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Can you exercise on test day?


A common question we get asked here at Stream Diagnostics is whether exercise is allowed on the day of breath testing. The answer is no. Why?

Well to begin, it helps to understand what hydrogen methane breath testing is. We wrote a blog around this, and you can check it out here.

As a quick summary breath testing works as the body usually does not produce hydrogen gas unless there are bacteria undergoing the fermentation of carbohydrates. [1] Bacteria ferment carbohydrates when they are not absorbed in the small intestine during digestion and therefore end up in the large intestine. [1] Therefore, we read the level of hydrogen that someone produces to understand if they are digesting or fermenting a specific sugar.

What about exercise then? Well exercise actually works to temporarily alter the concentration of hydrogen in the gut and therefore if you were to do the test after exercising, it may provide a false reading.  (2) So there you have, while it may seem like a small thing we definitely recommend against exercising on the day of your test so that you don’t influence your results.

Once you finish your test you are free to exercise!

Stay tuned for more blogs like this one on our page! If you have any questions check out our website or give us a call today!

[1] Simrén, M., & Stotzer, P. O. (2006). Use and abuse of hydrogen breath tests. Gut55(3), 297–303.

[2] Ostojic S. M. (2020). Exercise-Driven Increase in Gut Microbial Hydrogen Production as a Possible Factor of Metabolic Health. Frontiers in physiology11, 1065.