Physical exercise
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[[Image:Soldier running in water.jpg|thumb|right|200px|[[United States Marine Corps|U.S. Marine]] emerging from the swim portion of a [[triathlon]].]]
A '''physical exercise''' is any bodily activity that enhances or maintains [[physical fitness]] and overall [[health]]. It is often practiced to strengthen muscles and the cardiovascular system, and to hone [[sport|athletic]] skills. Frequent and regular physical exercise boosts the immune system, and helps prevent [[diseases of affluence]] such as [[heart disease]], [[cardiovascular disease]], [[Type 2 diabetes]] and [[obesity]].<ref>Stampfer, M., Hu, F., Manson, J., Rimm, E., Willett, W. (2000) Primary prevention of coronary heart disease in women through diet and lifestyle. ''The New England Journal of Medicine, 343''(1), 16-23. Retrieved October 5, 2006, from ProQuest database.</ref><ref>Hu., F., Manson, J., Stampfer, M., Graham, C., et al. (2001). Diet, lifestyle, and the risk of type 2 diabetes mellitus in women. ''The New England Journal of Medicine, 345''(11), 790-797. Retrieved October 5, 2006, from ProQuest database.''</ref> It also improves mental health and helps prevent depression.
==Types of exercise==
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 [[muscle]]s and joints.<ref>O'Connor, D., Crowe, M., Spinks, W. 2006. Effects of static stretching on leg power during cycling. ''Turin, 46''(1), 52-56. Retrieved October 5, 2006, from ProQuest database.</ref>
* [[Aerobic exercise]]s such as [[cycling]], [[walking]], [[running]], [[hiking]] or playing [[tennis]] focus on increasing [[cardio]]vascular endurance.<ref>Wilmore, J., Knuttgen, H. 2003. Aerobic Exercise and Endurance Improving Fitness for Health Benefits. ''The Physician and Sportsmedicine, 31''(5). 45. Retrieved October 5, 2006, from ProQuest database.</ref>
* [[Anaerobic exercise]]s such as [[weight training]], [[functional training]] or [[sprinting]] increase short-term muscle strength.<ref>de Vos, N., Singh, N., Ross, D., Stavrinos, T., et al. 2005. Optimal Load for Increasing Muscle Power During Explosive Resistance Training in Older Adults. ''The Journals of Gerontology, 60A''(5), 638-647. Retrieved October 5, 2006, from ProQuest database.</ref>
==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-being, reducing surgical risks, and strengthening the immune system.
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 [[clinical depression|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 cardiovascular benefits as aerobic exercises do.
There is conflicting evidence as to whether vigorous exercise (more than 70% of [[VO2 max|VO<sub>2</sub> Max]]) is more or less beneficial than moderate exercise (40 to 70% of [[VO2 max|VO<sub>2</sub> 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 (emotion)|euphoria]] and has been shown to be addictive), positively influence hormone production (i.e., increase testosterone and growth hormone),<ref>Hanc, J. 1987. Your Health Behind the Runner\'s Euphoria. \'\'Newsday, April 21, 1987,\'\' 11. Retrieved October 5, 2006, from ProQuest database</ref> benefits that are not as fully realized with moderate exercise.
Exercise has been shown to improve cognitive functioning via improvement of hippocampus-dependent spatial learning, and enhancement of synaptic plasticity and neurogenesis.<ref>{{cite journal | last = van Praag H, Kempermann G, Gage FH. | title = Ontogeny Running increases cell proliferation and neurogenesis in the adult mouse dentate gyrus. | journal = Nature Neuroscience. | volume = 2 | issue = 3 | pages = 266–70 | date = 1999 | url = http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10195220 | format = Abstract | accessdate = 2007-03-28 | doi = 10.1038/6368}}</ref> In addition, physical activity has been shown to be neuroprotective in many neurodegenerative and neuromuscular diseases.<ref>{{cite journal | last = Clément Grondard et al. | title = Regular Exercise Prolongs Survival in a Type 2 Spinal Muscular Atrophy Model Mouse. | journal = The Journal of Neuroscience. | volume = 25 | issue = 33 | pages = 7615–7622 | date = 2005 | doi = 10.1523/JNEUROSCI.1245-05.2005 | format = Abstract | accessdate = 2007-03-28 | pmid = 16107648}}</ref> For instance, it reduces the risk of developing [[dementia]].<ref name=wvdhhr> [http://www.wvdhhr.org/bph/oehp/hsc/dementia/prevent.htm West Virginia Department of Health and Human Resources]</ref> Furthermore, anecdotal evidence suggests that frequent exercise may reverse alcohol-induced brain damage.<ref>http://pn.psychiatryonline.org/cgi/content/full/41/23/20</ref>
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.<ref>{{cite journal | last = Edward McAuley,* Arthur F. Kramer, and Stanley J. Colcombe | title = Cardiovascular fitness and neurocognitive function in older Adults: a brief review. | journal = BRAIN,
BEHAVIOR, and IMMUNITY. | volume = 18 | issue = 2004 | pages = 214–220 | date = 2004 | url = http://www.kch.uiuc.edu/labs/exercise-psychology/Library/pubs/McAuley_Brain_Behavior_Immunity_2004.pdf | format = Full Article | accessdate = 2007-03-28 | doi = 10.1016/j.bbi.2003.12.007}}</ref>
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#Ventricular hypertrophy|Organ hypertrophy]]).
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.<ref name="bouchard_fam"> {{cite journal
| last = Bouchard
| first = Claude
| coauthors = Ping An, Treva Rice, James S. Skinner, Jack H. Wilmore, Jacques Gagnon, Louis Perusse, Arthus S. Leon, D. C. Rao
| year = 1999
| month = September
| title = Familial aggregation of VO(2max) response to exercise training: results from the HERITAGE Family Study.
| journal = Journal of Applied Physiology
| volume = 87
| issue = 3
| pages = 1003–1008
| pmid = 10484570
| url = http://jap.physiology.org/cgi/content/abstract/87/3/1003?ijkey=189eebcbc5a461258da582b4aef41ebcf7bec51f&keytype2=tf_ipsecsha
| accessdate = 2007-07-17
}} </ref><ref name="kolata">{{cite news
| first = Gina
| last = Kolata
| title = Why Some People Won't Be Fit Despite Exercise
| url = http://query.nytimes.com/gst/fullpage.html?res=9406EEDE113CF931A25751C0A9649C8B63&sec=health
| publisher = The New York Times
| date = [[February 12]], [[2002]]
| accessdate = 2007-07-17 }}</ref> Similarly, only a minority of people will show significant muscle growth after prolonged weight training, while a larger fraction experience improvements in strength.<ref>{{cite journal
| last = Hubal
| first = MJ
| coauthors = Gordish-Dressman H, Thompson PD, Price TB, Hoffman EP, Angelopoulos TJ, Gordon PM, Moyna NM, Pescatello LS, Visich PS, Zoeller RF, Seip RL, Clarkson PM
| year = 2005
| month = June
| title = Variability in muscle size and strength gain after unilateral resistance training.
| journal = Medicine and Science in Sports and Exercise
| volume = 37
| issue = 6
| pages = 964–972
| pmid = 15947721
| url = http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=15947721&dopt=Citation
| accessdate = 2007-07-17
}} </ref> This genetic variation in improvement from training is one of the key physiological differences between elite athletes and the larger population.<ref>{{cite journal
| last = Brutsaert
| first = Tom D.
| coauthors = Esteban J. Parra
| year = 2006
| title = What makes a champion? Explaining variation in human athletic performance.
| journal = Respiratory Physiology & Neurobiology
| volume = 151
| pages = 109–123
| doi = 10.1016/j.resp.2005.12.013
| url = http://www.erin.utoronto.ca/~eparra/profile/PDF%20files/Brutsaert%20and%20Parra,%202006.pdf
| accessdate = 2007-07-17
| format = {{dead link|date=June 2008}} – <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=author%3ABrutsaert+intitle%3AWhat+makes+a+champion%3F+Explaining+variation+in+human+athletic+performance.&as_publication=Respiratory+Physiology+%26+Neurobiology&as_ylo=2006&as_yhi=2006&btnG=Search Scholar search]</sup>
}} </ref><ref name="newsci_geddes">{{cite news
|last = Geddes
| first = Linda
| title = Superhuman
| pages = 35-41
| publisher = New Scientist
| date = [[2007-07-28]]
}}</ref> Studies have shown that exercising in middle age leads to better physical ability later in life.<ref>{{cite news
| url=http://www.nlm.nih.gov/medlineplus/news/fullstory_58065.html
| title=Being active combats risk of functional problems
}}</ref>
==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 regimen. [[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 caveat is that heavy weight training in adolescents can damage the [[epiphyseal plate]] of long bones. {{Fact|date=May 2008}}
===Targeted fat reduction===
[[Spot reduction]] is a myth that exercise and training a particular body part will preferentially shed the fat on that part; for example, that doing [[Sit-up (exercise)|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. Such exercise might help reduce overall body fat and shrink the size of fat cells. There is a very slight increase in the fat burnt at the area being exercised (e.g. abs) compared with the rest of the body, due to the extra blood flow at this area.
===Muscle and fat tissue===
Some people incorrectly believe 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.<ref>Austin, B. 2006. Don't Let Your Body Go Into Starvation Mode. ''Wisconsin State Journal, April 1, 2006,'' 46. Retrieved October 5, 2006, from ProQuest database.</ref> 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 into 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.
==Excessive exercise==
Exercise is a [[Stress (medicine)|stressor]] and the stresses of exercise have a [[Catabolism|catabolic]] effect on the body - contractile proteins within muscles are consumed for energy, carbohydrates and fats are similarly consumed and [[connective tissue]]s are stressed and can form micro-tears. However, given adequate nutrition and sufficient rest to avoid [[overtraining]], the body's reaction to this stimulus is to adapt and replete tissues at a higher level than that existing before exercising. The results are all the training effects of regular exercise: increased muscular strength, endurance, bone density, and connective tissue toughness.
Too much exercise can be harmful. The body parts exercised need at least a day of rest, which is why some health experts say one should exercise every other day or 3 times a week. Without proper rest, the chance of [[stroke]] or other [[Circulatory system|circulation]] problems increases,<ref>Alexander, C. 1998. Cutting weight, losing life. ''News & Observer, February 8, 1998,'' A.1. Retrieved October 5, 2006, from ProQuest database.</ref> and muscle tissue may develop slowly. It has also been noted by the medical field that expectant mothers should never exercise two days consecutively.{{Fact|date=April 2008}}
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.<ref>Jimenez, C., Pacheco, E., Moreno, A., Carpenter, A. 1996. A Soldier's Neck and Shoulder Pain. ''The Physician and Sportsmedicine, 24''(6), 81-82. Retrieved October 5, 2006, from ProQuest database.</ref> Another danger is [[overtraining]] in which the intensity or volume of training exceeds the body's capacity to recover between bouts.<ref name="uusitalo">[http://www.physsportsmed.com/issues/2001/05_01/uusitalo.htm The Physicial and Sportsmedicine on Overtraining]</ref>
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.
Too much exercise can also cause a female to miss her period, a symptom known as [[amenorrhea]].<ref>{{cite web
| url = http://www.uoregon.edu/~hphy/AT/FATriad/links/amenorrhea.htm
| title= Amenorrhea
| accessdate = 2007-08-14
| work = The Female Athlete Triad
| author = Julia Berry
| coauthors = Anne Bradley; Hillery Magness
| publisher = University of Oregon, Department of Human Physiology}}</ref>
==Nutrition and recovery==
Proper [[nutrition]] is at least as important to health as exercise. When exercising, it becomes even more important to have a good diet to ensure that the body has the correct ratio of [[Macronutrient (nutrition)|macronutrients]] whilst providing ample [[micronutrient]]s, in order to aid the body with the recovery process following strenuous exercise.<ref>Kimber, N., Heigenhauser, G., Spriet, L., and Dyck, D. 2003. Skeletal muscle fat and carbohydrate metabolism during recovery from glycogen-depleting exercise in humans. ''The Journal of Phsyiology, 548''(Pt. 3), 919-927.</ref>
Proper rest and recovery are 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 to allow adequate recovery between exercise sessions.
The above two factors can be compromised by psychological compulsions ([[eating disorder]]s such as [[exercise bulimia]], [[anorexia nervosa|anorexia]], and other [[bulimia]]s), 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.<ref>Mirkin, G. 2005. Exercise requires time for recovery. ''Washington Times, May 29, 2005,'' C.11. Retrieved October 5, 2006, from ProQuest database.</ref>
==Exercise and brain function==
{{wikiquote}}
In the long term, exercise is beneficial to the brain by:
*increasing the blood and oxygen flow to the brain
*increasing growth factors that help [[neurogenesis|create new nerve cells]] and promote [[synaptic plasticity]]<!--
--><ref name="pmid18059283">{{cite journal |author=Hunsberger JG, Newton SS, Bennett AH, Duman CH, Russell DS, Salton SR, Duman RS |title=Antidepressant actions of the exercise-regulated gene VGF |journal=Nat. Med. |volume=13 |issue=12 |pages=1476–82 |year=2007 |pmid=18059283 |doi=10.1038/nm1669}}</ref><!--
-->
*increasing chemicals in the brain that help [[cognition]], such as [[dopamine]], [[glutamate]], [[norepinephrine]], and [[serotonin]]<ref>Parker-Pope, T. (2001). For a Healthy Brain You Really Need to Use Your Head -- Physical and Mental Exercise Can Stave Off Mental Decline. ''The Wall Street Journal Europe, November 26, 2001,'' 8. Retrieved October 5, 2006, from ProQuest database.</ref>
==Categories of physical exercise==
* [[Aerobic exercise]]
* [[Anaerobic exercise]]
* [[Strength training]]
* [[Sport agility|Agility training]]
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-lifting) can cause the [[systolic]] pressure to rise significantly.
==Breathing==
Active [[exhalation]] during physical exercise helps the body to increase its maximum lung capacity. This results in greater efficiency, since the heart has to do less work to oxygenate the muscles, and there is also increased muscular efficiency through greater blood flow. Consciously breathing deeply during [[aerobic]] exercise helps this development of the heart and lungs.
==See also==
{{Portal|Health|Nuvola apps package favorite.png}}
{{Wiktionary|exercise}}
<div style="-moz-column-count:3; column-count:3;">
* [[Active Living]]
* [[Army Physical Fitness Test (APFT)]]
* [[Exercise physiology]]
* [[Exercise equipment]]
* [[Exercise hypertension]]
* [[Exercise-induced anaphylaxis]]
* [[Exercise induced nausea]]
* [[Kinesiology]]
* [[Exercise-induced asthma]]
* [[Exercise intensity]]
* [[Exercise intolerance]]
* [[Green exercise]]
* [[Hunter-gatherer fitness]]
* [[List of basic exercise topics]]
* [[Pilates]]
* [[Sports training]]
</div>
==References==
{{Reflist|2}}
==Sources==
*{{cite book | first =Rebecca J. | last =Donatelle | authorlink = | coauthors = | year =2005 | month = | title =Health, The Basics | chapter = | editor = | others = | edition =6th ed. | pages = | location=San Francisco | publisher=Pearson Education | id =ISBN 0-8053-2852-1 | url = }}
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[[Category:Self-care]]
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