Unmotivated to exercise? Blame your gut microbiome

If you find you are unmotivated to hit the gym these days it may be the bacteria in your gut that is to blame.  Scientists have recently discovered gut-dwelling bacteria that activate nerves in the gut and promote the desire to exercise. If these bacterium are not present due to antibiotics, stress, lifestyle or diet changes, you may lose the desire to exercise.

How does that work? “The study revealed the gut-to-brain pathway that explains why some bacteria boost exercise performance. In the study, the researchers found that differences in running performance within a large group of lab mice were largely attributable to the presence of certain gut bacterial species in the higher-performing animals. The researchers traced this effect to small molecules called metabolites that the bacteria produce—metabolites that stimulate sensory nerves in the gut to enhance activity in a motivation-controlling brain region during exercise.”

The study: “Researchers set up the study to search broadly for factors that determine exercise performance. They recorded the genome sequences, gut bacterial species, bloodstream metabolites, and other data for genetically diverse mice. They then measured the amount of daily voluntary wheel running the animals did, as well as their endurance.

The researchers analyzed these data using machine learning, seeking attributes of the mice that could best explain the animals’ sizeable inter-individual differences in running performance. They were surprised to find that genetics seemed to account for only a small portion of these performance differences—whereas differences in gut bacterial populations appeared to be substantially more important. In fact, they observed that giving mice broad-spectrum antibiotics to get rid of their gut bacteria reduced the mice running performance by about half.” wow.

The key findings:  “After many years of scientific detective work involving more than a dozen separate laboratories, the researchers found that two bacterial species closely tied to better performance, Eubacterium rectale and Coprococcus eutactus, produce metabolites known as fatty acid amides (FAAs). The latter stimulate receptors called CB1 endocannabinoid receptors on gut-embedded sensory nerves, which connect to the brain via the spine. The stimulation of these CB1 receptor-studded nerves causes an increase in levels of the neurotransmitter dopamine during exercise, in a brain region called the ventral striatum.  The striatum is a critical node in the brain’s reward and motivation network. The researchers concluded that the extra dopamine in this region during exercise boosts performance by reinforcing the desire to exercise.” (source)

The takeaway: Studies still need to be conducted on human subjects but scientists believe the results may well hold true for people. That would mean that getting and maintaining a healthy, balanced gut microbiome could mean that your expensive exercise equipment will never again be used to hang laundry.


Journal Reference: Dohnalová, L., et al. A microbiome-dependent gut–brain pathway regulates motivation for exercise, Nature, December, 2022. https://doi.org/10.1038/s41586-022-05525-z  Study


Contributor: A. Savelli, Ph.D.