Should You Wear Masks While Exercising?
By: Jonathan Adrian
Tags: Sports, Coronavirus, Exercise, Health, Life

By virtue of pure logic, the argument for wearing masks while exercising makes complete reasonable sense. Up to this point, most public health experts agree that the holy grail of Covid-19 prevention consists of physical distancing, avoiding crowds, and wearing masks when you leave home. Since most modern exercise regimens include activities in close quarters and public spaces, the safest bet to minimise transmission risk, even during exercise, is to don a mask. But is this reasonable logic?

In June, the World Health Organization released an official statement in an attempt to address this issue. Now embedded within the Mythbusters page on their website, the organisation advises NOT wearing masks when exercising, lest they “reduce the ability to breathe comfortably”.

We all know that oxygen is absolutely necessary for exercise, especially strenuous exercises like HIITs, long-distance running, and uphill cycling. Oxygen is required for aerobic respiration, which produces energy-storage molecules called ATP that are expended during physical exertion.

Masks give your body the illusion of hypoxia, or lack of oxygen, similar to what one will experience when they’re training in altitude, where oxygen availability is naturally low.

While the average healthy person can compensate for this oxygen decrease, it may be dangerous for people with preexisting health conditions, such as obesity and atherosclerosis.

Atherosclerosis is a condition in which a person’s blood vessels are clogged, usually by a lipid plaque that forms from years of constant exposure to risk factors, one of which is obesity.

When blood vessels of the heart are obstructed, blood flow to the organ is reduced, which can become fatal when a particular activity, such as exercise, induces a sharp and sudden increase in oxygen demand.

Science journalist Lindsey Bottoms, who wrote a similar article on the topic of masks during exercising, enrolled herself in an exercise test to measure the fraction of oxygen in inspired air while running on a treadmill (a) with a minimally occluding fencing mask, and (b) with a surgical mask.

Lindsey, who is a fencer, ran 10kph on the treadmill for 3 minutes to emulate the intensity of a fencing bout. With her fencing mask on, the oxygen concentration she breathed in was 19.5%, down from 21%, which is the normal oxygen fraction at sea level. While using a face mask, she breathed in just 17% of oxygen, a steep drop from 21% — equaling exercise at 1,500m above the sea level.

A lower fraction of inspired oxygen often drags blood oxygen concentration down with it, and this could trigger complications from atherosclerosis to manifest. When the tissues supplied by these obstructed vessels are deprived of oxygen for a prolonged period of time — especially during moments of increased demand — an ischemic event could occur. In the heart, this is commonly known as a heart attack. In the brain, a stroke.

What’s worse is that people don’t usually realise they have atherosclerosis until their first cardiac event, which often follows after a specific triggering incident. Classically, the trigger takes the form of emotional stress or physical exertion, which causes a sudden increase in metabolic demand and puts the system into temporary overload.

This momentary breach in the supply-demand equilibrium is sometimes all it takes to induce a devastating event.

A freshly published paper in Elsevier similarly advocated against the use of masks during exercise. Exercising with customised tight face-masks induces a hypercapnic hypoxia environment, which occurs as a direct result of inadequate O2-CO2 exchange in the lungs. This can lead to a dangerous build up of CO2 in the blood and subsequent acidosis, where your blood pH plunges below safe margins.

The problems range from headaches, functional impairment in a slurry of bodily systems, including immune cell motility, muscle metabolism, kidney function, cognition, cardiac perfusion, and an increase in cardiac load and anaerobic respiration.

The net effect of these impairments includes an ironic increase in susceptibility to infection, multi-organ damage, and acute heart failure.

The decrease in resistance to infection is thought to be due to a combination of carbon dioxide induced immune system down-regulation, and the mechanical limitation of such masks, which WHO claims can trap sweat, providing mechanical resistance for oxygen entry and promoting the growth of microorganisms.

But if the benefits of exercising without a mask on make mask-less exercise seem like the unanimous winner in this contention, the environmental context makes this advice seem less clear-cut. After all, there will always be circumstances that make the case for mask-less exercise less convincing.

While the spacious outdoors provide a safe environment to practice WHO’s advice, the crammed indoor space of gyms and fitness studios provides a persistent threat for viral spread to occur between individuals. In this context, the case for mask-less exercise is still a topic of hot debate.

Lead researcher Baskaran Chandrasekaran advises that social exercises perform low to moderate-intensity exercise, rather than vigorous exercise when they are wearing face masks. He also recommends people with known chronic disease to exercise in solitude at home, under adequate supervision, and without the use of masks.

The jury is still out for mask-wearing during exercise. Even if a safe inter-individual distance protocol is instituted, the risk from fomite spread (from the communal handles of gym equipment and water dispensers) is still not fully mitigated.

For now, it’s probably best to steer clear from crowded indoor areas when it comes to exercise. Baskaran underlines that social distancing and self-isolation appear to be better than wearing face-masks while exercising during this global crisis. So if you do find ample space outside that isn’t too crowded to plot an exercise course, then, by all means, ditch the mask.