Ultra-Endurance Triathlon Competition Shifts Fecal Metabolome Independent of Changes to Microbiome Composition

Understanding changes to gut microbiota composition and metabolic output in response to acute exercise may be necessary for understanding the mechanisms mediating the long-term health and performance benefits of exercise. Our primary objective was to characterize acute changes in the fecal microbiome and metabolome following participation in an ultra-endurance (3.9km swim, 180.2km bike, 42.2km run) triathlon. An exploratory aim was to determine associations between athlete-specific factors (race performance [i.e., completion time] and lifetime years of endurance training) with pre-race gut microbiota and metabolite profiles. Stool samples from 12 triathletes (9M/3F; 43±14 yrs, 23±2 kg/m ) were collected ≤48 hours before and the first bowel movement following race completion. Intra- and inter-individual diversity of bacterial species and individual bacterial taxa were unaltered following race completion (P>0.05). However, significant reductions (P