It has been previously found that exercise may play an important role in the overall health of the host by contributing to the diversity of gut microbiota. However, extreme dietary differences, especially high protein intakes, amongst the elite athletes studied may confound interpretations about the specific role of exercise in determining gut bacterial richness. How physical fitness contributes to intestinal microbial diversity is currently not known.


A recent study, led by Dr. Deanna L. Gibson from the Department of Biology at the University of British Columbia (Canada), has found that cardiorespiratory fitness is correlated with increased microbial diversity and increased production of faecal butyrate in healthy humans.


The researchers used high-throughput sequencing to analyse faecal microbiota of 39 healthy participants with similar age, body mass index, and diet, but with varying cardiorespiratory fitness (CRF) levels, as assessed by the peak oxygen uptake (VO2peak). Faecal short-chain fatty acids (SCFAs) were also analysed using gas chromatography.


Diet was not a confounding factor across fitness groups, as there was a lack of distinct dietary patterns amongst all fitness groups (low fitness, n=14; average fitness, n=12 and high fitness, n=13). It was shown that VO2peak, an indicator of physical fitness, accounted for more than 20% of the variation in taxonomic richness, after accounting for all other factors such as diet. Although VO2peak was not associated with specific bacterial taxa, it was correlated with distinct microbiome functions including chemotaxis, motility, and fatty acid biosynthesis.


VO2peak was strongly correlated with faecal butyric acid, which was represented primarily across high and average fitness participants. Increased butyrate levels were explained by increased abundances of key butyrate-producing taxa (Clostridiales, Roseburia, Lachnospiraceae, and Erysipelotrichaceae) among physically fit participants.


In conclusion, CRF, independent of diet, is correlated with increased microbial diversity and production of faecal butyrate. These findings support the use of exercise as an adjuvant therapy in combating those conditions associated with reduced microbial diversity such as diabetes, colorectal cancer, and inflammatory bowel disease.




Estaki M, Pither J, Baumeister P, et al. Cardiorespiratory fitness as a predictor of intestinal microbial diversity and distinct metagenomic functions. Microbiome. 2016; 4(1):42. doi: 10.1186/s40168-016-0189-7.