Can Gut Microbes Can Boost the Motivation to Exercise?
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.
AKA: there were a specific type of bacteria paying rent in the guts of 'high performing' rats that were not found in less-than-high-performing rats.
Penn Medicine's study on mice found that certain naturally produced substances in the gut-to-brain pathway (aka the vagus nerve) can indeed increase motivation to exercise. HOW?! Well, apparently these gut-dwelling bacteria "activate nerves in the gut to promote the desire to exercise.
You'll remember from "P" is for "PROBIOTICS" article that gut-bacteria are extremely helpful and vital to our mood and digestion ability. Recall that probiotics are living microorganisms naturally live in our bodies. They can also be found in foods like yogurt, kimchi, and sauerkraut.
These gut bacteria produce small molecules called metabolites. The researchers found that these metabolites were the cause of this exercise desire phenomenon: these metabolites actually stimulate sensory nerves in the gut to enhance activity in a motivation-controlling brain region during exercise.
How does the mechanism work?
Activation of these particular metabolites made by the gut-bacteria trigger dopamine release. We know that there is also an increase in dopamine during exercise...specifically in a brain region called the ventral striatum. For context, associate the striatum with reward and motivation. The researchers concluded that the extra dopamine in this region during exercise boosts performance by reinforcing the desire to exercise.
What was assessed in the mice?
Running performance. The researchers assessed each mouse's running performance and "runners high" experience! They assumed genetics were going to play a large part in the performance...but were surprised to find that gut bacterial populations were actually the defining factor!! In fact, they observed that giving mice broad-spectrum antibiotics to get rid of their gut bacteria reduced the mice’s running performance by about half.
What does this all mean?
“If we can confirm the presence of a similar pathway in humans, it could offer an effective way to boost people’s levels of exercise to improve public health generally,” said study senior author Christoph Thaiss, PhD, an assistant professor of Microbiology at Penn Medicine.