Is It Safe to Train When the Air Is Full of Wildfire Smoke?

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1:0410 ,000, built for however you train. Welcome back to the Barbell Medicine Podcast. I'm Dr. Jordan Weigenbaum, and what you're about to hear is a free preview of the direct line, our monthly Ask Us Anything for our Barbell Medicine Plus subscribers. We had about a dozen questions this month, and we're going to talk about two here. The first one is on training in wildfire smoke. And depending on where you live, that could be a few weeks out of the year where you're exposed to wildfire smoke. And the question is whether the air quality gets bad enough that the workout causes more harm than good.

1:36There's some new data on that, so we're going to talk about it. And the second question is about the effective reps model and the idea that only hard sets count towards your gains. But that doesn't really square with the fractional sets idea. So it goes something like this. If a set only counts when you're within five repetitions of failure, then the triceps contribution in a heavy ventress shouldn't count. But if you're going to count that as a fractional set for the triceps, then a warm-up set should count for the chest. Both of those things can't be true, so we're going to argue about it. And with me, as always, is the second most handsome doctor in North America, Dr.

2:11Austin Baraki. What's going on, man? Again, you're really setting out some ambitious goals for the collective us today to tackle all of these things. Well, you know, I think when I was writing, I tried to write a little something funny, you know, to introduce you because it brings me great pleasure and I only have so many creative outlets. In my head, the way that you answer all of this, you know, how should I rely on the air quality app? What do I think about a steroid taper? What do I think about the effective reps? I don't care. I'm kidding. You probably care about the steroid taper more than any of that.

2:46Yeah, fair enough. All right. Well, let's get into it. Okay. The question is, we're entering into the part of the year where some parts of the country are impacted by wildfire smoke and sometimes for weeks at a time. I understand that exercise reduces health risks and PM 2.5, that's particulate matter 2.5, we'll talk about that, raise health risks. Is there some crossover point above which a workout does net harm from a performance and health point of view? Am I right in saying that the crossover point for lifting and aerobic exercise are different since I usually lift indoors and don't breathe this heavily?

3:20I'm aware of the Taneo paper, but I'm not used to interpreting that sort of literature. I think that makes three of us on this. Now, we do have some expertise in interpreting research and applying it clinically. So, you know, we have a good, I call it a pinball machine of sort of like orientation. You try to find different, those little, I don't know what they're called in the pinball machine on the way down where the ball hits and you're like, oh, that trips me up. I need to figure out if that's legit or not, but we'll see if we can get you an answer here. So we're starting with the PM 2.5. This is any particle in the air smaller than two and a half microns across.

3:56That's small enough to slip past your nose and your throat. So it goes deep into the small airways and into your blood. That's what we think. It's measured by weight, micrograms per cubic meter of air. So on a clean day, that number is usually in the single digits around five, but wildfire smoke can push it up to 100, sometimes past 150. Now, that is different from what's on like the weather app, the AQI or air quality index. It takes the concentration and puts it into a zero to 500 scale. So every different pollutant reads out on one kind of scale. Less than 50 is green, good air. 50 to 100 is yellow, moderate, and above that it gets worse.

4:35Now, these are all 24-hour averages, the green, yellow, orange. So now cast is usually what's used on the phone. That's weighted towards the last few hours. So if like smoke is rolling in, for example, the app can read meaningfully lower than what you're seeing, basically because, again, it's an average. The Taneo paper he talks about, this is from 2016. This has been out, obviously, for 10 years now. Now, this is a modeling paper. So it's a simulation of years of city commuting, not like a heavy smoke day from wildfire. Again, it's mostly city pollutants. Its own authors say that short spikes weren't even modeled here.

5:13So this is more like a framework type paper. They took a curve for how much exercise helps you and a curve for how much particulate matter hurts you. They plugged in some assumed breathing rates for each sort of situation and calculated exposure. They predicted that 90 minutes a day of cycling at 100 micrograms per cubic meter is the tipping point. Now, it's worth knowing that the paper states the number three different ways. The abstract says an hour and a half. The discussion says an hour and 15. And the author's own follow-up review paper says just more than an hour. So 90 minutes is the highest one that they list, but it's hard to feel confident whether it's an hour and a half or it's an hour and 15 or just above an hour.

5:51So effectively, it had to be really like a wildfire kind of exposure for 90 minutes. This is a modeling paper. But again, it's from city particulate matter, which is maybe different. We'll get to that. Austin, before we get to those numbers, what sort of health concerns do you have, generally speaking, when somebody's breathing in air like this? Yeah, so some of the specifics are definitely outside of my realm of expertise, but breathing in particulate matter in general starts to raise concerns in a few different realms. There is some variation depending on the type of particulate matter that is being inhaled.

6:27And so in wildfires, I suspect that it is going to be a bit more of this kind of fine particular matter that is from like, we'll call it organic materials like trees and forests and things like that. That is to be contrasted with inhalation of non-organic types of like compounds from mineral dusts and things like that. So like you might remember from going through med school, you get test questions about like sandblasters and like the types of lung issues that they get. Those are called pneumoconiosis, these kind of fibrosing sort of lung diseases that come from inhaling different types of particles, those sorts of inorganic kind of mineral dusts and things like that.

7:08So here it's a little bit more what I suspect is like organic material, things like that. And so the health concerns that I'm concerned with can be broken down into those affecting people with pre-existing lung disease and or cardiovascular disease. So people who already have baseline COPD or emphysema, chronic bronchitis, asthma, other sorts of lung diseases. Because those are the types of people that I see much more frequently when these types of things happen. Because I end up admitting them to the hospital more often for exacerbations of their COPD and asthma and things like that. Separate from that is what is the impact on them?

7:41that's like a short-term impact on a vulnerable population. The others would be what would be long-term impacts on people who have like healthy lungs at baseline. That is not probably as well characterized. I suspect that there is an increased risk of developing some of these chronic lung diseases. There is certainly, we know from inhaling things like even from cigarette smoke, an increased risk of carcinogenesis and things like that. I suspect that it would take quite a lot of chronic exposure to wildfires to deliver a similar kind of dose, a cumulative dose exposure to increase that risk to a substantial degree.

8:15And then there's almost certainly going to be some cardiovascular risks as well. So those are kind of like the big picture breakdowns that I have is like, what is the nature of the material that is being inhaled? How vulnerable is the person from a pulmonary and a cardiac standpoint? And then what's the cumulative exposure that we're talking about here? Would it be fair to say that most of these like particulate matter inhalation type issues you're worried about are due to some sort of reactivity at the level of the lungs, whether it's like very acute causing like bronchospasm or like just general injury and then inflammation and subsequent decreased function.

8:52Is that really the nature of this at its core? Yeah, I mean, the lungs are essentially exposed to the environment, you know, in the same way that our skin and our GI tract are organs that are essentially wide open to the external environment, our lungs are as well. So it's no coincidence that they are a frequent site of pathology, of infection, of inflammation. There's tons of immune activity happening in the lungs. So you're right that something can very abruptly cause like a reactive, you know, bronchospastic sort of process, but you can also have things like hypersensitivity pneumonitis, basically a massive allergic reaction in the lungs.

9:25We saw this type of thing happen, for example, when like vaping started to get really popular. There was that like, you know, e-cigarette associated, or vaping-induced lung injury and things like that. So inhaling what we'll call foreign substances into the lungs can trigger a variety of responses. And the nature of that response will, again, depend on the host, the person, and their kind of genetic predisposition, their allergic or atopic predisposition, as well as what is the nature of the material that's being inhaled and what is the dose that they're being exposed to. I think that those are all of the different things that might influence what sort of reactive kind of process happens, how abrupt it is versus how chronic it is, the likelihood of developing cancer over very long periods of time and things like that with persistent exposure.

10:08Yeah, yeah, well said. Okay, well, the best evidence we have here is that this, we'll call it dirty air, blunts the benefits of exercise, but we can't really see a point where, or a tipping point where it erases it. And the AQI, air quality index of 80, is where the benefit roughly halves. We just don't have any evidence that exercise ever becomes harmful in a particular environment. So this is a study in BMC Medicine from last year. They took seven separate groups of people already followed for years and then combined them. About a million and a half adults with a median 12 years of follow-up.

10:42Below 25 micrograms a year, which is an AQI of about 80, so basically Los Angeles, hitting the exercise guidelines cut all-cause mortality by about 30%. Above that, in a city worse than LA on average, meeting the same guidelines still helped, but the benefit was roughly cut in half down to around 12 to 15 % in reduction of all-cause mortality. Now the data we have here runs up to a dose of 50 micrograms, which would be an AQI of 137, and it's still protective there. Wildfires are kind of around 100, but obviously it depends on the nature and size and your proximity to the fire, all these things can change.

11:16Still, in all seven groups that were followed, exercise still tracked with living longer, so some benefit. A few caveats. This data set relies heavily on this sort of Taiwanese cohort. There are two big studies there. The other studies didn't really show a separation here, including Hong Kong, which has worse air quality. But still, there's no real drop-off there either. Just really couldn't parse what was going on here. There's another study that modeled six cities, Helsinki, London, Sao Paulo, Warsaw, Beijing, and New Delhi, and asked what happens if active commuters switch to transit or work from home on high pollution days.

11:52The idea is, oh, reduced exposure. or this should probably show a benefit. So they tested it. Restricting these folks didn't lower mortality in a single one of those groups. In Beijing and Delhi, mortality actually went up from the reduced activity. At least that's what the models was intending to show. And again, this is a model. It's mostly about commuting, not training, doing like intervals or anything like that. But it is one of the only studies here that actually asks whether, hey, is it a higher risk to do the exercise versus not? Now he's also right on the lifting here, the breathing rate, which we sometimes call minute ventilation, the total volume of air that you move in and out in a minute, generally is lower with lifting.

12:29So at rest, you exchange about 10 liters per minute, walking's 23, cycling's 43. Researchers, when they have people do lifting, it's closer to walking than cycling. It was a pretty interesting study. What they did is they had people, both healthy individuals and folks with COPD, they had them do sets of 10 with 40 % of their max, leg extension as I recall and then again at 80 % of their max and the breathing like did not increase the effort increased right but their breathing rate and everything else didn't so and I thought it was interesting that they also included COPD's pretty elegant study there because you're like well look if there's a vulnerable population it's going to be somebody with a lung disease I think again a caveat here is that well they didn't look at circuit training and they didn't look at high rep sets and when you do look at that that does start to look more like conditioning, higher, higher, sort of minute ventilation, which is what you would expect.

13:23And again, this is like a single snapshot in time. Nobody's like, okay, well, look, they did this during wildfires and like, what happened? So we don't have really have clinical outcomes there. I suspect that, you know, most people would intuit that indoors is better. And we would agree with that. You have some barriers in place, but during the count, some California wildfires, researchers looked at over a thousand buildings during this time. and even with people being indoors and there's filtering, indoor particulate matter still nearly tripled basically because the outdoor air got so much worse that it still came in.

13:57So where I kind of end up here is that I would favor exercise like the majority of the time. It'd have to be pretty bad outside such that you may be considering like, should we get out of here? Because like things are real bad. Yeah. I suspect the benefit to health would shrink, right? mainly because you're going to get some exposure, but man, that tipping point is still pretty high. For performance, it's actually much easier. I don't think that there's like not doing it is ever going to really help performance unless you were doing too much before. That said, you could also delay it and still be fine.

14:30And it's not a huge deal. Would also favor indoor conditioning whenever possible. And again, most of this stuff is from city related stuff, pollution and wildfire may be different. And there's some evidence there. There's a Scripps study. where they looked at 1.6 million respiratory-based admissions to the hospital. And effectively, in the city, that particulate raised admissions by under 1.5 % per 10 microgram exposure, but wildfire was much more than that potentially, anywhere from 1.3 % up to 10%. So a pretty big range there, and depending on how you interpret that, you could say, oh, wildfire is much worse.

15:08But again, I think it depends on what the size of the fire is, how close you are to it, what's the nature of the birth i mean there's other stuff that we can't even comprehend or think about you know what direction is the wind blowing and how much of it and totally all sorts of things yeah yeah so and uh unfortunately no real updates on the masks here with respect to a wildfire smoke um because somebody asked that in uh that forum reply about six years ago so awesome let's say you got a healthy patient in this situation how are you approaching that that conversation if they're just asking you?

15:41And does that change if they have something like asthma and the sky is orange? Yeah, well, the color of the sky, I wouldn't say, is the predominant feature that would drive my decision-making here, but rather the person's underlying vulnerability and what they're proposing to do. I think that if you're in a situation where there is a significant increase in airborne particulate matter to which you are very vulnerable, susceptible, maybe you or somebody who has a history of, when this has happened in prior years, I have ended up in the hospital with an exacerbation or I have needed to go on prednisone or use my inhaler way more than I typically do just to maintain control or to be able to breathe.

16:18It's like, yeah, those are all things that obviously should modify what you're doing now. And to your point, I would not avoid exercise, but I would strongly favor indoor exercise. And as you mentioned, even being indoors is not foolproof, but that also means that there's like literally no escape in that situation unless you actually escape the area. So your options are like, be inside and don't exercise or be inside and exercise, in which case the being inside and exercise is in my mind more likely to benefit you than staying inside to avoid the particular matter and then not exercising out of fear of some detrimental effect, which is again, most likely outweighed by the benefits in that situation.

16:54So that would be where I would lean for a vulnerable person. Did you have a take there? Yeah. So my take is this, like if this is going to be temporary i think my concern over this almost drops to zero uh both in both ways so like one if it's just a week for example and you're talking about you know three outdoor sessions that are again you're not doing three or four hours at a time like i'm i'm pretty unconcerned right but also if it's a week i'm also unconcerned if you take the week off right because it's like your training load and where the accounting for that sort of kicks in like, oh, we have fully realized all of the potential adaptations from the amount of training that you've done is not over a day, it's not over a week, it's not over two weeks, it's many, many months stacked on top of each other, right?

17:37And so I'm like, look, if you take the week off because there's some concern here, I have minimal concerns about this sort of acute decline in health in response to that or acute decline in performance in response to that. I think what the studies that we've been able to find here are more like, yeah, chronically though, if people stopped exercising because it's so frequent or so pervasive in that environment, that's when you would see a real sort of decline in sort of health and we would intuit probably performance from there. Well, given that we like to try to turn things into contrived disagreement, I'll push back on your pushback here.

18:12And I think it's more so an artifact of the types of folks that we work with the most often. So on your side, doing more in the coaching space with athletes who are more likely to be motivated and engaged in the process. such that if they did happen to take a few days or to take a week off, it is almost a baked-in assumption because they have the same neurological affliction that affects you and I where we can't stop training, that we are guaranteed to come back the following week and get back on the horse. Whereas my experience, much more than coaching these days, working with patients and many patients who have, for example, struggled with various aspects of their health or their weight for long periods of time, for whom taking a week off of exercise for this reason, And whether for the wildfire reason or for some other reason could evolve into two weeks off, four weeks off, six months later, they're like, well, I took this one week off because of the wildfire.

19:03And then I kind of lost momentum. And I, you know, here we are six months or a year later, and I haven't been able to get back to it. And so that's kind of my, would be more my concern. And of course, this just means like, yeah, this stuff should be individualized to the person's situation. And, but that's kind of the perspective that I take and why my initial response was not just, you know, take the week off. It's instead, let's try to find a way to keep you active during the time in a way that's tolerable and doesn't flare up your, you know, if you have any breathing symptoms or intolerance or sensitivity or something like that.

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