Long-Distance Running: An Investigation Into its Impact on Human Health

 

Long-Distance Running: An Investigation Into its Impact on Human Health

Rachel Dermack
Categories: 
Published by the PIT Journal: 

Abstract: 

Long-distance running has helped our species survive and evolve. Elements of the human physique, like the Achilles tendon and the length of the human body, make our bodies primed for running. Studies show that running can ease depression and anxiety. It can reduce risk of heart disease, diabetes, and obesity. Admittedly, running can cause bone stress injury, bronchospasm, cramps, blisters, and other issues. These physiological and psychological benefits outweigh the health risks that go along with running. Despite the health risk, running’s popularity is still on the rise. Long-distance running has helped people become healthier and happier for millions of years.

Article: 

Long-distance running has shaped and sharpened the brains of human beings for millions of years. Anthropologists have hypothesized that endurance running allowed humans to capture prey, which ultimately supplied them with the energy for mating (Reynolds)1. Running is a high intensity and low-cost exercise that enables humans to fully utilize their anatomic structure. However, modern humans have failed to take advantage of their athletic capabilities due to time constraints such as long working hours (Lack of exercise)2. This lack of routine physical exercise that humans have adopted has increased the risk for developing health issues such as coronary heart disease (Lee et. al)3. Long-distance running is an exercise that has contributed to the evolution of the human anatomical structure and has influenced human physiological and psychological health over time; thus, the exercise possesses significance for human health today.
 
Since the initial presence of the Homo 2 million years ago, humans have maintained certain anatomic features that have made them well suited for long-distance running. Many of these features help humans save energy. For example, human legs are made up of long spring-like tendons that are connected to short muscle fascicles. This feature enables humans to expend less energy when lifting their feet off of the ground. Specifically, humans possess the Achilles tendon, which connects the heel to plantar flexors in the foot. In fact, these plantar flexors, or longitudinal arches, return approximately 17% of the energy that the foot expends. These spring-like capabilities help contribute to the stride lengths of 2 meters to 3.5 meters that humans are competent of making, allowing them to travel longer distances at a slower speed. These long stride lengths can also be attributed to the long leg length that humans have relative to their body mass (Bramble & Lieberman)4
 
Innate skeletal strength and stabilization mechanisms that humans possess also make their bodies adept for long distance running. When the heel of the foot strikes the ground, shock waves move up the body through the spine and into the head, spreading stress throughout the body. The human anatomy is made up of strong skeletal joints and limbs that are able to withstand these high stress levels. The human body is also made up of features that provide stability and balance for long-distance runners. For instance, the trunk and neck of humans incline forward when they run, providing balance for the entirety of the body. Also, when humans run, they swing their arms, which has the potential to cause an imbalance. However, the Homo maintains the derived characteristic of wide shoulders, which counterbalance these vast movements (Bramble & Lieberman)4. These innate features of the body exist to enable humans to excel in long-distance running; thus, the human body was designed to continue to utilize these structures. 
 
Although the original structure of the human body possessed features that made people capable long-distance runners, humans have adapted certain traits that have made them more suited for the activity. According to the evolutionary hypothesis, “natural selection drove early humans to become even more athletic.”This is because humans that were capable of running longer distances could catch more prey and thus survived to mate and produce viable offspring.1 Because of variation that is present in the human genome, the perhaps less-common traits that benefited the surviving generations became more prevalent. Thus, humans evolved to have longer legs and shorter toes to expend less energy and travel faster for shorter distance runs, less hair and multiplication of eccrine sweat glands to decrease metabolic heat, and inner-ear mechanisms to maintain balance and stability.1, 4 The evolution of these physical traits that have propelled humans to be more skillful runners illustrates the influence that the activity has had on their survival; thus, long-distance running must continue to have an impact on the development of the human bodily structure today. Furthermore, for as long as humans pursue long-distance running as a physical activity, bodily structures and mechanisms will continue to adapt to make them more skilled. 
 
Along with contributing to the evolution of anatomical human characteristics, long-distance running has remained a prevalent physical activity because it has had a history of providing psychological benefits. For instance, running causes the brain to release endorphins that are “associated with opioidergic activation in frontolimbic brain regions,” which produces a calming effect that puts one in a euphoric state, or a “runner’s high” (The Runner’s High; Roth).5, 6 This euphoria is closely linked with reward, since the sensation is typically felt after experiences involving training.5 Such training regimens may include “accomplishing a previously set goal, such as running 30 minutes without a break or finishing a 5 km run.”6 According to Selma Roth, completing such goals “gives a feeling of empowerment,” along with “increas[ing] self-esteem.”6 Regular running also helps one sustain a healthy weight and creates healthier looking hair and skin through improved blood circulation.6 It is the combination of the increase in internal empowerment induced by the runner’s high and the increased capability of maintaining a healthy external appearance that long-distance running provides that may maximize one’s potential physical attractiveness. It can be concluded that improved physical appearance helps build one’s self-confidence as well. Thus, it is the combination of the increase in confidence that results when one achieves long-distance goals and the maximization of one’s physical appearance that positively contribute to human psychological health. 
 
Running is also a type of physical exercise that can be used to treat and prevent psychological disorders. According to the Archives of Internal Medicine, regular exercise such as long-distance running “lifts depression just as well as prescription antidepressants” (Bauman).7 In one study, 156 men and women with major depressive disorders were split into 3 groups, and the group that exercised aerobically with activities such as running for 40 minutes three times a week had longer lasting effects than the initial response that prescription antidepressants provide.7 This can be attributed partially to the temporary euphoric sensations that one experiences with a “runner’s high.”5 However, if performed regularly, the psychological benefits will endure. Another study of diabetic patients found that when one performs a long-duration aerobic activity such as long-distance running on a long-term basis, it reduced “stress emotions” experienced in response to stressful stimuli and events by the disease. Additionally, smaller increases in physiological reactivity to stressors were found when the participants implemented aerobic exercise (Burish, Sementilli, & Vasterling).8 Another study that measured the effects of aerobic exercise on anxiety sensitivity discussed specifically how high-intensity exercises produced a more rapid reduction in anxiety sensitivity in comparison to low-intensity exercises. Further, only the high-intensity exercise participants had reduced fear of anxiety-related physiological sensations (Rabian et. al).9 Long-distance running is both a high-intensity and long-duration exercise; thus the studies regarding stress and exercise correlate with the psychological effects of such activity. In all, physical exercise provides psychological benefits for individuals. Long-distance running is a type of physical exercise, and is particularly advantaged because it is both long-duration and high-intensity. Therefore, long-distance running has provided a positive impact on psychological well-being that continues to impact human health today. 
 
Running has been shown to have an impact on the psychological function of sleep as well. According to one study, healthy adolescents who took part in a daily morning running routine for three weeks had decreased and overall lower insomnia severity scores compared to those of non-runners. Additionally, the runners were found to have higher sleep efficiency, with an increased proportion of deep Stage 3 and REM sleep and a lower proportion of lighter, Stage 1 sleep (Kalak et. al).10 However, partaking in a vigorous exercise like long-distance running approximately four to six hours before one plans to sleep is not recommended because doing so can potentially impair sleep (Youngstedt).11 Thus, one should plan to run in the morning or earlier in the day in order to receive any potential sleep benefits. The improvement of sleep quality that is associated with an exercise such as long-distance running could perhaps reduce the amount of sleep that one needs. This shorter time allocated to sleep could give people more time to fulfill obligations, perhaps making them feel more inclined to continue exercising due to reduced time constraints. 
 
Long-distance running also provides physiological benefits for the human body. Not only does the exercise stimulate the heart, respiratory system, and the brain, but it also reduces cardiovascular mortality.3 According to one study, adult men who ran, regardless of the time and distance, had 30% and 45% lower adjusted risks of all-cause cardiovascular mortality.3 In fact, because of the lowered risk of fatal coronary heart disease associated with marathon running, patients recovering from heart attacks in rehabilitation centers in Toronto and Honolulu implemented marathon training in order to recuperate. Incorporating marathon training by stressing that the “patient” was in fact an “athlete” increased motivation to recover as well (Bassler)12. Additionally, in the 1920s, Eliot Joslin identified exercise as a component of good diabetic therapy. Exercise also “has the potential to reduce plasma insulin” and to “improve metabolic control, insulin sensitivity, glucose tolerance, and the efficiency of the circulatory system.”8 Furthermore, the regimen helps one control his or her weight, burning approximately 374 calories for a 165-pound person who runs six miles per hour for 30 minutes (Burning calories).13 Maintaining a healthy weight is necessary if one wants to lower the risk of developing health issues as well. The plethora of physiological benefits that long-distance running provides should be considered for people who look to engage in the activity regularly today. Long-distance running is beneficial so much so that its physiological health impact is life altering and potentially life-saving. 
 
In fact, several studies have proven that regular running provides the physiological benefit of an increased life expectancy. For instance, the study of adult men who ran and had lower adjusted risks of all-cause cardiovascular mortality showed that the men also had an increased life expectancy of three years.3 Researchers taking part in the Copenhagen City Heart found that Danish men and women joggers had a 44% reduced death rate compared to non-joggers, along with an extension of lifespan of 6.2 years for men and 5.6 years for women. However, it should be noted that the benefit of an increased life expectancy due to running will not be achieved if one participates in it at extreme levels. Dr. Schnohr, the leader of the study, notes, “The relationship appears much like alcohol intakes” (Jogging).14 Moderate alcohol consumption can actually increase one’s lifespan, which Dr. Schnohr compares to the effect moderate running has on people’s health. Moderate running qualifies as participating in the exercise for approximately two to three hours per week according to a number of studies (Running too much).15 The longevity of life that distance running provides should certainly be noted if one wants to lower the possibility of death at a young age. 
 
Although endurance running has provided physiological benefits for humans, medical risks persist, many of which are short-term. In a review of medical problems of marathon runners, the following complications were found. Runners exhibited musculoskeletal problems such as cramps, blisters, and acute ankle and knee injuries. These runners also reported having gastrointestinal issues such as bloating, cramps, nausea, vomiting, diarrhea, and fecal incontinence. These gastrointestinal problems are due to the decrease of blood flow to such areas and increase of blood flow to muscles that are used to run. This redirection of blood flow of working muscles can also decrease renal perfusion, impairing concentrating activities to the kidneys. Runners also have the possibility of an exercise-induced bronchospasm (EIB), a pulmonary complication, which interrupts airflow five to fifteen minutes after the onset of exercise. All of these issues are definite concerns; however, exercise-associated collapse (EAC) is the most prevalent short-term problem that long-distance runners have exhibited. In fact, a 12-year study found that 59% of marathon medical tent visits were due to EAC. EAC typically results from heat exhaustion, which is associated with headaches, extreme fatigue, nausea, vomiting, dizziness, and profuse sweating (Sanchez, Corwell, &Berkhoff).16 These short-term problems in relation to distance running most likely exist because engaging in any type of movement can pose risks for the body, especially if it is high intensity. Therefore, one should be aware of such short-terms risks before engaging in distance running so that he or she can gain access to or make preparations for receiving proper medical attention if such problems were to persist. 
 
These short-term problems may not be avoidable, but certain factors can explain why one may be more at risk of developing such issues. In the review of medical problems at marathons, the number of miles a runner trained per week inversely correlated with the incidence of an injury.16 In other words, further training reduces the risk of short-term issues and those who train less carry a greater risk. Environmental factors can determine one’s chance of encountering post-marathon problems as well. If one were planning to run a spring marathon, he or she would have to train in the winter. The increase in heat between the seasons could make it difficult for the runner to adjust to the conditions. For instance, runners might not ingest the proper amount of fluids needed for their bodies to run in the warmer weather, and could become dehydrated as a result. Dehydration in turn can worsen or increase the risk for gastrointestinal issues and EAC. Fortunately, these problems are short-term and can be fixed within a few days. They also tend to resolve themselves with rest alone.16 These factors are important to consider when one plans on engaging in long-distance races such as marathons; however, the severity of such short-term abnormalities is low enough that long-distance runners should not be tremendously concerned about them. 
 
Risks of long-term physical injuries for distance runners exist as well. Specifically, long-distance runners are prone to developing bone stress injury (BSI) in long bones such as the tibia, fibula, and femur because of the rearfoot strike pattern that they use. Additionally, runners may develop BSI in the pelvis and lumbar spine. This condition makes the bone unable to withstand repetitive mechanical loading, resulting in structural fatigue and localized bone pain and tenderness (Warden, Davis, & Fredericson).17 Between one third and two thirds of competitive cross-country and long-distance runners have had this BSI condition.17 One can be classified as either low or high-risk, with the high-risk BSI patients being more prone to complete bone fracture. In addition, management of the condition depends on classification; however, both approaches involve temporary discontinuation of running, modification of workout regiments, and a gradual return to the exercise.17 Although BSI can be a treatable condition, long-distance running may present negative outcomes for participants of the activity; thus, the effects should be taken into account when considering engaging in the exercise. 
 
However, studies indicate that long-distance runners can avoid such long-term physiological injuries and risks. For instance, recent research has indicated that frequent long-distance runners, such as marathon and cross-country runners, are less prone to these injuries than novice, recreational, or even competitive runners.17 In other words, the more that an athlete trains his or her body, the lesser the risk he or she has of developing musculoskeletal injuries when running a long race.16 Furthermore, Roth reports that regular runners “will have stronger bones as they age compared to those who do not run” as well as stronger muscles which protect these bones.6 In fact, clinical studies have proven that muscle size and strength are directly related to BSI susceptibility.17 Other factors associated with training regimens such as shoe type, inserts, and surface type affect risk as well.17 Individual considerations such as age, body mass index (BMI), diet and nutrition, endocrine status and hormones, physical activity history, bone diseases, and medications influencing the bones modify the ability of the bones as well.17 The combination of factors that modify the load applied to bones and factors that modify the ability of bones determines one’s susceptibility.17 Yet, other risk factors remain unproven that might have to do with the role that genetics or specific inherited traits have on certain runners’ abilities (Incidence, risk factors and prevention).18 Nonetheless, it is still known that humans have adapted certain hereditary traits that have shaped them into a more athletically capable species.1 Ways to combat long-term physiological risks associated with long-distance running must be taken into account if one plans to take part in the exercise in the future in order to prevent conditions such as BSI. Furthermore, if people practice proper training regimens and considers their individual history and capabilities, then they can receive the maximum benefits from long-distance running. 
 
Modern humans have inherited traits such as longer limbs that make them more efficient runners; however, slower, long-distance running has remained widespread. According to one source, jogging “became popular in the 1970s when middle-aged men started running to reduce their risk of heart attacks and strokes.” However, some of these men who participated in the exercise died, and this prompted questions about whether such running was too strenuous on the body.13 Despite this ongoing debate about whether running is beneficial or harmful, popularity of distance running continues to be on the rise. Running USA reported that participation in marathons increased by 2.2% between 2010 and 2011 (Has the Marathon Boom Peaked?).19 The company also stated that there were a total of 425,000 marathon runners in the United States in 2008, increasing by 20 percent from the beginning of the decade (Parker-Pope).20 In total it is estimated that there are 30 million runners and 1,800 running clubs in the United States (Plack).21 Both the physiological and psychological impacts that the exercise has had could explain its ever-present and growing popularity. Perhaps it is the advantages that this physical activity has provided that have helped maintain its prevalence not only since the 1970s, but also for thousands of years prior. Thus, communal long-distance races such as 5ks, half-marathons, and marathons will continue to take place and follow this upward trend in popularity. 
 
Long-distance running has been practiced by humans for millennia, shaping and evolving their anatomical structure. Running has been proven to have both physiological and psychological effects, many of which have been shown to improve human health. Human health is a concern that remains ever-present, and physical exercise is necessary in order to maintain an active lifestyle. Thus, long-distance running is a popular sport with significant health benefits that addresses a variety of health issues such as obesity and depression. Incorporating long-distance running into one’s daily routine may prevent and treat such conditions and could even prove to be life-altering. 
 
 
 
 
References 
 
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11. Youngstedt SD, Kline CE. 2006. Epidemiology of exercise and sleep. Sleep and Biological Rhythms; 4(3): 215-221 
 
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13. Burning calories. 2009. Air Force Times :32. 
 
14. Jogging 'increases life expectancy'. 2012. BreakingNews.Ie;. 
 
15. Running too much could shorten your lifespan. Kashmir Monitor. 2014 Apr 04;. 
 
16. Sanchez LD, Corwell B, Berkoff D. 2006. Problems of marathon runners. American Journal of Emergency Medicine; 24: 608-615 
 
17. Warden SJ, Davis IS, Fredericson M. 2014. Management and Prevention of Bone Stress Injuries in Long-Distance Runners. Journal of Orthopaedic & Sports Physical Therapy; 44(1): 749-765. 
 
18. Tonoli DC, Cumps E, Aerts I, Verhagen E, Meeusen R. 2010. Incidence, risk factors and prevention of running related injuries in long-distance running: A systematic review injury, location and type. Sport & Geneeskunde; 43(5): 12-18. 
 
19. Has the Marathon Boom Peaked? 26 February 2013. Runner’s World;. 
 
20. Parker-Pope T. 2009. The human body is built for distance. New York Times.
 
21. Plack L. 2015. Can Running Cause Osteoarthritis?. ACSM’s Health & Fitness Journal; 19(1) 23-28 

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