Researchers at Edith Cowan University have discovered that varying training intensities can alter the gut bacteria composition in athletes. The study highlights how intense workouts influence microbial balance, while periods of rest lead to dietary shifts and slower digestion. These findings suggest potential links between gut health and athletic performance.
A study led by PhD candidate Ms. Bronwen Charlesson at Edith Cowan University examined the effects of different training loads on the gut microbiome of highly trained rowing athletes. The research, published in the Journal of the International Society of Sports Nutrition in 2025, found that athletes exhibit distinct gut microbiota compared to the general population. This includes greater concentrations of short-chain fatty acids, higher alpha diversity, increased abundance of some bacteria, and lower abundance of others.
Ms. Charlesson noted, "Based on previous research, it appears that athletes have a different gut microbiota when compared with the general population. This includes greater total short chain fatty acid concentrations, alpha diversity, an increased abundance of some bacteria and a lower abundance of others."
The investigation revealed that training intensity directly correlates with changes in gut health markers. During high-intensity periods, shifts in short-chain fatty acid levels and bacterial species were observed. One potential mechanism involves lactate produced during intense exercise, which may travel to the gut and promote the growth of specific bacteria, thereby reshaping the microbial environment.
In contrast, low training loads or rest periods brought notable changes. Athletes relaxed their diets, leading to a decline in food quality despite stable carbohydrate and fiber intake. This included increases in processed fast foods, decreases in fresh fruits and vegetables, and a moderate rise in alcohol consumption. Ms. Charlesson explained, "During low training load times, or periods of rest, athletes are often more relaxed about their diets... These changes did impact the composition of the gut microbiome."
Additionally, gut transit times slowed significantly during these rest phases, further affecting the microbiome. The study, involving authors B. Charlesson, J. Jones, C. Abbiss, P. Peeling, S. Watts, and C.T. Christophersen, underscores the interplay between training, diet, and digestion. While the full impact on performance remains under exploration, the gut may aid in lactate processing and pH regulation, potentially influencing recovery and output. More research is needed to clarify these interactions for optimizing athletes' routines.
