Editing Marathon (section)

==Health risks==
{{See also|List of marathon fatalities}}
Marathon running has various health risks, though these can be diminished with preparation and care.<ref>Keener, Candace. (27 February 2008) [http://entertainment.howstuffworks.com/marathon6.htm HowStuffWorks "The Health Risks of the Marathon"] {{Webarchive|url=https://web.archive.org/web/20100418183243/http://entertainment.howstuffworks.com/marathon6.htm |date=18 April 2010 }}. Entertainment.howstuffworks.com. Retrieved 19 April 2011.</ref> Training and the races themselves can put runners under stress. While very rare, even death is a possibility during a race.

Common minor health risks include [[blister]]s, [[tendonitis]], [[fatigue]], knee or ankle [[sprain]], dehydration ([[electrolyte imbalance]]), and other conditions. Many are categorised as overuse injuries.

===Cardiac health===
[[File:VVM 2007 foto 0284.JPG|thumb|Officers patrolling a marathon course in [[Ukraine]]]]
In 2016, a systematic medical review found that the risk of [[Sudden cardiac death of athletes|sudden cardiac death]] during or immediately after a marathon was between 0.6 and 1.9 deaths per 100,000 participants, varying across the specific studies and the methods used, and not controlling for age or gender.<ref>{{cite journal |journal=The Physician and Sportsmedicine |volume=44 |issue=1 |date=January 2016 |title=Sudden cardiac death in marathons: a systematic review |vauthors=Waite O, Smith A, Madge L, Spring H, Noret N |pages=79–84 |doi=10.1080/00913847.2016.1135036 |pmid=26765272 |s2cid=36458482 |url=http://ray.yorksj.ac.uk/id/eprint/1282/1/Waite%20et%20al%202016.pdf |access-date=19 March 2018 |archive-url=https://web.archive.org/web/20170921225307/https://ray.yorksj.ac.uk/id/eprint/1282/1/Waite%20et%20al%202016.pdf |archive-date=21 September 2017 |url-status=live}}</ref> Since the risk is small, cardiac screening programs for marathons are uncommon. However, this review was not an attempt to assess the overall cardiac health impact of marathon running.

A 2006 study of non-elite Boston Marathon participants tested runners for certain proteins that indicate heart damage or dysfunction (see [[Troponin]]) and gave them [[echocardiogram]] scans, before and after the marathon. The study revealed that, in that sample of 60 people, runners who had averaged fewer than {{convert|56|km|abbr=on}} of weekly training in the 4 months before the race were most likely to show some heart damage or dysfunction, while runners who had done more than {{convert|72|km|abbr=on}} of weekly training showed few or no heart problems.<ref>{{cite journal |journal=Circulation |date=28 November 2006 |volume=114 |issue=22 |pages=2325–2533 |title=Myocardial injury and ventricular dysfunction related to training levels among non-elite participants in the Boston Marathon |vauthors=Neilan TG, etal |pmid=17101848 |doi=10.1161/CIRCULATIONAHA.106.647461|doi-access=free }}</ref>

According to a Canadian study presented in 2010, running a marathon can temporarily result in decreased function of more than half the muscle segments in the heart's main pumping chamber, but neighboring segments are generally able to compensate. Full recovery is reached within three months. The fitter the runner, the less the effect. The runners with decreased left ventricle function had an average peak weekly training distance of {{convert|55.1|km|abbr=on}}, while those who did not averaged {{convert|69.1|km|abbr=on}}. The marathon was held in {{convert|35|C}} weather. According to one of the researchers: "Regular exercise reduces cardiovascular risk by a factor of two or three in the long run, but while we're doing vigorous exercise such as marathon running, our cardiac risk increases by seven."<ref>{{cite news |url=http://www.livescience.com/10211-temporary-heart-damage-explain-marathon-deaths.html |title=Temporary Heart Damage May Explain Marathon Deaths |first=Stephanie |last=Pappas |publisher=Live Science |date=25 October 2010 |access-date=15 May 2017 |archive-url=https://web.archive.org/web/20170417185619/http://www.livescience.com/10211-temporary-heart-damage-explain-marathon-deaths.html |archive-date=17 April 2017 |url-status=live}}</ref><ref>{{cite journal |journal=Canadian Journal of Cardiology |date=October 2013 |volume=29 |issue=10 |pages=1269–1276 |title=Transient Myocardial Tissue and Function Changes During a Marathon in Less Fit Marathon Runners |vauthors=Gaudreault V, etal |doi=10.1016/j.cjca.2013.04.022|pmid=23910227 }}</ref>

===Hydration===
[[File:Boston marathon mile 25 gatorade volunteer 050418.jpg|thumb|right|A volunteer hands out fluids at a marathon water stop.]]
Overconsumption is the most significant concern associated with water consumption during marathons. Drinking excessive amounts of fluid during a race can lead to dilution of sodium in the blood, a condition called [[exercise-associated hyponatremia]], which may result in vomiting, seizures, coma and even death.<ref>[http://www.merckmanuals.com/professional/sec12/ch156/ch156d.html Merck Manual: Hyponatremia] {{Webarchive|url=https://web.archive.org/web/20110111045040/http://www.merckmanuals.com/professional/sec12/ch156/ch156d.html |date=11 January 2011 }}. Merckmanuals.com. Retrieved 18 April 2013.</ref> Dr. Lewis G. Maharam, medical director for the New York City Marathon, stated in 2005: "There are no reported cases of dehydration causing death in the history of world running, but there are plenty of cases of people dying of hyponatremia."<ref>{{cite news | last=Kolata | first=Gina | date=20 October 2005 | url=https://www.nytimes.com/2005/10/20/sports/othersports/20marathon.html | title=Marathoners Warned About Too Much Water |newspaper=The New York Times| access-date=10 February 2017 | archive-url=https://web.archive.org/web/20120830070009/http://www.nytimes.com/2005/10/20/sports/othersports/20marathon.html | archive-date=30 August 2012 | url-status=live}}</ref>

For example, Dr. Cynthia Lucero died at the age of 28 while participating in the 2002 [[Boston Marathon]]. It was Lucero's second marathon.<ref>{{cite news|title=Fluid Cited in Marathoner's Death|url=https://apnews.com/424edce6ed89d8adcb14d4d97c0448a3|access-date=14 March 2014|work=Associated Press News|date=13 August 2002|archive-url=https://web.archive.org/web/20140419014128/http://www.apnewsarchive.com/2002/Fluid-Cited-in-Marathoner-s-Death/id-424edce6ed89d8adcb14d4d97c0448a3|archive-date=19 April 2014|url-status=live}}</ref> At mile 22, Lucero complained of feeling "dehydrated and rubber-legged."<ref>{{cite book|last=Noakes, MD, DSc|first=Tim|title=Waterlogged|date=1 May 2012|publisher=Human Kinetics|isbn=978-1450424974|page=4|url=https://books.google.com/books?id=3_zPW6FyqgAC&q=waterlogged|access-date=13 December 2015|archive-url=https://web.archive.org/web/20160521181405/https://books.google.com/books?id=3_zPW6FyqgAC&printsec=frontcover&dq=waterlogged&hl=en&sa=X&ei=mM8jU5PjII7xkQecv4HICw&ved=0CCwQ6AEwAA#v=onepage&q=waterlogged&f=false|archive-date=21 May 2016|url-status=live}}</ref> She soon wobbled and collapsed to the ground, and was unconscious by the time the paramedics reached her. Lucero was admitted to Brigham and Women's Hospital and died two days later.<ref>{{cite news|title=ROAD RACING; Boston Marathon Runner Dies|url=https://www.nytimes.com/2002/04/19/sports/plus-road-racing-boston-marathon-runner-dies.html|access-date=14 March 2014|newspaper=The New York Times|date=19 April 2002|archive-url=https://web.archive.org/web/20140423024040/http://www.nytimes.com/2002/04/19/sports/plus-road-racing-boston-marathon-runner-dies.html|archive-date=23 April 2014|url-status=live}}</ref>

Lucero's cause of death was determined to be [[hyponatremic encephalopathy]], a condition that causes swelling of the brain due to an imbalance of sodium in the blood known as [[exercise-associated hyponatremia]] (EAH). While EAH is sometimes referred to as "[[water intoxication]]", Lucero drank large amounts of [[Gatorade]] during the race,<ref name="WCVB">{{cite news|title=Doctors: Marathoner Died From Too Much Water|url=http://www.wcvb.com/Doctors-Marathoner-Died-From-Too-Much-Water/11334548|access-date=14 March 2014|newspaper=WCVB News|archive-url=https://web.archive.org/web/20140419012323/http://www.wcvb.com/Doctors-Marathoner-Died-From-Too-Much-Water/11334548|archive-date=19 April 2014|url-status=live}}</ref><ref>{{cite news|last=Nearman|first=Steve|title=Too much of a good thing|url=http://www.washingtontimes.com/news/2003/oct/23/20031023-114721-5381r/?page=all|access-date=14 March 2014|newspaper=The Washington Times|date=23 October 2003|archive-url=https://web.archive.org/web/20140419014642/http://www.washingtontimes.com/news/2003/oct/23/20031023-114721-5381r/?page=all|archive-date=19 April 2014|url-status=live}}</ref> demonstrating that runners who consume sodium-containing sports drinks in excess of thirst can still develop EAH.<ref name="WCVB" /><ref>{{cite journal |vauthors=Almond CS, Shin AY, Fortescue EB, etal |title=Hyponatremia among runners in the Boston Marathon |journal=N. Engl. J. Med. |volume=352 |issue=15 |pages=1550–6 |date=April 2005 |pmid=15829535 |doi=10.1056/NEJMoa043901 |s2cid=42909509 |doi-access=free }}</ref> Because hyponatremia is caused by excessive water retention, and not just loss of sodium, consumption of sports drinks or salty foods may not prevent hyponatremia.<ref>{{cite web |url=http://www.amaasportsmed.org/news_room/hyponatremia_reuters.htm |title=Marathon Dilemma: How Much Water is Too Much? |year=2003 |last=Engler |first=Natalie |work=AMAASportsMed.org |publisher=American Running Association |agency=Reuters|archive-url=https://web.archive.org/web/20151110033029/http://www.amaasportsmed.org/news_room/hyponatremia_reuters.htm |archive-date=10 November 2015}}</ref>

Women are more prone to hyponatremia than men. A study in the ''[[New England Journal of Medicine]]'' found that 13% of runners completing the 2002 Boston Marathon had hyponatremia.<ref>{{Cite journal |vauthors=Almond CS, Shin AY, Fortescue EB, etal |title=Hyponatremia among runners in the Boston Marathon |journal=The New England Journal of Medicine |volume=352 |issue=15 |pages=1550–6 |date=April 2005 |pmid=15829535 |doi=10.1056/NEJMoa043901|s2cid=42909509 |doi-access=free }}</ref>

The International Marathon Medical Directors Association (IMMDA) advised in 2006 that fluid intake should be adjusted individually according to factors such as body weight, sex, climate, pace, fitness ([[VO2 max|VO<sub>2</sub> max]]), and sweat rate, as fluid requirements can vary between people depending on these variables. The IMMDA also recommended sports drinks that include carbohydrates and electrolytes instead of plain water and said that runners should "drink to thirst", trying to refrain from drinking at every fluid station before feeling thirsty.<ref name="IMMDA 2006">{{cite web|url=http://aimsworldrunning.org/guidelines_fluid_replacement.htm|title=IMMDA's REVISED FLUID RECOMMENDATIONS FOR RUNNERS & WALKERS|date=6 May 2006|author=Writing committee: Lewis G. Maharam, MD.FACSM (chair), Tamara Hew DPM, Arthur Siegel MD, Marv Adner, MD, Bruce Adams, MD and Pedro Pujol, MD, FACSM|publisher=Association of International Marathons and Distance Races|url-status=dead|archive-url=https://web.archive.org/web/20120427085851/http://www.aimsworldrunning.org/guidelines_fluid_replacement.htm|archive-date=27 April 2012}}</ref> Heat exposure leads to diminished thirst drive and thirst may not be a sufficient incentive to drink in many situations.<ref name="Bethea, 2005">{{cite web|title=Dehydration Review, Report Number HSL/2005/29|url=http://www.hse.gov.uk/research/hsl_pdf/2005/hsl0529.pdf#page=31|author1=Bethea, Damian|author2=Powell, Shuma|date=July 2005|publisher=Health & Safety Laboratory Harpur Hill, Buxton, Derbyshire|access-date=7 July 2011|archive-url=https://web.archive.org/web/20110704112917/http://www.hse.gov.uk/research/hsl_pdf/2005/hsl0529.pdf#page=31|archive-date=4 July 2011|url-status=live}}</ref> The IMMDA and HSL Harpur Hill give recommendations to drink fluid in small volumes frequently at an approximate rate falling between {{convert|100|-|250|ml|USfloz|abbr=on}} every 15 minutes.<ref name="Bethea, 2005" /><ref name="IMMDA 2006"/> A patient suffering hyponatremia can be given a small volume of a concentrated [[sodium chloride|salt]] solution intravenously to raise [[sodium]] concentrations in the blood. Some runners weigh themselves before running and write the results on their bibs. If anything goes wrong, [[first aid]] workers can use the weight information to tell if the patient had consumed too much water.

===Body temperature===
Exertional [[heat stroke]] is an emergency condition in which [[thermoregulation]] fails and the body temperature rises dangerously above {{convert|40|C|F}}. It becomes a greater risk in warm and humid weather, even for young and fit individuals. Treatment requires rapid physical cooling of the body.<ref>{{cite journal |journal=Medicine & Science in Sports & Exercise |volume=39 |issue=3 |date=March 2007 |title=American College of Sports Medicine position stand: Exertional heat illness during training and competition |pages=556–572 |doi=10.1249/MSS.0b013e31802fa199 |pmid=17473783 | last1 = Armstrong | first1 = LE | last2 = Casa | first2 = DJ | last3 = Millard-Stafford | first3 = M | last4 = Moran | first4 = DS | last5 = Pyne | first5 = SW | last6 = Roberts | first6 = WO|s2cid=27001417 | doi-access = free }}</ref>