). Exercise Physiology.
VA: American
Bailey, C. (1991). The New Fit or Fat.
Mathews, D., Fox, E. (1971). The Physiological Basis of Physical Education and Athletics.
Willis, J., Campbell, L. (1992). Exercise Psychology.
Publishers.
Freudenrich, C. (1999). Entertainment – sports. How Exercise Works. Retrieved September 7,
2003 from the World Wide Web: http://www.howstuffworks.com/sports-physiology.htm/printable
Perry, P. (2003, Sept./Oct.). Weighing in on diabetes. Saturday Evening Post, 40-43.
Narin, S., Pinar, L., Erbas, D. (2003, November). The effects of exercise and exercise-related
changes in blood nitric oxide level on migraine headache. Clinical Rehabilitation, 624- 631.