The athletic gut microbiota

In the paper

“Calorie restriction, primarily in animals, can improve the composition and associated metabolism of the gut microbiota, including increasing the relative abundances of probiotic and butyrate-producing microbes [159] and increasing SCFA biosynthesis [160].”

What the sources say

• Supported

  The citation to this source, [159], is attached to the increase in probiotic and butyrate-producing microbes, not to SCFA biosynthesis, which has a separate citation [160]. The review’s Abstract reports increased relative abundance of both groups following calorie restriction, and its Probiotic strains section describes this finding in CR-treated mammals. (LLM, conf=0.93)

  cites [159] Zheng X, 2018, Front Med source
• Partly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites [160] Tanca A, 2018, Sci Rep sourceExperimental — accuracy not yet measured

In the paper

“a ketogenic diet alters gut microbiota composition leading to an increase in Akkermansia abundance.”

What the sources say

• Not checked yetcites [66] Olson CA, 2018, Cell. source
• ?Could not verify

  The Introduction discusses microbial fermentation of resistant starch, and the Methods describe resistant-starch and whey-protein test meals. Our copy does not address ketogenic diets or Akkermansia abundance (searched: ketogenic, Akkermansia, gut microbiota composition). (LLM, conf=0.77)

  cites [202] Gentile CL, 2015, Nutr J sourceExperimental — accuracy not yet measured

In the paper

“Akkermansia fed to mice has a positive impact on reducing seizures, providing a potential mechanism for the observed neuroprotective effects of a ketogenic diet [66, 202].”

What the sources say

• Not checked yetcites [66] Olson CA, 2018, Cell. source
• ?Could not verify

  The Introduction (page unavailable) describes resistant starch, protein intake, and metabolic effects in women, not seizure reduction in mice. Searches for Akkermansia, seizures, and ketogenic-diet neuroprotection found no passage in our copy addressing the claim. (LLM, conf=0.75)

  cites [202] Gentile CL, 2015, Nutr J sourceExperimental — accuracy not yet measured

In the paper

“The majority of this research has been conducted in relation to the study of obesity, weight loss, and malnourishment in children.”

In the paper

“Primer selection and hypervariable regions of 16S rRNA (i.e., V1-V9) influence the observed microbial community.”

In the paper

“Several studies report less stringent inclusion/exclusion criteria and did not fully account/control for confounding variables.”

In the paper

“feces is the only sample material used in the analyses of the gut microbiota from the studies included in this review.”

In the paper

“several reports did not provide adequate detail in regard to sample transportation and storage.”

In the paper

“Several studies in the present review did not provide adequate detail on sample collection and processing.”

In the paper

“the effects of high-protein consumption (without concurrent high-fat) on gut bacteria are not well studied but of increasing importance given the current popularity of high-protein diets, especially in athletes.”

In the paper

“Current microbiota sequencing methods rely heavily on 16S rRNA amplicon-based methodology which detects up to genus level with minimal capability for species-level detection.”

In the paper

“Important factors such as age, birth method, antibiotic use, and diet have been established as formative factors that shape the gut microbiota.”

• Also stated in: § Introduction · plain

  “Important factors such as age, birth delivery route, antibiotic use, and diet can shape the gut microbiota [7–10].”

What the sources say

• Not checked yetcites [7] Yatsunenko T, 2012, Nature. source
• Not checked yetcites [8] Dudek-Wicher RK, 2018, Prz Gastroenterol
• Not checked yetcites [9] Flint HJ, 2015, Proc Nutr Soc source
• Not checked yetcites [10] Wampach L, 2018, Nat Commun source

In the paper

“The human gut microbiota contains thousands of different bacterial taxa as well as various archaea, eukaryotic microbes and viruses, more than three million genes, and harbors an enormous metabolic capacity [1, 2].”

What the sources say

• Not checked yetcites [1] Human Microbiome Project C, 2012, Nature. source
• Not checked yetcites [2] Qin J, 2010, Nature. source

In the paper

“Moreover, confounding factors including training history, level of physical fitness, training environment, and dietary intake all have the potential to affect study outcomes substantially, and make detecting differences due to exercise/athletic regimens on the gut microbiota difficult to ascertain.”

In the paper

“While athlete type did not differ regarding gut microbiota alpha and beta diversity, it was significantly associated with the relative abundance of several bacteria.”

What the sources say

• Not checked yetcites [11] Jang LG, 2019, J Int Soc Sports Nutr source

In the paper

“Interestingly, total fat mass, serum lipids, C-reactive protein, depression scales, and smoking status were negatively associated (R2 = − 0.012 to − 0.256, P < 0.05) with microbiota diversity.”

What the sources say

• Not checked yetcites [57] Morkl S, 2017, Int J Eat Disord source

In the paper

“From the limited evidence, it appears that athletes harbor an increased abundance of functional pathways within the microbiome that are exploited by the host for potential health benefits, as well as carbohydrate degradation and secondary metabolite metabolism compared to control groups [60].”

What the sources say

• Not checked yetcites [60] Flint HJ, 2012, Gut Microbes source

In the paper

“Exercise type was associated with athlete diet patterns (i.e., bodybuilders: high-protein, high-fat, and low-carbohydrate/dietary fiber diet; distance runners: low-carbohydrate and low-dietary fiber diet).”

What the sources say

• Not checked yetcites [11] Jang LG, 2019, J Int Soc Sports Nutr source

In the paper

“The microbiota has an indirect influence on various indices of exercise performance, recovery, and patterns of illness, such as signaling through myokines and other cytokines, modulating activation of the hypothalamic–pituitary–adrenal axis, and affecting performance-associated metabolic pathways [13, 16–18].”

What the sources say

• Not checked yetcites [13] Barton W, 2018, Gut.
• Not checked yetcites [16] Scheiman J, 2019, Nat Med source
• Not checked yetcites [17] Cerda B, 2016, Front Physiol source
• Not checked yetcites [18] Petersen LM, 2017, Microbiome. source

In the paper

“Microbiota diversity was markedly lower in anorexia nervosa patients and obese participants compared to other groups, while athletes showed the highest alpha diversity (species richness).”

What the sources say

• Not checked yetcites [57] Morkl S, 2017, Int J Eat Disord source

In the paper

“Physical activity has been an area of growing interest in gut microbiota research and appears to promote a health-associated microbial community and increased metabolic functional potential.”

In the paper

“Exercise, associated dietary factors, and the athletic classification promote a more “health-associated” gut microbiota.”

In the paper

“However, these differences were observed despite no significant variation in dietary intakes across athletes from different classifications; suggesting that variations in training loads and competition requirements contributed to these microbiome and metabolome-related patterns.”

What the sources say

• Not checked yetcites [58] O'Donovan CM, 2020, J Sci Med Sport source

In the paper

“Athletes participating in sports with a high dynamic component were the most distinct compositionally (greater differences in proportions of species; see Table 1), while athletes participating in sports with both a high dynamic and static component were the most functionally distinct (greater differences in functional potential).”

What the sources say

• Not checked yetcites [58] O'Donovan CM, 2020, J Sci Med Sport source

In the paper

“For instance, at the genus level, Faecalibacterium, Sutterella, Clostridium, Haemophilus, and Eisenbergiella were the highest, while Bifidobacterium and Parasutterella were the lowest in bodybuilders.”

What the sources say

• Not checked yetcites [11] Jang LG, 2019, J Int Soc Sports Nutr source

In the paper

“Current research reports a higher abundance of health-promoting bacterial species and increased microbial diversity in athletes [13, 18, 19].”

What the sources say

• Not checked yetcites [13] Barton W, 2018, Gut.
• Not checked yetcites [18] Petersen LM, 2017, Microbiome. source
• Not checked yetcites [19] Clarke SF, 2014, Gut. source

In the paper

“Physical exercise was not related to differences in the microbiota diversity or richness (the total number of OTUs or species recorded); however, sedentary parameters (i.e., sedentary time and breaks) correlated negatively with microbiota richness.”

What the sources say

• Not checked yetcites [56] Bressa C, 2017, PLoS One source

In the paper

“In addition, Akkermansia was present in 30 out of 33 cyclists, with seven cyclists having relative abundances > 2% of this microbe in their metagenomic community.”

What the sources say

• Not checked yetcites [18] Petersen LM, 2017, Microbiome. source

In the paper

“Fecal and urine derived metabolites also varied between classification including increased lactate (urine) in sports with a static component and creatinine (feces) in sports with a high dynamic and low static component.”

What the sources say

• Not checked yetcites [58] O'Donovan CM, 2020, J Sci Med Sport source

In the paper

“A. muciniphilia is a mucin-degrading bacterium that resides in the nutrient-rich mucus layer of the gut that appears to be associated with positive metabolic function [59].”

What the sources say

• Not checked yetcites [59] Dao MC, 2016, Gut. source

In the paper

“Briefly, the health-related effects of butyrate are associated with anti-inflammatory properties, direct feeding of colonocytes, and an impact on satiety [64].”

What the sources say

• Not checked yetcites [64] den Besten G, 2013, J Lipid Res source

In the paper

“Lambert et al. [75] described that exercised mice presented a greater abundance of Firmicutes species and lower Bacteroides/Prevotella genera compared with sedentary mice.”

What the sources say

• Not checked yetcites [75] Lambert JE, 2015, Appl Physiol Nutr Metab source

In the paper

“In particular, Choi et al. [73] reported that, in comparison to a sedentary control, mice with running wheel exercise had higher phylum Firmicutes but fewer phyla Tenericutes and Bacteroidetes, which attenuated changes in gut microbiota induced by oral exposure to the environmental toxin, polychlorinated biphenyls.”

What the sources say

• Not checked yetcites [73] Choi JJ, 2013, Environ Health Perspect source

In the paper

“However, this is not always the same between studies [83, 84] and may be an oversimplification of phylum-level patterns in relation to host health.”

What the sources say

• Not checked yetcites [83] Walters WA, 2014, FEBS Lett source
• Not checked yetcites [84] Finucane MM, 2014, PLoS One source

In the paper

“Notably, butyrate, along with propionate and acetate, provides ~ 10% of the daily caloric requirements in humans who consume high (~ 60 g/day) amounts of dietary fiber [64].”

What the sources say

• Not checked yetcites [64] den Besten G, 2013, J Lipid Res source

In the paper

“Matsumoto et al. [72] reported that regular running exercise in rats was related to an increase in butyrate-producing bacteria in the microbiota composition along with an increase of butyrate concentration.”

What the sources say

• Not checked yetcites [72] Matsumoto M, 2008, Biosci Biotechnol Biochem source

In the paper

“Further, mechanisms by which specific members of the microbiota, such as Firmicutes and Bacteroidetes, can affect human phenotypes remain to be fully elucidated [85].”

What the sources say

• Not checked yetcites [85] Johnson EL, 2017, J Mol Med (Berl) source

In the paper

“In contrast, Evans et al. [74] concluded that exercise increased Bacteroidetes, while it decreased Firmicutes in mice, implying that exercise plays an important role in prevention of diet-induced obesity producing a microbial composition similar to lean mice.”

What the sources say

• Not checked yetcites [74] Evans CC, 2014, PLoS One

In the paper

“One leading theory on the pathogenesis of obesity emphasizes a close link between the metabolic and immune systems via the gut microbiota [68].”

What the sources say

• Not checked yetcites [68] Cox AJ, 2015, Lancet Diabetes Endocrinol source

In the paper

“Campbell et al. [88] asserted that exercised mice have bacteria related to Faecalibacterium prausnitzii which may protect the digestive tract by producing butyrate and lowering the oxygen tension in the lumen by a flavin/thiol electron shuttle.”

What the sources say

• Not checked yetcites [88] Campbell SC, 2016, PLoS One source

In the paper

“Barton et al. [13] speculated that the athlete gut microbiome may possess a functional capacity primed for tissue repair and a greater ability to harness energy from the diet with increased capacity for carbohydrate metabolism, cell structure, and nucleotide biosynthesis.”

What the sources say

• Not checked yetcites [13] Barton W, 2018, Gut.

In the paper

“This body of work suggests that increased intestinal permeability from high-fat / high sugar diets allows bacterial lipopolysaccharide (LPS), an outer membrane component of gram-negative bacteria linked with induction of inflammation, from the gut microbiota to translocate into the systemic circulation, resulting in systemic endotoxemia.”

What the sources say

• Not checked yetcites [68] Cox AJ, 2015, Lancet Diabetes Endocrinol source

In the paper

“A. muciniphilia has also been found to be enriched in mice fed a ketogenic diet, exhibiting gut-brain functions including conferring seizure protection in two preclinical models for refractory epilepsy [66].”

What the sources say

• Not checked yetcites [66] Olson CA, 2018, Cell. source

In the paper

“A. muciniphilia levels are decreased in obese and type 2 diabetic mice, and treatment with these bacteria reversed high-fat diet-induced metabolic disorders, including fat mass gain, metabolic endotoxemia, adipose tissue inflammation, and insulin resistance [65].”

What the sources say

• Not checked yetcites [65] Everard A, 2013, Proc Natl Acad Sci U S A source

In the paper

“While the role of A. muciniphila is less certain in humans, it is depleted in individuals with several metabolic and inflammatory disorders.”

What the sources say

• Not checked yetcites [59] Dao MC, 2016, Gut. source

In the paper

“It appears that being physically active is another important factor in the relationship between the microbiota and host metabolism.”

In the paper

“Aerobic capacity was inversely associated with Eubacterium rectale-Clostridium coccoides but not with other bacteria.”

What the sources say

• Not checked yetcites [94] Yang Y, 2017, Nutrients. source

In the paper

“The relative abundance of the bacterial genus Veillonella increased after the marathon and was the most differentially abundant microbial feature between the pre- and post-exercise states.”

What the sources say

• Not checked yetcites [16] Scheiman J, 2019, Nat Med source

In the paper

“Participants with low VO2max had lower Bacteroides, but higher Eubacterium rectale-Clostridium coccoides than the high VO2max group.”

What the sources say

• Not checked yetcites [94] Yang Y, 2017, Nutrients. source

In the paper

“At the genus level, half-marathon running reduced the abundance of fecal Ezakiella, Romboutsia, and Actinobacillus, but increased the abundance of Coprococcus and Ruminococcus bicirculans.”

What the sources say

• Not checked yetcites [20] Zhou Y, 2014, Genome Biol source

In the paper

“Coriobacteriaceae (phylum Actinobacteria) is involved in metabolism of bile salts and steroid hormones as well as activation of dietary polyphenols in the human gut [95].”

What the sources say

• Not checked yetcites [95] Clavel T, 2014

In the paper

“The bacterial abundance of Clostridiaceae and Bacteroidaceae families and Ruminoccocus genus were negatively associated with blood lactate levels in exercised animals, whereas a positive association was reported for Oscillospira genus [86].”

What the sources say

• Not checked yetcites [86] Petriz BA, 2014, BMC Genomics source

In the paper

“The inverse relationship between VO2peak and LPS biosynthesis pathways implies a beneficial consequence of increased physical activity which may result in decreased LPS biosynthesis.”

In the paper

“VO2peak was inversely correlated with LPS biosynthesis and LPS biosynthesis proteins which were elevated among less fit participants.”

What the sources say

• Not checked yetcites [14] Estaki M, 2016, Microbiome. source

In the paper

“Coriobacteriaceae was correlated positively with 15 metabolites, indicating that metabolism of Coriobacteriaceae may be a potential mechanism underlying the role of exercise in preventing disease and improving health outcomes.”

In the paper

“According to the alpha diversity analysis, there were few differences in diversity, nevertheless, abundances of certain microbiota members showed differences before and after running.”

What the sources say

• Not checked yetcites [20] Zhou Y, 2014, Genome Biol source

In the paper

“However, it was unclear if this effect was due to exercise, a high-protein diet, a combination of these two factors, or other factors [19].”

What the sources say

• Not checked yetcites [19] Clarke SF, 2014, Gut. source

In the paper

“Further, ~ 20% of the variation in gut bacterial alpha diversity could be explained by VO2peak alone; in fact, VO2peak stood as the only variable that contributed significantly to increased alpha diversity.”

What the sources say

• Not checked yetcites [14] Estaki M, 2016, Microbiome. source

In the paper

“Alterations to the microbiota exerted by exercise in rats following a high-fat diet were different to rats on a normal diet [89], as well as the alterations produced in diabetic mice were different to their control counterparts [75].”

What the sources say

• Not checked yetcites [89] Kang SS, 2014, Mol Neurodegener source
• Not checked yetcites [75] Lambert JE, 2015, Appl Physiol Nutr Metab source

In the paper

“Collectively, these findings indicate that modulation of the microbiota by chronic exercise depends not only on the physiological state of the individual, but also on the diet.”

In the paper

“Taken together, these experiments revealed that V. atypica improved run time via its metabolic conversion of exercise-induced lactate into propionate, thereby identifying a natural, microbiome-encoded enzymatic process that enhances athletic performance.”

In the paper

“While performed in animal model, this research is notable as it took an important step from correlative to causal function, implicating athlete microbiomes for broader human health and performance applications.”

In the paper

“It seems that the genus Veillonella is enriched in athletes after exercise and the metabolic pathway that Veillonella species utilize for lactate metabolism is also enriched.”

In the paper

“Those that did respond showed a remarkable decrease in fasting insulin and Homeostatic Model Assessment of Insulin Resistance index values (− 42.70% and − 49.60%, respectively).”

What the sources say

• Not checked yetcites [106] Liu Y, 2019, Cell Metab source

In the paper

“This study supports the notion that gut microbiota composition is linked to exercise status and that exercised-induced changes may be temporary and require continual stimulus [100].”

What the sources say

• Not checked yetcites [100] Hawley JA, 2019, Nat Rev Endocrinol source

In the paper

“A substantial improvement in mice gavaged with microbiota from responders was mimicked in glycemic control and insulin sensitivity, in contrast to the lack of change in mice colonized with microbiota from non-responders.”

What the sources say

• Not checked yetcites [106] Liu Y, 2019, Cell Metab source

In the paper

“The relative abundance of intestinal Bacteroides increased in subjects that completed aerobic exercise.”

What the sources say

• Not checked yetcites [103] Morita E, 2019, Nutrients. source

In the paper

“the relative abundance of Clostridioides difficile decreased, whereas that of Oscillospira increased during exercise compared to the control period”

What the sources say

• Not checked yetcites [101] Taniguchi H, 2018, Phys Rep

In the paper

“there was a clear segregation in compositional and functional changes between exercise responders and non-responders, accompanied by distinct alterations in microbial metabolites.”

What the sources say

• Not checked yetcites [106] Liu Y, 2019, Cell Metab source

In the paper

“Exercise-induced modulations of the gut microbiota and SCFA were strongly associated with changes in body composition in lean participants and VO2max in obese participants, independent of diet.”

What the sources say

• Not checked yetcites [98] Allen JM, 2018, Med Sci Sports Exerc source

In the paper

“It appears microbial SCFAs influence blood pressure by interacting with host SCFA receptors [102].”

What the sources say

• Not checked yetcites [102] Pluznick JL, 2017, Curr Hypertens Rep source

In the paper

“Beta diversity changed in all exercise groups compared to control, with participants in the vigorous intensity group showing decreased heterogeneity.”

What the sources say

• Not checked yetcites [108] Kern T, 2019, Int J Obes source

In the paper

“This connection is also supported by the observed shifts in metabolic capacity of the gut microbiota which may be transient and likely dependent on repeated exercise stimuli.”

In the paper

“It is widely accepted that lower levels of Bacteroides are associated with the higher prevalence of obesity and metabolic syndrome and that Bacteroides species may help in suppressing metabolic dysfunction [79, 104].”

What the sources say

• Not checked yetcites [79] Ley RE, 2006, Nature. source
• Not checked yetcites [104] Santacruz A, 2010, Br J Nutr source

In the paper

“Higher levels of lactic acid in athletes’ GI tract favor the growth of this genus and these bacteria may in turn produce a compound that could aid performance.”

In the paper

“In a pre-clinical crossover trial, Veillonella inoculated mice had a 13% improvement in time to exhaustion running tests as well as significant reductions in inflammatory cytokines post exercise compared to control.”

What the sources say

• Not checked yetcites [16] Scheiman J, 2019, Nat Med source

In the paper

“therefore, the increased relative abundance observed after the 12-week exercise intervention may be due to its ability to shift substrates compared to other taxa that more reproducibly decline with a high-fat diet (i.e., Bifidobacteria).”

What the sources say

• Not checked yetcites [105] Abenavoli L, 2019, Nutrients. source

In the paper

“Aerobic exercise also increases fecal SCFA concentration which can decrease pH in the colonic lumen [125].”

What the sources say

• Not checked yetcites [125] Walker AW, 2005, Appl Environ Microbiol source

In the paper

“increased intestinal permeability ensues, thought to be driven by the phosphorylation of several tight junction proteins [129].”

What the sources say

• Not checked yetcites [129] Zuhl M, 2014, Br J Sports Med source

In the paper

“These results highlight the importance of intestinal substrate uptake on the whole-body and changes, especially in glucose uptake, might have a positive effect on the gut microbiota.”

What the sources say

• Not checked yetcites [109] Motiani KK, 2019, Med Sci Sports Exerc source

In the paper

“longer colonic transit time is associated with decreased gut microbiota diversity, which is paralleled by an increase in pH during transit from the proximal to the distal colon [116, 117].”

What the sources say

• Not checked yetcites [116] Tottey W, 2017, J Neurogastroenterol Motil source
• Not checked yetcites [117] Abbas A, 2014, J Gastroenterol Hepatol Res

In the paper

“many of these microbial characteristics may be a result of ‘form fits function’, as communities in the gut are shaped by available resources, as determined by the physiology of their host.”

In the paper

“physically active individuals are more likely to be exposed to their environmental biosphere (e.g., time spent outdoors) and follow an overall healthy lifestyle and, consequently, harbor a richer microbiota.”

In the paper

“Clostridium plays an important role in whole-body immune responses, while Blautia purportedly increases the release of proinflammatory cytokines [111].”

What the sources say

• Not checked yetcites [111] Tuovinen E, 2013, Anaerobe. source

In the paper

“Bacteroidetes increased and the Firmicutes/Bacteroidetes ratio decreased.”

What the sources say

• Not checked yetcites [109] Motiani KK, 2019, Med Sci Sports Exerc source

In the paper

“Intestinal ischemia may result, particularly in the setting of dehydration, manifesting as abdominal cramps, diarrhea, or occasionally bloody diarrhea [127].”

What the sources say

• Not checked yetcites [127] de Oliveira EP, 2009, Curr Opin Clin Nutr Metab Care source

In the paper

“These and other potential adaptive mechanisms, such as a change in gut pH, may create an environmental setting that allows for richer community diversity and metabolic functions.”

In the paper

“metabolites that are a by-product of exercise and circulate throughout the body (e.g., lactate) may filter through the gut and serve as an energy source for certain bacterial taxa (e.g., Veillonella).”

In the paper

“This increase occurred independent of any change in cardiorespiratory fitness, with VO2max similar pre- and post-race.”

What the sources say

• Not checked yetcites [99] Keohane DM, 2019, J Sci Med Sport source

In the paper

“Prolonged intestinal hypo-perfusion impairs mucosal homeostasis and causes enterocyte injury.”

In the paper

“Changes in GI transit time have been reported to affect the pH within the colonic lumen which could lead to alterations in the composition of the gut microbiota.”

What the sources say

• Not checked yetcites [116] Tottey W, 2017, J Neurogastroenterol Motil source
• Not checked yetcites [117] Abbas A, 2014, J Gastroenterol Hepatol Res

In the paper

“colonic glucose concentrations associated positively with Bacteroidetes and inversely with Firmicutes phylum, the Firmicutes/Bacteroidetes ratio, and Blautia genus.”

What the sources say

• Not checked yetcites [109] Motiani KK, 2019, Med Sci Sports Exerc source

In the paper

“Changes in essential amino acid availability influence hematopoiesis, which in turn may increase oxygen carrying capacity and cardiorespiratory fitness [112].”

What the sources say

• Not checked yetcites [112] Ohtani M, 2006, J Nutr source

In the paper

“Athletes often consume a diet that differs from the general population with implications on the composition of the gut microbiome.”

In the paper

“athletes consume higher energy diets compared to sedentary individuals and are often encouraged to consume a diet high in carbohydrate and protein and lower in fat [140].”

What the sources say

• Not checked yetcites [140] Kerksick CM, 2018, J Int Soc Sports Nutr source

In the paper

“Gnotobiotic mice are inefficient at processing food, yet when colonized with conventional mouse gut biota they gain weight by increasing their energy stores [152].”

What the sources say

• Not checked yetcites [152] Turnbaugh PJ, 2006, Nature. source

In the paper

“Nearly all studies included in this review have shown positive correlations between gut taxa and exercise. Overall exercise appears to enrich microbiota diversity, stimulate the proliferation of bacteria which can modulate mucosal immunity, improve barrier functions, and functional pathways capable of producing substances (e.g., butyrate and propionate) that can increase performance and health.”

In the paper

“Studies of lean and obese mice indicate that the gut microbiota affects energy balance by influencing the efficiency of calorie harvest from the diet and how this harvested energy is used and stored.”

In the paper

“exercise appears to enrich microbiota diversity, stimulate the proliferation of bacteria which can modulate mucosal immunity, improve barrier functions, and stimulate bacteria and functional pathways capable of producing substances that protect against gastrointestinal disorders and improve performance (i.e., SCFAs).”