Exercise with a mask on can be really good for you, actually

For most of the pandemic, I saw masks as a necessary evil when going out for my daily 5K run. I'd stick it on if someone was coming the other way down the street, of course, and cross over to the other side or run in the road where possible. That's just good manners in the COVID era. But at all other moments my mask was a potential menace. It felt suffocating, and was forever getting sweaty and gross. I took to running with it catching the wind in one hand, almost flying it like a kite to keep it dry.

But that was before I read up on the latest news from the world of breathing and exercise, spurred by James Nestor's groundbreaking book Breath: The New Science of a Lost Art. You can read my full story on that science here, but the TL;DR is that you should always aim to breathe slowly through your nose, even while working out, and that a little bit of extra carbon dioxide actually helps your body absorb more oxygen — a counterintuitive but well-established rule known as the Bohr effect.

In putting those rules into action, my mask suddenly became my best friend. It encouraged nose breathing, because to do otherwise was to risk a mouthful of sweaty cloth. Instead of worrying about suffocating, I was thinking about the extra oxygen molecules being delivered via my hemoglobin thanks to the Bohr effect. More O2 in the muscles means lower levels of lactic acid, the thing that makes our muscles painful when we exercise.

The more I ran in a mask with proper breathing, in other words, the less exhausted my legs felt. My 5K times dropped suddenly, by about 10 minutes on average, and they have stayed there throughout the last couple of months. Now I keep my mask on the whole time, especially as the weather turns cold; the rosy running nose of winter is a thing of the past.

So it was heartening to see my experience replicated in two new studies on masks and workouts this fall, one in the International Journal of Environmental Research and Public Health, the other in the Scandinavian Journal of Medicine & Science in Sports. As noted by the New York Times, both of these studies surprised both sets of researchers, who had all hypothesized that mask-wearing would lead to exhaustion. Carbon dioxide levels were elevated, especially in N95 masks, but no headaches or breathing issues were reported.

Caution is warranted, of course. These two studies used participants who were already healthy and active; the second used men only. They studied cycling, not other forms of activity; the researchers presume it also applies to running and weight training, though we won't know for sure without more masked studies. As with nose breathing and raising your CO2 in general, you should not try to change too much about your workout routine too quickly. Consider it the equivalent of altitude training, because that's basically what it is.

But in a study of studies published in November's Annals of the American Thoracic Society, 10 American and Canadian researchers reviewed all the literature and found "there is no current evidence to support sex-based or age-based differences in the physiological responses to exercise while wearing a facemask." There were no negative effects to muscles, blood flow or the brain detected in any study, except for a small number of people with severe cardiopulmonary disease — folks who really shouldn't be working out without advice from their doctor in any case.

"Wearing a face mask can be uncomfortable," the study's first author, Susan Hopkins of UC San Diego said in a press release. "You may re-inhale warmer, slightly-enriched CO2 air, and if you're exercising, the mask can cause your face to become hot and sweaty. But these are sensory perceptions. They do not impact cardiopulmonary function in healthy people."

I won't exactly be sorry to see the masks go in our brave new vaccine-driven post-COVID world, presuming that aligns with the warmer weather of spring and summer 2021. But until then I will relish the winter warmth and training in better breathing that masks provide. Indeed, my next step on the workout mask front is to buy more and stuff my pockets with them — so I can swap them out when things get a little too sweaty.