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<\/small><\/p>\nFigure 1. <\/span>The diversity of the gut microbiome<\/span><\/strong>The concept of diversity is prevalent in gut microbiome analysis. In individual-level assessments, it primarily refers to two components: the richness (number of microbial species) and the evenness (how evenly these species are distributed).<\/p>\n<\/div>\n However, when it comes to the assumption that the gut environment is readily affected by environmental factors including diet, sleep, stress, and aging, it is difficult to determine what is the cause and what is the result. In addition, the composition of gut microbiomes varies depending on the amount of exercise and the type of sport, and there are also individual differences. In my own experience, even among couples with similar exercise and dietary habits, or siblings competing in the same sport with similar training volume and diet, there were differences in their gut microbiome, including in the predominant microorganisms.<\/p>\n Gut microbes are subcategorized in descending order into phyla, classes, orders, families, genera, and species, and the level at which a microbe can be identified differs according to the analytical method used. Although these characteristics make gut microbiome research more complex, I believe that it is important first of all to gain a broad-brush understanding of trends in the relationship between exercise and the gut microbiome in specific target groups.<\/p>\n In athletes-focused research, many studies are centered on improving exercise performance. One famous study looks at runners who have participated in the Boston Marathon, a race that attracts competitors from across the globe. In this study, stool samples collected before and after the marathon were analyzed, and the researchers observed an increase in the abundance of bacteria belonging to the genus Veillonella<\/i> among runners after the marathon.<\/p>\n The research team also inoculated mice with a Veillonella<\/i> strain called Veillonella atypica<\/i> that had been isolated from the stool samples, and reported that the inoculated mice took 13% longer to reach exhaustion than the uninoculated mice.<\/p>\n Veillonella<\/i> bacteria use lactate as a source of energy and are known to produce propionate and acetate as terminal metabolites. Lactate is produced when sugar (glycogen) stored in the muscles is broken down to produce the energy required to move the muscles. When the lactate produced in the muscles by exercise reaches the gut via the bloodstream, Veillonella<\/i> species metabolize it, producing propionate. This propionate is then absorbed from the gut and promotes gluconeogenesis<\/span> in the liver, as well as being incorporated into the tricarboxylic acid (TCA) cycle (citric acid cycle)<\/span> in the muscles and other tissues for use in producing a form of energy called adenosine triphosphate (ATP). This suggests the possibility that, after Veillonella<\/i> species convert lactate into propionate in this way, the propionate is then reused as a source of energy, resulting in improved exercise performance.<\/p>\n A recent Japanese study has also attracted attention. Focused on long-distance runners at a university, the study reported that Bacteroides<\/i> uniformis<\/i> was more abundant in the runners than in non-athletic males of the same age, and that there was a relationship to an improvement in running times. The research team then administered α-cyclodextrin ——<\/span> a cyclic oligosaccharide used by the same bacterium ——<\/span> to healthy Japanese males aged in their 20s to 40s who exercised regularly. Eight weeks after administration, the researchers found increased abundance of Bacteroides<\/i> uniformis<\/i> in the participants. Those who had taken α-cyclodextrin showed improved endurance performance and reduced post-exercise fatigue compared to the placebo group. It is presumed that, via this mechanism, the acetate and propionate produced by Bacteroides<\/i> uniformis<\/i> contribute to increased endurance by promoting the supply of energy via the TCA cycle.<\/p>\n Thus, a number of studies have reported results suggesting the possibility that certain gut microbial species improve exercise performance.<\/p>\n The Japan Institute of Sport Sciences is also studying athletes from Japanese national teams. As elite athletes train constantly, physical stress from exercise may lead to a deterioration in their physical condition. Accordingly, a study involving 92 athletes was conducted to investigate the relationship between gut microbiome and physical condition based on the analysis of their gut microbiome and a questionnaire concerning their stool status and pattern, and their subjective physical condition. <\/p>\n As a result, they found that the incidence of constipation, diarrhea, and the like was low in athletes who felt they were in good physical condition, and that Faecalibacterium<\/i> species were significantly more abundant in such athletes than in athletes who felt their physical condition was poorer (Figure 2). As Faecalibacterium<\/i> species have an anti-inflammatory effect, scientists believe that they are effective in curbing inflammation due to exercise, and previous studies have also reported that they are abundant in endurance athletes. Thus, the study indicated that gastrointestinal symptoms have a major impact on the physical condition of elite athletes, and that there is an association between physical condition and the composition of gut microbes. I believe the results of this study are of great interest, as they provide new insights that will assist in improving performance and managing health.<\/p>\n Figure 2. <\/span>Physical condition and gut microbiome in Japan’s elite athletes<\/span><\/strong>Differences in gastrointestinal symptoms such as constipation and diarrhea, and in the composition of gut microbes were observed between athletes who felt they were in good physical condition and athletes who felt they were not. These findings provide new insights into performance improvement and health management in athletes.<\/p>\n<\/div>\n In their training, athletes use a technique called periodization, which involves dividing their training period into a number of stages and systematically altering the intensity, amount, and type of training. In order to observe changes in gut microbes due to periodization, a research team carried out a cross-sectional study of 84 athletes from a variety of sports, and a longitudinal study of 10 short-track speed skate athletes.<\/p>\n In the cross-sectional study, the researchers compared the gut microbiome compositions of different groups in the transition and preparation periods of their training. The transition period refers to the off-season and other periods when athletes rest or engage in lighter exercise, training at a lower volume and intensity to allow them to recover from physical and mental fatigue. The preparation period is the period in which athletes engage in training to reach peak readiness for the competitive season. Overall, athletes engage in training at a higher volume and intensity during the preparation period than in the transition period. The study indicated that the proportion of Prevotella<\/i> species was significantly lower in the preparation period than in the transition period, while the percentages of Bifidobacterium<\/i>, Parabacteroides<\/i>, and Alistipes<\/i> species were significantly higher.<\/p>\n In the longitudinal study, the research team measured the athletes’ maximal oxygen uptake (V<\/span>O2<\/sub>max), which is an indicator of general endurance, during both the general preparation phase (the period in which they increase the volume of training to enhance their basic physical fitness) and the specific preparation phase (the period in which they reduce the volume of training but increase its intensity and quality to enhance their competitive skills). They also measured maximal anaerobic power, which indicates the power exerted during short-duration exercise at full effort, and took stool samples. The results showed changes as the athletes moved from the general to the specific preparation phase, including a decrease in Bacteroides<\/i> species, significant increases in Blautia<\/i> and Bifidobacterium<\/i> species, and a tendency for an increase in Fusicatenibacter<\/i> species.<\/p>\n In addition, looking at associations between gut microbiome and endurance, a significant correlation was observed between a decrease in Bacteroides<\/i> species and an increase in V<\/span>O2<\/sub>max. Species in the genus Bacteroides<\/i> are the most prevalent bacteria in the gut microbiome and are known to be connected to the metabolism of carbohydrates.<\/p>\n Other highly interesting findings were significant correlations between stool condition and the gut microbiome, and between stool condition and maximal anaerobic power. In addition, athletes with elevated levels of Fusicatenibacter<\/i> species tended to have stools in ideal condition, and as their stools got closer to the ideal condition, their maximal anaerobic power also increased. Bacteria of the genus Fusicatenibacter<\/i> promote lactose decomposition and produce lactic acid and short-chain fatty acids, among others.<\/p>\n These results suggest that periodization changes the levels of Bacteroides<\/i>, Fusicatenibacter<\/i>, and other gut microbes that could potentially be involved in improving physical ability through energy metabolism and training.<\/p>\n While there are differences depending on the sport, training type, and intensity, there is a strong possibility that exercise and the gut microbiome interact in athletes and others who exercise regularly. But what about people who do not regularly exercise, whose physical composition and metabolic functions differ from athletes? Some studies focused on people with obesity and on the elderly have reported that gut microbiome diversity increases as a result of exercise, but studies focused on healthy adults who do not exercise regularly suggest that it is hard to achieve dynamic changes in the gut microbiome.<\/p>\n I conducted a study of healthy adult men and women in their 20s to 60s who did not exercise regularly, in which the subjects undertook an eight-week program of exercise using a bicycle ergometer at an intensity level at which they could maintain a conversation while exercising. I evaluated their gut microbiome and short-chain fatty acids, and conducted physical fitness tests. I also instructed the participants not to alter their usual dietary habits. After training, a significant increase was observed in peak oxygen uptake (V<\/span>O2<\/sub>peak), which is an indicator of general endurance.<\/p>\n While the results for gut microbial composition showed no change in the percentage of microbial species at the phylum level after training, there was a significant increase in the number of bacterial species, which is an indicator of diversity. However, no significant difference was observed in the indicator that accounted for bacterial species evenness (Figure 3). In other words, although the number of bacterial species increased (new bacterial species emerged) as a result of training, it was perhaps difficult to detect them as significant changes in percentage terms.<\/p>\n Figure 3. <\/span>Changes in gut microbiome diversity due to exercise-based intervention<\/span><\/strong>An eight-week athletic training program was carried out among healthy adult men and women who did not exercise regularly. After the program, while no change was observed in the relative abundance of microbial species at the phylum level (a), there was a significant increase in the number of bacterial species (b), but no significant change was observed in species evenness (c).<\/p>\n<\/div>\n Based on the degree of change in V<\/span>O2<\/sub>peak due to training, I then divided the subjects into a high-change group (H group) and a low-change group (L group) for analysis. Overall, I observed a tendency for the H group to have a lower number of bacterial species than the L group, but the indicator that accounted for bacterial species evenness showed significantly higher results in the L group. This is thought to be because V<\/span>O2<\/sub>peak in the H group was low before starting the training program, and therefore they demonstrated greater adaptation to exercise (increase in V<\/span>O2<\/sub>peak). On the other hand, a significant correlation between the degree of increase in V<\/span>O2<\/sub>peak and the degree of change in microbial diversity was observed in the L group, suggesting an association between microbial diversity and adaptation to training.<\/p>\n These results suggest that the increase in endurance (increase in V<\/span>O2<\/sub>peak) may be affected by both the condition of the gut microbiome before training and changes in gut microbes as a result of training. In addition, as the number and evenness of gut microbial species are involved in adaptation to training, there is a possibility that a training strategy tailored to the features of an individual’s gut microbiome could assist in further improving their endurance and exercise performance.<\/p>\n Based on these results, I also conducted a simulation to identify the factors that increase V<\/span>O2<\/sub>peak. The fact that the results showed high levels of short-chain fatty acids (acetate and propionate) and Bacteroides<\/i> species suggests the possibility that they promote increases in V<\/span>O2<\/sub>peak via training (Figure 4). These results show that, as in previous studies conducted among athletes, short-chain fatty acids do appear to be closely involved in increasing the endurance of nonathletes. On the other hand, the association between high levels of Bacteroides<\/i> species and increases in V<\/span>O2<\/sub>peak indicated here is not consistent with previous studies, so further verification will be required.<\/p>\n Figure 4. <\/span>Factors potentially contributing to an increase in maximal oxygen uptake<\/span><\/strong>Results of a simulation investigating factors that may increase peak oxygen uptake. As with athletes, short-chain fatty acids may also play a significant role in enhancing endurance in nonathletes.<\/p>\n<\/div>\n As we have seen above, no clear answers have yet emerged concerning the question of which specific forms of exercise alter the gut microbiome and what kinds of change they bring about. However, the fact that exercise and the gut microbiome affect each other is becoming apparent. I intend to continue my research to provide evidence that improving the gut microbiome is one option available to athletes to maintain their health and physical condition and improve their exercise performance. I also believe it is important for individuals to understand their own gut microbiome. There are already companies and medical facilities that provide gut microbiome tests, enabling people to obtain information about their state of health based on the proportions and balance of their gut microbes.<\/p>\n In the future, I hope it will become easier for individuals to ascertain the state of their gut microbiome and to obtain more appropriate advice tailored to their objectives in terms of physical condition and exercise performance. It might even become possible to regulate or improve not only exercise, but also lifestyle and health management based on the state of each individual’s gut microbiome. I am keen to undertake research that further clarifies the relationship between the gut microbiome and physical ability to develop new strategies that contribute to more effective performance improvement and health maintenance.<\/p>\n The fact that gut microbes are closely related to biological activity is common knowledge, and scientists are bringing to light the effects of the gut microbiome on human health, an ecosystem composed of around 1,000 intestinal microbial species. As athletes and other people who exercise regularly are known to have a more diverse range of gut microbes than individuals who do not engage in regular physical activity, scientists have indicated a link between exercise and the gut microbiome. Although the precise mechanism is yet to be identified, there are hopes that in the future, regulating and improving the gut microbiome will help to improve performance and maintain health.<\/p>\n","protected":false},"author":2,"featured_media":2475,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[15],"tags":[],"class_list":["post-2478","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-nutrition"],"acf":{"author":"composition by Yumi Ohuchi","intro":" The fact that gut microbes are closely related to biological activity is common knowledge, and scientists are bringing to light the effects of the gut microbiome on human health, an ecosystem composed of around 1,000 intestinal microbial species. As athletes and other people who exercise regularly are known to have a more diverse range of gut microbes than individuals who do not engage in regular physical activity, scientists have indicated a link between exercise and the gut microbiome. Although the precise mechanism is yet to be identified, there are hopes that in the future, regulating and improving the gut microbiome will help to improve performance and maintain health.<\/p>","person":[{"acf_fc_layout":"personcontent","personimg":2476,"personsholder":"Researcher, Department of Sport Science and Research, Japan Institute of Sports Sciences","personname":"Yuko Tanimura","persondetail":"Graduated from Fujita Health University in 2004, qualifying as a clinical laboratory technician. In 2009, she successfully completed a doctoral program at the University of Tsukuba’s Graduate School of Comprehensive Human Sciences, gaining a Ph.D. in sports medicine. That same year, she became a postdoctoral fellow at Kyoto Prefectural University of Medicine’s Graduate School of Medical Science and was subsequently appointed assistant professor in the graduate school. In 2014, she became an assistant professor in the Department of Human Health at Aichi Toho University’s Faculty of Human Studies. She was appointed associate professor at the university in 2018 and took up her current post in 2021. Her fields of research are life sciences, sport sciences, and exercise biochemistry."}],"issue":2459,"custom_css":"span.v291_middot[data-ruby]:before{\r\ncontent:attr(data-ruby);\r\ndisplay:inline-block;\r\nfont-size:1.6rem;\r\nfont-style:normal;\r\nleft:0;\r\nmargin:0 auto;\r\nposition:absolute;\r\nright:0;\r\ntop:-0.4em;\r\nletter-spacing:0;\r\nline-height:1;\r\ntext-align:center;\r\ntext-indent:-0.05em;\r\n}\r\n"},"_links":{"self":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/posts\/2478","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/comments?post=2478"}],"version-history":[{"count":0,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/posts\/2478\/revisions"}],"acf:post":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/issue\/2459"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/media\/2475"}],"wp:attachment":[{"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/media?parent=2478"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/categories?post=2478"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/healthist.net\/en\/wp-json\/wp\/v2\/tags?post=2478"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Presumed to contribute to increased endurance<\/h2>\n
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<\/small><\/p>\nSignificant correlation between stool condition and maximal anaerobic power<\/h2>\n
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<\/small><\/p>\nClear correlation between exercise and the gut microbiome<\/h2>\n
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<\/small><\/p>\n