I had a debate with a friend about her exercising with a mask on, so I decided to do a little research. I found some interesting articles on mask wearing while exercising and I’m sharing a few excerpts from those articles.

Is it safe to wear a mask while exercising?

Yes it’s safe to wear a mask while exercising, but considerations should be made. For example, it’s recommended that you perform low- to moderate-intensity exercise rather than vigorous exercise while wearing a mask. This is because of the decreased airflow allowed through the mask which can affect breathing and your ability to properly regulate body temperature.

Remember to try the talk test. As a rule of thumb, a person performing a moderate-intensity aerobic activity can talk, but not sing, during the activity. A person performing vigorous-intensity activity cannot say more than a few words without pausing for a breath.

Who should not use a mask while exercising?

It’s recommended that people with chronic diseases exercise alone at home, under supervision when required, without using a mask. Some of the most common illnesses include chronic obstructive pulmonary disease, asthma, occupational lung diseases, like mesothelioma, and pulmonary hypertension.

What should happen when exercising with a mask on?

In most situations, you should expect to experience an increase in your heart rate while exercising with a mask on. Because of this, people often experience a perceived increased rate of exertion and decreased performance during resistance training and aerobic exercise. This feeling is similar to the physical and psychological effects experienced while training in locations at higher altitudes.
Reference: https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/wearing-a-mask-while-exercising-faq

FACT: People should NOT wear masks while exercising 

People should NOT wear masks when exercising, as masks may reduce the ability to breathe comfortably.

Sweat can make the mask become wet more quickly which makes it difficult to breathe and promotes the growth of microorganisms. The important preventive measure during exercise is to maintain physical distance of at least one meter from others.

Wearing a mask while exercising will feel different.

First, it’s important to recognize that wearing a mask when you exercise will change up how you feel during your workout.

“Wearing a mask makes whatever exercise you’re doing a little bit harder to do,” says Irvin Sulapas, M.D., sports medicine physician and assistant professor of family and community medicine at Baylor College of Medicine. “You may breathe a little bit harder, or feel like you’re not quite getting enough air.”

The reason this happens is simple: Anything that’s covering your nose and mouth will block airflow. Because of this added resistance, you’ll need to inhale and exhale a little bit harder to get air in and out, Cedric X. Bryant, Ph.D., exercise physiologist and president and chief science officer of the American Council on Exercise, tells SELF. You’re still able to get in the air you need—you just need to work a little harder to get it. (The claims that a mask will cut off your oxygen just aren’t true, as SELF reported previously.)

That resistance to airflow also increases your perceived exertion—how hard your workout feels—as well as the cardiovascular demand it requires. That means your heart rate will likely be a little higher than when you do the same exercise at the same intensity without a mask, says Bryant. He notes that during his own workouts, he’s noticed his heart rate is 8 to 10 beats per minute higher when he’s wearing a mask. (If you wear a fitness tracker with heart rate capabilities, you may have noticed a similar pattern.)

A mask can also make your workout more challenging because you feel hotter,  Jennifer C. Richards, Ph.D., assistant professor in the Human Cardiovascular Physiology Laboratory at Colorado State University, tells SELF. “The moisture in your breath tends to get trapped within the cloth and creates a more humid environment around the skin on your face, making it more difficult to stay cool or comfortable during exercise.” That’s especially true the hotter and more humid the weather is.
Reference: https://www.self.com/story/exercising-in-a-mask-outside

If you insist on going to the gym during this pandemic, you should always wear a mask to help slow the spread of the virus.