Gut microbiota refers to those microorganisms in the human digestive tract that display activities fundamental in human life. With at least 4 million different bacterial types, the gut microbiota is composed of bacteria that are present at levels sixfold greater than the total number of cells in the entire human body. Among its multiple functions, the microbiota helps promote the bioavailability of some nutrients and the metabolization of food, and protects the intestinal mucosa from the aggression of pathogenic microorganisms. Moreover, by stimulating the production of intestinal mediators able to reach the central nervous system (gut/brain axis), the gut microbiota participates in the modulation of human moods and behaviors. Several endogenous and exogenous factors can cause dysbiosis with important consequences on the composition and functions of the microbiota. Recent research underlines the importance of appropriate physical activity (such as sports), nutrition, and a healthy lifestyle to ensure the presence of a functional physiological microbiota working to maintain the health of the whole human organism. Indeed, in addition to bowel disturbances, variations in the qualitative and quantitative microbial composition of the gastrointestinal tract might have systemic negative effects. Here, we review recent studies on the effects of physical activity on gut microbiota with the aim of identifying potential mechanisms by which exercise could affect gut microbiota composition and function. Whether physical exercise of variable work intensity might reflect changes in intestinal health is analyzed.

肠道微生物群是指人体消化道中表现出对人类生命至关重要的活动的微生物。肠道微生物群至少有 400 万种不同的细菌类型，其细菌数量是整个人体细胞总数的六倍。在其多种功能中，微生物群有助于促进某些营养素的生物利用度和食物的代谢，并保护肠粘膜免受病原微生物的侵袭。此外，通过刺激能够到达中枢神经系统（肠/脑轴）的肠道介质的产生，肠道微生物群参与了人类情绪和行为的调节。一些内源性和外源性因素可导致生态失调，对微生物群的组成和功能产生重要影响。最近的研究强调了适当的身体活动（如运动）、营养和健康生活方式的重要性，以确保存在功能性生理微生物群，从而维持整个人体的健康。事实上，除了肠道紊乱，胃肠道微生物组成的定性和定量变化可能会产生全身性的负面影响。在这里，我们回顾了最近关于身体活动对肠道微生物群影响的研究，目的是确定运动可能影响肠道微生物群组成和功能的潜在机制。