Some people think working out in a mask is dumb or even harmful. Even some professionals, like the doctor in this post on Twitter/X tell people not to wear masks. But what if breathing through a mask while exercising isn’t just harmless, it’s actually training your lungs and makes you stronger? In a study at the University of Wisconsin, researchers randomly assigned some people to exercise while wearing this mask.

The Mask Designed to Make Breathing Harder

If you’re scared about the idea that masks might damage the respiratory system, then you should be scared of this mask! When companies make pollution masks, they want to make them as breathable as possible.

But the company behind this “Elevation Training Mask” tried to make this mask as restrictive as possible. Why would they do that? They say it mimics the benefits of high-altitude training.

But that’s what the company says. Companies say lots of things. So researchers in Wisconsin decided to put it to the test.

Can Exercising With a Mask Improve Your Fitness?

They got college students to train on a stationary bike for six weeks. During that training, the scientists randomly assigned some students to wear the mask and some not.

When they were wearing the mask, their bodies had to work harder. One challenge their bodies faced was that they had roughly 3% less oxygen in their blood.

But that extra challenge seemed to help. After six weeks, the mask group scored higher on a measure of cardiovascular fitness called VO2 max (although the difference was not statistically significant).

But the biggest effect of the mask was on people’s lungs. Here’s how it works.

When we exercise hard, we breathe more so that we can take in more oxygen. But after a while, our breathing changes. Soon, lactic acid starts building up so fast that we start breathing harder not to take in oxygen, but mostly to get rid of carbon dioxide.

Scientists call that tipping point between oxygen and carbon dioxide the ventilatory threshold. Couch potatoes will reach that threshold real quick. But athletes can go much longer before hitting the threshold.

On those stationary bikes, the mask group held out longer before reaching that ventilatory threshold. Or in dummy terms, the mask made people better at breathing.