Gut microbiome delays fatigue and ensures better performance in endurance horses. Metagenome equine athletes

Emerging evidence indicates that gut microbiome contributes to endurance exercise response but their extant functional and metabolic potential remains unknown. To understand the influence gut microbial diversity, abundance and metabolic capacity have on exercise performance in elite horse runners, we first reconstructed a gut microbial reference catalog with > 25 million non-redundant genes representing 4,696 genera spanning 95 phyla. By leveraging the gut microbiome and physiological and metabolic response to exercise, we showed that loss of microbiome diversity and an enrichment of Lachnospiraceae reliant upon dietary glycans declined the competitive advantage. Conversely, rare microbial communities ensured higher fuel flexibility and enhanced oxidative reserve capacities in the mitochondria, leaving room for greater ATP production, enhanced resistance to fatigue and cardiac output. Validated across an independent cohort of highly trained horse athletes, highly diverse ecosystems boosted cardiac function. In sum, the findings suggest that gut microbiome influence the cardiac output and the resulting athletic performance by mitochondria-mediated mechanisms.