2024-01-01 18:02:07
Hyeongja Kim, science columnist
Planning/Organization = Reporter Kim Yun-ju
Graphics = Jin Bong-gi
The new year has arrived. The resolution that many people make as they welcome the new year is, “I need to exercise more.” My resolution is to live a healthier life in the new year. So, starting from the beginning of the new year, I go to the gym and run hard. But not many people last until the end. According to a survey by the global economic magazine ‘Forbes’, New Year’s resolutions are broken on average following 3.74 months. However, according to a research team at the University of Pennsylvania, the reason we give up exercise may be because the intestinal microorganisms in the body do not help. What role do intestinal microorganisms play?
Intestinal microorganisms are the ‘second genome’
Most of the microorganisms in our bodies are intestinal microorganisms. There are usually regarding 4,000 to 10,000 species. The number of intestinal microorganisms is more than twice that of cells and regarding 100 times more than that of genes. It is impossible to discuss the human body without mentioning the microorganisms in the body. That’s why intestinal microorganisms are called the ‘second genome.’
It is said that intestinal microorganisms affect the human immune system, metabolic activity, and even mental health. It exchanges signals and stimulation closely with the cells in the body, maximizing the cell’s capabilities. This helps humans quickly adapt to the external environment. Without intestinal microorganisms, we cannot digest food.
A research team led by Professor Christoph Theiss of the Department of Microbiology at the University of Pennsylvania School of Medicine, USA, discovered the possibility that these intestinal microorganisms can also increase a person’s desire to exercise. This was done through experiments on genetically diverse mice.
To find factors that determine exercise ability, the research team recorded data by examining the genome sequences, types of bacteria, and blood metabolites of several mice. Next, we measured the distance and endurance that the mice voluntarily run every day on a treadmill or treadmill. Some rats ran more than 30 km in a treadmill in 48 hours, while others barely ran at all. The study found that genetics was not the biggest factor contributing to differences in the mice’s running activity. It depended on the presence of specific gut microbes. Of course, genetic factors were not at all unrelated, but their influence was minimal.
Bacteria enhance the desire to exercise
The microorganisms closely related to rat exercise were two types of bacteria. Mice with this microbe liked exercise. That’s because two bacteria were involved in making mice feel happy when they exercised. They created a substance called ‘fatty acid amide’. Fatty acid amides stimulate the intestinal sensory nervous system, which is connected to the brain through the spine, causing the brain to secrete more of a hormone called dopamine. Dopamine is a hormone that creates a happy feeling.
Mice with both bacteria secreted more dopamine when exercising. Thanks to the ‘happiness hormone’ dopamine, the rats’ desire to exercise became stronger and their exercise abilities also improved. Mice that exercised a lot also experienced more so-called ‘runner’s high’, a feeling of pleasure while exercising. On the other hand, mice that were artificially deprived of the two bacteria had their exercise volume reduced by half, regardless of genetic differences.
Regarding this phenomenon, the research team explained, “Intestinal microorganisms stimulate the nerves in the intestines, promoting the secretion of dopamine in the brain and motivating the mice to want to exercise more.” The research team’s research results were published in the international academic journal ‘Nature’.
The research team is said to be conducting additional research to determine which path between the intestines and the brain stimulates the desire to exercise in humans. If the connection between the gut and the brain is confirmed, we may be able to find ways to exercise consistently or find the secret to effectively increasing the amount of exercise.
Sedentary people have fewer intestinal microorganisms
Conversely, research has also shown that consistent exercise causes changes in intestinal microorganisms. Professor Alexander Kostic’s team in the Department of Microbial Immunology at Harvard University Medical School compared the intestinal microorganisms of long-distance runners who exercised regularly and those who were sedentary and lacked exercise. Additionally, stool samples were collected from 15 runners who participated in the 2015 Boston Marathon, one week before the marathon and one week following the marathon. They then analyzed the genetic information of the microorganisms in the samples.
As a result, it was revealed that ‘Bayonella bacteria’ is abundant in athletes who exercise continuously. There was almost no Bayonella in the cabinet of someone who just liked to sit around. Also, these bacteria increased significantly following running the marathon compared to before. It means that the composition of microorganisms changes just through exercise. Bayonella breaks down lactic acid produced in muscles during exercise into fatty acid. This by-product supplies energy to the muscles, increasing exercise capacity.
New Year’s resolutions are a great way to rejuvenate your life. What if you resolve to exercise more and become healthier in the new year? There’s no magic solution to keeping your New Year’s exercise resolution. However, it is said that once you start exercising consistently, the intestinal microorganisms help create a desire to exercise. With the support of intestinal microorganisms, let’s make our exercise resolutions come true in the New Year.
Hyeongja Kim, science columnist
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