Unless you’ve been chewing on the kettlebells, tasting metal mid-workout comes from the iron in your blood. And while that totally makes sense, that raises another question: Why are you tasting blood when you work out?

There are a few possible reasons, but they all center around the fact that the tongue has receptors that are very sensitive to the taste of iron, says Jeffrey Laubmeier, D.M.D., a dentist in Lakewood, OH and member of the Academy for Sports Dentistry.

When you work out, it increases your blood pressure, which then increases the pressure within the lungs. “The thin tissue membrane in the lungs allows a small amount of red blood cells to leak into the air sacs. Then, during exhalation, the tongue is able to pick up trace amounts of blood that causes the taste of metal,” Laubmeier explains.

That same increase in blood pressure can also lead to more blood flow into your gums, which your tongue can pick up on—especially if you have gum disease, Laubmeier adds.

In colder months, there’s a little something different going on: If your nose, throat, or mouth is especially dry from breathing in the icy air, the tissue in these areas can become irritated and even cracked, which releases small amounts of blood onto your taste buds.

For the most part, if you only taste metal every once in a while and you’re in otherwise good health, it shouldn’t be cause for alarm, Laubmeier assures. Also of note: If you notice the metallic taste outside of just a workout, you could be looking at a cracked filling, he adds.

But mostly, please don't gnaw on any kettlebells.