Masks and Exercising
Let’s be blunt – it’s pretty unpleasant running in a mask. The scientific term is “it sucks”. It restricts breathing, it feels uncomfortable and hot, and adds to the challenge of running in a way that isn’t rewarding. However, it’s our reality – as long as covid-19 remains a societal challenge, it’s what we have rightly been asked to do, and so it is what we should do.
There is now growing evidence that masks are an effective tool for reducing the risk of transmission of coronavirus. Indeed, they may be the most effective tool we have when we are in close proximity with other people. A recent review in the prestigious journal Lancet concluded that “Face mask use could result in a large reduction in risk of infection”. Another has found that states in the USA that had a compulsory mask policy had much lower growth rates of the virus than states that did not.
A mask does not replace behaviours like social distancing, ensuring that we keep 2m or more from people, and avoided relatively crowded indoor spaces. You can’t wear the mask and then think you’re protected enough to ignore everything else – it would be like getting in your new car that you know has airbags and saying “That means I don’t need to wear my seatbelt”. Both beats one!
Nor are masks perfect – a lot of people have criticized the use of masks because they don’t eliminate the risk of transmission. This seems particularly stupid to me – if you were dying of thirst, and I offered you half a glass of water, of course you wouldn’t reject it just because the glass isn’t 100% full. If we can achieve reductions in transmission, if not complete elimination, then that is an action worth taking.
But there’s a trade-off. We wear the mask for protection, but we create discomfort. The question is whether it’s “just” discomfort, or whether masks also create health risks? We’ve found ourselves in a situation not of our choosing, but we can try to make the best of that situation and manage the challenges so that we fulfil our responsibility to others by wearing masks, and to ourselves by exercising and enjoying it!
So let’s get scientific about exercise. What are the physiological realities of running while wearing a mask, and how can you bypass some of the major challenges to ensure that the negative impacts are kept to a minimum? Here are some frequently raised concerns.
Isn’t it dangerous to exercise in a mask? It’ll cause hypoxia or carbon dioxide poisoning.
There is, as yet, no evidence that healthy people wearing masks experience health risks. The only consistent finding in research studies is that the perception of effort for any given exercise intensity is higher when wearing a mask than without. This means that if you do your normal run, say 45 minutes at a pace of 5:30 per kilometer, it’ll feel like you’re running 5:10 per kilometer, or you’ll have to run quite a bit slower to achieve the same ‘feeling’.
What happens then is that we assume that our slower pace, or harder effort, means there is a risk or danger or some harmful physiological change, when all data to date suggest only small negative physiological changes associated with masks. What we feel is not necessarily a reflection of any threat to their bodies.
The main source of this health risk concern is that masks starve us of oxygen. That’s not the case – studies on the best quality masks (the N95 type used in the medical world) have found very small, often non-existent differences in how much oxygen makes it into the blood. In another study, masks were designed to massively increase resistance to breathing, and the overall effect on oxygen levels was to reduce them by a very small amount. It was about the equivalent of exercising 10% to 20% harder, which is no danger at all.
The same is true for carbon dioxide. The theory is that the mask will ‘trap’ our expired air between it and our faces, and then we’ll just breathe that expired air in over and over again, basically ‘poisoning’ ourselves with CO2. This is an exaggeration, for many reasons. The main one is that the amount of air we breathe in and out during exercise is enormous compared to the tiny volume of air that a mask might trap. That space, the area that could in theory trap the air, is called the deadspace, and it’s tiny for cloth masks and buffs that most people use during training. Even N95 masks, which have a larger deadspace, have been studied and found to cause trivial, insignificant increases in carbon dioxide.
So on both fronts – CO2 and O2 – masks do not pose a danger to you. That said, I appreciate that when we exercise with a mask, you’ll feel like you’re suffocating, and the effort of running your normal pace will be considerably higher than normal. It’s easy, then to confuse that perception with the physiological reality. The reason for this perception increase is a combination of resistance, heat and moisture. The mask is a physical barrier to breathing – that’s how it works, after all. And so we have to work harder to move air in and out. Then there is a thermal problem – the temperature of that deadspace around our mouths has been measured at over 50oC when exercising in the N95 mask. Add the fact that the air is going to be humid because our expired water vapour, and our faces start to feel very uncomfortable indeed.
So bottom line – if you’re healthy, there’s no major threat to you. It’s all perceptual, because of very small, physiologically insignificant changes that you can tolerate really easily, by simply slowing down a little, and doing sensible things with masks (as described below). That said, there are populations of people for whom masks may well create risks. For instance, people who begin with a breathing challenge, like those with emphysema and asthma, may find that the added resistance to breathing is the straw that breaks the camel’s back. Those with cardiovascular conditions may have the same problem. These populations are vulnerable to begin with, and they’re vulnerable to covid-19 on top of this, and so for them, the better strategy is to completely avoid strenuous exercise in places where other people are training. They can walk, while wearing a mask, because it’s easy and tolerable, or they can train harder in areas with no people, such that they don’t need the mask.
Choosing the right mask
For everyone else, the solution is, somewhat simplistically, avoidance or evasion. You have to side-step the two main sources of discomfort, which we’ve discovered are the physical barrier and the heat. The physical barrier is very much dependent on the quality of the mask, and this creates a trade-off. The N95 masks used by medical professionals are without doubt the most effective and preventing droplet spread, followed by surgical masks, then multi-layer cloth masks, and then buffs. So if you’re after an effective mask for indoor use, in crowded spaces, aim high.
For exercise, because you’re outdoors, where research suggests the risk of transmission is much, much lower than indoors, you can afford to go with a mask that is a little less effective, but which allows easier breathing.
I’ve tried all the possible masks, and I’ve discovered a few principles that might be of use:
- Thinner material is way more comfortable. Buffs are easiest to run with, because they provide a single or double layer of material. Again, remember the trade-off – the thin material is more comfortable, but it’s also less protective. So, if you are running in a crowded area, you might not want to use a buff. If you are in a much less dense area, then it would be appropriate
- Masks with a wire border that goes over the nose are much more pleasant, because they allow for a bit more air flow under the mask, and make it feel more “rigid”. The result is that when you breathe in, the mask won’t “suck itself” onto your mouth, which is a very unpleasant experience indeed
- Speaking of rigidity, the most comfortable masks are more rigid for that same reason – they don’t suck in and blow out with your breathing, and that helps with a sense of fresh air. They also tend to have an outlet of air at the bottom of the mask, under the chin, which feels like ventilation, and would also be safe because any droplets escaping that way are directed downward
- It might be worth running with two masks and replacing the first halfway through the run. The accumulated moisture is part of the challenge, and if you can ‘reset’ at halfway, it makes a huge difference
And then finally, remember that it’s about expectation. I understand that it’s frustrating that you can’t run your normal pace and feel like you normally do. But that’s OK, if you anticipate and accept this, then you can deal with it by either slowing down by 10 seconds per kilometer so that your run still feels like a “7 out of 10” instead of an 8 or 9. Or, you can run the same pace and accept that feeling of higher discomfort. Knowledge empowers you to control your own response to the challenge, so get out there, be socially responsible, and exercise within the boundaries of your own physiology, perception and these peculiar times!