Adventure running

Long-distance running, or endurance running, is a form of continuous running over distances of at least . Physiologically, it is largely aerobic in nature and requires stamina as well as mental strength.

Within endurance running comes two different types of respiration. The more prominent side that runners experience more frequently is aerobic respiration. This occurs when oxygen is present, and the body is able to utilize oxygen to help generate energy and muscle activity. On the other side, anaerobic respiration occurs when the body is deprived of oxygen, and this is common towards the final stretch of races when there is a drive to speed up to a greater intensity. Overall, both types of respiration are used by endurance runners quite often, but are very different from each other.

Among mammals, humans are well adapted for running significant distances, and particularly so among primates. 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.

Endurance running is often a component of physical military training. Long-distance running as a form of tradition or ceremony is known among the Hopi and Tarahumara people, among others.

In the sport of athletics, long-distance events are defined as races covering 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.

History

Hunting

Anthropological observations of modern hunter-gatherer communities have provided accounts for long-distance running as a historic method for hunting among the San of the Kalahari, American Indians, and the Australian Aborigines. In this method, the hunter would run at a slow and steady pace between one hour and a few days, in an area where the animal has no place to hide. The animal, running in spurts, has to stop to pant in order to cool itself, but as the chase goes on it would not have enough time before it has to start running again, and after a while would collapse from exhaustion and heat.Sears, Edward Seldon. ''Running through the Ages''. McFarland, 2001. The body structure of a skeleton of a 12 years old Nariokatome boy is suggested to prove that early humans from 1.5 million years ago were eating more meat and less plants, and hunted by running down animals.

Messengers

With developments in agriculture and culture, long-distance running took more and more purposes other than hunting: religious ceremonies, delivering messages for military and political purposes, and sport.

Running messengers are reported from early Sumer, were named ''lasimu'' as military men as well as the king's officials who disseminated documents throughout the kingdom by running. Ancient Greece was famous for its running messengers, who were named ''hemerodromoi'', meaning “day runners”. One of the most famous running messengers is Pheidippides, who according to the legend ran from Marathon to Athens to announce the victory of the Greek over the Persians in the Battle of Marathon in 490 B.C. He collapsed and died as he delivered the message “we won”. While there are debates around the accuracy of this historical legend, whether Pheidippides actually ran from Marathon to Athens or between other cities, how far this was, and if he was the one to deliver the victory message, the marathon running event of 26.2 miles / 42.195 km is based on this legend.

Competition

Typical long-distance track races range from 3000 metres (1.87 miles) to 10,000 metres (6.2 miles), cross country races usually cover 5 to 12 km (3 to 7 miles), while road races can be significantly longer, reaching and beyond. In collegiate cross country races in the United States, men race 8,000 or 10,000 meters, depending on their division, whereas women race 6,000 meters. The Summer Olympics features four long-distance running events: the 3000 metres steeplechase (which also involves jumping over barriers and water), the 5000 metres, 10,000 metres and marathon (42.195 kilometres, or 26 miles and 385 yards).

Physiology

Humans are considered among the best distance runners among all running animals: game animals are faster over short distances, but they have less endurance than humans.Carrier, D. R., Kapoor, A. K., Kimura, T., Nickels, M. K., Satwanti, Scott, E. C., So, J. K., & Trinkaus, E. (1984). The energetic paradox of human running and hominid evolution. ''Current Anthropology'', Vol. 25, No. 4 (Aug. - Oct. 1984), pp. 483-495. Unlike other primates whose bodies are suited to walk on four legs or climb trees, the human body has evolved into upright walking and running around 2-3 million years ago.Lovejoy, C. O. (1988). Evolution of human walking. ''Scientific American'' (0036-8733), 259 (5), p. 82. The human body can endure long-distance running through the following attributes:
# Bone and muscle structure: unlike quadruped mammals, which have their center of mass in front of the hind legs or limbs, in biped mammals including humans the center of mass lies right above the legs. This leads to different bone and muscular demands especially in the legs and pelvis.
# Dissipation of metabolic heat: humans’ ability to cool the body by sweating through the body surface provides many advantages over panting through the mouth or nose. These include a larger surface of evaporation and independence of the respiratory cycle.
One distinction between upright walking and running is energy consumption during locomotion. While walking, humans use about half the energy needed to run.

Factors

Aerobic capacity

One's aerobic capacity or VO₂Max is the ability to maximally take up and consume oxygen during exhaustive exercise. Long-distance runners typically perform at around 75–85% of peak aerobic capacity, while short-distance runners perform at closer to 100% of peak.

Aerobic capacity depends on the transportation of large amounts of blood to and from the lungs to reach all tissues. This in turn is dependent on having a high cardiac output, sufficient levels of hemoglobin in blood, and an optimal vascular system to distribute of blood. A 20 fold increase of local blood flow within skeletal muscle is necessary for endurance athletes, like marathon runners, to meet their muscles' oxygen demands at maximal exercise that are up to 50 times greater than at rest.

Elite long-distance runners often have larger hearts and decreased resting heart rates that enable them to achieve greater aerobic capacities. Increased dimensions of the heart enable an individual to achieve a greater stroke volume. A concomitant decrease in stroke volume occurs with the initial increase in heart rate at the onset of exercise. Despite an increase in cardiac dimensions, a marathoner's aerobic capacity is confined to this capped and ever decreasing heart rate.

The amount of oxygen that blood can carry depends on blood volume, which increases during a race, and the amount of hemoglobin in blood.

Other physiological factors affecting a marathon runner's aerobic capacity include pulmonary diffusion, mitochondria enzyme activity, and capillary density.

A long-distance runner's running economy is their steady state requirement for oxygen at specific speeds and helps explain differences in performance for runners with very similar aerobic capacities. This is often measured by the volume of oxygen consumed, either in liters or milliliters, per kilogram of body weight per minute (L/kg/min or mL/kg/min). the physiological basis for this was uncertain, but it seemed to depend on the cumulative years of running, and reaches a cap that longer individual training sessions cannot overcome.

Lactate threshold

A long-distance runner's velocity at the lactate threshold is strongly correlated to their performance. Lactate threshold is the cross over point between predominantly aerobic energy usage and anaerobic energy usage and is considered a good indicator of the body's ability to efficiently process and transfer chemical energy into mechanical energy. For most runners, the aerobic zone doesn't begin until around 120 heart beats per minute. Lactate threshold training involves tempo workouts that are meant to build strength and speed, rather than improve the cardiovascular system's efficiency in absorbing and transporting oxygen. By running at your lactate threshold, your body will become more efficient at clearing lactic acid and reusing it to fuel your muscles. Uncertainty exists in regards to how lactate threshold affects endurance performance.

Fuel

In order to sustain high intensity running, a marathon runner must obtain sufficient glycogen stores. Glycogen can be found in the skeletal muscles or liver. With low levels of glycogen stores at the onset of the marathon, premature depletion of these stores can reduce performance or even prevent completion of the race. ATP production via aerobic pathways can further be limited by glycogen depletion. Free Fatty Acids serve as a sparing mechanism for glycogen stores. The artificial elevation of these fatty acids along with endurance training demonstrate a marathon runner's ability to sustain higher intensities for longer periods of time. The prolonged sustenance of running intensity is attributed to a high turnover rate of fatty acids that allows the runner to preserve glycogen stores later into the race.

Long-distance runners generally practice carbohydrate loading in their training and race preparation.

Thermoregulation and body fluid loss

The maintenance of core body temperature is crucial to a marathon runner's performance and health. An inability to reduce rising core body temperature can lead to hyperthermia. In order to reduce bodily heat, the metabolically produced heat needs to be removed from the body via sweating, which in turn requires re-hydration to compensate for. Replacement of fluid is limited but can help keep the body's internal temperatures cooler. Fluid replacement is physiologically challenging during exercise of this intensity due to the inefficient emptying of the stomach. Partial fluid replacement can serve to avoid a marathon runner's body over heating but not enough to keep pace with the loss of fluid via sweat evaporation. Environmental factors can especially complicate heat regulation.

Altitude

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. High altitude, combined with endurance training, can lead to an increase in red blood cells, allowing increased oxygen delivery via arteries. The majority of these East African successful runners come from three mountain districts that run along the Great Rift Valley. While altitude may be a contributing factor, a culture of hard work, teamwork, as well as an advanced institutional structure also contributes to their success.

Impact on health

"… an evolutionary perspective indicates that we did not evolve to run long distances at fast speeds on a regular basis. As a result, it is unlikely there was selection for the human body to cope with some of the extreme demands runners place on their bodies."

The impact of long-distance running on human health is generally positive. Various organs and systems in the human body are improved: bone mineral density is increased, and cholesterol is lowered.

However, beyond a certain point, negative consequences might occur. Older male runners (45-55) who run more than per week face reduced testosterone levels, although they are still in the normal range. Running a marathon lowers testosterone levels by 50% in men, and more than doubles cortisol levels for 24 hours. Low testosterone is thought to be a physiological adaptation to the sport, as excess muscle caused may be shed through lower testosterone, yielding a more efficient runner. Veteran, lifelong endurance athletes have been found to have more heart scarring than controls groups, but replication studies and larger studies should be done to firmly establish the link, which may or may not be causal. Some studies find that running more than per week yields no lower risk for all-cause mortality than non-runners, although these studies are in conflict with large studies that show longer lifespans for any increase in exercise volume.

Elite-level long-distance running is associated with a 3 to 7 times higher risk of knee osteoarthritis later in life compared to non-runners.

The effectiveness of shoe inserts has been contested. Memory foam and similar shoe inserts may be comfortable, but they can make foot muscles weaker in the long term. Running shoes with special features, or lack thereof in the case of minimalist designs, do not prevent injury. Rather, comfortable shoes and standard running styles are safer.

In sport

Many sporting activities feature significant levels of running under prolonged periods of play, especially during ball sports like association football and rugby league. However, continuous endurance running is exclusively found in racing sports. Most of these are individual sports, although team and relay forms also exist.

The most prominent long-distance running sports are grouped within the sport of athletics, where running competitions are held on strictly defined courses and the fastest runner to complete the distance wins. The foremost types are long-distance track running, road running and cross-country running. Both track and road races are usually timed, while cross country races are not always timed and typically only the placing is of importance. Other less popular variants such as fell running, trail running, mountain running and tower running combine the challenge of distance with a significant incline or change of elevation as part of the course.

Multisport races frequently include endurance running. Triathlon, as defined by the International Triathlon Union, may feature running sections ranging from to the marathon distance (42.195 kilometres, or 26 miles and 385 yards), depending on the race type. The related sport of duathlon is a combination of cycling and distance running. Previous versions of the modern pentathlon incorporated a three or four kilometre (1.9–2.5 mi) run, but changes to the official rules in 2008 meant the running sections are now divided into three separate legs of one kilometre each (0.6 mi).

Depending on the rules and terrain, navigation sports such as foot orienteering and rogaining may contain periods of endurance running within the competition. Variants of adventure racing may also combine navigational skills and endurance running in this manner.

Running competitions

Track running

The history of long-distance track running events are tied into the track and field stadia where they are held. Oval circuits allow athletes to cover long distances in a confined area. Early tracks were usually on flattened earth or were simply marked areas of grass. The style of running tracks became refined during the 20th century: the oval running tracks were standardised to 400 metres in distance and cinder tracks were replaced by synthetic all-weather running track of asphalt and rubber from the mid-1960s onwards. It was not until the 1912 Stockholm Olympics that the standard long-distance track events of 5000 metres and 10,000 metres were introduced.

* The 3000 metres steeplechase is a race that involves not only running but also jumping over barriers and a water pit. While it can be considered a hurdling event, it is also widely regarded as a long-distance running event as well. The obstacles for the men are high, and for the women .
**The world record for men is 7:53.63 by Saif Saaeed Shaheen of Qatar in Brussels, Belgium set on 3 September 2004.
**The world record for women is 8:44.32 by Beatrice Chepkoech

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