Athletes had higher levels of plasma creatinine kinase (marker of extreme exercise), less inflammation and better metabolic markers. They also had a much bigger diversity of gut bugs - 113 genera compared to 65 genera for controls. Athletes ate more protein than controls which accounted for 22% of their total energy intake versus 16% in the control group.
High protein intake, high levels of creatinine kinase were drivers of gut biodiversity. Microbial diversity is important because that is how you can strengthen your immunity and increase your metabolic rate.