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Aerobic exercise is the continuous elevation of one's heart rate. Covert Bailey, author of The New Fit of Fat defines exercise as aerobic that has four criteria:
Almost any movement which meets this definition, especially cycling and running, constitute aerobic exercise. During aerobic exercise a person's heart and respiratory rates increase resulting in more oxygen and blood being pumped throughout the body. This kind of exercise strengthens a person's cardiovascular system and increases stamina.
Heart rate is the clear indicator of aerobic exercise. The Aerobics and Fitness Association of America defines aerobic exercise as "A variety of exercises creating an increased demand for oxygen over a minimum twenty to thirty minutes and maintaining the heart rate at 55 to 85% of estimated heart rate." (Aerobics and Fitness ...). Heart rate is an important indicator of an aerobic exercise state. Generally, a person can reach a "comfortable pace" at 65% of their maximum heart rate. A person's maximum heart rate can be estimated by subtracting a person's age from 220, then multiply by 0.65 to determine a comfortable aerobic heart rate at 65% of maximum. For athletes the heart rate should be at 80% of maximum (Howard 156). The positive effects of aerobic exercise on the brain and body increase with the level of heart rate.
Many Americans seek and enjoy exercise; however, many do no physical activity. The Center for Disease Control (CDC) reports that most Americans are overweight to obese. Cable News Network reports that in a study by the CDC sixty-one percent of American adults are weigh too much. The CDC reported that, "People are getting heavier from a combination of too many calories and too little exercise. An estimated 40 percent of U.S. adults are physically inactive." (CDC says...). The problem of over-eating and lack of exercise is getting worse in the United States. The February 5th, 2001 issue of Time Magazine reports in the article "Repairing The Damage," that, "Nearly 50 million Americans continue to smoke. More than 60% are obese or overweight--20 years ago, it was 47%. One in four Americans gets no regular exercise at all" (Gorman 54).
The Arizona Daily Star reported on January 23. 2001 that according to American Cancer Society, " more than half of all adult Arizonans - 51.3 percent - acknowledge that they do no physical activity during their leisure time, according to 1999 Cancer Society statistics. " The lack of physical activity shows that Arizona is a state of "couch potatoes" or sedentary persons. "A sedentary lifestyle is emerging as a major risk for colon cancer and a strongly suggested risk for breast cancer, say Arizona Cancer Center researchers." Arizona has twice the percentage of couch potatoes as the rest of the country according to the article.
Elena Martinez a University of Arizona Cancer Center epidemiologist, reports that studies show that exercise dramatically cuts the risk of colon cancer because it is linked to chemicals the body produces, known as prostaglandins. "These chemicals appear at significantly higher levels in colon tumor tissue but drop in response to physical activity" ("Arizonans tempting cancer").
Being a heavy-set does not preclude one from the benefits of aerobic exercise for the brain and heart. Many large people are in good shape, and size for these people is not an indicator of physical conditioning. A good example is triathlete Dave Alexander. The Arizona Daily Star in Tucson, Arizona reported on December 26, 2000 that,
Since June 23, 1983, when he did his first one (triathlon) at age 38, he estimates he's finished 276 triathlons in 37 countries. In a recent super-triathlon in Eastern Hungary, he swam 9.6 miles, cycled 448, and ran what he calls, "a 104.8 mile Bataan death march." His time, he said without hesitation, was 85 hours, 46 minutes, 38 seconds.
Those are pretty remarkable numbers. But Alexander has a few more: He's 55 years old, 5 feet 8 inches tall and weighs 260 pounds" ("Triathlete doesn't let his weight slow him down").
At 55 years old, 5'8" and 260 pounds Alexander shows that fitness and weight are not mutually exclusive. Contrary to common knowledge an obese person who is physically fit has a lower rate of death due to cardiovascular illness. Time reports in its February 5, 2001 issue that,
Somewhat unexpectedly, the benefits of regular exercise appear to be relatively independent of how much you weigh. A 1999 study of 25,000 men (average age: 44) showed that, all other things being equal, men who were obese and physically fit had about the same risk of death over a 10-year period as men who were both physically fit and of normal weight. By contrast, men of normal weight who were unfit were twice as likely to die as the obese but fit men. "It's pretty clear that if you follow a healthy diet and don't smoke but don't exercise, you are still at high risk [of chronic illness]," says Steve Blair, an author of the study and director for research at the Cooper Institute in Dallas. Men who were both obese and inactive faced the worst odds: they were three times as likely to die of heart disease as physically fit men of normal weight (Gorman 56).
Americans, in general, are getting larger and more out of shape. The result is greater stress, more depression and less mental ability. Athletic training, regardless of a person's physical size, gives the cardiovascular system preparation for other stressful situations. The Heart Information Network reports that,
Exercise prepares the heart and blood vessels for other incidents of stress. When the heart is used to performing at an increased level, as it does during exercise, it can react more efficiently in an emergency. Exercise benefits the dilation of blood vessel linings, or endothelium, as well. Routine physical activity leads to more efficient dilation of blood vessels, improving overall blood flow. Blood vessels that do not dilate regularly respond more slowly when called to action ("Why is exercise so good for the heart?").
It is the physiological development of the cardiovascular system that has the most important impact on brain chemistry.
In a study by the Brookhaven National Laboratory researcher found that obese people have similar additive brain chemistry as drug addicts. "Brain scans show that obese people, just like drug addicts, have fewer receptors for dopamine, a neurotransmitter that helps produce feelings of satisfaction and pleasure." In the past, obese people were given dexamphetamines to reduce craving and increase dopamine levels. The study found exercise to be as effective. "In animal studies ... exercise has been found to increase dopamine levels and to raise the number of dopamine receptors," said study co-author Dr. Nora Volkow, a psychiatrist at Brookhaven. ("Link found between obesity and brain receptors").
It was once believed that a person was born with a specific number of brain cells that only decreased with age. Recent studies show that the brain can produce new neurons well into old age. In fact, older brains may be at an advantage. The nerve cells that communicate with one another are called neurons. Creation of new neuron growth does not happen automatically; a person must increase the blood flow to the brain in order for neuron growth to occur. At birth our 100 billion neurons and their trillions of connections are, "primed to reorganize themselves in response to your new environment no matter the culture, climate, language, or lifestyle" ("Mental and Physical Exercise for Brain Health and Fitness"). Exercise can therefore make a person smarter.
Research on mammals shows that regular aerobic exercise is a trigger for new brain cell growth. The Seattle Times reported in its June 19, 1999 issue that,
In separate studies published in Nature Neuroscience, scientists at the Salk Institute for Biological Studies in San Diego and at Princeton University discovered that some kinds of physical and mental exercise promoted the growth of new neurons, while also measurably prolonging the survival of existing brain cells. The changes took place in a part of the brain called the hippocampus, which is crucial to the formation of new memories ("Exercise encourages brain growth, studies find").
In the Salk Institute study, neurobiologist Fred Gage, senior author of the study said, "The difference was so striking, and because we know now that human brains also make new cells, it just might be that running or other vigorous exercise stimulates brain-cell production in people as well." The authors found that "voluntary exercise in a running wheel (for mice) increased cell proliferation, doubling the number of surviving newborn cells in the hippocampus" ("Exercise, variety stimulate brain cells").
The hippocampus is the part of the brain responsible for memory and learning. "Memory is learning that sticks" (Howard 526). The hippocampus is a postage size area of the brain about an inch behind the right eye. Learning takes place when the brain chemistry creates new connections between cells in the hippocampus and the cerebral cortex.
Aerobic exercise increases the chemicals in the brain responsible for nerve growth, particularly of nuerotrophins in the brain. Nuerotrophins stimulate the growth of connections in brain cells. (Howard 157) "Exercise also stimulates the production of two brain-boosting substances: nerve growth factor (NGF) and brain-derived growth factor (BDGF). Both not only promote nerve growth but also strengthen the connection and communication between nerves and nerves cells. And there are many millions of them!" (Maher).
Brain.com in its September 29, 1999 on-line article, "Mental and Physical Exercise for Brain Health and Fitness" reports,
When you are physically active, especially when your mind is challenged with learning something new very quickly, your brain produces an important hormone known as "brain-derived nerve growth factor." It stimulates the growth of dendrites, if not neurons, especially in your primary memory center, the hippocampus and increases the production of important neurotransmitters, acetylcholine and dopamine.
Aerobic exercise increases breathing and heart rates thus sending more blood flow to the brain, enhancing energy production and waste removal ("Mental and Physical Exercise ...).
This effect is demonstrated in a 1984 report in "Neurobiology and Aging," The report states, "After participating in a four-month aerobic fitness program, a group of men and women between the ages of 55 and 70 improved their performance on a battery of mental exams by about 10 percent" ("Mental and Physical Exercise ...). Nearly all serious athletes would report the same finding.
Exercise over the span of human history, especially running, may be responsible for the connection between aerobic exercise and learning. As our ancestors showed the "fight or flight." instinct, new challenges were faced that included exercise and learning. Hotz writes that Neal J. Cohen, a cognitive neuroscientist at the University of Illinois said, "Exercise itself over the eons may have become associated with a bunch of effects that help the brain prepare itself for new information, new learning, new brain work." ("Active Mind, Body Linked to Brain Growth).
The "fight or flight" instinct and its results reflect research on exercise and the hippocampus and cell growth, "Intense exercise in a natural environment may be associated with a need for increased navigation skills" ("Active Mind, Body Linked to Brain Growth."). The hippocampus plays an essential role in the learning processes involved in understanding and navigating the physical world. It is the flight or fight instinct which is also the source of stress in humans. As people are forced to choose between running from or facing a problem, they are often left "stewing," stressed and depressed at the choice of fight or flight. Aerobic exercise clearly alleviates depression and boost a person's mood.
Exercise can make a person happy. "As reported in a National Institute of Medical Health study of over nineteen hundred individuals, people with no recreational activity are twice as likely to have depressive symptoms as people who regularly do aerobic exercise." (Howard 157) The act of aerobic exercise provides an emotional boost. Endorphins produced during physical activity help increase an exerciser's sense of well-being (Why is exercise so good for the heart?).
In addition to strengthening the cardiovascular system, increasing oxygen to the body and lowering blood pressure, regular workouts give a person a time-out from the daily demands and pressures. In an exercise session, the release of endorphins combines with the person's work-out time to sensibly reflect on the day's stressful events, helping them keep it all in perspective. "By using exercise to release pent-up physical and psychological energy, you will be free to enjoy more restful sleep and a more worry-free psyche" (Exercise, Stress and Your Heart). Exercise is the easiest and most important thing a person can do to guard against the unhealthy by-products of stress.
Numerous research studies demonstrate the affect of exercise at lowering stress. "Studies performed on humans show that regular exercisers tend to take daily stress in stride compared with inactive persons. Other studies confirm that when presented with stressful situations, those who exercised less often were 21 percent more likely to experience anxiety and depression than fit individuals" (Exercise ,Stress and your Heart).
In addition to stress relief, regular exercise acts as a powerful anti-depressant.
"In a study by Gregg A. Tkachuk and Dr. Garry L. Martin of the department of psychology at the University of Manitoba in Winnipeg, Manitoba, Canada of the benefits of exercise among seriously depressed individuals, people who ran, walked or performed strengthening exercises three times a week for about 20 to 60 minutes at a time were significantly less depressed after 5 weeks and the improvements lasted for up to 1 year ("Exercise helps several psychiatric disorders").
In the era of Prozac and numerous other medications for depression, exercise is the natural and fun treatment. "Moreover, the oxygen-rich blood supply that exercise fosters increases production of three 'feel good and focused' brain messenger chemicals involved in memory and mood- the neurotransmitters acetylcholine, dopamine, and norepinephrine" (Mood and Memory Wellness).
While exercise is shown to increase brain-cell growth in the hippocampus, CNN reports that, "In the brain chemicals take the form of stress hormones, which studies have shown can shrink the area of the brain called the hippocampus. Chronic stress, says Dr. Douglas Bremner, of Emory University in Atlanta, Georgia, can also harm mental concentration and reduce a person's learning ability." (qtd. in "Experts: A healthy brain doesn't need too much stress") A person can grow brain cells in the hippocampus and reduce stress through exercise, or the person reduces the brain cells in the hippocampus through a stressful and/or sedentary life style. The increased blood flow throughout the body is both physiologically and psychologically rewarding. Many individuals use exercise as the proactive approach to health and stress release.
Mark Seegar, an active road cyclist living in Santa Cruz County, Arizona, is an example of a person using the proactive approach to health and stress relief. Seegar said of his training and exercise,
My training schedule is extremely variable due to demands from work, family, conditioning, natural disasters, injuries, illness, and the occasional bout of laziness. My goal is to keep myself amused and reasonably healthy, using several races per year for feedback/reality checks and cheap thrills.
When I get systematic and follow a plan, I generally try to use high volume (mileage, some weight training and cross training) in the early season, then more intense and race specific training with less volume in the weeks before competition. My mileage has decreased from about 250 per week 10 years ago to about 120 to 190 per week now (Seegar Interview 1/9/01).
Seegar's aerobic exercise level is impressive. One hundred twenty to 190 road cycling miles per week is a high a degree of aerobic exercise. Mark's experience shows the benefits of exercise on mind and body. Of his mental state and in the prevention of stress and depression Seegar said,
Many people have made comments about the state of my mental health, alleging or inquiring as to whether it's a direct result of riding around on a bicycle and breathing diesel fumes. It probably helps me to take a relaxed and objective approach to work and life, especially after a hard workout, when I'm too tired to leap to conclusions or beat a dead horse. I suspect the endorphins and other chemicals produced internally by vigorous exercise are beneficial up to a point.
Exercise is definitely a stress reliever, except during and right before competition, but that's fun, too. As for the depression, I don't know if I've actually experience clinical depression as described in the DSM IV (a dictionary of official lunacies I have on the shelf here), but I think exercise does mitigate, to a certain extent, the effects of slings and arrows of outrageous fortune (Seegar interview).
Mark uses his cycling for mental as well as physical health. Mark suffers from thyroid cancer and is faced wit the stress of illness and the physical demand of treatment for his cancer. Mark is at the top of his age ability as a road-racing cyclist in spite of his treatments and illness.
Cancer survivor and Tour de France champion Lance Armstrong is an incredible example of exercise health and stress dilution. In both 1999 and 2000, Armstrong dominated the 2300 mile, 21 day world's toughest test of aerobic ability, the Tour of France. What is remarkable is that Armstrong won the Tour after he nearly died of testicular cancer.
It is said that the mind and the body are linked inextricably and that how you think can promote or hinder the healing process. Perhaps that as much as anything else explains the miraculous recovery of Lance Armstrong in the year from 1996 to 1997. .. It was a year of pain and misery. But it was not a year of depression, resignation or failure (Shepler).
Through much of Armstrong's treatment, he had to give up the bike, but his incredible 100% recovery from severe cancer is a good example of the ability of aerobic exercise to reduce depression and stress and to improve overall health.
Research clearly shows that that aerobic
exercise boosts brain functions, improves mood and accelerates
learning. The millions of coach-potato, non-active, sedentary
Americans should get up and find out for themselves that there
is a reason people like to get out and sweat, it makes them calmer,
smarter, less stressed, and better able to deal with illness.
Forty-five year old cyclist Mark Seegar said of his cycling, "It
obviously doesn't prevent cancer, hemorrhoids, or an enlarged
prostate, but most people my age look a lot older than me."
The ultimate conclusion might be, "if you don't use it you'll
lose it." Exercise keeps a person looking younger and thinking
smarter.
Aerobics Fitness Association of America. "The Do's of Aerobic Exercise."1996: http://www.muscularmen.com/training/THE%20DOs%20OF%20AEROBIC%20EXERCISE.htm
"Arizonans tempting cancer." Arizona Daily Star. January 22, 2001. http://www.azstarnet.com/star/today/10123cancer.html
Bailey, Covert. The New Fit of Fat. Boston: Houghton Mifflin, 1991.
"CDC says 61 percent of U.S. adults overweight." CNN (2000): 9 pars. 15 December, 2000 <http://www.cnn.com/2000/HEALTH/diet.fitness/12/15/fat.america.ap/index.html>
"Exercise encourages brain growth, studies find." Seattle Times (1999): 14 pars. 23 February 1999 <http://seattletimes.nwsource.com/news/nation-world/html98/exer_19990223.html>
"Exercise helps several psychiatric disorders." Brain.com. Reuters Health (1999) 18 pars. Jun 14,1999. < http://www.brain.com/about/article.cfm?ID=840&cat_ID=34>
"Exercise, variety stimulate brain cells." Brain.com (1999) 10 pars. 22 Feb. 1999. <http://www.brain.com/about/article.cfm?ID=2145&cat_ID=34>
"Experts: A healthy brain doesn't need too much stress." CNN (2000): 5 pars. 26 December, 2000 < http://www.cnn.com/2000/HEALTH/12/26/stress.brain/index.html>
Gorman, Christine. "Repairing The Damage." Time Magazine February 5, 2001 Vol.. 157 NO. 5. Available on-line at: < http://www.time.com/time/magazine/article/0,9171,97086,00.html>
Howard, Pierce, J. The Owner's Manual for the Brain. Austin: Bard Press, 1999.
Hotz, Robert Lee. "Active Mind, Body Linked to Brain Growth." Brain.com (2000) 21 pars. February 23, 1999 <http://www.brain.com/about/article.cfm?ID=841&cat_ID=34>
"Link found between obesity and brain receptors." CNN.com (2001) 16 pars. 2 Feb, 2001 <http://www.cnn.com/2001/HEALTH/02/01/obesity.dopamine/index.html>
Maher , Dr. John H. "Re: Mood and Memory Wellness." Discussion group posting. December 13, 2000<http://x55.deja.com/=yahoo/getdoc.xp?AN=700707771.3&CONTEXT=978099325.1795686418&hitnum=43>
"Mental and Physical Exercise for Brain Health and Fitness." Brain.com (1999) 22 pars. 29 Sep. 1999. < http://www.brain.com/about/article.cfm?id=2092&cat_ID=34>
Seegar, Mark. Personal Interview. 9 Jan. 2001.
Shepler, John. "Lance Armstrong's Tour de Force." A Positive Light. On-line article. (2000). 2 January 2001 <http://www.execpc.com/~shepler/armstrong.html>
"Triathlete doesn't let his weight slow him down." Arizona Daily Star. December 26, 2000. <http://www.azstarnet.com/star/today/001226rfattriathlete.html>
"Why is exercise so good for the heart?" Heart Information Network (1997): 6 pars. 1 May, 1997 <http://www.heartinfo.org/news97/exerc5197.htm>
Thesis:
Aerobic exercise boosts brain functions, improves mood and accelerates
learning.
I. Aerobic exercise, a definition
...A. Aerobic vs. anaerobic
...B. Overweight Americans
...C. Aerobic exercise and lower-back
pain relief
II. Physiological Brain Effects
.....A. Cell growth in hippocampus
.......1. axon increase
........2. memory and learning
.............a. bad memory ability
linked to heart disease
.....B. Brain Chemistry and Neurotransmitters
..........1. Nerve Growth Factor
(NGF)
...........2. Brain Derived Growth
Factor (BDGF)
.....C. Increase capillaries and
oxygen and blood flow to the brain
III. Psychological Brain Effects
......A. Mood
......B. "Executive functions"
......C. Reaction time
......D. Stress relief
...........1. acetylcholine
............2. dopamine
............3. norepinephrine
............4. endorphins
......E. Treatment for mental disorders
...........1. schizophrenia
...........2. depression
...........3.
Alzheimer's
IV. Aerobic exercise and serious illness
......A. Lance Armstrong
......B. Mark Seegar