Exercise and the Body
by Scott Howard
Exercise is an important part of health. It is an integral part of weight loss programs
as well as slowing the aging process. Any amount of exercise is good, although there may
be certain health conditions that one may have that will prevent them from exercising.
When an individual is doing any kind of exercise training, his maximum heart rate (MHR)
should be monitored frequently(especially if you are just starting an exercise regime.)
The objective is to reach a target heart rate which should be 70-85% of one=s MHR. The MHR is calculated by the formula
(220-age.) Physical success is indicated by the anaerobic threshold (AT.) AT
is where there is not adequate oxygen to support the tissues of the body. At AT,
the heart rate increases and the performance decreases. AT is elevated by short but
intense activity. One=s best training is done
just below AT. To accomplish good training, one is recommended to have intervals
5-by-5. 5 minutes at target and 5 minutes to slow down to regain heart rate and then
repeat 5-by-5.
Exercise can also build or tone muscle and strengthen bone. When muscles are used
against a weighted device, the force applied to the bone actually causes an increase in
bone mass at that location. The increase in muscle size has several advantages such as:
increase number of muscle fibers
up to 120% increase in mitochondria enzymes
60-80% increase in muscle fuel formation
50% increase in stored muscle glycogen
Exercise has many benefits to the body. For instance, the metabolic rate (MR),
which is related to lean tissue, is increased. As you age, your body=s MR decreases as well as your lean tissue,
hence the advantage of exercise. MR is influenced by several factors which are:
Thyroxine-t4
Growth hormone (GH)
Testosterone
Epinephrine
Exercise increases levels of GH which promotes protein synthesis, stimulates
gluconeogenesis and promotes lipolysis. Lipolysis is the degradation of fat cells.
So, once again, exercise also helps burn fat. Thyroid hormones are also elevated
with exercise and along with GH stay elevated for quite some time after exercise.
The epinephrine that is elevated causes an increase in blood glucose (sugar) and stimulates
lipolysis which once again shows that exercise helps burn fat. Exercise also decreases
insulin levels, increases blood plasma, decreases cholesterol, LDL
and triglycerides. It also increases the good HDL levels which are known to
help prevent atherosclerosis and releases endorphins which help sedate pain and
give euphoria.
The physical activity depends mainly on three systems of energy for muscle contraction.
The first to be used is called the ATP-phosphocreatine system which only lasts for
8-10 seconds. Then the second system kicks in, which is called the lactic-acid
(anaerobic) system which lasts approx. 1.3-1.6 minutes. This lactic-acid is formed
when there is insufficient oxygen supplied to the muscle cells. The third and last system
is the aerobic system which has an unlimited time frame but produces the least
energy. With the aerobic system, one burns fat much more readily than the other two
systems. Both aerobic and anaerobic systems are boosted with the increase in muscle
size/quality and therefore increases the efficiency of energy production.
Increased amounts of exercise requires proper nutrition for longer lasting muscle fuel.
There are supplements on the market that one can take as well as certain foods one can
eat. Glucose stores in the muscle called muscle glycogen, are the immediate fuel
stores for exercise. To build up or restore this type of glucose, one should eat
carbohydrates. Studies have shown that the muscles are most susceptible to insulin 2-4
hours after exercise and therefore, that is the best time to replace the muscle glucose
stores. Certain activities can deplete these stores such as:
Anxiety and nervousness
Muscle damage
Exercise past AT
Stress
Hot and humid conditions
Dehydration
Complex carbohydrates are the best carbohydrates because of the lasting effect. The
supplements that are on the market that can be helpful in exercise are supplements that
contain L-carnitine and chromium. L-carnitine is helpful in the
transportation of fatty acids, which come from dissolved fats, into the
mitochondria(energy producing organelle) which is then used for energy production. Chromium,
which can also be found in brewer's yeast, can correct impaired blood sugar tolerance by
increasing the body's sensitivity to insulin. Chromium can also reduce cholesterol
and raise levels of HDL.
One important factor that can impair exercise is smoking. The nicotine constricts
terminal bronchioles of the lungs which reduces the oxygen exchange. Nicotine also
paralyzes the cilia which are hair-like cells that propel foreign substances back out the
airway. Smoke also irritates the lungs surfaces causing fluid to be secreted into the
tubes of the lungs resulting in impaired oxygen flow.
Last but not least, the heart is greatly affected by exercise. In individuals that
train for endurance, the heart output increases because of the heart chambers increase in
size. The muscle walls of the heart also thicken and become stronger resulting in a
stronger heart.
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