Endurance Exercise, Gut Health, Recovery & Probiotics


Ultramarathons. When one marathon is not satisfying enough, why not run several? In a row. Day and night, up mountains, across deserts. Yes, ultramarathon runners enjoy a uniquely punishing yet rewarding activity. They truly test the limits of human endurance, of mind, body and spirit, to keep running well beyond what any seemingly rational person would choose. If you’ve read any interviews with ultramarathon runners, they have unique stories behind their passion for the sport.

As you might guess, running for this length of time is not without its downsides. Triathalon, marathon and ultramarathon runners pay the price with run-time symptoms and post-race recovery that often involve a lot of GI distress like nausea, cramping, diarrhea, gastric pain and gut barrier damage.

During these long events, hypoperfusion of the digestive system occurs. Blood flow to the digestive system is dramatically reduced, coupled with intense physical activity, leading to intestinal inflammation and increased gut barrier permeability. Immune function also takes a hit in days following the races.

In a study of 272 runners doing the 161-kilometer Western States Endurance Run, 96 percent experienced GI symptoms during the event, and 35 percent of non-finishers of the run dropped out due to GI symptoms like nausea. Another study of ultramarathon runners found 93 percent had GI symptoms with 45 percent being severe. Endotoxaemia and increased markers for inflammation were found in 68 percent of athletes post-race. Endotoxaemia is where toxins and food particles in the gut enter the bloodstream due to increased gut barrier permeability, aka “leaky gut.” Specifically, leakage of lipopolysaccharides (LPS), an endotoxin, into the bloodstream, along with post-race muscle damage led to the inflammatory immune response.

What can be done? The body is clearly not happy with 16-24 hours of running through mud, snow, gravel, over tree roots, down hills, sometimes in intense heat and lacking anything remotely resembling a comfy bed for that whole period. Enter the “lowly” bacteria…

Probiotics are beneficial, “good” bacteria that populate our intestines and from there exert a wide, systemic influence over our digestive and immune health. They communicate in their own chemical language with our immune system, help maintain and repair our intestinal lining, and ferment fiber from our diet into things like short-chain fatty acids that are absorbed systemically to help with inflammation and energy. Truly amazing for something so microscopic!

Saccharomyces boulardii (Travel Care) is a well-studied probiotic that can help prevent diarrhea and help repair damage to the intestinal lining to prevent leaky gut. Other studies of probiotics have found that they can also help support immune health and reverse immune health deficiencies in fatigued athletes by restoring interferon levels and reducing the duration of colds/upper respiratory tract infections.

One of the most interesting aspects of probiotics is how they can affect and influence parts of the body outside the gut. To quote one of the researchers: “The intestinal microbiota is able to alter homeostasis at distant mucosal sites, including the respiratory tract, through the common mucosal immune system.”

Many of Flora’s athlete ambassadors are ultramarathon runners and, wise as they are, already use probiotics as part of their health and recovery regimen. Probiotics tend to work best when taken for at least several weeks to months—in this case, already during training leading up to races and for the recovery period afterwards.

Robert Dadd is a Master Herbalist (Dominion Herbal College) with a BA in Communications from Simon Fraser University. His areas of research include adaptogens, probiotics, and essential fatty acids. He is currently the Product Information Supervisor for Flora Manufacturing and Distributing.

Further reading: