Exploring the association between physical activity and gut microbiota composition: a review of current evidence.

The gut microbiota is implicated in digestive, metabolic and immune processes of the host. The physiological and pathophysiological functions of the intestinal microbiota depend of its composition, and several individual or external factors may be associated with the presence of some categories, phyla or species of microorganisms in the gut. In particular, two bacterial phyla - Firmicutes and Bacteroidetes - are predominant in the human gut and their relative concentrations seem to be related with age, gender, diet habits and weight status. In the last decade, several studies have tried to characterize the possible role of physical activity in determining qualitative and quantitative composition of the intestinal microbiota. This review is aimed at exploring the current evidences regarding the association between physical activity and gut microbiota composition in animal models and in the humans. Further studies are needed to clarify the mutual relationships among exercise, diet, nutritional supplements/doping agents and gut microbiota.