When thinking of marathon running, what comes to mind? Is it exceptional fitness, maintaining health, or honing your body? If so, you’re not wrong. However, these benefits overshadow the looming side effects of extreme, strenuous exercise. These side effects range all the way from permanent muscle damage to life threatening destruction of lymphocyte DNA. In rare cases, we can see cardio issues and even kidney injury. These alarming discoveries are recent and have been given little attention. However, modern scientists have taken up the responsibility of studying the negative effects of marathon running.
Recently, studies have been conducted to determine trends between strenuous endurance running and negative consequences to organ systems. On February 28, 2016, a study was published in the Journal of Physical Therapy. Scientists conducted an experiment to show how running different distances impacted muscle and lymphocyte DNA damage in beginner runners. In specifics, the hypothesis was that “irregular strenuous exercise would have negative effects on health. The results of the study show that marathon running has alarming side effects.
The scientists who conducted this groundbreaking study were Jae Hoon Ryu (Exercise Physiology Laboratory, Department of Physical Education, Yonsei University, Republic of Korea), Young Paik (Exercise Physiology Laboratory, Department of Physical Education, Yonsei University, Republic of Korea), Jin Hee Woo (Department of Physical Education, College of Arts and Physical Education, Dong-A University), Ki Ok Shin (Department of Physical Education, College of Arts and Physical Education, Dong-A University), Su Youn Cho (Exercise Physiology Laboratory, Department of Physical Education, Yonsei University, Republic of Korea), and Hee Tae Roh (Department of Physical Education, College of Arts and Physical Education, Dong-A University).
From 2014 to 2016, Scientists studied marathon runners from the Hangang marathon race in Seoul, South Korea. In total, there were thirty healthy men. Each who had completed at least three marathon runs in their career. The men were split into a ten kilometer, a twenty-one kilometer, and a forty two kilometer group. Scientists then tested two sets of blood samples. One of which was conducted before the race and one that was taken three days after the race. In labs, the scientists studied the blood samples and searched for any signs of damage. One method of studying blood cells was the comet assay. It shows DNA breaks, in doing so determining lymphocyte DNA damage. The next method of damage determination was testing the levels of Serum CK and LDH present in the blood. These two chemicals show signs of muscle damage and are seen through a chemical chemistry analyzer.
Next, the results. They found that indicators of muscular skeletal damage went up as the marathon running distance increased. They also found that longer distanced marathons caused more lymphocyte damage than shorter ones. On top of this, all three marathon distances caused some level of DNA damage.
The researchers did not admit any limitations or flaws. However, their sample size which was to represent all of humanity was only thirty people and the subjects were all men from Seoul, Korea. This is problematic because it leads to sample bias. Ultimately, this study is useful, but it cannot be applied to the entire human population due to the small size and lack of racial and sexual diversity in the study set. The study would be more trustworthy with a larger sample size and participants that differed in age, race, sex, location, and living conditions.
Still, The Hangang marathon study was successful in showing us two life-threatening factors of marathon running. For instance, the discovered Lymphocyte DNA damage. This could cause fatal complications due to the vital role of lymphocytes. According to Britannica, these are a type of white blood cells that determine the response to an infectious microorganism (Britannica, 2022).
The Hangnam Marathon study is one of many recent experiments on the detrimental effects of marathon running. We see similar, sometimes even more alarming, side effects from other experimental studies. For example, the article, “Long-term health issues in ultra-endurance runners: should we be concerned?”, reviewed studies on how ultra-endurance running affects cardiovascular, renal, and respiratory function. This retrospective study showed that “ultra endurance running” (UER) can cause long term cardiac issues, acute kidney injury, and respiratory afflictions like exercise induced asthma (Sheer et al. 2021). On top of this, these authors found more evidence of musculoskeletal damage resulting from (UER). These include injuries such as rhabdomyolysis (Sheer et al. 2021). Rhabdomyolysis is a possibly fatal disorder when muscle tissue releases its proteins and electrolytes into the blood (CDC, 2019).
Additionally, the article, “Running pace decrease during a marathon is positively related to blood markers of muscle damage”, shows that muscle damage correlates to fatigue while running a marathon. (Coso et al. 2013). So if you find yourself running a marathon and feel extremely fatigued, remember that there is a correlation with muscle breakdown.
Why were the scientists compelled to conduct this study? What is the importance of the experiment? The Hangang Marathon study was imperative considering the trends in today’s society. Around the world, we are seeing an increase in marathon running. This interest was due to the health benefits such as a lower risk of noncommunicable diseases (Wagner et al. 2011). However, there were studies that proved strenuous exercise had negative consequences on biochemical processes (Smith et al. 2004). As a result, scientists like Jae Hoon Ryu began investigating more into the detrimental effects on the human body.
The veil of marathon running’s consequences is slowly being torn away. So, we will see more studies being conducted in the future. For the time being, do what you can to stay healthy. Feel free to go on a run, or even a marathon. However, you should be conscious of the life-threatening side effects that could possibly affect your body. Remember the lymphocyte damage which can impair your immune system. Also, be aware of the muscle damage that can lead to fatal blood infections. The Hangang Marathon study, is alarming, but it is just the tip of the iceberg, so be wary of what lies underneath.
Bibliography:
April 19, 2022. Centers for Disease Control and Prevention. Rhabdomyolysis. https://www.cdc.gov/niosh/topics/rhabdo/default.html#:~:text=Rhabdomyolysis%20(often%20called%20rhabdo)%20is,permanent%20disability%20or%20even%20death.
Britannica, The Editors of the Encyclopedia. Sept 14, 2022. Lymphocyte. Encyclopedia Britannica .https://www.britannica.com/science/lymphocyte
Coso J, Fernandez D, Vicen J, Salinero J, Millan C, Areces F, Ruiz D, Gallo C, Gonzalez J, Gonzolez B. 2013 Feb 27. Running Pace Decrease during a Marathon Is Positively Related to Blood Markers of Muscle Damage. Plos One. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3583862/. doi:10.1371/journal.pone.0057602
Ryu J, Paik Y, Woo J, Shin K, Cho S, Roh H. 2016. Feb 26. Impact of different running distances on muscle and lymphocyte DNA damage in amateur marathon runners. Journal of Physical Therapy Science. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4792989/. doi:10.1589/jpts.28.450: 450–455
Sheer V, Valverde D. 2021 July 20. Long-term health issues in ultraendurance runners: should we be concerned? BMJ Open Sport Excercise Medicine. https://pubmed.ncbi.nlm.nih.gov/34367656/. doi:10.1136/bmjsem-2021-001131
Smith J, Garbutt G, Lopes P. 2004 Jun. Effects of prolonged strenuous exercise (marathon running) on biochemical and hematological markers used in the investigation of patients in the emergency department. British Journal of Sports Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1724837/. doi:10.1136/bjsm.2002.002873
Wagner K, Reichold S, Neubauer O. 2011 July 27. Impact of endurance and ultraendurance exercise on DNA damage. Annals of the New York Academy of Sciences. https://nyaspubs.onlinelibrary.wiley.com
Featured image:
Gettys Images. 2022. Sara Hall of USA showing determination to finish second at the 2020 London Marathon. https://olympics.com/en/featured-news/marathon-runner-sara-hall