The importance of Gut Microbiota in Athletes
6 Jan 2022

Gut microbiota (collection of bacteria living in the human gut) has received special attention in the last years due to the numerous studies that link its functioning with health. Thus, dysbiosis of the gut microbiota (this is, alteration in the composition or functioning of such bacteria), which can happen due to multiple factors such as poor nutrition, high levels of stress or antibiotics overuse, is linked to the development of numerous metabolic and inflammatory pathologies.

Does the gut microbiota affect performance?

While there is ample evidence supporting the role of gut microbiota in health, the role of this ‘organ’ in sports performance is not so known. However, only two years ago a striking study was published in the prestigious magazine Nature Medicine showing how the functioning of the microbiota could alter performance.1 In such study, samples of gut microbiota (this is, fecal samples) of Boston marathon runners were collected from the week before the marathon until the week after it, and the results showed a higher quantity of Veillonella (bacteria of gut microbiota able to metabolize lactate) after the marathon. Besides, researchers tried to analyze if these bacteria could have effects on performance using experiments on mice. In this way, animals were inoculated with a control bacterium which is not able to metabolize lactate (Lactobacillus bulgaricus gavage) or Veillonella bacterium obtained from the runners after running the marathon and observed that in the latter case mice were able to run for a longer time (mean 13%) until exhaustion. So, this study showed that gut microbiota composition can affect performance, at least in mice, and from then on diverse studies have shown that fitter and more active people have a healthier and more diverse gut microbiota composition in general. 2

Microbiota and muscle development

Apart from these studies that relate gut microbiota health to performance, it has recently been observed that gut microbiota could also play a key role in adaptations obtained from training, especially in muscle mass.  A study recently published in the Journal of Physiology analyzed 42 mice under strength training meant to increase muscle mass.3 Some of those mice were treated with antibiotics during the program, while others were not. At the end of the study, the authors observed that the antibiotic resulted in a gut microbiota disruption, remarkably reducing the diversity of the bacteria.  Besides, even though both groups, the one with antibiotics and the one without them, made the same amount of exercise, the authors observed lower muscle hypertrophy and lower abundance of satellite cells (in charge of muscle regeneration) in the former, as well as a lower oxidative capacity in type 2 fibers. So, these results show that alterations in gut microbiota (which can happen, for example, due to continued antibiotic intake) could reduce some muscle adaptations to training. 


Gut microbiota plays a key role in health, and more and more evidence (although it is preliminary and mainly obtained from animal models) suggests that it could also condition the adaptations obtained from training and sports performance in general. That is why it is necessary to try to maintain a healthy and diverse gut microbiota, avoiding, for example, overuse of antibiotics and processed food, and trying to prioritize food high in fiber and probiotics.


  1. Scheiman J, Luber JM, Chavkin TA, et al. Meta-omics analysis of elite athletes identifies a performance-enhancing microbe that functions via lactate metabolism. Nat Med. 2019;25(7):1104-1109. doi:10.1038/s41591-019-0485-4
  2. Ortiz-Alvarez L, Xu H, Martinez-Tellez B. Influence of Exercise on the Human Gut Microbiota of Healthy Adults: A Systematic Review. Clin Transl Gastroenterol. 2020;11(2):e00126. doi:10.14309/ctg.0000000000000126
  3. Valentino TR, Vechetti IJ, Mobley CB, et al. Dysbiosis of the gut microbiome impairs mouse skeletal muscle adaptation to exercise. J Physiol. 2021;21:4845-4863. doi:10.1113/JP281788


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