View source for Walking

{{short description|Gait of locomotion among legged animals}}
{{about|the mode of transportation}}
{{redirect|Walk}}
[[File:Women walking in Hyderabad street.jpg|thumb|Women walking in Hyderabad]]
'''Walking''' (also known as '''ambulation''') is one of the main [[gait]]s of [[terrestrial locomotion]] among legged [[animals]]. Walking is typically slower than [[running]] and other gaits. Walking is defined as an "[[inverted pendulum]]" gait in which the body vaults over the stiff limb or limbs with each step. This applies regardless of the usable number of limbs—even [[arthropod]]s, with six, eight, or more limbs, walk.<ref>{{ cite journal |vauthors=Cavagna GA, Heglund NC, Taylor CR |year=1977 |title= Mechanical work in terrestrial locomotion: two basic mechanisms for minimizing energy expenditure. |journal=[[American Journal of Physiology]] |volume=233 |issue=5 |pages= R243-261|doi=10.1152/ajpregu.1977.233.5.R243|pmid=411381 |s2cid=15842774 }}</ref> In humans, walking has health benefits including improved [[mental health]] and reduced risk of [[cardiovascular disease]] and death.

==Difference from running==
{{main|Running}}
{{See also|Jogging}}
[[File:1987WorldCupTrials.jpg|thumb|Racewalkers at the World Cup Trials in 1987]]

The word ''walk'' is descended from the [[Old English language|Old English]] ''wealcan'' 'to roll'. In [[human]]s and other [[biped]]s, walking is generally distinguished from running in that only one foot at a time leaves contact with the ground and there is a period of double-support. In contrast, running begins when both feet leave the ground during each step. This distinction has the status of a formal requirement in [[Racewalking|competitive walking]] events. For [[quadruped]]al species, there are numerous [[gait]]s which may be termed walking or running, and distinctions based upon the presence or absence of a suspended phase or the number of feet in contact any time do not yield mechanically correct classification.<ref name="Bie">{{cite book |last=Biewener |first=A. A. |year=2003 |title=Animal Locomotion |publisher=Oxford University Press |isbn= 978-0-19-850022-3 |url=https://books.google.com/books?id=yMaN9pk8QJAC&q=biomechanics+biewener }}</ref> The most effective method to distinguish walking from running is to measure the height of a person's [[centre of mass]] using [[motion capture]] or a [[force plate]] at mid-stance. During walking, the centre of mass reaches a maximum height at mid-stance, while running, it is then at a minimum. This distinction, however, only holds true for locomotion over level or approximately level ground. For walking up grades above 10%, this distinction no longer holds for some individuals. Definitions based on the percentage of the stride during which a foot is in contact with the ground (averaged across all feet) of greater than 50% contact corresponds well with identification of 'inverted pendulum' mechanics and are indicative of walking for animals with any number of limbs; however, this definition is incomplete.<ref name="Bie"/> Running humans and animals may have contact periods greater than 50% of a gait cycle when rounding corners, running uphill or carrying loads.

Speed is another factor that distinguishes walking from running. Although walking speeds can vary greatly depending on many factors, such as height, weight, age, terrain, surface, load, culture, effort, and fitness, the average human [[Preferred Walking Speed|walking speed]] at crosswalks is about 5.0 kilometres per hour (km/h), or about 1.4 meters per second (m/s), or about 3.1 miles per hour (mph). Specific studies have found [[pedestrian]] walking speeds at crosswalks ranging from {{convert|4.51|to|4.75|km/h|mph|abbr=on}} for older individuals and from {{convert|5.32|to|5.43|km/h|mph|abbr=on}} for younger individuals;<ref>{{cite web|url=http://www.usroads.com/journals/p/rej/9710/re971001.htm|title=Study Compares Older and Younger Pedestrian Walking Speeds|publisher=TranSafety, Inc|date=1997-10-01|access-date=2009-08-24|archive-date=2009-07-03|archive-url=https://web.archive.org/web/20090703084118/http://www.usroads.com/journals/p/rej/9710/re971001.htm}}</ref><ref>{{cite web|url=http://www.westernite.org/datacollectionfund/2005/psu_ped_summary.pdf|title=Establishing Pedestrian Walking Speeds|first=Karen|last=Aspelin|date=2005-05-25|publisher=[[Portland State University]]|access-date=2009-08-24|archive-url=https://web.archive.org/web/20051225181534/http://www.westernite.org/datacollectionfund/2005/psu_ped_summary.pdf|archive-date=2005-12-25|url-status=live}}</ref> a brisk walking speed can be around {{convert|6.5|km/h|mph|abbr=on}}.<ref>{{cite web|url=http://walking.about.com/od/measure/f/howfastwalking.htm|access-date=2012-08-17|title=about.com page on walking speeds|archive-date=2016-04-14|archive-url=https://web.archive.org/web/20160414183615/http://walking.about.com/od/measure/f/howfastwalking.htm}}</ref> In Japan, the standard measure for walking speed is 80&nbsp;m/min (4.8&nbsp;km/h).
Champion [[racewalking|racewalkers]] can average more than {{convert|14|km/h|mph|abbr=on}} over a distance of {{convert|20|km|mi|abbr=on}}.

An average human child achieves independent walking ability at around 11 months old.<ref>{{cite journal |vauthors=Samra HA, Specker B |title=Walking Age Does Not Explain Term vs. Preterm Differences in Bone Geometry |journal=J. Pediatr. |volume=151 |issue=1 |pages=61–6, 66.e1–2 |date=July 2007 |pmid=17586192 |pmc=2031218 |doi=10.1016/j.jpeds.2007.02.033 }}</ref>

==Health benefits==
{{main|Physical_exercise#Benefits|l1=Physical exercise}}

Regular, brisk [[exercise]] can improve [[confidence]], [[Endurance|stamina]], [[energy]], [[weight control]] and may reduce [[Chronic stress|stress]].<ref name="references">References:

* {{cite book |last1=Edlin |first1=Gordon |url=https://books.google.com/books?id=0MUi2yslAS0C&pg=PA156 |title=Health and wellness |last2=Golanty |first2=Eric |publisher=Jones & Bartlett Publishers |year=2007 |isbn=978-0-7637-4145-7 |page=156}} (Google Books)
* {{cite book |last=Tolley |first=Rodney |url=https://books.google.com/books?id=738aG1QxoBUC&pg=PA72 |title=Sustainable transport: planning for walking and cycling in urban environments |publisher=Woodhead Publishing |year=2003 |isbn=1-85573-614-4 |page=72}}</ref> Scientific studies have also shown that walking may be beneficial for the mind, improving [[memory]] skills, [[learning]] ability, [[attentional control|concentration]], mood, creativity, and abstract reasoning.<ref name="references"/> Sustained walking sessions for a minimum period of thirty to sixty minutes a day, five days a week, with the correct walking posture may improve health.<ref>{{Cite web|title=Proper walking technique|url=https://www.mayoclinic.org/healthy-lifestyle/fitness/multimedia/proper-walking-technique/img-20007670|access-date=2023-01-02|website=Mayo Clinic|language=en}}</ref><ref>{{Cite web |date=2017-07-29 |title=Perfecting your walking technique |url=https://www.health.harvard.edu/staying-healthy/perfecting-your-walking-technique |access-date=2024-03-02 |website=Harvard Health |language=en}}</ref>

The [[Centers for Disease Control and Prevention]]'s fact sheet on the "Relationship of Walking to Mortality Among U.S. Adults with Diabetes" states that those with diabetes who walked for two or more hours a week lowered their mortality rate from all causes by 39 percent. Women who took 4,500 steps to 7,500 steps a day seemed to have fewer premature deaths compared to those who only took 2,700 steps a day.<ref>{{Cite news|title=Taking steps so you may live longer|url=https://www.irishtimes.com/life-and-style/health-family/fitness/taking-steps-so-you-may-live-longer-1.3923407|access-date=2023-01-02|newspaper=The Irish Times|language=en}}</ref> "Walking lengthened the life of people with diabetes regardless of age, sex, race, body mass index, length of time since diagnosis and presence of complications or functional limitations."<ref>{{cite web |url=https://www.cdc.gov/diabetes/pubs/factsheets/walking.htm |title=Relationship of walking to mortality among U.S. adults |publisher=[[Centers for Disease Control]] |date=20 May 2011 |access-date=16 October 2013 |archive-url=https://web.archive.org/web/20130129041207/http://www.cdc.gov/diabetes/pubs/factsheets/walking.htm |archive-date=29 January 2013}}</ref> One limited study found preliminary evidence of a relationship between the speed of walking and health, and that the best results are obtained with a speed of more than {{convert|2.5|mph|km/h|abbr=on}}.<ref>
{{cite journal
|author1=Paul T. Williams mail |author2=Paul D. Thompson | title = The Relationship of Walking Intensity to Total and Cause-Specific Mortality. Results from the National Walkers' Health Study
| journal = PLOS ONE
| doi=10.1371/journal.pone.0081098
|pmid=24260542 | date =  November 19, 2013
| volume=8
|issue=11 | article-number=e81098
| pmc=3834211
|bibcode=2013PLoSO...881098W |doi-access=free }}</ref>
Even a [[fart walk|light walk after a meal]] offers benefits in reducing postprandial glucose spikes in people with or at risk for type 2 diabetes.<ref>{{cite journal|author1=Bellini, M. |display-authors=etal |year=2022 |title=The Effects of Postprandial Walking on the Glucose Response after Meals with Different Characteristics | journal=Nutrients |volume=14 |issue=5 |page=1080 |doi=10.3390/nu14051080 |doi-access=free |pmid=35268055 |pmc=8912639}}</ref>

A 2023 study by the ''[[European Journal of Preventive Cardiology]]'', the largest study to date, found that walking at least 2,337 steps a day reduced the risk of dying from [[cardiovascular disease]]s, and that 3,967 steps a day reduced the risk of dying from any cause. Benefits continued to increase with more steps.<ref name=":0">{{Cite news |last=Geddes |first=Linda |date=2023-08-08 |title=Revealed: walking just 4,000 steps a day can reduce risk of dying |language=en-GB |work=[[The Guardian]] |url=https://www.theguardian.com/society/2023/aug/09/revealed-walking-just-4000-steps-a-day-can-reduce-risk-of-dying |access-date=2023-08-09 |issn=0261-3077}}</ref> James Leiper, associate medical director at the [[British Heart Foundation]], said that if the benefits of walking could be sold as a medicine "we would be hailing it as a wonder drug".<ref name=":0" />

==Origins==
[[File:Gait-of-healthy-Hamster.ogv|thumb|A walking hamster]]
It is theorized that "walking" among [[tetrapods]] originated underwater with air-breathing fish that could "walk" underwater, giving rise (potentially with vertebrates like ''[[Tiktaalik]]'')<ref>{{Cite web|url=https://evolution.berkeley.edu/evolibrary/news/060501_tiktaalik|title=What has the head of a crocodile and the gills of a fish?|website=evolution.berkeley.edu|date=May 2006|access-date=2018-06-06}}</ref> to the plethora of land-dwelling life that walk on four or two limbs.<ref>{{cite web|last=Choi |first=Charles |url=http://www.nbcnews.com/id/45645209 |archive-url=https://web.archive.org/web/20200716010438/http://www.nbcnews.com/id/45645209 |archive-date=July 16, 2020 |title=Hopping fish suggests walking originated underwater; Discovery might redraw the evolutionary route scientists think life took from water to land |publisher=NBC News |date=2011-12-12 |access-date=2012-08-22}}</ref> While terrestrial [[tetrapods]] are theorised to have a single origin, [[arthropods]] and their relatives are thought to have independently evolved walking several times, specifically in [[Hexapoda|hexapods]], [[myriapods]], [[chelicerates]], [[tardigrades]], [[onychophorans]], and [[crustaceans]].<ref>{{cite book|url=https://books.google.com/books?id=Ql6Jl6wKb88C&q=arthropod+invasion+of+the+land&pg=PA109 |title=Evolution of the Insects – David Grimaldi, Michael S. Engel – Google Books |date=2005-05-16 |access-date=2018-06-11|isbn=978-0-521-82149-0 |last1=Grimaldi |first1=David |last2=Engel |first2=Michael S. |last3=Engel |first3=Michael S. |publisher=Cambridge University Press }}</ref> [[Little skate]]s, members of the [[demersal]] fish community, can propel themselves by pushing off the ocean floor with their pelvic fins, using neural mechanisms which evolved as early as 420 million years ago, before vertebrates set foot on land.<ref>{{Cite journal|last1=Jung|first1=Heekyung|last2=Baek|first2=Myungin|last3=D'Elia|first3=Kristen P.|last4=Boisvert|first4=Catherine|last5=Currie|first5=Peter D.|last6=Tay|first6=Boon-Hui|last7=Venkatesh|first7=Byrappa|last8=Brown|first8=Stuart M.|last9=Heguy|first9=Adriana|last10=Schoppik|first10=David|last11=Dasen|first11=Jeremy S.|date=2018-02-08|title=The Ancient Origins of Neural Substrates for Land Walking|journal=Cell|language=English|volume=172|issue=4|pages=667–682.e15|doi=10.1016/j.cell.2018.01.013|issn=0092-8674|pmid=29425489|pmc=5808577 }}</ref><ref>{{Cite web|date=2018-02-08|title=The wiring for walking developed long before fish left the sea|url=https://www.sciencenews.org/article/wiring-walking-developed-long-fish-left-sea|access-date=2023-01-02|language=en-US}}</ref>

=== Hominin ===
Data in the fossil record indicate that among hominin ancestors, bipedal walking was one of the first defining characteristics to emerge, predating other defining characteristics of ''[[Hominidae]]''.<ref name=":02">{{Cite journal |last1=Rodman |first1=Peter S. |last2=McHenry |first2=Henry M. |date=January 1980 |title=Bioenergetics and the origin of hominid bipedalism |url=https://onlinelibrary.wiley.com/doi/10.1002/ajpa.1330520113 |journal=American Journal of Physical Anthropology |language=en |volume=52 |issue=1 |pages=103–106 |doi=10.1002/ajpa.1330520113 |pmid=6768300 |bibcode=1980AJPA...52..103R |issn=0002-9483|url-access=subscription }}</ref> Judging from footprints discovered on a former shore in Kenya, it is thought possible that ancestors of modern humans were walking in ways very similar to the present activity as long as 3 million years ago.<ref>{{cite news
 | url = https://www.reuters.com/article/scienceNews/idUSTRE51P82420090226
 | title = Footprints show human ancestor with modern stride
 | first = Will | last = Dunham | work = Reuters
 | date = February 26, 2009 }}</ref><ref>{{cite magazine
 | url = http://www.sciam.com/article.cfm?id=15-million-footprints-uncover
 | title = Researchers Uncover 1.5 Million-Year-Old Footprints
 | first = Katherine | last = Harmon | magazine = Scientific American
 | date = February 26, 2009 }}</ref>

Today, the walking gait of humans is unique and differs significantly from [[Bipedalism|bipedal]] or [[Quadrupedalism|quadrupedal]] walking gaits of other primates, like chimpanzees. It is believed to have been selectively advantageous in hominin ancestors in the [[Miocene]] due to metabolic [[Efficient energy use|energy efficiency]]. Human walking has been found to be slightly more energy efficient than travel for a quadrupedal [[mammal]] of a similar size, like chimpanzees.<ref name=":13">{{Cite journal |last1=Sockol |first1=M. D. |last2=Raichlen |first2=D. A. |last3=Pontzer |first3=H. |date=2007-07-16 |title=Chimpanzee locomotor energetics and the origin of human bipedalism |journal=Proceedings of the National Academy of Sciences |volume=104 |issue=30 |pages=12265–12269 |doi=10.1073/pnas.0703267104 |pmid=17636134 |pmc=1941460 |bibcode=2007PNAS..10412265S |issn=0027-8424|doi-access=free }}</ref> The energy efficiency of human locomotion can be accounted for by the reduced use of muscle in walking, due to an upright posture which places ground reaction forces at the hip and knee.<ref name=":13"/> When walking bipedally, chimpanzees take a crouched stance with bent knees and hips, forcing the [[quadriceps]] muscles to perform extra work, which costs more energy.<ref name=":23">{{Cite book |last=DeSilva |first=Jeremy |title=First steps: how upright walking made us human |date=2021 |isbn=978-0-06-293849-7 |edition=1st |location=New York, NY |oclc=1244114018}}</ref> Comparing chimpanzee quadrupedal travel to that of true quadrupedal animals has indicated that chimpanzees expend one-hundred and fifty percent of the energy required for travel compared to true quadrupeds.

In 2007, a study further explored the origin of human [[bipedalism]], using chimpanzee and human energetic costs of locomotion.<ref name=":13"/> They found that the energy spent in moving the human body is less than what would be expected for an animal of similar size and approximately seventy-five percent less costly than that of chimpanzees. Chimpanzee quadrupedal and bipedal energy costs are found to be relatively equal, with chimpanzee bipedalism costing roughly ten percent more than quadrupedal. The same 2007 study found that among chimpanzee individuals, the energy costs for bipedal and quadrupedal walking varied significantly, and those that flexed their knees and hips to a greater degree and took a more upright posture, closer to that of humans, were able to save more energy than chimpanzees that did not take this stance. Further, compared to other apes, humans have longer legs and short dorsally oriented ischia (hipbone), which result in longer hamstring extensor moments, improving walking energy economy.<ref name=":3">{{Cite journal |last1=Kozma |first1=Elaine E. |last2=Webb |first2=Nicole M. |last3=Harcourt-Smith |first3=William E. H. |last4=Raichlen |first4=David A. |last5=D'Août |first5=Kristiaan |last6=Brown |first6=Mary H. |last7=Finestone |first7=Emma M. |last8=Ross |first8=Stephen R. |last9=Aerts |first9=Peter |last10=Pontzer |first10=Herman |date=2018-04-02 |title=Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins |journal=Proceedings of the National Academy of Sciences |volume=115 |issue=16 |pages=4134–4139 |doi=10.1073/pnas.1715120115 |pmid=29610309 |pmc=5910817 |bibcode=2018PNAS..115.4134K |issn=0027-8424|doi-access=free }}</ref><ref name=":13"/> Longer legs also support lengthened [[Achilles tendon]]s which are thought to increase energy efficiency in bipedal locomotor activities.<ref>{{Cite journal |last1=Blazevich |first1=Anthony J. |last2=Fletcher |first2=Jared R. |date=December 2023 |title=More than energy cost: multiple benefits of the long Achilles tendon in human walking and running |journal=Biological Reviews |language=en |volume=98 |issue=6 |pages=2210–2225 |doi=10.1111/brv.13002 |issn=1464-7931|doi-access=free |pmid=37525526 |arxiv=2205.13298 }}</ref> It was thought that hominins like ''[[Ardipithecus ramidus]],'' which had a variety of both terrestrial and arboreal adaptions would not be as efficient walkers, however, with a small body mass ''A. ramidus'' had developed an energy efficient means of bipedal walking while still maintaining arboreal adaptations.<ref name=":3" /> Humans have long [[femoral neck]]s, meaning that while walking, hip muscles do not require as much energy to flex while moving.<ref name=":23"/> These slight [[Kinematics|kinematic]] and [[Anatomy|anatomic]] differences demonstrate how bipedal walking may have developed as the dominant means of locomotion among early hominins because of the energy saved.<ref name=":13"/>

==Variants==
[[File:Nordic Walkers near Ilkley 020.JPG|thumb|[[Nordic walking|Nordic walkers]]]]
* [[Scrambling]] is a method of ascending a hill or mountain that involves using both hands, because of the steepness of the terrain.<ref>See Terry Adby and Stuart Johnston, ''The Hillwalker's Guide to Mountaineering'', (Milnthorpe: Cicerone, 2003), {{ISBN|1-85284-393-4}}, pp. 62–65 for more on defining scrambles.</ref> Of necessity, it will be a slow and careful form of walking and with the possibility of occasional brief, easy [[rock climbing]]. Some scrambling takes place on narrow exposed ridges where more attention to balance will be required than in normal walking.
* [[Snow shoe]]ing – Snowshoes are footwear for walking over the snow. Snowshoes work by distributing the weight of the person over a larger area so that the person's foot does not sink completely into the snow, a quality called "flotation". It is often said by snowshoers that if you can walk, you can snowshoe. This is true in optimal conditions, but snowshoeing properly requires some slight adjustments to walking. The method of walking is to lift the shoes slightly and slide the inner edges over each other, thus avoiding the unnatural and fatiguing "straddle-gait" that would otherwise be necessary. A snowshoer must be willing to roll his or her feet slightly as well. An exaggerated stride works best when starting out, particularly with larger or traditional shoes.
*[[Cross-country skiing]] – originally conceived like snow shoes as a means of travel in deep snow. Trails hiked in the summer are often skied in the winter and the [[Norwegian Trekking Association]] maintains over 400 huts stretching across thousands of kilometres of trails which hikers can use in the summer and skiers in the winter.<ref name=volken>{{cite book|last1= Volken|first1= Martin|last2= Schnell|first2= Scott|last3= Wheeler|first3= Margaret|title= Backcountry Skiing: Skills for Ski Touring and Ski Mountaineering|date= 2007|publisher= Mountaineers Books|isbn= 978-1-59485-038-7|page= [https://archive.org/details/backcountryskiin00volk/page/12 12]|url= https://archive.org/details/backcountryskiin00volk/page/12|access-date= 2014-07-12}}</ref>
* Beach walking is a sport that is based on a walk on the sand of the [[beach]]. Beach walking can be developed on compact sand or non-compact sand. There are beach walking competitions on non-compact sand, and there are world records of beach walking on non-compact sand in Multiday distances. Beach walking has a specific technique of walk.
[[Image:Wdomenada2003b.jpg|right|thumb|Free heels are a defining characteristic of ski touring]]
* [[Nordic walking]] is a physical activity and a sport, which is performed with specially designed [[walking pole]]s similar to [[ski pole]]s. Compared to regular walking, Nordic walking (also called pole walking) involves applying force to the poles with each stride. Nordic walkers use more of their entire body (with greater intensity) and receive fitness building stimulation not present in normal walking for the chest, lats, triceps, biceps, shoulder, abdominals, spinal and other core muscles that may result in significant increases in heart rate at a given pace.<ref>''Medicine & Science in Sports & Exercise''. 27, No. 4 April 1995: 607–11</ref> Nordic walking has been estimated as producing up to a 46% increase in energy consumption, compared to walking without poles.<ref>Cooper Institute, ''Research Quarterly for Exercise and Sports'', 2002</ref><ref>{{cite journal|title=  Field testing of physiological responses associated with Nordic Walking|date=2013-03-25 |pmid=12230336 | doi=10.1080/02701367.2002.10609023 |volume=73 |issue=3 |journal=Res Q Exerc Sport |pages=296–300 |vauthors=Church TS, Earnest CP, Morss GM |s2cid=24173445 }}</ref>
* [[Pedestrianism]] is a sport that developed during the late eighteenth and nineteenth centuries, and was a popular spectator sport in the [[British Isles]]. By the end of the 18th century, and especially with the growth of the popular press, feats of foot travel over great distances (similar to a modern [[ultramarathon]]) gained attention, and were labeled "pedestrianism". Interest in the sport, and the wagering which accompanied it, spread to the United States, Canada, and Australia in the 19th century. By the end of the 19th century, Pedestrianism was largely displaced by the rise in modern [[spectator sport]]s and by controversy involving rules, which limited its appeal as a source of wagering and led to its inclusion in the amateur athletics movement. Pedestrianism was first codified in the last half of the 19th century, evolving into what would become [[racewalking]], By the mid 19th century, competitors were often expected to extend their legs straight at least once in their stride, and obey what was called the "fair heel and toe" rule. This rule, the source of modern racewalking, was a vague commandment that the toe of one foot could not leave the ground before the heel of the next foot touched down. This said, rules were customary and changed with the competition. Racers were usually allowed to jog in order to fend off cramps, and it was distance, not code, which determined gait for longer races. Newspaper reports suggest that "[[Jogging|trotting]]" was common in events.<ref>Phil Howell (1986).</ref>
* [[Speed walking]] is the general term for fast walking. Within the Speed Walking category are a variety of fast walking techniques: Power Walking, Fit Walking, etc.
* [[Power walking]] is the act of walking with a speed at the upper end of the natural range for walking gait, typically {{convert|7|to|9|km/h|mph|abbr=on}}. To qualify as power walking as opposed to [[jogging]] or running, at least one foot must be in contact with the ground at all times.
* [[Racewalking]] is a long-distance [[Athletics (sport)|athletic]] event. Although it is a foot race, it is different from [[running]] in that one foot must appear to be in contact with the ground at all times. Stride length is reduced, so to achieve competitive speeds, racewalkers must attain [[Cadence (gait)|cadence]] rates comparable to those achieved by [[Olympic Games|Olympic]] 800-meter runners,<ref>{{Cite journal | url=https://www.csmonitor.com/World/Olympics/2012/0803/Wait-that-s-an-Olympic-event |title = Wait ... That's an Olympic event?|journal = Christian Science Monitor|date = 3 August 2012}}</ref> and they must do so for hours at a time since the Olympic events are the [[20 kilometers race walk|{{convert|20|km|mi|abbr=on}} race walk]] (men and women) and [[50 kilometers race walk|{{convert|50|km|mi|abbr=on}} race walk]] (men only), and [[50 miles race walk|{{convert|50|mi|km|adj=on}}]] events are also held. See also '''pedestrianism''' above.
* Afghan walking: The Afghan Walk is a rhythmic breathing technique synchronized with walking. It was born in the 1980s on the basis of the observations made by the Frenchman Édouard G. Stiegler, during his contacts with Afghan caravaners, capable of making walks of more than 60&nbsp;km per day for dozens of days.<ref>Stiegler, Édouard., ''Régénération par la marche afghane'', G. Trédaniel, 2013 (ISBN 978-2-8132-0631-2 et 2-8132-0631-8, OCLC 864714304)</ref><ref>Isabel Conway, "Stepping out the Afghan way".''The Irish Times'', Apr 20 2010 [https://www.irishtimes.com/news/health/stepping-out-the-afghan-way-1.654699]
</ref>
* [[Backward walking]]: In this activity, an individual walks in reverse, facing away from their intended direction of movement. This unique form of exercise has gained popularity for its various health and fitness benefits. It requires more attention and engages different muscles than forward walking, making it a valuable addition to a fitness routine. Some potential benefits of retro walking include improved balance, enhanced coordination, strengthened leg muscles, and reduced knee stress. It is also a rehabilitation exercise for certain injuries and can be a way to switch up one's workout routine.

==Biomechanics==

[[File:Muybridge human male walking animated.gif|alt=An 1887 stop-motion of a human walking.|thumb|upright=.65|Human walking cycle animation by [[Eadweard Muybridge]]]]
[[File:CGI Human Walk.jpg|thumb|Computer simulation of a human walk cycle. In this model the head keeps the same level at all times, whereas the hip follows a sine curve.]]
Human walking is accomplished with a strategy called the [[double pendulum]]. During forward motion, the leg that leaves the ground swings forward from the hip. This sweep is the first pendulum. Then the leg strikes the ground with the heel and rolls through to the toe in a motion described as an inverted pendulum. The motion of the two legs is coordinated so that one foot or the other is always in contact with the ground. While walking, the muscles of the calf contract, raising the body's center of mass, and during muscle contraction, [[potential energy]] is stored. Then [[gravity]] pulls the body forward and down onto the other leg and the potential energy is then transformed into [[kinetic energy]]. The process of human walking can save approximately sixty-five percent of the energy used by utilizing gravity in forward motion.<ref name=":23"/>

Walking differs from a [[running]] [[gait]] in a number of ways. The most obvious is that during walking one leg always stays on the ground while the other is swinging. In running there is typically a [[Ballistics|ballistic]] phase where the runner is airborne with both feet in the air (for bipedals).

Another difference concerns the movement of the [[centre of mass]] of the body. In walking the body "vaults" over the leg on the ground, raising the centre of mass to its highest point as the leg passes the vertical, and dropping it to the lowest as the legs are spread apart. Essentially [[kinetic energy]] of forward motion is constantly being traded for a rise in [[potential energy]]. This is reversed in running where the centre of mass is at its lowest as the leg is vertical. This is because the impact of landing from the ballistic phase is absorbed by bending the leg and consequently storing energy in [[muscles]] and [[tendons]]. In running there is a conversion between kinetic, potential, and [[elastic energy]].

There is an absolute limit on an individual's speed of walking (without special techniques such as those employed in [[speed walking]]) due to the upwards acceleration of the centre of mass during a stride – if it is greater than the acceleration due to gravity the person will become airborne as they vault over the leg on the ground. Typically, however, animals switch to a run at a lower speed than this due to energy efficiencies.

Based on the 2D inverted pendulum model of walking, there are at least five physical constraints that place fundamental limits on walking like an inverted pendulum.<ref>{{Cite journal|last=Patnaik|first=Lalit |display-authors=etal |date=October 2015|title=Physical constraints, fundamental limits, and optimal locus of operating points for an inverted pendulum based actuated dynamic walker|journal=Bioinspiration & Biomimetics|volume=10|issue=6 |article-number=064001|doi=10.1088/1748-3190/10/6/064001 |pmid=26502096 |s2cid=206102181 }}</ref> These constraints are: take-off constraint, sliding constraint, fall-back constraint, steady-state constraint, and high step-frequency constraint.

==Leisure activity==<!--this is a link anchor, please check what links here if you change it-->
{{main|Hiking|Walking tour}}
[[File:0 15e16 17027a85 orig.jpg|thumb|Hiking with full packs]]
Many people enjoy walking as a recreation in the mainly urban modern world, and it is one of the best forms of [[exercise]].<ref>{{cite web|author=Ramblers |url=http://www.ramblers.org.uk/go-walking/advice-for-walkers/walking-and-your-health.aspx |title=Walking benefits |publisher=Ramblers.org.uk |access-date=2012-08-22}}</ref> For some, walking is a way to enjoy nature and the outdoors; and for others the physical, sporting and endurance aspect is more important.

There are a variety of different kinds of walking, including [[bushwalking]], [[racewalking]], beach walking, [[hillwalking]], [[volksmarching]], [[Nordic walking]], [[trekking]], [[dog walking]] and [[hiking]]. Some people prefer to walk indoors on a [[treadmill]], or in a gym, and fitness walkers and others may use a [[pedometer]] to count their steps. Hiking is the usual word used in Canada, the United States and South Africa for long vigorous walks; similar walks are called tramps in New Zealand, or hill walking or just walking in Australia, the UK and the [[Irish Republic]]. In the UK, rambling is also used. Australians also bushwalk. In English-speaking parts of North America, the term walking is used for short walks, especially in towns and cities. [[Snow shoe]]ing is walking in snow; a slightly different [[gait]] is required compared with regular walking.

===Tourism===
In terms of tourism, the possibilities range from guided [[walking tours]] in cities, to organized [[trekking]] holidays in the [[Himalayas]]. In the UK the term walking tour also refers to a multi-day walk or hike undertaken by a group or individual. Well-organized systems of trails exist in many other European countries, as well as Canada, United States, New Zealand, and [[Nepal]]. Systems of lengthy [[waymark]]ed walking trails now stretch across Europe from Norway to [[Turkey]], Portugal to [[Cyprus]].<ref>See [[European long-distance paths]]</ref> Many also walk the traditional [[Pilgrimage|pilgrim routes]], of which the most famous is El Camino de [[Santiago]], The [[Way of St. James]].

Numerous walking festivals and other walking events take place each year in many countries. The world's largest multi-day walking event is the [[International Four Days Marches Nijmegen]] in the [[Netherlands]]. The "Vierdaagse" (Dutch for "Four day Event") is an annual walk that has taken place since 1909; it has been based at [[Nijmegen]] since 1916. Depending on age group and category, walkers have to walk 30, 40 or 50 kilometers each day for four days.{{citation needed|date=July 2015}} Originally a military event with a few civilians, it now is a mainly civilian event. Numbers have risen in recent years, with over 40,000 now taking part, including about 5,000 military personnel.{{citation needed|date=July 2015}} Due to crowds on the route, since 2004 the organizers have limited the number of participants. In the U.S., there is the annual [[Labor Day]] walk on [[Mackinac Bridge]], [[Michigan]], which draws over 60,000 participants; it is the largest single-day walking event;{{citation needed|date=July 2015}} while the [[Chesapeake Bay Bridge]] Walk in [[Maryland]] draws over 50,000 participants each year.{{citation needed|date=July 2015}} There are also various walks organised as [[Charitable organisation|charity]] events, with walkers sponsored for a specific cause. These walks range in length from two miles (3&nbsp;km) or five km to 50 miles (80&nbsp;km). The [[MS Challenge Walk]] is an 80&nbsp;km or 50-mile walk which raises money to fight [[multiple sclerosis]], while walkers in the Oxfam Trailwalker cover 100&nbsp;km or 60 miles.

===Rambling===
In Britain, [[The Ramblers]], a registered [[charitable organisation|charity]], is the largest organisation that looks after the interests of walkers, with some 100,000 members.<ref>{{cite web|url=http://www.ramblers.org.uk/about-us/our-history.aspx |title=Our history |publisher=Ramblers |date=1935-01-01 |access-date=2018-06-11}}</ref> Its "Get Walking Keep Walking" project provides free route guides, led walks, as well as information for people new to walking.<ref>{{cite web|url=http://www.getwalking.org |archive-url=https://web.archive.org/web/20100211124049/http://www.getwalking.org/ |url-status=usurped |archive-date=February 11, 2010 |title=Get Walking Keep Walking website |publisher=Getwalking.org |access-date=2012-08-22}}</ref> The [[Long Distance Walkers Association]] in the UK is for the more energetic walker, and organizes lengthy challenge hikes of 20 or even 50 miles (30 to 80&nbsp;km) or more in a day. The LDWA's annual "Hundred" event, entailing walking 100 miles or 160&nbsp;km in 48 hours, takes place each British [[Spring Bank Holiday]] weekend.<ref>[Ramblers, " Our History".http://www.ldwa.org.uk/history.php] Long Distance Walkers Association: History.</ref>

===Walkability===
{{main|Walkability}}
[[File:Gauchetière Street, pedestrian section (take 2), Montreal 2005-10-21.JPG|thumb|Gauchetière Street, [[Montreal, Quebec]], Canada]]
There has been a recent focus among [[urban planning|urban planners]] in some communities to create [[pedestrian-friendly]] areas and roads, allowing [[commuting]], shopping and recreation to be done on foot. The concept of [[walkability]] has arisen as a measure of the degree to which an area is friendly to walking. Some communities are at least partially [[Auto-free zone|car-free]], making them particularly supportive of walking and other modes of transportation. In the United States of America, the [[active living]] network is an example of a concerted effort to develop communities more friendly to walking and other physical activities.

An example of such efforts to make urban development more pedestrian friendly is the [[pedestrian village]]. This is a compact, pedestrian-oriented neighborhood or town, with a mixed-use village center. Shared-use lanes for [[pedestrians]] and those using [[bicycles]], [[Segways]], [[wheelchairs]], and other small rolling conveyances that do not use [[internal combustion engines]]. Generally, these lanes are in front of the houses and businesses, and streets for motor vehicles are always at the rear. Some pedestrian villages might be nearly car-free with cars either hidden below the buildings or on the periphery of the village. [[Venice, Italy]] is essentially a pedestrian village with canals. The canal district in [[Venice, California]], on the other hand, combines the front lane/rear street approach with canals and walkways, or just walkways.

Walking is also considered to be a clear example of a [[sustainable]] mode of [[transport]], especially suited for urban use and/or relatively shorter distances. Non-motorized transport modes such as walking, but also [[cycling]], small-wheeled transport (skates, skateboards, push scooters and hand carts) or wheelchair travel are often key elements of successfully encouraging clean urban transport.<ref>{{cite web |url=http://www.eu-portal.net/material/material2.phtml?sprache=en&kt=kt11 |title=Non Motorised Transport, Teaching and Learning Material |publisher=Eu-portal.net |access-date=2012-08-22 |archive-date=2012-08-02 |archive-url=https://web.archive.org/web/20120802003601/http://www.eu-portal.net/material/material2.phtml?sprache=en&kt=kt11 }}</ref> A large variety of case studies and good practices (from European cities and some worldwide examples) that promote and stimulate walking as a means of transportation in cities can be found at [[Eltis]], Europe's portal for local transport.<ref>{{Cite web|title=Eltis &#124; The urban mobility observatory|url=https://www.eltis.org/|access-date=2023-01-02|website=www.eltis.org}}</ref>

The development of specific rights of way with appropriate infrastructure can promote increased participation and enjoyment of walking. Examples of types of investment include [[pedestrian mall]]s, and [[foreshoreway]]s such as [[oceanway]]s and also river walks.

The first purpose-built [[Pedestrian zone|pedestrian street]] in Europe is the [[Lijnbaan]] in [[Rotterdam]], opened in 1953. The first pedestrianised shopping centre in the [[United Kingdom]] was in [[Stevenage]] in 1959. A [[List of car-free places|large number of European towns and cities]] have made part of their centres car-free since the early 1960s. These are often accompanied by [[car park]]s on the edge of the pedestrianised zone, and, in the larger cases, [[park and ride]] schemes. Central [[Copenhagen]] is one of the largest and oldest: It was converted from car traffic into pedestrian zone in 1962.

==In robotics==
{{Main|Robot locomotion}}
{{Multiple issues|section=yes|
{{more citations needed section|date=September 2009}}
{{Update|section|2009|date=July 2018}}
}}
Generally, the first successful walking [[robot]]s had six legs. As microprocessor technology advanced, the number of legs could be reduced and there are now robots that can walk on two legs. One, for example, is [[ASIMO]]. Although there has been significant advances, robots still do not walk nearly as well as human beings as they often need to keep their [[knee]]s bent permanently in order to improve stability.

In 2009, Japanese roboticist [[Tomotaka Takahashi]] developed a robot that can jump three inches off the ground. The robot, named [[Ropid]], is capable of getting up, walking, running, and jumping.<ref name="CBS Interactive">{{cite web| url= http://news.cnet.com/8301-17938_105-10387001-1.html| title= Ropid the robot can walk, run, and hop| publisher= CBS Interactive| access-date= 2012-06-19| archive-date= 2011-08-11| archive-url= https://web.archive.org/web/20110811050240/http://news.cnet.com/8301-17938_105-10387001-1.html}}</ref>

Many other robots have also been able to walk over the years like a bipedal walking robot.<ref>{{Cite journal |last1=Kim |first1=Kyunam |last2=Spieler |first2=Patrick |last3=Lupu |first3=Elena-Sorina |last4=Ramezani |first4=Alireza |last5=Chung |first5=Soon-Jo |date=2021-10-13 |title=A bipedal walking robot that can fly, slackline, and skateboard |url=https://www.science.org/doi/10.1126/scirobotics.abf8136 |journal=Science Robotics |language=en |volume=6 |issue=59 |article-number=eabf8136 |doi=10.1126/scirobotics.abf8136 |pmid=34613821 |s2cid=238423102 |issn=2470-9476|url-access=subscription }}</ref>

== Mathematical models ==
Multiple mathematical models have been proposed to reproduce the kinematics observed in walking. These may be broadly broken down into four categories: rule-based models based on mechanical considerations and past literature, weakly coupled phase oscillators models, control-based models which guide simulations to maximize some property of locomotion, and phenomenological models which fit equations directly to the kinematics.

=== Rule-based models ===
The rule-based models integrate the past literature on motor control to generate a few simple rules which are presumed to be responsible for walking (e.g. "loading of the left leg triggers unloading of right leg").<ref>{{Cite journal |last1=Schilling |first1=Malte |last2=Hoinville |first2=Thierry |last3=Schmitz |first3=Josef |last4=Cruse |first4=Holk |date=2013-07-04 |title=Walknet, a bio-inspired controller for hexapod walking |journal=Biological Cybernetics |volume=107 |issue=4 |pages=397–419 |doi=10.1007/s00422-013-0563-5 |pmid=23824506 |pmc=3755227 |issn=0340-1200}}</ref><ref>{{Cite journal |last1=Geyer |first1=Hartmut |last2=Herr |first2=Hugh |date=June 2010 |title=A Muscle-Reflex Model That Encodes Principles of Legged Mechanics Produces Human Walking Dynamics and Muscle Activities |journal=IEEE Transactions on Neural Systems and Rehabilitation Engineering |volume=18 |issue=3 |pages=263–273 |doi=10.1109/TNSRE.2010.2047592 |pmid=20378480 |bibcode=2010ITNSR..18..263G |hdl=1721.1/70926 |s2cid=2041375 |issn=1558-0210|hdl-access=free }}</ref> Such models are generally most strictly based on the past literature and when they are based on a few rules can be easy to interpret. However, the influence of each rule can be hard to interpret when these models become more complex. Furthermore, the tuning of parameters is often done in an ad hoc way, revealing little intuition about why the system may be organized in this way. Finally, such models are typically based fully on sensory feedback, ignoring the effect of descending and rhythm generating neurons, which have been shown to be crucial in coordinating proper walking.

=== Coupled oscillator models ===
Dynamical system theory shows that any network with cyclical dynamics may be modeled as a set of [[Coupled oscillators|weakly coupled phase oscillators]], so another line of research has been exploring this view of walking.<ref>{{Cite journal |last1=Couzin-Fuchs |first1=Einat |last2=Kiemel |first2=Tim |last3=Gal |first3=Omer |last4=Ayali |first4=Amir |last5=Holmes |first5=Philip |date=2015-01-15 |title=Intersegmental coupling and recovery from perturbations in freely running cockroaches |journal=Journal of Experimental Biology |volume=218 |issue=2 |pages=285–297 |doi=10.1242/jeb.112805 |pmid=25609786 |pmc=4302167 |bibcode=2015JExpB.218..285C |issn=1477-9145}}</ref> Each oscillator may model a muscle, joint angle, or even a whole leg, and is coupled to some set of other oscillators. Often, these oscillators are thought to represent the [[central pattern generator]]s underlying walking. These models have rich theory behind them, allow for some extensions based on sensory feedback, and can be fit to kinematics. However, they need to be heavily constrained to fit to data and by themselves make no claims on which gaits allow the animal to move faster, more robustly, or more efficiently.

=== Control based models ===
Control-based models start with a simulation based on some description of the animal's anatomy and optimize control parameters to generate some behavior. These may be based on a musculoskeletal model,<ref>{{Cite journal |last1=Geijtenbeek |first1=Thomas |last2=van de Panne |first2=Michiel |last3=van der Stappen |first3=A. Frank |date=November 2013 |title=Flexible muscle-based locomotion for bipedal creatures |journal=ACM Transactions on Graphics |volume=32 |issue=6 |pages=1–11 |doi=10.1145/2508363.2508399 |s2cid=9183862 |issn=0730-0301}}</ref> skeletal model,<ref>{{cite arXiv | eprint=1707.02286 | last1=Heess | first1=Nicolas | last2=TB | first2=Dhruva | last3=Sriram | first3=Srinivasan | last4=Lemmon | first4=Jay | last5=Merel | first5=Josh | last6=Wayne | first6=Greg | last7=Tassa | first7=Yuval | last8=Erez | first8=Tom | last9=Wang | first9=Ziyu | last10=Ali Eslami | first10=S. M. | last11=Riedmiller | first11=Martin | last12=Silver | first12=David | title=Emergence of Locomotion Behaviours in Rich Environments | year=2017 | class=cs.AI }}</ref><ref>{{Cite journal |last1=Peng |first1=Xue Bin |last2=Abbeel |first2=Pieter |last3=Levine |first3=Sergey |last4=van de Panne |first4=Michiel |date=2018-08-31 |title=DeepMimic |journal=ACM Transactions on Graphics |volume=37 |issue=4 |pages=1–14 |doi=10.1145/3197517.3201311 |arxiv=1804.02717 |s2cid=215808400 |issn=0730-0301}}</ref> or even simply a ball and stick model.<ref>{{Cite journal |last1=Szczecinski |first1=Nicholas S. |last2=Bockemühl |first2=Till |last3=Chockley |first3=Alexander S. |last4=Büschges |first4=Ansgar |date=2018-11-16 |title=Static stability predicts the continuum of interleg coordination patterns in Drosophila |journal=Journal of Experimental Biology |volume=221 |issue=22 |pages=jeb189142 |doi=10.1242/jeb.189142 |pmid=30274987 |s2cid=52903595 |issn=0022-0949|doi-access=free }}</ref> As these models generate locomotion by optimizing some metric, they can be used to explore the space of optimal locomotion behaviors under some assumptions. However, they typically do not generate plausible hypotheses on the neural coding underlying the behaviors and are typically sensitive to modeling assumptions.

=== Statistical models ===
Phenomenological models model the kinematics of walking directly by fitting a [[dynamical system]], without postulating an underlying mechanism for how the kinematics are generated neurally. Such models can produce the most realistic kinematic trajectories and thus have been explored for simulating walking for [[Computer animation|computer-based animation]].<ref>{{Cite journal |last1=Holden |first1=Daniel |last2=Komura |first2=Taku |last3=Saito |first3=Jun |date=2017-07-20 |title=Phase-functioned neural networks for character control |journal=ACM Transactions on Graphics |volume=36 |issue=4 |pages=42:1–42:13 |doi=10.1145/3072959.3073663 |hdl=20.500.11820/c09514d6-427f-4e00-adcc-1466f0125135 |s2cid=7261259 |issn=0730-0301|hdl-access=free }}</ref><ref>{{Cite journal |last1=Zhang |first1=He |last2=Starke |first2=Sebastian |last3=Komura |first3=Taku |last4=Saito |first4=Jun |date=2018-07-30 |title=Mode-adaptive neural networks for quadruped motion control |journal=ACM Transactions on Graphics |volume=37 |issue=4 |pages=145:1–145:11 |doi=10.1145/3197517.3201366 |s2cid=51692385 |issn=0730-0301|hdl=20.500.11820/b7f8ce75-5774-4005-b7bf-478bdae6f76f |hdl-access=free }}</ref> However, the lack of underlying mechanism makes it hard to apply these models to study the biomechanical or neural properties of walking.

==Animals==
{{main|Terrestrial locomotion}}
{{See also|Gait}}

===Horses===
{{main|Horse gait}}
[[File:Muybridge horse walking animated.gif|thumb|The walk, a four-beat gait]]
The walk is a four-beat gait that averages about {{convert|4|mph|km/h}}. When walking, a horse's legs follow this sequence: left hind leg, left front leg, right hind leg, right front leg, in a regular 1-2-3-4 beat. At the walk, the horse will always have one foot raised and the other three feet on the ground, save for a brief moment when weight is being transferred from one foot to another. A horse moves its head and neck in a slight up and down motion that helps maintain balance.<ref name=Harris33>Harris, Susan E. ''Horse Gaits, Balance and Movement'' New York: Howell Book House 1993 {{ISBN|0-87605-955-8}} pp. 32–33</ref>

Ideally, the advancing rear hoof oversteps the spot where the previously advancing front hoof touched the ground. The more the rear hoof oversteps, the smoother and more comfortable the walk becomes. Individual horses and different [[List of horse breeds|breeds]] vary in the smoothness of their walk. However, a rider will almost always feel some degree of gentle side-to-side motion in the horse's hips as each hind leg reaches forward.{{citation needed|date=July 2018}}

The fastest "walks" with a four-beat footfall pattern are actually the lateral forms of [[ambling]] gaits such as the running walk, singlefoot, and similar rapid but smooth intermediate speed gaits. If a horse begins to speed up and lose a regular four-beat cadence to its gait, the horse is no longer walking but is beginning to either [[Horse gait#Trot|trot]] or pace.{{citation needed|date=July 2018}}

===Elephants===
[[File:Elephant Walking animated.gif|thumb|right|An Asian elephant walking]]
[[Elephants]] can move both forwards and backwards, but cannot [[trot]], [[jumping|jump]], or [[Horse gait|gallop]]. They use only two gaits when moving on land, the walk and a faster gait similar to running.<ref>{{cite journal | last1 = Shoshani | first1 = J. | last2 = Walter | first2 = R. C. | last3 = Abraha | first3 = M. | last4 = Berhe | first4 = S. | last5 = Tassy | first5 = P. | last6 = Sanders | first6 = W. J. | last7 = Marchant | first7 = G. H. | last8 = Libsekal | first8 = Y. | last9 = Ghirmai | first9 = T. | last10 = Zinner | first10 = D. | year = 2006 | title = A proboscidean from the late Oligocene of Eritrea, a "missing link" between early Elephantiformes and Elephantimorpha, and biogeographic implications | journal = Proceedings of the National Academy of Sciences | volume = 103 | issue = 46| pages = 17296–301 | doi=10.1073/pnas.0603689103 | pmid=17085582 | pmc=1859925| bibcode = 2006PNAS..10317296S | doi-access = free }}</ref> In walking, the legs act as pendulums, with the hips and shoulders rising and falling while the foot is planted on the ground. With no "aerial phase", the fast gait does not meet all the criteria of running, although the elephant uses its legs much like other running animals, with the hips and shoulders falling and then rising while the feet are on the ground.<ref name="kinetics">{{cite journal |author = Hutchinson, J. R. |author2=Schwerda, D. |author3=Famini, D. J. |author4=Dale, R. H. |author5=Fischer, M. S. |author6=Kram, R. |name-list-style=amp |year=2006|title=The locomotor kinematics of Asian and African elephants: changes with speed and size|journal=Journal of Experimental Biology|volume=209|issue=19|pages=3812–27|pmid=16985198 |doi = 10.1242/jeb.02443|doi-access=free |bibcode=2006JExpB.209.3812H }}</ref> Fast-moving elephants appear to 'run' with their front legs, but 'walk' with their hind legs and can reach a top speed of {{convert|18|km/h|abbr=on}}.<ref>{{cite journal|author=Genin, J. J.|author2= Willems, P. A. |author3=Cavagna, G. A. |author4=Lair, R. |author5=Heglund, N. C. |name-list-style=amp |year=2010|title=Biomechanics of locomotion in Asian elephants|journal=Journal of Experimental Biology|volume=213|pages=694–706|doi=10.1242/jeb.035436|issue=5|pmid=20154184|doi-access=|bibcode= 2010JExpB.213..694G |hdl=2078.1/29686|hdl-access=free}}</ref> At this speed, most other [[Quadrupedalism|quadrupeds]] are well into a gallop, even accounting for leg length.

===Walking fish===
{{Main|Walking fish}}
[[File:Periophthalmus gracilis.jpg|thumb|right|A [[mudskipper]], a type of walking fish, perched on land]]
[[Walking fish]] (or ambulatory fish) are [[fish]] that are able to travel over [[Terrestrial ecoregion|land]] for extended periods of time. The term may also be used for some other cases of nonstandard [[fish locomotion]], e.g., when describing fish "walking" along the [[seabed|sea floor]], as the [[handfish]] or [[frogfish]].

=== Insects ===
Insects must carefully coordinate their six legs during walking to produce gaits that allow for efficient navigation of their environment. Interleg coordination patterns have been studied in a variety of insects, including locusts (''Schistocerca gregaria''), cockroaches (''Periplaneta americana''), stick insects (''[[Carausius morosus]]''), and fruit flies (''[[Drosophila melanogaster]]'').<ref name=stick-insect-walking>{{cite journal | vauthors = Graham, DA | title = A behavioural analysis of the temporal organisation of walking movements in the 1st instar and adult stick insect (Carausius morosus) | journal = Journal of Comparative Physiology| volume = 81 | pages = 23–52 | date = 1972 | doi = 10.1007/BF00693548| s2cid = 38878595 }}</ref><ref name=static-stability>{{cite journal | vauthors = Szczecinski NS, Bockemühl T, Chockley AS, Büschges A | title = Static stability predicts the continuum of interleg coordination patterns in Drosophila | journal = The Journal of Experimental Biology | volume = 221 | issue = Pt 22 | pages = jeb189142 | date = November 2018 | article-number = jeb.189142 | pmid = 30274987 | doi = 10.1242/jeb.189142 | doi-access = free }}</ref><ref name=cockroach-walking>{{cite journal | vauthors = Spirito CP, Mushrush DL | title = Interlimb Coordination During Slow Walking in the Cockroach: I. Effects of Substrate Alterations| journal = Journal of Experimental Biology | volume = 78 | pages = 233–243| date = 1979 | doi = 10.1242/jeb.78.1.233| url = https://jeb.biologists.org/content/78/1/233| url-access = subscription}}</ref> Different walking gaits have been observed to exist on a speed dependent continuum of phase relationships.<ref name=stick-insect-walking /><ref name=cockroach-walking /> Even though their walking gaits are not discrete, they can often be broadly categorized as either a metachronal wave gait, tetrapod gait, or tripod gait.<ref name=insect-walking>{{cite journal | vauthors = Wilson, Donald M | title = Insect Walking | journal = Annual Review of Entomology| volume = 11 | issue = 1 | pages = 103–122 | date = 1966 | pmid = 5321575 | doi = 10.1146/annurev.en.11.010166.000535 | doi-access =  }}</ref>

In a metachronal wave gait, only one leg leaves contact with the ground at a time. This gait starts at one of the hind legs, then propagates forward to the mid and front legs on the same side before starting at the hind leg of the contralateral side.<ref name=insect-walking /> The wave gait is often used at slow walking speeds and is the most stable, since five legs are always in contact with the ground at a time.<ref name=hughes1957>{{cite journal | vauthors = Hughes, GM | title = The Co-Ordination of Insect Movements | journal = Journal of Experimental Biology | volume = 34 | pages = 306–333| date = 1957 | issue = 3 | doi = 10.1242/jeb.34.3.306 | bibcode = 1957JExpB..34..306H | url =https://jeb.biologists.org/content/34/3/306| url-access = subscription }}</ref>

In a tetrapod gait, two legs swing at a time while the other four legs remain in contact with the ground. There are multiple configurations for tetrapod gaits, but the legs that swing together must be on contralateral sides of the body.<ref name=insect-walking /> Tetrapod gaits are typically used at medium speeds and are also very stable.<ref name=static-stability />

A walking gait is considered tripod if three of the legs enter the swing phase simultaneously, while the other three legs make contact with the ground.<ref name=insect-walking /> The middle leg of one side swings with the hind and front legs on the contralateral side.<ref name=insect-walking /> Tripod gaits are most commonly used at high speeds, though it can be used at lower speeds.<ref name=hughes1957 /> The tripod gait is less stable than wave-like and tetrapod gaits, but it is theorized to be the most robust.<ref name=static-stability /> This means that it is easier for an insect to recover from an offset in step timing when walking in a tripod gait. The ability to respond robustly is important for insects when traversing uneven terrain.<ref name=static-stability />

==See also==
{{portal|Sport of athletics}}
{{div col|colwidth=20em}}
* [[Arm swing in human locomotion]]
* [[Duckwalk]]
* [[Footpath]]
* [[Gait training]]
* [[Hand walking]]
* [[Hot Girl Walk]]
* [[Kinhin]]
* [[List of longest walks]]
* [[New Urbanism]]
* [[Obesity and walking]]
* [[Pedestrian village]]
* [[Pedestrian zone]]
* [[Preferred walking speed]]
* [[Student transport]]
* [[Tobler's hiking function]]
* [[Walkability]]
* [[Walkathon]]
* [[Walking audit]]
* [[Walking bus]]
* [[Walking city]]
* [[Walking tour]]
{{div col end}}

==References==
{{Reflist|25em}}

==External links==
{{Wiktionary|walk}}
{{Commons category|Walking}}
{{Wikiversity|Benefits of walking}}
* [http://www.eltis.org European Local Transport Information Service] ([[Eltis]]) provides case studies concerning walking as a local transport concept.

{{Walking}}
{{Locomotion}}
{{Activities of daily living}}
{{Physical exercise}}
{{Human-powered vehicles}}
{{Authority control}}

[[Category:Walking| ]]
[[Category:Hiking]]
[[Category:Private transport]]
[[Category:Articles containing video clips]]