A month has already passed since the new year 2023 began. In the new year, most people make new resolutions and make plans. Among them, the goal that should never be missed is exercise. According to the Statistical Brain Research Institute (SBRI), an American market analysis agency, the probability of success in New Year’s resolutions is regarding 8%, and most of them are likely to fail. Why do New Year’s resolutions always fall apart? Studies have shown that this may be due to ‘intestinal microbes’.
The reason why exercise resolutions are not kept well every time is revealedㅣSource: Getty Image Bank
Intestinal microbes stimulate the gut-brain circuit to increase exercise motivation
Gut microbes make up most of the microorganisms in our body. The number of microbes in the gut is more than twice the number of cells and the number of genes is 100 times more. Intestinal microbes are closely connected to cells in the body, closely exchanging signals and stimuli, and play a role in maximizing the function of cells. It affects the human immune system, metabolism, and mental health, and helps humans quickly adapt to the external environment.
A research team led by Christoph Thaiss, professor of microbiology at the University of Pennsylvania Perelman School of Medicine, found that gut microbes can increase a person’s desire to exercise. The research team set out to find a wide range of factors that determine exercise capacity, and conducted experiments in genetically diverse mice. The research team obtained data on various factors that can affect exercise activity, such as genes, distribution of intestinal microbes, and metabolites. The main cause of frequent running was thought to be due to genes, but contrary to the research team’s expectations, the factor that had the greatest impact on running activity was the distribution of intestinal microbes.
Afterwards, the research team found two types of bacteria (Eubacterium rectale and Coprococcus euatactus) that affect the movement of mice, and also identified the mechanism by which these bacteria affect movement motivation. These bacteria produce metabolites called fatty acid amides (FAs), which activate CB1 receptors that accept nerve substances called endocannabinoids in the intestinal sensory nervous system. When the receptor is activated, dopamine secretion becomes active in the striatum, a brain region involved in motivation and reward.
Mice with these bacteria released more dopamine than other mice when they exercised. Thanks to dopamine, the desire to exercise became stronger, and accordingly, the exercise ability improved. Rats that exercised a lot also experienced more ‘Runner’s high’, which is the feeling of pleasure while exercising. When the research team eliminated intestinal microbes by administering antibiotics, the test mice’ motor activity was cut in half. On the other hand, when fatty acid amide was injected, dopamine secretion was activated and exercise capacity improved once more.
“If a similar gut-brain pathway exists in humans, it might provide an effective way to increase people’s motivation and level of exercise to improve public health,” said Professor Christoph Thaiss, first author. It might also be used to treat addiction related to dopamine.” In this way, it can be used to treat addiction or depression by adjusting reward-related activities in the brain, and even ordinary people can find a way to exercise steadily like an athlete by adjusting their diet. The research results of the research team were published in the international journal Nature.
If you exercise regularly, your gut microbes will improve your athletic performance.
There have been previous studies on the correlation between gut microbes and exercise. Researchers at Harvard Medical School found that only people who exercised regularly had abundant gut microbes, and revealed that gut microbes affect athletic performance. The research team published the results of a study in the international journal Nature Medicine in 2019, which found that certain types of intestinal microbes supply energy to muscles and improve exercise performance for those who have been exercising steadily.
The research team collected stool samples 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 microbes in the stool samples. As a result, it was found that the number of bacteria in ‘Bayonella’ increased rapidly following the marathon than before. The research team found that there was little bayonella in the intestines of people who like to sit, but it is abundant in people who have been exercising regularly.
Bayonella breaks down lactic acid produced by muscles during exercise into short-chain fatty acids such as propionic acid. These by-products move the muscles and are used as energy sources. The research team also found a gene group that produces lactase in Bayonella’s genetic information, and also conducted an experiment in which bayonella collected from human stool samples was administered to the intestines of mice. The time the rats ran on the treadmill then increased. Professor Aleksandar Kostic explained, “Bayonella decomposes lactic acid produced in muscles during exercise and supplies energy to muscles to improve exercise performance.”
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