The gut microbiome – the invisible coach in sports?
The trillions of microbes in the gut, also called the gut microbiome, have, during the last decade, received a lot of interest for their ability to affect digestion, physiology, and maybe even our mood and mental health. Yet, with recent studies suggesting a bidirectional relationship between exercise and the gut microbiome, scientists are now starting also to investigate the role of the gut microbiome as an invisible coach in sports affecting physical performance.
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Physical activity and gastrointestinal distress
Physical activity is, in its nature, putting stress on the body, particularly if it is intense or prolonged. While moderate amounts of exercise have a positive effect on gut permeability and inflammation 1, sustained and intense exercise can have deleterious effects on the gut functionality 2, in agreement with gastrointestinal distress and disorders being common, especially among endurance athletes. 3
Since the gut microbiome is linked to the gastrointestinal physiology 4, the gut microbiome could potentially play a role in gastrointestinal distress and physiological responses to exercise, influencing athletic performance.
Effects of the gut microbiota on endurance exercise
Pointing towards a more direct effect of the gut microbiota on endurance exercise, a landmark study published in Nature Medicine in 2019 10, found that marathon runners have elevated levels of Veillonella. The researchers found that lactate, formed during prolonged endurance, was transported from the circulation into the intestine where it was metabolized by Veillonella into propionate.
Flora, microbiota, microbiome: false friends and true synonyms
When the scientists fed mice the lactate-utilizing Veillonella microbes or administered propionate via intracolonic infusion, the endurance of the mice improved, as reflected by increased treadmill run performance. 10 Intriguingly, the study proposed that gut microbes may directly enhance athletic performance. Another recent study also reported that the gut microbiome is involved in stimulating gut-derived signals to the brain affecting motivation for exercise in mice. 11
These discoveries suggest that by targeting the gut microbiome, athletes could potentially improve their athletic performance.
Gut-centric dietary strategies to influence athletic performance
An obvious way to target the gut microbiome is through the diet, since microbes feed on dietary components reaching the colon. Traditionally, many sports-centric dietary strategies focused on high protein, high carbohydrates, low fiber intake, and food avoidance. While such strategies may be sufficient to support host metabolism, restore glycogen stores, and reduce gastrointestinal distress during exercise 12, the lack of dietary fiber could over time be detrimental to the athlete’s gut microbiota and bowel habits. 13
In contrast, gut-directed dietary strategies including adequate dietary fiber from a variety of foods, probiotics, and prebiotics, could support a diverse gut microbiome 13 and contribute to regular bowel habits. 4 The intake of dietary fiber and prebiotics fuels the resident gut microbes as they serve as substrates for the microbes. Once these indigestible components reach the colon, the microbes ferment them into gas and short-chain fatty acids.
While too much gas can cause discomfort and bloating, the resulting three main short-chain fatty acids – acetate, propionate and butyrate are associated with colonic health and integrity. These molecules can act locally in the gut, affecting our intestinal barrier function, motility, nervous system, and immune system, as well as in distant organs, affecting host metabolism. 14
Probiotics is another way to target the gut
Probiotics are living microbes that, when administered in adequate amounts, confer a health benefit. Multiple studies have found that particular probiotic strains can protect against gastrointestinal distress and upper respiratory tract infections in athletes. 15–17 However, at this stage, the underlying mechanisms remain largely unknown, and effects are likely to be probiotic strain-dependent, making it hard for athletes to navigate this space.
To nurture our invisible microbial coach in the gut, scientists and athletes need to develop gut-centric dietary strategies that, on the one hand, reduce gastrointestinal symptoms during exercise and, on the other hand, support a diverse gut microbiome, stimulate colonic fermentation, and promote regular bowel movements — aspects that may all be key for athletic performance.
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"#microbiota "Since the gut microbiome is linked to the gastrointestinal physiology, the gut microbiome could potentially play a role in gastrointestinal distress and physiological responses to #exercise, influencing athletic performance.." -@rddp10 (From Biocodex Microbiota Institute on X)
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