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Physical activity can be incredibly beneficial for your immune system. Modest exercise both boosts immunity and lowers the risk of infection.
It’s also the case that you can have too much of a good thing. Continuous, hard efforts (like running a marathon or ultra marathon) can absolutely affect your immune system especially in the following 24 to 72 hours. Researchers call this immune depression the “open window.” And the “post-marathon plague” that sneaks in can hit as a cold, flu, or other upper respiratory illness and last for a week or two.
Experts refer to this as the J-curve—the point at which exercise stops benefitting your immune system and the risk of infection actually increases.
But for those wishing to stave off the icky post-race bug and keep riding your marathon high, new research shows a promising prevention option: Probiotics. In a study published in April in the journal Nutrients, researchers looked at how 30 days of probiotic supplementation affected the immune system of seven male marathoners compared to a group of seven marathoners who received a placebo.
After running their time-trial marathon they found that upper respiratory tract infection symptoms were 29 percent lower and less severe in runners who took probiotics than those who didn’t.
These preliminary results, though incredibly small, are encouraging for understanding how runners might be able to better support their immune system after hard efforts.
In late 2019, the International Society of Sports Nutrition released their position statement on probiotics to offer a critical review of how to best utilize probiotics for optimal health, performance, and recovery. They state: “Approximately 70% of the immune system is located in the gut, and probiotic supplementation has been shown to promote a healthy immune response. In an athletic population, specific probiotic strains can reduce the number of episodes, severity and duration of upper respiratory tract infections.”
But the results you get from the probiotic supplement depend on the strain you are ingesting. Lactobacillus acidophilus is one of the most common seen in supplements. This particular study supplemented with 5 billion CFU (colony forming units) of a multi-strain probiotic containing Lactobacillus acidophilus, Lactobacillus paracasei, Lactococcus lactis, Bifidobacterium animalis lactis, and Bifidobacterium bifidum.
If you’re looking for more information about how probiotics can be best added into your nutrition plan, consulting with a registered dietitian is the best route to go.