Running

Running is a method of terrestrial locomotion allowing humans and other animals to move rapidly on foot. Running is a type of gait characterized by an aerial phase in which all feet are above the ground (though there are exceptions[1]). This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion.[2] A characteristic feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride occur simultaneously, with energy storage accomplished by springy tendons and passive muscle elasticity.[3] The term running can refer to any of a variety of speeds ranging from jogging to sprinting.

It is assumed that the ancestors of humankind developed the ability to run for long distances about 2.6 million years ago, probably in order to hunt animals.[4] Competitive running grew out of religious festivals in various areas. Records of competitive racing date back to the Tailteann Games in Ireland between 632 BCE and 1171 BCE,[5][6][7] while the first recorded Olympic Games took place in 776 BCE. Running has been described as the world's most accessible sport.[8]

Ludovic and Lauren (8425515069)
Marathon runners at Carlsbad Marathon, USA, 2013
Video of human running action

History

Long Distance Runners, Ancient Greece, Amphora
A scene depicting long distance runners, originally found on a Panathenaic amphora from Ancient Greece, circa 333 BCE

It is thought that human running evolved at least four and a half million years ago out of the ability of the ape-like Australopithecus, an early ancestor of humans, to walk upright on two legs.[9]

Early humans most likely developed into endurance runners from the practice of persistence hunting of animals, the activity of following and chasing until a prey is too exhausted to flee, succumbing to "chase myopathy" (Sears 2001), and that human features such as the nuchal ligament, abundant sweat glands, the Achilles tendons, big knee joints and muscular glutei maximi, were changes caused by this type of activity (Bramble & Lieberman 2004, et al.).[10][11][12] The theory as first proposed used comparative physiological evidence and the natural habits of animals when running, indicating the likelihood of this activity as a successful hunting method. Further evidence from observation of modern-day hunting practice also indicated this likelihood (Carrier et al. 1984). [12][13] According to Sears (p. 12) scientific investigation (Walker & Leakey 1993) of the Nariokotome Skeleton provided further evidence for the Carrier theory.[14]

Competitive running grew out of religious festivals in various areas such as Greece, Egypt, Asia, and the East African Rift in Africa. The Tailteann Games, an Irish sporting festival in honor of the goddess Tailtiu, dates back to 1829 BCE, and is one of the earliest records of competitive running. The origins of the Olympics and Marathon running are shrouded by myth and legend, though the first recorded games took place in 776 BCE.[15] Running in Ancient Greece can be traced back to these games of 776 BCE.

...I suspect that the sun, moon, earth, stars, and heaven, which are still the gods of many barbarians, were the only gods known to the aboriginal Hellenes. Seeing that they were always moving and running, from their running nature they were called gods or runners (Thus, Theontas)...

— Socrates in Plato – Cratylus [16]

Running kinematic description

Muybridge runner
Eadweard Muybridge photo sequence

Running gait can be divided into two phases in regard to the lower extremity: stance and swing.[17][18][19][20] These can be further divided into absorption, propulsion, initial swing and terminal swing. Due to the continuous nature of running gait, no certain point is assumed to be the beginning. However, for simplicity, it will be assumed that absorption and footstrike mark the beginning of the running cycle in a body already in motion.

Footstrike

Footstrike occurs when a plantar portion of the foot makes initial contact with the ground. Common footstrike types include forefoot, midfoot and heel strike types.[21][22][23] These are characterized by initial contact of the ball of the foot, ball and heel of the foot simultaneously and heel of the foot respectively. During this time the hip joint is undergoing extension from being in maximal flexion from the previous swing phase. For proper force absorption, the knee joint should be flexed upon footstrike and the ankle should be slightly in front of the body.[24] Footstrike begins the absorption phase as forces from initial contact are attenuated throughout the lower extremity. Absorption of forces continues as the body moves from footstrike to midstance due to vertical propulsion from the toe-off during a previous gait cycle.

Midstance

Midstance is defined as the time at which the lower extremity limb of focus is in knee flexion directly underneath the trunk, pelvis and hips. It is at this point that propulsion begins to occur as the hips undergo hip extension, the knee joint undergoes extension and the ankle undergoes plantar flexion. Propulsion continues until the leg is extended behind the body and toe off occurs. This involves maximal hip extension, knee extension and plantar flexion for the subject, resulting in the body being pushed forward from this motion and the ankle/foot leaves the ground as initial swing begins.

Propulsion phase

Most recent research, particularly regarding the footstrike debate, has focused solely on the absorption phases for injury identification and prevention purposes. The propulsion phase of running involves the movement beginning at midstance until toe off.[18][19][25] From a full stride length model however, components of the terminal swing and footstrike can aid in propulsion.[20][26] Set up for propulsion begins at the end of terminal swing as the hip joint flexes, creating the maximal range of motion for the hip extensors to accelerate through and produce force. As the hip extensors change from reciporatory inhibitors to primary muscle movers, the lower extremity is brought back toward the ground, although aided greatly by the stretch reflex and gravity.[20] Footstrike and absorption phases occur next with two types of outcomes. This phase can be only a continuation of momentum from the stretch reflex reaction to hip flexion, gravity and light hip extension with a heel strike, which does little to provide force absorption through the ankle joint.[25][27][28] With a mid/forefoot strike, loading of the gastro-soleus complex from shock absorption will serve to aid in plantar flexion from midstance to toe-off.[28][29] As the lower extremity enters midstance, true propulsion begins.[25] The hip extensors continue contracting along with help from the acceleration of gravity and the stretch reflex left over from maximal hip flexion during the terminal swing phase. Hip extension pulls the ground underneath the body, thereby pulling the runner forward. During midstance, the knee should be in some degree of knee flexion due to elastic loading from the absorption and footstrike phases to preserve forward momentum.[30][31][32] The ankle joint is in dorsiflexion at this point underneath the body, either elastically loaded from a mid/forefoot strike or preparing for stand-alone concentric plantar flexion. All three joints perform the final propulsive movements during toe-off.[25][27][28][29] The plantar flexors plantar flex, pushing off from the ground and returning from dorsiflexion in midstance. This can either occur by releasing the elastic load from an earlier mid/forefoot strike or concentrically contracting from a heel strike. With a forefoot strike, both the ankle and knee joints will release their stored elastic energy from the footstrike/absorption phase.[30][31][32] The quadriceps group/knee extensors go into full knee extension, pushing the body off of the ground. At the same time, the knee flexors and stretch reflex pull the knee back into flexion, adding to a pulling motion on the ground and beginning the initial swing phase. The hip extensors extend to maximum, adding the forces pulling and pushing off of the ground. The movement and momentum generated by the hip extensors also contributes to knee flexion and the beginning of the initial swing phase.

Swing phase

Initial swing is the response of both stretch reflexes and concentric movements to the propulsion movements of the body. Hip flexion and knee flexion occur beginning the return of the limb to the starting position and setting up for another footstrike. Initial swing ends at midswing, when the limb is again directly underneath the trunk, pelvis and hip with the knee joint flexed and hip flexion continuing. Terminal swing then begins as hip flexion continues to the point of activation of the stretch reflex of the hip extensors. The knee begins to extend slightly as it swings to the anterior portion of the body. The foot then makes contact with the ground with footstrike, completing the running cycle of one side of the lower extremity. Each limb of the lower extremity works opposite to the other. When one side is in toe-off/propulsion, the other hand is in the swing/recovery phase preparing for footstrike.[17][18][19][20] Following toe-off and the beginning of the initial swing of one side, there is a flight phase where neither extremity is in contact with the ground due to the opposite side finishing terminal swing. As the footstrike of the one hand occurs, initial swing continues. The opposing limbs meet with one in midstance and midswing, beginning the propulsion and terminal swing phases.

Upper extremity function

Upper extremity function serves mainly in providing balance in conjunction with the opposing side of the lower extremity.[18] The movement of each leg is paired with the opposite arm which serves to counterbalance the body, particularly during the stance phase.[25] The arms move most effectively (as seen in elite athletes) with the elbow joint at an approximately 90 degrees or less, the hands swinging from the hips up to mid chest level with the opposite leg, the Humerus moving from being parallel with the trunk to approximately 45 degrees shoulder extension (never passing the trunk in flexion) and with as little movement in the transverse plane as possible.[33] The trunk also rotates in conjunction with arm swing. It mainly serves as a balance point from which the limbs are anchored. Thus trunk motion should remain mostly stable with little motion except for slight rotation as excessive movement would contribute to transverse motion and wasted energy.

Footstrike debate

Recent research into various forms of running has focused on the differences, in the potential injury risks and shock absorption capabilities between heel and mid/forefoot footstrikes. It has been shown that heel striking is generally associated with higher rates of injury and impact due to inefficient shock absorption and inefficient biomechanical compensations for these forces.[21] This is due to forces from a heel strike traveling through bones for shock absorption rather than being absorbed by muscles. Since bones cannot disperse forces easily, the forces are transmitted to other parts of the body, including ligaments, joints and bones in the rest of the lower extremity all the way up to the lower back.[34] This causes the body to use abnormal compensatory motions in an attempt to avoid serious bone injuries.[35] These compensations include internal rotation of the tibia, knee and hip joints. Excessive amounts of compensation over time have been linked to higher risk of injuries in those joints as well as the muscles involved in those motions.[27] Conversely, a mid/forefoot strike has been associated with greater efficiency and lower injury risk due to the triceps surae being used as a lever system to absorb forces with the muscles eccentrically rather than through the bone.[21] Landing with a mid/forefoot strike has also been shown to not only properly attenuate shock but allows the triceps surae to aid in propulsion via reflexive plantarflexion after stretching to absorb ground contact forces.[26][36] Thus a mid/forefoot strike may aid in propulsion. However, even among elite athletes there are variations in self selected footstrike types.[37] This is especially true in longer distance events, where there is a prevalence of heel strikers.[38] There does tend however to be a greater percentage of mid/forefoot striking runners in the elite fields, particularly in the faster racers and the winning individuals or groups.[33] While one could attribute the faster speeds of elite runners compared to recreational runners with similar footstrikes to physiological differences, the hip and joints have been left out of the equation for proper propulsion. This brings up the question as to how heel striking elite distance runners are able to keep up such high paces with a supposedly inefficient and injurious foot strike technique.

Stride length, hip and knee function

Biomechanical factors associated with elite runners include increased hip function, use and stride length over recreational runners.[33][39] An increase in running speeds causes increased ground reaction forces and elite distance runners must compensate for this to maintain their pace over long distances.[40] These forces are attenuated through increased stride length via increased hip flexion and extension through decreased ground contact time and more force being used in propulsion.[40][41][42] With increased propulsion in the horizontal plane, less impact occurs from decreased force in the vertical plane.[43] Increased hip flexion allows for increased use of the hip extensors through midstance and toe-off, allowing for more force production.[25] The difference even between world class and national level distance runners has been associated with more efficient hip joint function.[44] The increase in velocity likely comes from the increased range of motion in hip flexion and extension, allowing for greater acceleration and velocity. The hip extensors and hip extension have been linked to more powerful knee extension during toe-off, which contributes to propulsion.[33] Stride length must be properly increased with some degree of knee flexion maintained through the terminal swing phases, as excessive knee extension during this phase along with footstrike has been associated with higher impact forces due to braking and an increased prevalence of heel striking.[45] Elite runners tend to exhibit some degree of knee flexion at footstrike and midstance, which first serves to eccentrically absorb impact forces in the quadriceps muscle group.[44][46][47] Secondly it allows for the knee joint to concentrically contract and provides major aid in propulsion during toe-off as the quadriceps group is capable of produce large amounts of force.[25] Recreational runners have been shown to increase stride length through increased knee extension rather than increased hip flexion as exhibited by elite runners, which serves instead to provide an intense braking motion with each step and decrease the rate and efficiency of knee extension during toe-off, slowing down speed.[39] Knee extension however contributes to additional stride length and propulsion during toe-off and is seen more frequently in elite runners as well.[33]

Elements of good running technique

Soldier running in water original
The runner's posture should be upright and slightly tilted forward.

Upright posture and a slight forward lean

Leaning forward places a runner's center of mass on the front part of the foot, which avoids landing on the heel and facilitates the use of the spring mechanism of the foot. It also makes it easier for the runner to avoid landing the foot in front of the center of mass and the resultant braking effect. While upright posture is essential, a runner should maintain a relaxed frame and use his/her core to keep posture upright and stable. This helps prevent injury as long as the body is neither rigid nor tense. The most common running mistakes are tilting the chin up and scrunching shoulders.[48]

Stride rate and types

Exercise physiologists have found that the stride rates are extremely consistent across professional runners, between 185 and 200 steps per minute. The main difference between long- and short-distance runners is the length of stride rather than the rate of stride.[49][50]

During running, the speed at which the runner moves may be calculated by multiplying the cadence (steps per second) by the stride length. Running is often measured in terms of pace[51] in minutes per mile or kilometer. Different types of stride are necessary for different types of running. When sprinting, runners stay on their toes bringing their legs up, using shorter and faster strides. Long distance runners tend to have more relaxed strides that vary.

Benefits of running

How to achieve your weight loss goals
U.S. Army soldier running to maintain his health
Speedsuit
A woman running in a speedsuit

Cardiovascular benefits

While there exists the potential for injury while running (just as there is in any sport), there are many benefits. Some of these benefits include potential weight loss, improved cardiovascular and respiratory health (reducing the risk of cardiovascular and respiratory diseases), improved cardiovascular fitness, reduced total blood cholesterol, strengthening of bones (and potentially increased bone density), possible strengthening of the immune system and an improved self-esteem and emotional state.[52] Running, like all forms of regular exercise, can effectively slow[53] or reverse[54] the effects of aging. Even people who have already experienced a heart attack are 20% less likely to develop serious heart problems if more engaged in running or any type of aerobic activity. [55]

Although an optimal amount of vigorous aerobic exercise such as running might bring benefits related to lower cardiovascular disease and life extension, an excessive dose (e.g., marathons) might have an opposite effect associated with cardiotoxicity.[56]

Weight loss benefits

Running can assist people in losing weight, staying in shape and improving body composition. Research suggests that the person of average weight will burn approximately 100 calories per mile run.[57] Running increases one's metabolism, even after running; one will continue to burn an increased level of calories for a short time after the run.[58] Different speeds and distances are appropriate for different individual health and fitness levels. For new runners, it takes time to get into shape. The key is consistency and a slow increase in speed and distance.[57] While running, it is best to pay attention to how one's body feels. If a runner is gasping for breath or feels exhausted while running, it may be beneficial to slow down or try a shorter distance for a few weeks. If a runner feels that the pace or distance is no longer challenging, then the runner may want to speed up or run farther.[59]

Mental health

Running can also have psychological benefits, as many participants in the sport report feeling an elated, euphoric state, often referred to as a "runner's high".[60] Running is frequently recommended as therapy for people with clinical depression and people coping with addiction.[61] A possible benefit may be the enjoyment of nature and scenery, which also improves psychological well-being[62] (see Ecopsychology § Practical benefits).

In animal models, running has been shown to increase the number of newly created neurons within the brain.[63] This finding could have significant implications in aging as well as learning and memory. A recent study published in Cell Metabolism has also linked running with improved memory and learning skills.[64]

Running is an effective way to reduce stress, anxiety, depression, and tension. It helps people who struggle with seasonal affective disorder by being more outside running when it's sunny and warm. Running can improve mental alertness and also improve sleep which is needed for good mental health. Both research and clinical experience have shown that exercise can be a treatment for serious depression and anxiety even some physicians prescribe exercise to most of their patients. Running can have a longer lasting effect than anti-depressants. [65]

Running injuries

High impact

Bad-running-form
Person with a bad running form. Heel striking and leaning forward are some of the most common mistakes and cause of injuries among beginners.

Many injuries are associated with running because of its high-impact nature. Change in running volume may lead to development of patellofemoral pain syndrome, iliotibial band syndrome, patellar tendinopathy, plica syndrome, and medial tibial stress syndrome. Change in running pace may cause Achilles Tendinitis, gastrocnemius injuries, and plantar fasciitis.[66] Repetitive stress on the same tissues without enough time for recovery or running with improper form can lead to many of the above. Runners generally attempt to minimize these injuries by warming up before exercise,[24] focusing on proper running form, performing strength training exercises, eating a well balanced diet, allowing time for recovery, and "icing" (applying ice to sore muscles or taking an ice bath).

Some runners may experience injuries when running on concrete surfaces. The problem with running on concrete is that the body adjusts to this flat surface running, and some of the muscles will become weaker, along with the added impact of running on a harder surface. Therefore, it is advised to change terrain occasionally – such as trail, beach, or grass running. This is more unstable ground and allows the legs to strengthen different muscles. Runners should be wary of twisting their ankles on such terrain. Running downhill also increases knee stress and should, therefore, be avoided. Reducing the frequency and duration can also prevent injury.

Barefoot running has been promoted as a means of reducing running related injuries,[67] but this remains controversial and a majority of professionals advocate the wearing of appropriate shoes as the best method for avoiding injury.[68] However, a study in 2013 concluded that wearing neutral shoes is not associated with increased injuries.[69]

Chafing
Chafing of skin following a marathon run

Chafing

Another common, running-related injury is chafing, caused by repetitive rubbing of one piece of skin against another, or against an article of clothing. One common location for chafe to occur is the runner's upper thighs. The skin feels coarse and develops a rash-like look. A variety of deodorants and special anti-chafing creams are available to treat such problems. Chafe is also likely to occur on the nipple. There are a variety of home remedies that runners use to deal with chafing while running such as band-aids and using grease to reduce friction. Prevention is key which is why form fitting clothes are important.[70]

Iliotibial Band Syndrome

An iliotibial band is a muscle and tendon that is attached to the hip and runs the length of the thigh to attach to the upper part of the tibia, and the band is what helps the knee to bend. This is an injury that is located at the knee and shows symptoms of swelling outside the knee. Iliotibial band syndrome is also known as "runner's knee" or "jogger's knee" because it can be caused by jogging or running. Once pain or swelling is noticeable it is important to put ice on it immediately and it's recommended to rest the knee for better healing. [71] Most knee injuries can be treated by light activity and lots of rest for the knee. In more serious cases, arthroscopy is the most common to help repair ligaments but severe situations reconstructive surgery would be needed. [72] A survey was taken in 2011 with knee injuries being 22.7% of the most common injuries. [73]

Medial Tibial Stress Syndrome

A more known injury is MTSS which is the accurate name for shin splints. This is caused during running when the muscle is being overused along the front of the lower leg with symptoms that affect 2 to 6 inches of the muscle. Shin Splints have sharp, splinter-like pain, that is typically X- rayed by doctors but is not necessary for shin splints to be diagnosed. To help prevent shin splints it's commonly known to stretch before and after a workout session, and also avoid heavy equipment especially during the first couple of workout sessions. [74] Also to help prevent shin splints don't increase the intensity of a workout more than 10% a week.[75] To treat shin splints it's important to rest with the least amount of impact on your legs and apply ice to the area. A survey showed that shin splints 12.7% of the most common injuries in running with blisters being the top percentage at 30.9%. [76]

Running events

Running is both a competition and a type of training for sports that have running or endurance components. As a sport, it is split into events divided by distance and sometimes includes permutations such as the obstacles in steeplechase and hurdles. Running races are contests to determine which of the competitors is able to run a certain distance in the shortest time. Today, competitive running events make up the core of the sport of athletics. Events are usually grouped into several classes, each requiring substantially different athletic strengths and involving different tactics, training methods, and types of competitors.

Running competitions have probably existed for most of humanity's history and were a key part of the ancient Olympic Games as well as the modern Olympics. The activity of running went through a period of widespread popularity in the United States during the running boom of the 1970s. Over the next two decades, as many as 25 million Americans were doing some form of running or jogging – accounting for roughly one tenth of the population.[77] Today, road racing is a popular sport among non-professional athletes, who included over 7.7 million people in America alone in 2002.[78]

Limits of speed

Footspeed, or sprint speed, is the maximum speed at which a human can run. It is affected by many factors, varies greatly throughout the population, and is important in athletics and many sports.

The fastest human footspeed on record is 44.7 km/h (12.4 m/s, 27.8 mph), seen during a 100-meter sprint (average speed between the 60th and the 80th meter) by Usain Bolt.[79]

Running speed over increasing distance based on world record times

(see Category:Athletics (track and field) record progressions)

Human speed distance portrait
Maximum human speed [km/h] and pace [min/km] per distance
Distance metres Men m/s Women m/s
100 10.44 9.53
200 10.42 9.37
400 9.26 8.44
800 7.92 7.06
1,000 7.58 6.71
1,500 7.28 6.51
1,609 (mile) 7.22 6.36
2,000 7.02 6.15
3,000 6.81 6.17
5,000 6.60 5.87
10,000 track 6.34 5.64
10,000 road 6.23 5.49
15,000 road 6.02 5.38
20,000 track 5.91 5.09
20,000 road 6.02 5.30
21,097 Half marathon 6.02 5.29
21,285 One hour run 5.91 5.14
25,000 track 5.63 4.78
25,000 road 5.80 5.22
30,000 track 5.60 4.72
30,000 road 5.69 5.06
42,195 Marathon 5.69 5.19
90,000 Comrades 4.68 4.23
100,000 4.46 4.24
303,506 24-hour run 3.513 2.82

Events by type

Track running
Grayson running the 4x100
A man running with a baton during a relay race.

Track running events are individual or relay events with athletes racing over specified distances on an oval running track. The events are categorized as sprints, middle and long-distance, and hurdling.

Road running

Road running takes place on a measured course over an established road (as opposed to track and cross country running). These events normally range from distances of 5 kilometers to longer distances such as half marathons and marathons, and they may involve scores of runners or wheelchair entrants.

Cross-country running

Cross country running takes place over the open or rough terrain. The courses used for these events may include grass, mud, woodlands, hills, flat ground and water. It is a popular participatory sport and is one of the events which, along with track and field, road running, and racewalking, makes up the umbrella sport of athletics.

Vertical running

The majority of popular races do not incorporate a significant change in elevation as a key component of a course. There are several, disparate variations that feature significant inclines or declines. These fall into two main groups.

The naturalistic group is based on outdoor racing over geographical features. Among these are the cross country-related sports of fell running (a tradition associated with Northern Europe) and trail running (mainly ultramarathon distances), the running/climbing combination of skyrunning (organised by the International Skyrunning Federation with races across North America, Europe and East Asia) and the mainly trail- and road-centred mountain running (governed by the World Mountain Running Association and based mainly in Europe).

The second variety of vertical running is based on human structures, such as stairs and man-made slopes. The foremost type of this is tower running, which sees athletes compete indoors, running up steps within very tall structures such as the Eiffel Tower or Empire State Building.

Events by distance

Sprints

Sina Schielke (192) wins the 100 metres race - ISTAF 2006 - Berlin, 3 September
International level women athletes competing in 100 m sprint race at ISTAF Berlin, 2006

Sprints are short running events in athletics and track and field. Races over short distances are among the oldest running competitions. The first 13 editions of the Ancient Olympic Games featured only one event – the stadion race, which was a race from one end of the stadium to the other.[80] There are three sprinting events which are currently held at the Olympics and outdoor World Championships: the 100 metres, 200 metres, and 400 metres. These events have their roots in races of imperial measurements which were later altered to metric: the 100 m evolved from the 100-yard dash,[81] the 200 m distances came from the furlong (or 1/8 of a mile),[82] and the 400 m was the successor to the 440 yard dash or quarter-mile race.[83]

At the professional level, sprinters begin the race by assuming a crouching position in the starting blocks before leaning forward and gradually moving into an upright position as the contest progresses and momentum is gained.[84] Athletes remain in the same lane on the running track throughout all sprinting events,[83] with the sole exception of the 400 m indoors. Races up to 100 m are largely focused upon acceleration to an athlete's maximum speed.[84] All sprints beyond this distance increasingly incorporate an element of endurance.[85] Human physiology dictates that a runner's near-top speed cannot be maintained for more than thirty seconds or so as lactic acid builds up, and leg muscles begin to be deprived of oxygen.[83]

The 60 metres is a common indoor event and it an indoor world championship event. Other less-common events include the 50 metres, 55 metres, 300 metres and 500 metres which are used in some high and collegiate competitions in the United States. The 150 metres, is rarely competed: Pietro Mennea set a world best in 1983,[86] Olympic champions Michael Johnson and Donovan Bailey went head-to-head over the distance in 1997,[87] and Usain Bolt improved Mennea's record in 2009.[86]

Middle distance

Middle distance running events are track races longer than sprints up to 3000 metres. The standard middle distances are the 800 metres, 1500 metres and mile run, although the 3000 metres may also be classified as a middle distance event.[88] The 880 yard run, or half mile, was the forebear to the 800 m distance and it has its roots in competitions in the United Kingdom in the 1830s.[89] The 1500 m came about as a result of running three laps of a 500 m track, which was commonplace in continental Europe in the 1900s.[90]

Long distance

Examples of longer-distance running events are long distance track races, marathons, ultramarathons, and multiday races.

See also

References

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External links

1992 United States presidential election

The 1992 United States presidential election was the 52nd quadrennial presidential election. It was held on Tuesday, November 3, 1992. Democratic Governor Bill Clinton of Arkansas defeated incumbent Republican President George H. W. Bush, independent businessman Ross Perot of Texas, and a number of minor candidates.

Bush had alienated many of the conservatives in his party by breaking his 1988 campaign pledge against raising taxes, but he fended off a primary challenge from conservative commentator Pat Buchanan. Bush's popularity after his success in the Gulf War dissuaded high-profile Democratic candidates like Mario Cuomo from entering the 1992 Democratic primaries. Clinton, a leader of the centrist Democratic Leadership Council, established himself as the front-runner for the Democratic nomination by sweeping the Super Tuesday primaries. He defeated former and future Governor of California Jerry Brown, former Massachusetts Senator Paul Tsongas, and other candidates to win his party's nomination, and chose Senator Al Gore as his running mate. Billionaire Ross Perot launched an independent campaign, emphasizing his opposition to the North American Free Trade Agreement and his plan to reduce the national debt.

The economy was in recession and Bush's greatest strength, foreign policy, was regarded as much less important following the dissolution of the Soviet Union and the end of the Cold War and the relatively peaceful climate in the Middle East after the Gulf War. Perot led in several polls taken in June 1992, but severely damaged his candidacy by temporarily dropping out of the race in July. The Bush campaign criticized Clinton's character and emphasized Bush's foreign policy successes, while Clinton focused on the economy.

Clinton won a plurality in the popular vote and a majority of the electoral vote, breaking a streak of three straight Republican victories. Clinton swept the Northeastern United States, marking the start of Democratic dominance in the region in presidential elections, while also performing well in the Midwest and the West. Along with Jimmy Carter and Gerald Ford, Bush is one of three incumbent presidents since World War II to be defeated in the general election. Perot won 18.9% of the popular vote, the highest share of the vote won by a candidate outside of the two major parties since 1912. Although he failed to win any electoral votes, Perot found support in every state, and Clinton's home state of Arkansas was the lone state to give a majority of its vote to any candidate.

2020 Democratic Party presidential primaries

The 2020 Democratic Party presidential primaries and caucuses will be a series of electoral contests organized by the Democratic Party to select the approximately 3,768 pledged delegates to the Democratic National Convention, who by pledged votes shall elect the Democratic nominee for President of the United States in the 2020 U.S. presidential election. The elections are scheduled to take place from February to June 2020, within all fifty U.S. states, the District of Columbia, five U.S. territories, and Democrats Abroad.

Independently of the result of primaries and caucuses, the Democratic Party will, from its group of party leaders and elected officials, also appoint 764 unpledged delegates (superdelegates) to participate in its national convention. In contrast to all previous election cycles, superdelegates will no longer have the right to cast decisive votes at the convention's first ballot for the presidential nomination (limiting their voting rights to either non-decisive votes on the first ballot or decisive votes for subsequent ballots on a contested convention).Twenty-seven major candidates have entered the race for the 2020 Democratic Party presidential nomination. Two of them, Richard Ojeda and Eric Swalwell, have opted to withdraw so far. This is the largest field of presidential candidates for any political party in the post-reform era of American history, exceeding the field of 17 major candidates that sought the Republican presidential nomination in 2016.

2020 United States Senate elections

Elections to the United States Senate will be held on November 3, 2020, with the 33 Class 2 seats of the Senate being contested in regular elections. The winners will be elected to six-year terms extending from January 3, 2021, until January 3, 2027. Additionally, there will be a special election in Arizona to fill the vacancy created by the death of John McCain in 2018.

In 2014, the last regularly scheduled elections for Class 2 Senate seats, the Republicans won a net gain of nine seats from the Democrats and gained a majority in the Senate. Republicans defended that majority in 2016 and 2018, and held 53 Senate seats following the 2018 elections. Democrats held 45 seats after the 2018 elections, while independents caucusing with the Democratic Party held two seats.

Including the special election in Arizona, Republicans will be defending 22 seats in 2020, while the Democratic Party will be defending 12 seats. Because the vice president of the United States has the power to break ties in the Senate, a Senate majority requires either 51 Senate seats without control of the vice presidency or 50 seats with control of the vice presidency. Thus, assuming that the two independents continue to caucus with the Senate Democratic Caucus, the Democrats will have to pick up at least three Senate seats to win a majority. If a Republican is elected as vice president in the 2020 election, then the Democratic Party will have to pick up at least four Senate seats to win a majority.

American football positions

In American football each team has 11 players on the field at one time. The specific role that a player takes on the field is called their position. Under the modern rules of American football, teams are allowed unlimited substitutions; that is, teams may change any number of players after any play. This has resulted in the development of three "platoons" of players: the offense (the team with the ball, which is trying to score), the defense (the team trying to prevent the other team from scoring, and to take the ball from them), and the special teams (who play in kicking situations). Within those platoons, various specific positions exist depending on what each player's main job is.

Cross country running

Cross country running is a sport in which teams and individuals run a race on open-air courses over natural terrain such as dirt or grass. Sometimes the runners are referred to as harriers (dogs). The course, typically 4–12 kilometres (2.5–7.5 mi) long, may include surfaces of grass, and earth, pass through woodlands and open country, and include hills, flat ground and sometimes gravel road. It is both an individual and a team sport; runners are judged on individual times and teams by a points-scoring method. Both men and women of all ages compete in cross country, which usually takes place during autumn and winter, and can include weather conditions of rain, sleet, snow or hail, and a wide range of temperatures.

Cross country running is one of the disciplines under the umbrella sport of athletics, and is a natural terrain version of long-distance track and road running. Although open-air running competitions are pre-historic, the rules and traditions of cross country racing emerged in Britain. The English championship became the first national competition in 1876 and the International Cross Country Championships was held for the first time in 1903. Since 1973 the foremost elite competition has been the IAAF World Cross Country Championships.

List of Running Man episodes

Running Man (Korean: 런닝맨) is a South Korean variety show, part of SBS's Good Sunday lineup. This show is classified as a game-variety show, where the cast members and guests complete missions in a landmark to win a race. Running Man first aired on July 11, 2010.

As of July 21, 2019, 460 episodes of Running Man have aired.

Long-distance running

Long-distance running, or endurance running, is a form of continuous running over distances of at least 3 kilometres (1.8 miles). Physiologically, it is largely aerobic in nature and requires stamina as well as mental strength.Among mammals, humans are well adapted for running significant distances, and particularly so among primates. The endurance running hypothesis suggests that running endurance in the genus Homo arose because travelling over large areas improved scavenging opportunities and allowed persistence hunting. The capacity for endurance running is also found in migratory ungulates and a limited number of terrestrial carnivores, such as bears, dogs, wolves and hyenas.In modern human society, long-distance running has multiple purposes: people may engage in it for physical exercise, for recreation, as a means of travel, for economic reasons, or for cultural reasons. Long distance running can also be used as a means to improve cardiovascular health. Running improves aerobic fitness by increasing the activity of enzymes and hormones that stimulate the muscles and the heart to work more efficiently. Endurance running is often a component of physical military training and has been so historically. Professional running is most commonly found in the field of sports, although in pre-industrial times foot messengers would run to deliver information to distant locations. Long-distance running as a form of tradition or ceremony is known among the Hopi and Tarahumara people, among others. Distance running can also serve as a bonding exercise for family, friends, colleagues, and has even been associated with nation-building. The social element of distance running has been linked with improved performance.In the sport of athletics, long-distance events are defined as races covering three kilometres (1.86 miles) and above. The three most common types are track running, road running and cross country running, all of which are defined by their terrain – all-weather tracks, roads and natural terrain, respectively. Typical long-distance track races range from 3000 metres to 10,000 metres (6.2 miles), cross country races usually cover 5 to 12 km (3 to 7½ miles), while road races can be significantly longer, reaching 100 kilometres (60 miles) and beyond. In collegiate cross country races in the United States, men race 8000 or 10000 meters, depending on their division, whereas women race 6000 meters [2]. The Summer Olympics features three long-distance running events: the 5000 metres, 10,000 metres and marathon (42.195 kilometres, or 26 miles and 385 yards). Since the late 1980s, Kenyans, Moroccans and Ethiopians have dominated in major international long-distance competitions. The high altitude of these countries has been proven to help these runners achieve more success. Mountain air, combined with endurance training, can lead to an increase in red blood cells, allowing more oxygen to be passed through the veins. The majority of these East African successful runners come from three mountain districts that run along the Great Rift Valley.

Marathon

The marathon is a long-distance race with an official distance of 42.195 kilometres (approximately 26 miles 385 yards), usually run as a road race. The event was instituted in commemoration of the fabled run of the Greek soldier Pheidippides, a messenger from the Battle of Marathon to Athens, who reported the victory. The marathon can be completed by running or with a run/walk strategy. There are also wheelchair divisions.

The marathon was one of the original modern Olympic events in 1896, though the distance did not become standardized until 1921. More than 800 marathons are held throughout the world each year, with the vast majority of competitors being recreational athletes, as larger marathons can have tens of thousands of participants.

O. J. Simpson

Orenthal James Simpson (born July 9, 1947), nicknamed The Juice, is an American former football running back, broadcaster, actor, advertising spokesman, and defendant in what has been described as the "trial of the century".

Simpson attended the University of Southern California (USC), where he played football for the USC Trojans and won the Heisman Trophy in 1968. He played professionally as a running back in the NFL for 11 seasons, primarily with the Buffalo Bills from 1969 to 1977. He also played for the San Francisco 49ers from 1978 to 1979. In 1973, he became the first NFL player to rush for more than 2,000 yards in a season. He holds the record for the single season yards-per-game average, which stands at 143.1. He was the only player to ever rush for over 2,000 yards in the 14-game regular season NFL format.

Simpson was inducted into the College Football Hall of Fame in 1983 and the Pro Football Hall of Fame in 1985. After retiring from football, he began new careers in acting and football broadcasting.

In 1994, Simpson was arrested and charged with the murders of his ex-wife, Nicole Brown Simpson, and her boyfriend, Ron Goldman. He was acquitted by a jury after a lengthy and internationally publicised trial. The families of the victims subsequently filed a civil suit against him, and in 1997 a civil court awarded a $33.5 million judgment against him for the victims' wrongful deaths. In 2000, he moved to Florida to avoid paying any more of the liability judgment, settling in Miami.

In 2007, Simpson was arrested in Las Vegas, Nevada, and charged with the felonies of armed robbery and kidnapping. In 2008, he was convicted and sentenced to 33 years imprisonment, with a minimum of nine years without parole. He served his sentence at the Lovelock Correctional Center near Lovelock, Nevada. Simpson was granted parole on July 20, 2017. He was eligible for release from prison on October 1, 2017, and was released on that date.

Operating system

An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.

Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources.

For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers.

The dominant desktop operating system is Microsoft Windows with a market share of around 82.74%. macOS by Apple Inc. is in second place (13.23%), and the varieties of Linux are collectively in third place (1.57%). In the mobile (smartphone and tablet combined) sector, use in 2017 is up to 70% of Google's Android and according to third quarter 2016 data, Android on smartphones is dominant with 87.5 percent and a growth rate 10.3 percent per year, followed by Apple's iOS with 12.1 percent and a per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent. Linux distributions are dominant in the server and supercomputing sectors. Other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications.

Platform game

Platform games, or platformers, are a video game genre and subgenre of action game. In a platformer the player controlled character must jump and climb between suspended platforms while avoiding obstacles. Environments often feature uneven terrain of varying height that must be traversed. The player often has some control over the height and distance of jumps to avoid letting their character fall to their death or miss necessary jumps. The most common unifying element of games of this genre is the jump button, but now there are other alternatives like swiping a touchscreen. Other acrobatic maneuvers may factor into the gameplay as well, such as swinging from objects such as vines or grappling hooks, as in Ristar or Bionic Commando, or bouncing from springboards or trampolines, as in Alpha Waves. These mechanics, even in the context of other genres, are commonly called platforming, a verbification of platform. Games where jumping is automated completely, such as 3D games in The Legend of Zelda series, fall outside of the genre.

Platform games originated in the early 1980s, which were often about climbing ladders as much as jumping, with 3D successors popularized in the mid-1990s. The term describes games where jumping on platforms is an integral part of the gameplay and came into use after the genre had been established, no later than 1983. The genre is frequently combined with elements of other genres, such as the shooter elements in Contra, Beat 'em up elements of Viewtiful Joe, adventure elements of Flashback, or role-playing game elements of Castlevania: Symphony of the Night.

While commonly associated with console gaming, there have been many important platform games released to video arcades, as well as for handheld game consoles and home computers. North America, Europe and Japan have played major parts in the genre's evolution. Platform themes range from cartoon-like games to science fiction and fantasy epics.

At one point, platform games were the most popular genre of video game. At the peak of their popularity, it is estimated that between one-quarter and one-third of console games were platformers, but have since been supplanted by first-person shooters . As of 2006, the genre had become far less dominant, representing a two percentage market share as compared to fifteen percent in 1998, but is still commercially viable, with a number of games selling in the millions of units. Since 2010, a variety of endless running platformers for mobile devices have brought renewed popularity to the genre.

Running Man (TV series)

Running Man (Korean: 런닝맨) is a South Korean variety show, forming part of SBS's Good Sunday lineup. It first aired on July 11, 2010.

Running Man was classified as an "urban action variety"; a genre of variety shows in an urban environment. The MCs and guests were to complete missions at a landmark to win the race. The show has since shifted to a more familiar reality-variety show concept focused on games. It has garnered attention as being the comeback program for Yoo Jae-suk, the main MC of the program, after leaving Good Sunday's Family Outing in February 2010.The show has become popular in other parts of Asia, and has gained online popularity among Hallyu fans, having been fansubbed into various languages, such as English, Persian, Spanish, Portuguese, French, Italian, Thai, Vietnamese, Chinese, Malay, Indonesian, Burmese, Arabic, Russian, and Turkish.The show has made it to the list of Business Insider's 20 TV Shows of 2016.Since April 2017, Running Man is airing as the first part of Good Sunday at 4:50 pm KST and competing against KBS2's The Return of Superman and MBC's King of Mask Singer. Running Man previously aired at 6:25 pm KST on Sundays, as the second part of Good Sunday, competing against KBS2's 1 Night 2 Days.

Running back

A running back (RB) is an American and Canadian football position, a member of the offensive backfield. The primary roles of a running back are to receive handoffs from the quarterback for a rushing play, to catch passes from out of the backfield, and to block. There are usually one or two running backs on the field for a given play, depending on the offensive formation. A running back may be a halfback (in certain contexts also referred to as a tailback), a wingback or a fullback. A running back will sometimes be called a "feature back" if he is the team's starting running back.

Running of the bulls

The running of the bulls (Spanish: encierro, from the verb encerrar, 'to corral, to enclose'; Occitan: abrivado, literally 'haste, momentum'; Catalan: correbous, 'street-bulls') is an event that involves running in front of a small group of cattle, typically six but sometimes ten or more, that have been let loose on a course of a sectioned-off subset of a town's streets, usually as part of a summertime festival. Particular breeds of cattle may be favored, such as the toro bravo in Spain, also often used in post-run bullfighting, and Camargue cattle in Occitan France, which are not fought. Actual bulls (non-castrated male cattle) are typically used in such events.

The most famous bull-run – what a capitalized "the Running of the Bulls" most often refers to in English – is the encierro held in Pamplona during the nine-day festival of Sanfermines in honour of Saint Fermin. It has become a major global tourism event, today very different from the traditional, local festival. More traditional summer bull-runs are held in other places such as towns and villages across Spain and Portugal, in some cities in Mexico, and in the Occitan (Camargue) region of southern France. Bull-running was formerly also practiced in rural England, most famously at Stamford until 1837.

The origin of this event comes from the need to transport the bulls from the fields outside the city, where they were bred, to the bullring, where they would be killed in the evening. During this "run", youngsters would jump among them to show off their bravado. In Pamplona and other places, the six bulls in the event are still those that will feature in the afternoon bullfight of the same day.

Spanish tradition holds that bull-running began in northeastern Spain in the early 14th century. While transporting cattle in order to sell them at the market, men would try to speed the process by hurrying their cattle using tactics of fear and excitement. After years of this practice, the transportation and hurrying began to turn into a competition, as young adults would attempt to race in front of the bulls and make it safely to their pens without being overtaken. When the popularity of this practice increased and was noticed more and more by the expanding population of Spanish cities, a tradition was created and stands to this day.

Sport of athletics

Athletics is a collection of sporting events that involve competitive running, jumping, throwing, and walking. The most common types of athletics competitions are track and field, road running, cross country running, and race walking.

The results of racing events are decided by finishing position (or time, where measured), while the jumps and throws are won by the athlete that achieves the highest or furthest measurement from a series of attempts. The simplicity of the competitions, and the lack of a need for expensive equipment, makes athletics one of the most commonly competed sports in the world. Athletics is mostly an individual sport, with the exception of relay races and competitions which combine athletes' performances for a team score, such as cross country.

Organized athletics are traced back to the Ancient Olympic Games from 776 BC. The rules and format of the modern events in athletics were defined in Western Europe and North America in the 19th and early 20th century, and were then spread to other parts of the world. Most modern top level meetings are conducted by the International Association of Athletics Federations and its member federations.

The athletics meeting forms the backbone of the Summer Olympics. The foremost international athletics meeting is the IAAF World Championships in Athletics, which incorporates track and field, marathon running and race walking. Other top level competitions in athletics include the IAAF World Cross Country Championships and the IAAF World Half Marathon Championships. Athletes with a physical disability compete at the Summer Paralympics and the World Para Athletics Championships.

The word athletics is derived from the Ancient Greek ἀθλητής (athlētēs, "combatant in public games") from ἆθλον (athlon, "prize") or ἆθλος (athlos, "competition"). Initially, the term was used to describe athletic contests in general – i.e. sporting competition based primarily on human physical feats. In the 19th century, the term athletics acquired a more narrow definition in Europe and came to describe sports involving competitive running, walking, jumping and throwing. This definition continues to be the most prominent one in the United Kingdom and most of the areas of the former British Empire. Furthermore, foreign words in many Germanic and Romance languages which are related to the term athletics also have a similar meaning.

In much of North America, athletics is synonymous with sports in general, maintaining a more historical usage of the term. The word "athletics" is rarely used to refer to the sport of athletics in this region. Track and field is preferred, and is used in the United States and Canada to refer to most athletics events, including racewalking and marathon running (although cross country running is typically considered as a separate sport).

Sprint (running)

Sprinting is running over a short distance in a limited period of time. It is used in many sports that incorporate running, typically as a way of quickly reaching a target or goal, or avoiding or catching an opponent. Human physiology dictates that a runner's near-top speed cannot be maintained for more than 30–35 seconds due to the depletion of phosphocreatine stores in muscles, and perhaps secondarily to excessive metabolic acidosis as a result of anaerobic glycolysis.In athletics and track and field, sprints (or dashes) are races over short distances. They are among the oldest running competitions, being recorded at the Ancient Olympic Games. Three sprints are currently held at the modern Summer Olympics and outdoor World Championships: the 100 metres, 200 metres, and 400 metres.

At the professional level, sprinters begin the race by assuming a crouching position in the starting blocks before leaning forward and gradually moving into an upright position as the race progresses and momentum is gained. The set position differs depending on the start. Body alignment is of key importance in producing the optimal amount of force. Ideally the athlete should begin in a 4-point stance and push off using both legs for maximum force production. Athletes remain in the same lane on the running track throughout all sprinting events, with the sole exception of the 400 m indoors. Races up to 100 m are largely focused upon acceleration to an athlete's maximum speed. All sprints beyond this distance increasingly incorporate an element of endurance.

Steeplechase (athletics)

The steeplechase is an obstacle race in athletics, which derives its name from the steeplechase in horse racing. The foremost version of the event is the 3000 metres steeplechase. The 2000 metres steeplechase is the next most common distance. The 1900 Olympics featured a 2500 metres steeplechase and a 4000 metres steeplechase, and a 2590 metres steeplechase was held at the 1904 Olympics. A 1000 metres steeplechase is occasionally used in youth athletics.

Track and field

Track and field is a sport which includes athletic contests established on the skills of running, jumping, and throwing. The name is derived from where the sport takes place, a running track and a grass field for the throwing and some of the jumping events. Track and field is categorized under the umbrella sport of athletics, which also includes road running, cross country running, and race walking.

The foot racing events, which include sprints, middle- and long-distance events, race walking and hurdling, are won by the athlete with the fastest time. The jumping and throwing events are won by the athlete who achieves the greatest distance or height. Regular jumping events include long jump, triple jump, high jump and pole vault, while the most common throwing events are shot put, javelin, discus and hammer. There are also "combined events" or "multi events", such as the pentathlon consisting of five events, heptathlon consisting of seven events, and decathlon consisting of ten events. In these, athletes participate in a combination of track and field events. Most track and field events are individual sports with a single victor; the most prominent team events are relay races, which typically feature teams of four. Events are almost exclusively divided by gender, although both the men's and women's competitions are usually held at the same venue. If a race has too many people to run all at once, preliminary heats will be run to narrow down the field of participants.

Track and field is one of the oldest sports. In ancient times, it was an event held in conjunction with festivals and sports meets such as the Ancient Olympic Games in Greece. In modern times, the two most prestigious international track and field competitions are athletics competition at the Olympic Games and the IAAF World Championships in Athletics. The International Association of Athletics Federations is the international governing body.

Records are kept of the best performances in specific events, at world and national levels, right down to a personal level. However, if athletes are deemed to have violated the event's rules or regulations, they are disqualified from the competition and their marks are erased.

In North America, the term track and field may be used to refer to other athletics events, such as cross country, the marathon and road running, rather than strictly track-based events.

Triathlon

A triathlon is a multisport race with three continuous and sequential endurance races. The word is of Greek origin, from τρεῖς or treis (three) and ἆθλος or athlos (competition).While variations of the sport exist, the most common form includes swimming, cycling, and running over various distances. Triathletes compete for fastest overall course completion, including timed transitions between the three races.A transition area is set up where the athletes change gear for different segments of the race. This is where the switches from swimming to cycling and cycling to running occur. These areas are used to store bicycles, performance apparel, and any other accessories needed for the next stage of the race. The transition from swim to bike is referred to as T1 and that between the bike and run is referred to as T2. The athlete's overall time for the race includes time spent in T1 and T2. Transition areas vary in size depending on the number of participants expected. In addition, these areas provide a social headquarters before the race.The nature of the sport focuses on persistent and often periodized training in each of the three disciplines, as well as combination workouts and general strength conditioning.

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