What is already known
Physical activity has been shown to lower the risk of several conditions, yet many people tend to have a sedentary lifestyle. Recent studies have suggested that the gut microbiota influences exercise performance, but whether it regulates an individual’s motivation to exercise is unclear.
What this research adds
Researchers analyzed gut bacteria, bloodstream metabolites and other data from nearly 200 mice. Then, the team measured how much time the mice spent on a wheel or treadmill, as well as their performance. Treating mice with antibiotics to alter their gut microbiota reduced the animals’ performance by about 50%. The antibiotic treatment appeared to reduce the levels of the neurotransmitter dopamine and dampen the activity of certain genes in the mice’s brain. The team found that two bacterial species, i>Eubacterium rectale and Coprococcus eutactus, were associated with better performance. These bacteria produce metabolites that stimulate specific receptors on brain cells, leading to an increase in dopamine levels during exercise.
Conclusions
The findings suggest that signals derived from the gut can boost the motivation to exercise.
Physical activity has been shown to lower the risk of several conditions, yet many people tend to have a sedentary lifestyle. Now, a study found that mice with an intact gut microbiota spend more time exercising.
The results, published in Nature, suggest that signals derived from the gut can boost the motivation to exercise, but it’s unclear if the findings can be applied to people.
Recent studies have suggested that the gut microbiota influences exercise performance, however little is known about the effects of the gut microbiota on an individual’s motivation to exercise.
To assess the role of gut microbes in exercise motivation and performance, Christoph Thaiss at the University of Pennsylvania School of Medicine and his colleagues analyzed gut bacteria, bloodstream metabolites and other data from nearly 200 mice.
High performance
The researchers ranked the mice according to their performances when spinning on wheels or running on treadmills, and they observed great variability among the animals. Genetic or metabolic factors didn’t explain these differences, but the composition of the gut microbiota did.
Mice lacking gut bacteria exercised more than usual when given gut microbes from high-performing mice, whereas treating high-performing animals with antibiotics reduced their performance by up to 50%.
The antibiotic treatment appeared to decrease the levels of the neurotransmitter dopamine and dampen the activity of certain genes in the mice’s brain, the researchers found. Dopamine has been linked to the sense of wellbeing that people experience after exercising — the so-called ‘runner’s high’.
Boosting exercise
To find out how gut bacteria influence dopamine levels in the brain, the researchers inhibited a set of neurons that relay messages from the gut to the brain. This treatment reduced exercise rates in high-performing mice, they found.
Further experiments showed that two bacterial species, Eubacterium rectale and Coprococcus eutactus, were associated with better performance. These bacteria produce metabolites called fatty acid amides, which stimulate specific receptors on brain cells. This stimulation in turn leads to an increase in dopamine levels during exercise.
“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,” Thaiss says.
