 When it comes to fueling up for sports, science has produced numerous sure-fire strategies, each designed to contain the ideal balance of proteins, fats, carbs, and other nutrients for different athletes. But scientists are only beginning to understand a critical player in this balancing act, the gut microbiome. The gut microbiome refers to the community of trillions of microorganisms that live throughout the gastrointestinal tract. Dr. Riley Hughes and Hannah Hulsher from the University of Illinois at Urbana-Champaign compiled the available evidence to explore the known interactions between diet, exercise, and the gut microbiome in athletes. Their work highlights the role of diet in modulating the gut microbiome and, ultimately, health and performance. The composition of this microbial community is as unique to each person as their fingerprint. That's important because these organisms play an important role in converting nutrients gained from food into fuel for the body. So, understanding an athlete's unique gut microbiome provides vital clues on how it might be harnessed to maximize performance. The two researchers found numerous published studies suggesting that diet influences the behavior of gut bacteria. Certain bacteria ferment dietary fiber, yielding short-chain fatty acids, or SCFAs, in the process. Chain fatty acids are major byproducts of the breakdown of complex carbs, making them important in fueling muscles. Some articles also demonstrated that it's important for athletes who generally consume high-protein diets to consume adequate amounts of fiber. Doing so can prevent problems such as gastrointestinal distress and inflammation. But they also found more recent studies showing how diet-gut-exercise interactions run the other way around. How physical exercise influences the microbiome. These studies explore the effects of exercise type, intensity, and duration in shaping gut physiology. For instance, while exercise is generally tied to positive effects on gut health, there is evidence that long and high-intensity workouts can drain the gut of fuel, causing, for example, abdominal pain. However, only a limited number of studies have investigated the effects of combined exercise and dietary interventions on athlete's gut microbiome. Further research is needed to determine which dietary strategies may have the most synergistic or optimal effects on athlete health and performance. This area of sports science has uncovered several keys to optimizing athletic performance and still has much to offer. Future studies could provide recommendations on how athletes can design diets that fuel their microbes and give them a leg up on the competition.