Exercising While Wearing a Mask: Common Misconceptions

Patients ask me questions about their face masks all the time. “Is it okay to exercise while wearing my mask?” “Is breathing my own carbon dioxide dangerous?” “How do you breathe in these things all day?!” “What is the best type of mask to wear?” If you have been pondering these same questions, then let’s clear the air, so to speak!

Is it Okay to Exercise While Wearing a Mask?

The short answer is yes!

Research studies show that wearing a mask while exercising does not significantly affect your heart rate, respiratory rate, blood pressure, oxygen level or time to exhaustion (1).

True, masks make it more difficult to breathe. This is because the mask increases resistance to airflow. You are still able to breathe, but your breathing muscles must work harder.

If you have any chronic lung disease, then you should talk to your doctor before exercising in a mask.

Is Breathing My Own Carbon Dioxide Dangerous?

No. This is a common misconception that people have. Masks do not trap carbon dioxide near your face. And this is why: a molecule of carbon dioxide (CO2) is 0.33 nanometers in diameter(2). A nanometer is one-billionth of a meter or 0.0000000001 meters across! This is so tiny that it’s hard to even comprehend.

Most face masks do not create an air-tight seal, so the carbon dioxide is able to escape out the sides and/or bottom of your face covering. Also, masks have pores in the fabric. The size of these openings varies depending on the material but the pores are all large enough to allow CO2 to escape, even from an N95 mask (3). (Specifically, N95 masks can filter particles up to 0.1-0.3 microns across. A micron is one-millionth of a meter, which is 1,000x bigger than the size of a molecule of CO2.)

On the other hand, a covid-19 virus particle is approximately 100 nanometers across (4), which is roughly 300x larger than a molecule of CO2. Covid-19, however, does not spread by itself. Instead, it attaches to droplets from the respiratory tract. These particles are formed when we talk, cough, or sneeze and are between 20-200 micrometers in size (5).

So, a mask is porous enough to allow tiny molecules of CO2 to escape while at the same time trapping large droplets that may be carrying the covid-19 virus.

How Do You Breathe in These Things All Day?

Honestly, it’s not that bad. After 10 months we healthcare providers are used to it.

What is the Best Type of Mask to Wear?

N95 masks without valves are the most protective against covid-19 for both the person wearing the mask as well as others. This type of mask is most appropriate for people who work in close proximity to covid-19 patients (6).

Cloth and medical grade face masks are also very good at reducing the spread of droplets, up to 80% effective. Look for a cloth face mask with three layers of fabric. The more layers, the better it will block droplets (6).

Bandanas and neck gaiters are not recommended. Although they are better than nothing, bandanas are open at the bottom which can allow droplets to escape. And gaiters are typically only made of one thin layer of fabric which is a poor barrier (6).

No matter what type of mask you choose, it should completely cover your nose and mouth without having any large openings at the sides or bottom. Be sure to wash your mask regularly and replace it when it begins to show signs of wear.

If you have any other questions or concerns about exercise and masks, feel free to ask your physical therapist.



2) https://www.sciencedirect.com/topics/engineering/molecular-diameter

3) Y Qian, K Willeke, SA Grinshpun, J Donnelly, CC Coffey. Performance of N95 respirators: filtration efficiency for airborne microbial and inert particles. Am Ind Hyg Assoc J. 1998 Feb;59(2):128-32. doi.org/10.1080/15428119891010389

4) YM Bar-On, A Flamholz, R Phillips, R Milo. SARS-CoV-2 (COVID-19) by the numbers. eLife. 2020; 9: e57309. Published online 2020 Apr 2. doi: 10.7554/eLife.57309

5) JP Duguid. The size and the duration of air-carriage of respiratory droplets and droplet-nuclei. J Hyg (Lond). 1946 Sep; 44(6): 471–479. doi: 10.1017/s0022172400019288

6) EP Fischer, MC Fischer, D Grass, I Henrion, WS Warren, E Westman. Low-cost measurement of face mask efficacy for filtering expelled droplets during speech. Science Advances  02 Sep 2020:
Vol. 6, no. 36, eabd3083. DOI: 10.1126/sciadv.abd3083