Author(s): HSU, Y., Institution: NATIONAL TAIWAN SPORT UNIVERSITY, Country: TAIWAN, Abstract-ID: 385

INTRODUCTION:
Endurance athletes exhibit substantial inter-individual variability in lactate metabolism, potentially influenced by gut microbial lactate utilization and short-chain fatty acid production. Building on our previously presented findings in elite marathon runners, which identified Prevotella copri (P. copri) as a key taxon differentiating individuals with high (HL) and low (LL) lactate clearance, the present study aimed to examine whether these microbiota-associated metabolic and performance phenotypes are transferable. We therefore established humanized germ-free (GF) mouse models colonized with microbiota from HL and LL donors to assess whether donor-derived microbiota could recapitulate post-exercise blood lactate kinetics and endurance performance differences across hosts.
METHODS:
Elite marathon runners were stratified by lactate clearance rate, and fecal samples from HL and LL donors were transplanted into germ-free mice to generate humanized gnotobiotic mice (HL hGM: N = 16; LL hGM: N = 17). After a 2-week colonization period, mice completed a 4-week progressive swimming training program (5 sessions/week), with training duration gradually increased from 5 to 20 minutes/day. Following the intervention, gut microbiota composition was assessed using 16S rRNA sequencing. Mice then underwent a graded exercise test and an endurance performance test. The graded exercise test consisted of three-bout graded treadmill protocol (4 minutes per bout), with blood lactate measured at baseline, after each bout, and at 5, 15, 30, and 60 minutes after the final workload. Statistical analyses included independent t-tests and Mann–Whitney U tests (p < 0.05).
RESULTS:
HL hGM and LL hGM exhibited distinct gut microbial profiles after fecal microbiota transplantation. P. copri DSM 18205 was successfully transferred and remained significantly higher in HL hGM, representing the only bacterial species consistently reflecting the donor phenotype. Peak blood lactate concentrations during the graded exercise test was comparable between groups, whereas HL hGM demonstrated greater early lactate clearance at 5 minutes post-exercise (p < 0.05). In addition, HL hGM achieved a significantly longer swimming time to exhaustion compared with LL hGM (p < 0.05).
CONCLUSION:
Gut microbiota derived from elite marathon runners with high lactate clearance partially transferred donor-linked metabolic and performance phenotypes to humanized germ-free mice. Despite similar peak lactate accumulation during exercise, HL hGM mice exhibited enhanced early post-exercise lactate clearance and improved endurance performance, suggesting that microbiota may influence lactate handling during recovery. P. copri DSM 18205 was the only taxon consistently enriched in HL donors and retained in HL-derived mice, supporting its relevance as a microbial marker associated with lactate metabolism. These findings highlight a potential microbiota–lactate–performance link and warrant further mechanistic investigation.