I am an exercise physiologist who specializes in the gut microbiota. Humans live in symbiosis with clusters of microbes in various parts of the body ranging from the skin, gut, oral cavity, vagina, and other areas exposed to the environment. These bacterial communities are primary constituents of the microbiome which encompasses the complete genetic potential of a bacterial population as well the products of the microbiota (microbial taxa) and host environment. Balance in the gut regulates dietary energy harvest as well as the metabolism of microbial and host derived chemicals. Thus, any perturbations in the microbiota may interrupt intestinal homeostasis. The most common contributor to microbial changes is human behavior, through diet and exercise, which are also important factors for healthful aging. Exercise is effective at reducing the risk of many chronic conditions like obesity, diabetes, and heart disease. Exercise training enhances antioxidant capacity and reduced inflammation. Exercise is also known to exert a role in energy homeostasis and regulation and has been shown to manipulate gut bacterial populations. However, little is known about the forces/factors that drive microbial diversity resulting from exercise training.