Okay, So You Have Decided to Get Fit: Where Is a Good Place to Start?
Okay, So You Have Decided to Get Fit: Where Is a Good Place to Start?
Cardiovascular fitness is sometimes referred to as "cardiovascular
endurance" because a person who possesses this type of fitness can persist
in physical exercise for long periods of time without undue fatigue. It has
been referred to as "cardio-respiratory fitness" because it requires
delivery and utilization of oxygen, which is only possible if the circulatory
and respiratory systems are capable of these functions.
The term "aerobic fitness" has also been used as a synonym for
cardiovascular fitness because "aerobic capacity" is considered to be
the best indicator of cardiovascular fitness and aerobic physical activity or
exercise is the preferred method for achieving it. Regardless of the words used
to describe it, cardiovascular fitness is complex because it requires fitness
of several body systems.
Good cardiovascular fitness requires a fit heart muscle. The heart is a
muscle; to become stronger it must be exercised like any other muscle in the
body. If the heart is exercised regularly, its strength increases; if not, it
becomes weaker. Contrary to the belief that strenuous work harms the heart,
research has found no evidence that regular progressive exercise is bad for the
normal heart. In fact, the heart muscle will increase in size and power when called
upon to extend itself. The increase in size and power allows the heart to pump
a greater volume of blood with fewer strokes per minute. The average individual
has a resting heart rate of between seventy (70) and eighty (80) beats per
minute, whereas it is not uncommon for a trained athlete's pulse to be in the
low fifties or even in the forties.
The healthy heart is efficient in the work it does. It can convert about
half of its fuel into energy. An automobile engine in good running condition
converts about one-fourth of its fuel into energy. By comparison, the heart is
an efficient engine. The heart of a normal individual beats reflexively about
40 million times a year. During this time, over 4,000 gallons, or 10 tons, of
blood are circulated each day, and every night the heart's workload is
equivalent to a person carrying a thirty-pound pack to the top of the 102-story
Empire State Building.
Good cardiovascular fitness requires a fit vascular system. Healthy
arteries are elastic, free of obstruction and expand to permit the flow of
blood. Muscle layers line the arteries and control the size of the arterial
opening upon the impulse from nerve fibers. Unfit arteries may have a reduced
internal diameter because of deposits on the anterior of their walls, or they
may have hardened, nonelastic walls.
Fit coronary arteries are especially important to good health. The blood
in the four chambers of the heart does not directly nourish the heart. Rather,
numerous small arteries within the heart muscle provide for coronary
circulation. Poor coronary circulation precipitated by unhealthy arteries can
be the cause of a heart attack.
Veins have thinner, less elastic walls than arteries. Also, veins
contain small valves to prevent the backward flow of blood to the heart. The
veins are intertwined in the muscle; therefore, when the muscle is contracted
the vein is squeezed, pushing the blood on its way back to the heart. A
malfunction of the valves results in a failure to remove used blood at the
proper rate. As a result, venous blood pools, especially in the legs, causing a
condition known as varicose veins.
Good cardiovascular fitness requires a fit respiratory system and fit
blood. The process of taking in oxygen (through the mouth and nose) and
delivering it to the lungs, where the blood picks it up, is called external
respiration. External respiration requires fit lungs as well as blood with
adequate hemoglobin in the red blood cells. Insufficient oxygen-carrying
capacity of the blood is called anemia.
Delivering oxygen to the tissues from the blood is called internal
respiration. Internal respiration requires an adequate number of healthy
capillaries. In addition to delivering oxygen to the tissues, these systems
remove CO2. Good vascular fitness requires fitness of both the external and
internal respiratory systems.
Cardiovascular fitness requires fit muscle tissue capable of using
oxygen. Once the oxygen is delivered, the muscle tissues must be able to use
oxygen to sustain physical performance. Cardiovascular fitness activities rely
mostly on slow-twitch muscle fibers. These fibers, when trained, undergo
changes that make them especially able to use oxygen. Outstanding distance
runners often have high numbers of slow-twitch fibers and sprinters often have
high numbers of fast-twitch fibers.
Regular physical activity reduces the risk of heart disease. There is
considerable evidence that regular physical reduces the incidence of heart
disease. Also, it reduces the chances of early death from heart disease. In
fact, the benefits of exercise in preventing heart disease have been shown to
be independent of other risk factors. Inactivity is now considered a primary
risk factor for heart disease.
People with low cardiovascular fitness have increase risk of heart
disease. The best evidence indicates that cardiovascular fitness is associated
with heart disease. Research has shown that low fit people are especially at
risk. In addition it has now been demonstrated that improving your fitness
(moving from low fitness to the good fitness zone) has a positive effect on
health.
The frequency, intensity and time of your physical activity will vary
depending on the benefits you hope to achieve. The term "threshold of
training" suggests that there is one level of physical activity that all
people must do to achieve cardiovascular fitness as well as the health benefits
of activity. We now know that the threshold differs for people depending on
their current fitness and activity levels and the benefits they hope to
achieve. New studies show that health benefits can be achieved by doing less
activity than previously thought. However, those who desire "performance
benefits" as indicated by a high level cardiovascular fitness, in addition
to the health benefits of physical activity, will need to do activity at a
higher threshold level than those who are interested primarily in the basic
health benefits.
The type of physical activity you select is important to the benefits
you will receive. Lifestyle physical activities, such as walking, yard work,
climbing stairs and normal daily tasks, can promote health benefits and make
contributions to your cardiovascular fitness. Aerobic activities such as
running, skiing, cycling, and active sports are considered to be the most
beneficial in promoting health benefits and are effective in promoting
performance increases needed for high-level performance. Though sports can be
effective in contributing to the development of cardiovascular fitness, some
are relatively ineffective and others can be very effective.
As a minimum, adults should participate in regular physical activity
equal to 30 minutes of brisk walking most, preferably all, days of the week.
Research shows that 30 minutes of physical activity equal to brisk walking most
days of the week is an important contributor to personal cardiovascular health.
To achieve health benefits, physical activity can be accumulated in several 10
to 15 minute bouts that total 30 minutes daily. However, when possible, bouts
of 30 minutes duration are recommended. Near daily activity is recommended
because each activity session actually has short-term benefits, which do not
occur if activity is not relatively frequent. This is sometimes referred to as
the "last bout effect".
Calories can be counted to determine if you are doing enough to receive
cardiovascular benefits of physical activity. The threshold of training for
producing many of the health benefits can be determines using a weekly calorie
count. Scientific evidence suggests that people who regularly expend calories each
week in lifestyle activities such as walking, stair climbing and sports reduce
death rates considerably compared to those who do not exercise. As few as 500
to 1,000 calories expended in exercise per week can reduce death rate, but most
experts suggest that to insure a health benefit no less than 1.35 calories per
pound of body weight each day. This amounts to 1,000 to 2,000 calories per week
for most people if exercise is done daily.
For optimal health benefits an expenditure of 2,000 to 3,500 calories
per week is recommended, because people doing this much physical activity have
48 to 64 percent less risk of heart disease when compared to sedentary people.
As the calories expended per week increase the death rate decreases
proportionately up to 3,500 calories. Because additional benefits do not occur
for those expending more than 3,500 calories per week, the target zone is 1,000
to 3,500 calories per week. For health benefits to occur, calories must be
expended on most days of the week and over long periods of time. In other
words, moderate physical activity is described here must become regular
lifetime physical activity if optimal health benefits are to be obtained. It
should also be pointed out that some vigorous sports participation as part of
the calories expended each week enhances the benefits of moderate regular
calorie expenditure.
Heart rate can provide the basis for determining if a person is doing
enough exercise to improve fitness. We know that expending a significant number
of calories each week can result in reduced risk of cardiovascular disease and
improved health. To achieve these benefits it is only necessary to do
relatively low-level exercise for extended periods of time. Both cardiovascular
health and performance benefits could be obtained in much shorter periods of
time if exercise is done more intensely. For busy people this method is often
preferred. To achieve fitness by using shorter duration exercise, your heart
rate must be elevated to target zone intensity. In addition to producing
cardiovascular health benefits, exercise that elevates the heart rate into the
target zone has the added advantage of improved cardiovascular fitness test
scores and improved performances in cardiovascular activities such as running,
swimming and cycling.
Whether you are just trying to improve your cardiovascular health or
wanting to improve your performance at a specific sport, it is important to
apply these methods on a regular basis. Just remember these three principles;
frequency, intensity and time. Apply these principles and you will enjoy good
cardiovascular fitness and avoid risk of heart disease.
Stay healthy, Stay happy
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