Whilst we all understand as each year passes there are ever more intricate links between the organisms that exist in our gut and our health – have you ever thought that a eubiotic gut (A healthy and balanced state marked by high diversity and abundance of microbial populations in the GI tract) may be one of the reasons some people find exercise motivation easier than those with a dysbiotic digestive tract.
Examining the variations between those mice that like to exercise and those that do not, it appears that genetics had very little influence, but the gut microbiome did. The findings, published in the journal Nature in December, suggest that at least the gut microbiome in mice may help regulate the desire to exercise[1].
If confirmed in humans, this hypothesis could help explain why so many people (about half) fail to get the recommended amount of physical activity. Some may blame a lack of time, energy, or interest. But perhaps the reason could come down to the trillions of microbes living in their gut.
The gut-brain axis
The researchers revealed that the mice treated with antibiotics to alter their microbiome and develop dysbiosis had a reduced expression of dopamine receptors, reducing the emotive feeling of pleasure associated with accomplishing something. The authors suggest this gut-brain pathway may have evolved to couple the initiation of prolonged physical activity to the nutritional status of the gastrointestinal tract. Gut bacteria monitor what’s in your colon and tell your brain whether you have enough food to fuel a workout.
The key to remember at this stage is that the genetic impact on the microbiome is rather minor, but lifestyle factors strongly impact the composition of the gut microbiome. It will be some time before human studies are concluded, but the simple message is that the healthier the microbiome, the easier it will be to retain exercise motivation.
Reverse implications
In another study, researchers confirmed that physical exercise in women affects the microbiome. They found that exercise was correlated with a higher representation of bacteria with health-promoting functions in females.[2]
These included F. prausnitzii and Roseburia hominis, known for their butyrate-producing abilities, and Akkermansia muciniphila, abundant in athletes. Low levels are associated with metabolic conditions, like obesity and diabetes.
Several studies indicate a relationship between microbiota composition and cardiorespiratory fitness that can account for more than 20% of the variation in “taxonomic richness” (diversity of bacteria identified in the microbiome).[3] These changes were noted to be independent of other factors, including age, fat intake, and carbohydrate intake.
More recently a narrative review qualified that cardio exercise has a beneficial impact on the gut microbiome with related enhancements in taxonomy, mental health and physical fitness that in turn is enhanced by compositional changes.[4]
What next
The interaction between motivation to exercise and the act of exercising seems to at least in part have its nexus in the microbiome, which is further enhanced if the exercise habit starts early in life and is maintained.
The implication is that a lifetime of habituation and a good diet will be a substantive (but not the only) reason for those that find exercise a pleasure and those that find it unappealing.
The combination of lifestyle factors, as well as food supplements best employed to enhance the virtuous circle, are also the same as those utilised for healthy aging strategies.[5] Of course aging is a plastic process that can be influenced by dietary habits. Nutrition affects gene expression and metabolism of the host and gut microbiota, representing a link between the two symbionts.
Anti-Sars Cov-2 Secret
One of the spin offs from the action of exercising and in turn supporting the maintenance and development of a eubiotic gut is that exercise has also been demonstrated to be a key factor in reducing the risk of hospitalisation with COVID.
The Centers for Disease Control, based on a systematic review of the evidence, has reported that “physical activity is associated with a decrease in COVID-19 hospitalisations and deaths, while inactivity increases that risk. Other research has linked regular physical activity with a lower risk of infection, hospitalisation, and death from COVID.[6]
A December 2022 study, from Kaiser Permanente, suggests that exercise in almost any amount can cut the risk of severe or fatal COVID even among high-risk patients like those with hypertension or cardiovascular disease, suggesting that even modest amounts of exercise are a powerful component of immune optimisation.[7]
Proactive medicine, where individuals optimise nutrition, exercise, sleep, and whole-body meditation is not a priority in the current health ecosystem. It is changing (slowly), and this is good news.
Brain Health
A research team at University College London published a fascinating study after analysing just under 1500 UK citizens from the 1970 British Cohort study. They were able to determine that brief bouts of moderate and vigorous physical activity (MVPA) Vs sedentary behaviour enhanced cognitive function and cognitive durability. The benefit as with the other factors presented in this summary are relative to consistency of MVPA. Any reduction in MVPA has a deleterious effect on cognition and by inversion, increasing MVPA has a beneficial impact
Clinical outcomes
The variations in food production over the last 50 years is a double-edged sword. Choice has grown exponentially but at a significant cost. Whilst there are always some who argue that the universal challenge with obesity is genetic, the reality is that highly processed foods, change in eating habits and physical activity modify millions of genes in the microbiome far more easily than they do the human genes.
The role of food supplements is increasingly seen as a safe and predictable option for the enhancement of microbiome functionality, albeit there are still wide variations in the outcome because humans are rather inconveniently varied in their makeup.
A healthy lifestyle, with a balanced and expansive diet, rich in unrefined foods of natural origin (such as a modified Mediterranean diet), together with adequate physical exercise, aerobic or combined, sustained for sufficiently long periods, allows for restoration and maintenance of a healthy microbiota even in old age, promoting healthy aging.
Obviously, the use of supplements must be targeted, individualised and calibrated to the needs of the individual subject, and appropriate nutrition, supplement and lifestyle strategies must be implemented to maintain the restored microbiota.
References
[1] Dohnalová, L., Lundgren, P., Carty, J.R.E. et al. A microbiome-dependent gut–brain pathway regulates motivation for exercise. Nature 612, 739–747 (2022).
[2] Bressa C, Bailén-Andrino M, Pérez-Santiago J, González-Soltero R, Pérez M, Montalvo-Lominchar MG, Maté-Muñoz JL, Domínguez R, Moreno D, Larrosa M. Differences in gut microbiota profile between women with active lifestyle and sedentary women. PLoS One. 2017 Feb 10;12(2)
[3] Durk RP, Castillo E, Márquez-Magaña L, Grosicki GJ, Bolter ND, Lee CM, Bagley JR. Gut Microbiota Composition Is Related to Cardiorespiratory Fitness in Healthy Young Adults. Int J Sport Nutr Exerc Metab. 2019 May 1;29(3):249-253.
[4] Cataldi S, Poli L, Şahin FN, Patti A, Santacroce L, Bianco A, Greco G, Ghinassi B, Di Baldassarre A, Fischetti F. The Effects of Physical Activity on the Gut Microbiota and the Gut-Brain Axis in Preclinical and Human Models: A Narrative Review. Nutrients. 2022 Aug 11;14(16):3293
[5] Donati Zeppa S, Agostini D, Ferrini F, Gervasi M, Barbieri E, Bartolacci A, Piccoli G, Saltarelli R, Sestili P, Stocchi V. Interventions on Gut Microbiota for Healthy Aging. Cells. 2022 Dec 22;12(1):34.
[6] Ezzatvar Y, Ramírez-Vélez R, Izquierdo M, et al Physical activity and risk of infection, severity and mortality of COVID-19: a systematic review and non-linear dose–response meta-analysis of data from 1 853 610 adults
British Journal of Sports Medicine 2022;56:1188-1193
[7] Young DR, Sallis JF, Baecker A, Cohen DA, Nau CL, Smith GN, Sallis RE. Associations of Physical Inactivity and COVID-19 Outcomes Among Subgroups. Am J Prev Med. 2022 Dec 10:S0749-3797(22)00526-8.