Physical exercise
From Wikipedia, the free encyclopedia
U.S. Marine emerging from the swim portion of a triathlon.
Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health. It is performed for many different reasons. These include strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance and for enjoyment. Frequent and regular physical exercise boosts the immune system, and helps prevent the "diseases of affluence" such as heart disease, cardiovascular disease, Type 2 diabetes and obesity.[1][2] It also improves mental health and helps prevent depression. Childhood obesity is a growing global concern and physical exercise may help decrease the effects of childhood obesity in developed countries.
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 cycling, swimming, walking, rowing, running, hiking or playing tennis, focus on increasing cardiovascular endurance.[4]
- Anaerobic exercises, such as weight training, functional training or sprinting, increase
short-
term muscle strength. [5]
Categories of physical exercise
Sometimes the terms 'dynamic' and 'static' are used. 'Dynamic' exercises such as
steady running, tend to produce a lowering of the diastolic blood pressure during
exercise, due to the improved blood flow. Conversely, static exercise (such as weight-
Exercise benefits
Physical exercise is important for maintaining physical fitness and can contribute
positively to maintaining a healthy weight, building and maintaining healthy bone
density, muscle strength, and joint mobility, promoting physiological well-
Exercise also reduces levels of cortisol, thereby benefiting health. Cortisol is a stress hormone that builds fat in the abdominal region, making weight loss difficult. Cortisol causes many health problems, both physical and mental.[6]
Frequent and regular aerobic exercise has been shown to help prevent or treat serious
and life-
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 (a.k.a. endorphins, naturally occurring opioids that in
conjunction with other neurotransmitters are responsible for exercise-
Exercise has been shown to improve cognitive functioning via improvement of hippocampus-
Physical activity is thought to have other beneficial effects related to cognition as it increases levels of nerve growth factors, which support the survival and growth of a number of neuronal cells.[13]
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). Such changes are generally beneficial and healthy if they occur in response to exercise.
Not everyone benefits equally from exercise. There is tremendous variation in individual response to training: where most people will see a moderate increase in endurance from aerobic exercise, some individuals will as much as double their oxygen uptake, while others will never get any benefit at all from the exercise.[14][15] Similarly, only a minority of people will show significant muscle growth after prolonged weight training, while a larger fraction experience improvements in strength.[16] This genetic variation in improvement from training is one of the key physiological differences between elite athletes and the larger population.[17][18] Studies have shown that exercising in middle age leads to better physical ability later in life.[19]
Common misconceptions
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 plain water and insufficient replenishment of electrolytes, especially salt and potassium (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 at an appropriate level of fitness for that particular activity. A doctor should always be consulted before any radical changes are made to a person's current exercise routine. Rhabdomyolysis is also a risk. Other common dangers may occur from extreme overheating or aggravation of a physical defect, such as a thrombosis or aneurysm.
- That weightlifting makes you short or stops growth. One highly debated caveat is that heavy weight training in adolescents can damage the epiphyseal plate of long bones.[citation needed]
Targeted fat reduction
Spot reduction is a myth that consists in believing that exercising and training
a particular body part will preferentially shed the fat on that part. For example,
doing sit-
Muscle and fat tissue
One misconception is that muscle tissue will turn into fat tissue once a person stops
exercising. This is not literally true fat tissue and muscle tissue are fundamentally
different but the common expression that "muscle will turn to fat" is truthful in
the sense that catabolism of muscle fibers for energy can result in excess glucose
being stored as fat.[20] Moreover, the composition of a body part can change toward
less muscle and more fat, so that a cross-