The microbiome, the bacteria that reside in the gut, is involved in functions outside of our gastrointestinal system.
Not everything is in the brain. Motivation to exercise can come from the gut, as well as the brain.
A study carried out in mice reveals that certain gut bacteria may increase dopamine release during physical activity, which contributes to motivation.
Although most of us know that exercise has many benefits, the amount of exercise that people do varies widely, says Christoph Thaiss of the University of Pennsylvania (USA). He and his colleagues wanted to identify physiological factors that might explain this variation.
They collected data from 106 mice on exercise capacity, genetics, gut microbiome composition, etc., and fed it into a machine learning model for analysis. The model found that how often the mice exercised was closely related to the composition of their microbiome.
In a subsequent series of experiments, they found that mice with weakened gut microbiomes spent half the time voluntarily running on a wheel as those with intact microbiomes. Additionally, dopamine levels in their brains dropped during physical activity, suggesting that they found exercise less rewarding. The team repeated these experiments in mice with intact microbiomes but no neurons connecting the gut to the brain, and saw the same effects as in mice with reduced microbiomes. Taken together, these findings demonstrate that the gut plays an integral role in motivation to exercise, Thaiss says.
Motivation to exercise may come from the gut, as well as the brain
The team also identified molecules produced by certain gut bacteria called fatty acid amides that, when given to mice with depleted microbiomes, restored the frequency with which they exercised to levels seen in mice with intact microbiomes. “Surprisingly, the motivation to exercise is not intrinsic to the brain, but rather is regulated by the gastrointestinal tract», explains Thaiss.
It is not the first time that it has been discovered that the microbiome intervenes in functions outside of our gastrointestinal system. In fact, previous studies have shown that the bacteria in our intestines can influence our moodcontrol blood sugar levels and even protect against inflammation associated with diseases such as heart disease and dementia.
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