Surprising? Not when you consider that their DNA outnumbers our body’s DNA 150:1. So who is running the show?

A sobering question for our inflated egos to ponder.

Reference

A microbiome exercise

CHRISTOPH A. THAISS. H. J. SCIENCE 6 Jul 2023, Vol 381, Issue 6653

“Exercise is arguably the most potent and attainable lifestyle factor that individuals can use to safeguard themselves against a large variety of diseases, including metabolic, cardiovascular, neurodegenerative, and neoplastic diseases (1). Despite its vast health benefits, only a small fraction of the population adheres to the World Health Organization’s recommendation of 150 to 300 minutes of moderate-intensity exercise per week (2). Busy schedules and rainy weather aside, what are the physiological bottlenecks that prevent us from engaging in regular physical activity?

My research team at the University of Pennsylvania, spearheaded by PhD student Lenka Dohnalová, set out to answer this question using a large cohort of genetically diverse outbred mice. We observed marked interindividual variability in exercise capacity, with the top performers outrunning the weakest animals by more than 10-fold (3). We then carried out deep molecular and physiological profiling of these mice and used a machine-learning approach to nominate individual measurements that predict treadmill and wheel running. To our surprise, elements of the gut microbiome topped the list. We thus probed the functional importance of the microbiome in exercise performance and carried out ergometric measurements under gnotobiotic conditions (i.e., with defined microbial colonization). We noted that the absence of the microbiome in germ-free or antibiotics-treated mice diminishes voluntary and endurance exercise capacity by ∼50%. We determined that this effect of the microbiota was driven by certain taxonomic elements, including members of the Lachnospiraceae family. These experiments suggest that the gut microbiome may be an important contributor to the interindividual variability in physical activity.

The question of how the microbiome affects exercise performance led us to an intriguing discovery. Contrary to our expectations, the effects of intestinal microbes on physical performance were not mediated by tissues classically associated with exercise, such as skeletal muscle. Rather, the microbiome appeared to fundamentally influence the impact of exercise on the brain. Intense physical activity stimulates numerous neurochemical responses in the brain, including a surge in dopamine release in the striatum (4). And interestingly, in the absence of the microbiome, this surge was severely diminished.”