1. Introduction
(1) Background: Probiotics in the form of nutritional supplements are safe and potentially useful for strategic application among endurance athletes. Probiotics are defined by the FAO (Food and Agriculture Organization of the United Nations) and the WHO (World Health Organization) as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host [Probiotics are considered a safe strategy for optimizing the health, sports performance, and recovery of athletes, especially endurance athletes [With the development of metagenomics and metabolomics, it provides us more possibilities to explore the effect of 