The ecosystem of bacteria, fungi, and viruses — living on and inside our bodies — is known as the microbiome. Even if you take baths daily, brush your teeth, and wash your hands, you are walking around accompanied by your own unique ecosphere of microbes, roughly a hundred trillion bacteria, some good, and some bad. In fact, our human cells are outnumbered ten to one by these nonhuman cells along for the ride. Mapping the microbiome, like the genome-mapping project, is an ongoing global effort. An unhealthy microbiome has now been linked with multiple diseases and conditions, including clostridium difficile infection, psoriasis, reflux esophagitis, obesity, childhood- onset asthma, gastrointestinal disorders, neuropsychiatric illness like depression and anxiety, multi-drug-resistant organisms, cardiovascular disease, and cancer.
A new study published by scientists from the University of Illinois at Urbana-Champaign found that exercise reliably modified aspects of the microbiome. The subjects, who had been previously sedentary, participated in supervised exercise three days a week for six weeks. They engaged in moderate to vigorous intensity exercise for 30-60 minutes each time. Importantly, they were asked to not change their diets. At the end of the six weeks the investigators found clear changes in the participants gut microbiome compared to before they started exercising. This was especially true for the normal weight individuals compared to those who were extremely overweight at the start. After only six weeks of exercise, the microbiome showed an increase in constituents reflective of decreased inflammation. The participants then reverted to their pre-exercise sedentary behavior for six weeks and their microbiome profile reverted back to the way it was prior to the study. These findings suggest that exercise can innervate the gut and modify the microbiome in a short period of time but sustaining these changes will require regular exercise.