Masks have become more than just something to wear over the nose and mouth. They have become politically divisive, for some a proxy for the freedom of personal choice. Here, we will ignore the politics and focus on the physiology, asking the question, "How do masks work with exercise and do they affect performance?"
We can pull in a couple of areas to answer that question. First, let's set the ground rules. Since masks can range from more restrictive N95 to simple cloth masks, we will have to generalize the results.
We'll start with a little mask history, way back in the halcyon days of 2015. Remember those altitude training masks that became briefly popular? The ones that we all thought looked a little weird when you saw someone running or cycling in one?
Now, of course, at least in San Francisco, seeing someone exercising while wearing a mask is commonplace. A 2016 article in The Journal of Sports Science and Medicine sought to determine if the altitude training mask actually worked. To do that they had 24 moderately trained subjects complete 6 weeks of high-intensity cycle ergometer training. Half wore masks while they trained, half did not. At the end the researchers compared several lung and cardiovascular variables.
While the masks did not improve performance over and above that of the non-mask exercisers--both groups equally improved cardiovascular fitness--the researchers found that the training masks improved lung variables, acting "More like an inspiratory muscle training device than a simulator of altitude." So, if we can extrapolate to our current mask wearing situation, given that masks increase the work of breathing, wearing a mask while exercising might strengthen the muscles associated with breathing.
In another study, this one in the Journal of Strength and Conditioning Research, wearing an altitude training mask did not limit heavy resistance training, including performance on the bench press, squat and a sprint test. The authors did note that anxiety and fatigue was higher when subjects exercised with a mask. Other research in the same journal suggested that wearing an altitude training mask increased the perception of fatigue, decreasing muscular performance.
But while interesting, we aren't wearing altitude training masks to the grocery store or on bike rides. Those masks are designed to make it harder to breathe. Let's look at more recent research. A just published article in Clinical Research in Cardiology looked at exercise and masks, specifically surgical masks and N95 masks, the masks that we are using daily.
Each of the subjects in the study underwent three exercise tests, one with no mask, one with a surgical mask and one with a N95 mask. Well, what they found makes sense if you've ever worn a mask during exercise. Both masks had a negative effect have on power and VO2max, especially the N95 masks, reducing VO2max by 13-percent.
What's more, not surprisingly, the subjects in the study reported that wearing the masks had a significant impact on breathing resistance. Like the altitude training mask, the increased breathing resistance requires the respiratory muscles to work harder. Perhaps most importantly, the more effortful breathing might make the heart work harder as it seeks to compensate for the lung limitations.
The researchers conclude that, "In patients with impaired myocardial function, this compensation may not be possible." Meaning that, in those with more significant heart disease, wearing a more restrictive mask during exercise, like an N95, might put the heart under a greater degree of stress than normal exercise. You might be exercising at 70-percent capacity but your heart is at 90-percent.
Wearing masks is vitally important to stopping the spread of Covid-19, so in no way do the researchers use their conclusions to dissuade anyone from wearing a mask. What we can take from the research is that wearing masks while exercising makes it more effortful and for those with cardiovascular limitations, especially lung or cardiac disease, a cloth or less restrictive mask might be the best choice. If all you have is a N95, keep it on but dial back the effort.
As a footnote, there's been a recent controversy about a face covering many use to exercise, the gaiter or buff. A study out of Duke University, using a novel method of assessing airflow, reported that gaiters actually increased the amount of droplets expelled while talking. However, subsequent research has shown that, while N95s, surgical masks and triple layer fabric masks are superior when it comes to protection, gaiters are effective as face coverings and do not increase the risk to those around you. The follow-up study also noted that a gaiter, when doubled up, blocked 90-of all the particles measured (by comparison, a standard cloth mask blocked 40-percent).
What's compelling is that almost every study cites heightened fatigue or anxiety as common side effects of wearing a mask, something many of us might have experienced first hand. That perception of fatigue, real or imagined, might even signal the body to back off exercise, inhibiting normal levels of performance. In other words, you might not be able to bench press as much, plank for as long or run as fast as usual amount in a mask. That's ok, adjust your exercise expectations and gradually build to a level your brain, heart and lungs can tolerate.
The take home is this--keep wearing masks when exercising near others, but choose a face covering or mask that allows for easier breathing. And, while cumbersome and uncomfortable, there are positives to exercising with a mask. According to the research we can think of masks as a pandemic performance enhancer. A “workout for the lungs” that creates a new training effect, more power to expand and contract the chest cavity and lungs.
Feeling the burn just took on a whole new meaning for 2020. Wear a mask, stop the spread, strengthen your lungs.
