Physical exercise is the performance of some activity in
order to develop or maintain physical fitness and overall health. It is often
directed toward also honing athletic ability or skill. Frequent and regular
physical exercise is an important component in the prevention of some of the
diseases of affluence such as heart disease, cardiovascular disease, Type 2
diabetes and obesity.[1][2]
Exercises are generally grouped into three types depending on the overall effect
they have on the human body:
Flexibility exercises such as stretching improve the range of motion of muscles
and joints.[3]
Aerobic exercises such as walking and running focus on increasing cardiovascular
endurance.[4]
Anaerobic exercises such as weight training, functional training or sprinting
increase short-term muscle strength.[5]
Physical exercise is considered important for maintaining physical fitness
including healthy weight; building and maintaining healthy bones, muscles, and
joints; promoting physiological well-being; reducing surgical risks; and
strengthening the immune system.
Proper nutrition is at least as important to health as exercise. When exercising
it becomes even more important to have good diet to ensure the body has the
correct ratio of macronutrients whilst providing ample micronutrients, this is
to aid the body with the recovery process following strenuous exercise.[6]
Proper rest and recovery is also as important to health as exercise, otherwise
the body exists in a permanently injured state and will not improve or adapt
adequately to the exercise. Hence, it is important to remember not to do the
same type of exercise two days in a row.
The above two factors can be compromised by psychological compulsions (eating
disorders such as exercise bulimia, anorexia, and other bulimias),
misinformation, a lack of organization, or a lack of motivation. These all lead
to a decreased state of health.
Delayed Onset Muscle Soreness can occur after any kind of exercise, particularly
if the body is in an unconditioned state relative to that exercise.[7]
Exercise benefits
Frequent and regular aerobic exercise has been shown to help prevent or treat
serious and life-threatening chronic conditions such as high blood pressure,
obesity, heart disease, Type 2 diabetes, insomnia, and depression. Strength
training appears to have continuous energy-burning effects that persist for
about 24 hours after the training, though they do not offer the same cardio
vascular benefits of aerobic exercises. Exercise can also increase energy and
raise one's threshold for pain.
There is conflicting evidence as to whether vigorous exercise (more than 70% of
VO2 Max) is more or less beneficial than moderate exercise (40 to 70% of VO2
Max). Some studies have shown that vigorous exercise executed by healthy
individuals can effectively increase opioid peptides (aka endorphins, a
naturally occurring opiate that in conjunction with other neurotransmitters is
responsible for exercise induced euphoria and has been shown to be addictive),
positively influence hormone production (i.e., increase testosterone and growth
hormone), and help prevent neuromuscular diseases,[8] benefits that are not as
fully realized with moderate exercise.
Both aerobic and anaerobic exercise also work to increase the mechanical
efficiency of the heart by increasing cardiac volume (aerobic exercise), or
myocardial thickness (strength training, see Organ hypertrophy).
Common myths
Many myths have arisen surrounding exercise, some of which have a basis in
reality, and some which are completely false. Myths include:
That excessive exercise can cause immediate death. Death by exercise has some
small basis in fact. Water intoxication can result from prolific sweating
(producing electrolyte losses) combined with consumption of large amounts of
water (e.g. when running a marathon). It is also possible to die from a heart
attack or similar affliction if overly intense exercise is performed by someone
who is not in a reasonable state of fitness for that particular activity. A
doctor should always be consulted before any radical changes are made to a
person's current exercise regimen. Rhabdomyolysis is also a risk.
That weightlifting makes you short or stops growth. One caveat is that heavy
weight training in adolescents can damage the epiphyseal plate of long bones.[9]
Targeted fat reduction
It is a common belief that exercise and training a particular body part will
preferentially shed the fat on that part; for example, that doing sit-ups is the
most direct way to reduce subcutaneous belly fat. This is false: one cannot
reduce fat from one area of the body to the exclusion of others. Most of the
energy derived from fat gets to the muscle through the bloodstream and reduces
stored fat in the entire body, from the last place where fat was deposited.
Sit-ups may improve the size and shape of abdominal muscles but will not
specifically target belly fat for loss. Instead, such exercise will help reduce
overall body fat and shrink the size of fat cells.
Muscle and fat tissue
Some people incorrectly believe that muscle tissue will turn into fat once a
person stops exercising. In reality, fat tissue and muscle tissue are
fundamentally different. However, the more common expression of this myth
"muscle will turn to fat" has a grain of truth. Although a muscle cell will not
become a fat cell, the material that makes up muscle can in fact turn to fat.
The catabolism of muscle fibers releases protein, which can be converted to
glucose that can be burned as fuel, and excesses of which can be stored as
fat.[10] Moreover, the composition of a body part can change toward less muscle
and more fat, so that a cross-section of the upper-arm for example, will have a
greater area corresponding to fat and a smaller area corresponding to muscle.
This is not muscle "turning to fat" however, it is simply a combination of
muscle atrophy and increased fat storage in different tissues of the same body
part. Another element of increased fatty deposits is that of diet, as most
trainees will not significantly reduce their diet in order to compensate for the
lack of exercise/activity.
Abdominal muscles
Abdominal muscles are like any other muscle tissue; they don’t necessarily
respond to hundreds of repetitions. If an individual can easily do 15 reps of
any abdominal exercise, they should consider switching exercises or adding
resistance. Abdominal muscles can be over-trained like any other muscle. It is
important that abdominal muscles have enough rest to recover from a bout of
exercise. Over-training will result in diminished gains. Many conventional
abdominal exercises solely tone the superficial muscles of the abdomen whereas
core-stability exercises, such as the plank, target internal muscles in the
abdomen which may be more conducive to obtaining a flatter stomach. Futhermore,
men and women all have the same anatomy that responds the same way to exercise.
Men and women must follow the same rules regarding diet, exercise and life-style
to achieve aesthetic and health related goals.[citations needed]
Excessive exercise
Too much exercise can be harmful. The body part needs at least a day of rest,
which is why most health experts say one should exercise every other day or 3
times a week. Without proper rest, the chance of stroke or other circulation
problems increases,[11] and muscle tissue may develop slowly.
Inappropriate exercise can do more harm than good, with the definition of
"inappropriate" varying according to the individual. For many activities,
especially running, there are significant injuries that occur with poorly
regimented exercise schedules. In extreme instances, over-exercising induces
serious performance loss. Unaccustomed overexertion of muscles leads to
rhabdomyolysis (damage to muscle) most often seen in new army recruits.[12]
Another danger is overtraining in which the intensity or volume of training
exceeds the body's capacity to recover between bouts.[13]
Stopping excessive exercise suddenly can also create a change in mood. Feelings
of depression and agitation can occur when withdrawal from the natural
endorphins produced by exercise occurs. Exercise should be controlled by each
body's inherent limitations. While one set of joints and muscles may have the
tolerance to withstand multiple marathons, another body may be damaged by 20
minutes of light jogging. This must be determined by each individual.
Exercise helps brain function
In the long term, exercise helps the brain by:
increasing the blood and oxygen flow to the brain
increasing growth factors that help create new nerve cells
increasing chemicals in the brain that help cognition[14]
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