Dynamics of gut microbiota and short-chain fatty acids during a cycling Grand Tour are related to exercise performance and modulated by dietary intake

Objective: The aim of this study was to analyse the dynamics of faecal microbiota composition and short-chain fatty acids (SCFAs) content of professional cyclists over a Grand Tour, and their relationship with performance and dietary intake. Design: 16 professional cyclists competing in La Vuelta 2019 were recruited. Faecal samples were collected at four time points: The day before the first stage (A); After 9 stages (B); After 15 stages (C); On the last stage (D). Faecal microbiota populations and SCFAs content were analysed using 16S rRNA sequencing and gas chromatography, respectively. Results: A principal component analysis (PCA) followed by Generalized Estimating Equation (GEE) models were carried out to explore the dynamics of microbiota and SCFAs, and its relationship with performance. Bifidobacteriaceae, Coriobacteriaceae, Erysipelotrichaceae, and Sutterellaceae dynamics showed a strong final performance predictive value (R2=0.83, ranking and R2=0.81, accumulated time). Positive correlations were observed between Coriobacteriaceae and acetate and isovalerate and Bifidobacteriaceae and isobutyrate. No relationship was observed between SCFAs and performance. The abundance of Bifidobacteriaceae, Coriobacteriaceae, and Erysipelotrichaceae at the beginning of La Vuelta was directly related to the previous intake of a complex-carbohydrate-rich food, potatoes, while during the competition the abundance of Bifidobacteriaceae was negatively affected by the intake of simple carbohydrates from supplements. Conclusion: An ecological perspective represents more realistically the relationship between gut microbiota composition and performance, compared to single-taxon approaches. The composition and periodisation of diet and supplementation during a Grand Tour, particularly carbohydrates, could be designed to modulate gut microbiota composition that allow better performance.