Enteric nervous system in exercise physiology: a microbiota-neural interface

Exercise responses vary widely among individuals, yet the biological basis of this variability remains poorly understood. Microbiota-derived metabolites operate on timescales of hours to days, making them insufficient to explain rapid gastrointestinal and performance changes that emerge within minutes of exercise. We propose that the enteric nervous system (ENS) fills this regulatory gap by integrating mechanical, immune, and microbial signals in real time. We review evidence that the ENS modulates gut motility, barrier function, and microbial ecology during exercise, engages in bidirectional crosstalk with the microbiota, and relays gut-derived signals to muscle and brain via neural and humoral routes. We further introduce the concept of neuro-enteric phenotypes to account for inter-individual differences in exercise tolerance and adaptation.