exercise and air pollution

Exercise and Air Pollution: Training and Racing When Air Quality is Poor

Topics Covered In This Episode:

  • How does exercise make your exposure to pollution worse?
  • Health effects vs. performance effects of air pollution.
  • Which pollutants are more harmful to athletes during exercise?
  • How and when to adapt workouts due to poor air quality.
  • Mask or no mask during exercise on days with poor air quality?


Dr. Michael Koehle, MD, PhD, is an Assistant Professor in both the School of Kinesiology and the Division of Sports Medicine in the Department of Family Practice at UBC. His current areas of research include the interaction between exercise and environmental pollution and the effect of altered environments (hypoxia, hyperbaria, hyperthermia).

Show Links:

Twitter: https://twitter.com/mskoehle
Pollution Lab at UBC: https://www.pollutionlab.com/bios/faculty/detail-Koehle.html
Sao Paulo Study: https://www.sciencedirect.com/science/article/abs/pii/S0045653520310109

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Episode Transcription:

Please note that this is an automated transcription and may contain errors. Please refer to the episode audio for clarification.

Corrine Malcolm (00:07):

From the team at CTS. This is the train rate podcast. Our show for endurance athletes who wanna learn how to train more effectively and improve their performance. I’m coach Kern, Malcolm, your host for the running edition of this show, where it’s my job to interview top coaches, scientists, experts, and athletes in the world of running to bring you actionable training tips, you can apply to your training. Make sure you also listen into our cycling edition of the show with my co-host coach, Adam Pulford, which alternates weekly with the running episodes. Now let’s dive into the show and learn how you can train, right?

Corrine Malcolm (00:48):

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Corrine Malcolm (01:46):

My guest today is Dr. Michael Koehle. Dr. Koehle is a researcher, physician, and athlete. He currently works at the university of British Columbia in Vancouver, Canada as a sports medicine doc professor, and as the director of the environmental physiology laboratory, where he studies, how extremes in the environment impact health and athletic performance. Dr. Koehle also the team doctor for athletics, Canada, working closely with the team at the Canadian sports Institute. I wanted to have Dr. Koehle on to tackle questions about health and exercise in and around air pollution. This is an area that Michael is a leading expert in and may a topic that I get asked about most frequently as we deal with different environmental extremes, like wildfire smoke exercising in metropolitan areas and enduring cold winter air temps. Hopefully we answer some of your burning questions here today, and if we missed anything, reach out, we’d love to tackle them in another episode,

Corrine Malcolm (02:36):

Dr. Koehle, welcome to the show.

Dr. Michael Koehle (02:37):

Thank you very much. It’s a pleasure to be here.

Corrine Malcolm (02:40):

Yeah. I’m excited to have you on you are someone that I’ve been thinking about reaching out to for a very long time. Um, the Pacific Northwest has been my home for a long time. I was a grad student up in Vancouver. Um, so I’ve kind of been following your career at UBC for a while now. And from following along with the publications, it sounds like things are been slowly shifting from when I think back in 2017, I spent a night at hotel hypoxia <laugh>. Um, and so I’m wondering for a listening audience who might not be as familiar with your work, if you can tell us a little bit about yourself as a researcher, as a physician, as an athlete, and then the work that you’ve been like that you have been doing in the past, and then what you’re working on kind of right now, actively in the lab.

Dr. Michael Koehle (03:26):

Certainly. Um, yeah, and I think both of us spent a bunch of time in the same lab at SFU. Um, I just did it a long time ago. I finished, I did a postdoc there until I don’t know, stock there until, I dunno, 2008 or something like that. So a while ago. So, um, uh, in terms of my background, so you’re right, I’m a, a physician, I practice sports medicine at, uh, the university of British Columbia. Uh, and I have a clinical practice there and I also take care of, uh, a few professional endurance athletes and I’m also a physician with athletics Canada. So that’s our track and field, uh, national team. And, uh, from a research point of view, uh, most of my research, uh, is environmental physiology. So really the interaction between exercise and the environment. And so in the past, I’ve done a bit of stuff related to heat and maybe a bit related to cold and diving, but, um, most of the work has been related to high altitude, uh, and, um, and now more recently air pollution.

Dr. Michael Koehle (04:33):

And so in terms of the high altitude stuff, that’s where you mentioned hotel hypoxia in, in one of our labs at UBC, we have a altitude chamber, um, with, uh, bunk beds in it. Uh, and, uh, we were doing a lot of research, uh, in the sort of health effects around altitude illness, uh, uh, and acute mountain sickness and high altitude cerebral edema, um, uh, and doing a lot of that in the past. And then a bit more performance work, uh, you’re probably involved in a, or, or you were definitely involved in a study that was looking really at performance at altitude, especially in runners. And, uh, uh, one of the things they were looking at is, you know, how, how does the altitude affect your performance and how does sleeping the night before an event affect your performance? And that was, uh, now, uh, Dr.

Dr. Michael Koehle (05:25):

Eric Carter’s PhD thesis that you’re involved in. Um, but more recently, uh, I’ve moved into more and more air pollution. I guess the first we started researching air pollution and exercise in about 2009, but it’s taken a while to build, um, build our capacity there. And so that hotel hypoxia altitude, the chamber is now also an ozone chamber. And so we can, uh, deliver high levels of ozone air pollution. And actually we were talking about doing a combined study cuz uh, I was just talking to a physiologist who was just down in Dr. Garris, Sanford down in, he was in Flagstaff with athletics, Canada, and finding that some of the athletes were responding a bit to combined ozone and altitude negatively responding. And so that’s something we’ll need to look at too. So environment and exercise and how they interact, I guess, is, is our research

Corrine Malcolm (06:19):

Yeah. Broadly. And that was at a horrible study. I think they woke us up early in the morning and then we had to do two VO, two max tests, like right away. And it was a rude awakening, but, um, very fun to kind of get to be a part of someone else’s, um, PhD work. And Eric is, I don’t know, maybe the, one of the fastest PhDs out there, um, very, very talented athlete and coach in his own. Right as well. Um, I’m, I’m curious a little bit about the kind of the pivot, the environmental stuff I think is so interesting. And I think I know my interest going into grad school was really, you know, was, was spurred by this applied physiology, this athletic performance lens. And then it very rapidly shifted to kind of this yes, this performance lens, but also this broader, the broader health implications of these environmental conditions. And I’m wondering if any of that has kind of, I mean, one it’s funding, right. What, what is getting funded and what is the reality of the world that we’re living in. Um, but I’m wondering if that at all, has, has shaped your lens of research going from some of this performance stuff, but also adding in obviously air pollution. Yes. It does affect, um, exercise and performance, but it’s got very real world health implications as well.

Dr. Michael Koehle (07:33):

Yeah. Yeah, exactly. And, and you mentioned, uh, the funding, uh, issue in that it’s, it’s easy, generally easier to get funded for things that are health related as opposed to performance related, but um, still it’s still possible to do both. And I’m, I’m fortunate to be able to do both. I think, um, moving, even when I was doing altitude stuff, it was mostly health, uh, work in that I did a bit in our, our lab, but I did a lot of the research in Nepal, uh, uh, field work, uh, and Nepal. And that was a bit, uh, I was working there clinically and then I sort of, uh, was working in Ohio to do clinic and that sort of spurred some ideas of, of, of research we could do. And it was, you know, it it’s a bit self-serving and that, that kind of field work is naturally pretty fun too.

Dr. Michael Koehle (08:24):

And so one of the quotations that as a scientist I live by is someone I forget who said it, it certainly wasn’t me is it’s. Um, if you can study a fish in Cleveland study a different fish, um, and, uh, hopefully, uh, your, uh, listeners from Cleveland, won’t be too offended by that. But, uh, it’s just, uh, the, the idea was just that, you know, if you can make your research interesting and take you to interesting places then, um, that’s, that’s, uh, that’ll make things a little more interesting and both clinically and research wise, I I’ve been fortunate to be able to travel a fair bit. And so in Nepal you’re really studying health and, uh, health side of things. And then I guess, uh, my very first PhD student, Dr. Lua Giles, um, it’s very, uh, we actually were working together at SFU Simon Fraser university at the time.

Dr. Michael Koehle (09:23):

And we were really interested in active commuting, right. Uh, cycling or walking to work as sort of all the benefits personally in both both personally, but also environmentally. And, uh, we kept sort of coming back to the question about air pollution and how that affects things. And so I think that was the framework upon which she built her thesis. And, you know, her first question was that she wanted to get to the, to the bottom of was if the air pollution is bad, should you, uh, really take it easy on your bike on the way to work and spend more time in the air pollution, but have lower exercise intensity, or should you get on your bike at hammer? And so that was sort of one of the studies for her thesis and that, that was the beginning of our work in the air pollution area. And that’s been, it’s been, uh, interesting, uh, and, uh, you know, there’s lots and lots more to do.

Corrine Malcolm (10:18):

Yeah. It’s definitely a growing a growing, a growing field of interest. And one that I think I’m really happy is a growing field of interest. And, and part of that, right? You talk, you’ve mentioned like ozone, um, air pollution, but obviously there’s many different kind of types of air pollution. Many of us in the mountain west are too well versed in wildfire smoke, for example, or we get dust storms that blow that blow sand, you know, from, from the desert all the way to Texas or all the way to the mountain slopes in France, um, air quality, like ha there are many, many things that impact air quality. And I’m wondering for our listening audience, how can we differentiate what those types of, I guess, air pollution factors are, or air quality things that would impact air quality, just so that we can kind of wrap our brains around. Okay, what are we talking about when we say ozone, what are we talking about when we say like particulate matter in a way that, you know, makes sense to their in their day to day lives, be it commuting, be it dealing with wildfires, et cetera.

Dr. Michael Koehle (11:17):

Yeah. Yeah. You’re really, uh, wise to bring up that point because air pollution, isn’t one, you know, one single thing. It’s a, it’s like, it’s like a recipe and your air pollution late summer and wildfire season in the mountain west is very different from say air pollution that we had during the Olympics, uh, last August in Japan, right? And every day, every time of day, every location ch the weather, it all changes the air pollution. And it’s sort of to, to understand it. You have to understand the recipe and the recipe for air pollution is basically you mix a bunch of particles, solid and liquid particles add gases, and those solid and liquid particles are many of the things you talked about. So dust, uh, dust coming up off the, the, the roads and the prairies and pollen, and then, uh, soot from carbon particles from wildfire is, is a huge issue, uh, especially in the mountain west and the Pacific Northwest a and then, uh, we also have other particles, heavy metals that come out from internal combustion and liquids, uh, little droplets and how they mix and the various concentrations of each affect their pollution.

Dr. Michael Koehle (12:36):

And that’s just the particle side of things. And then there’s the gas side of things. And so you mentioned ozone, uh, ground level ozone is a, is a common pollutant. Something that we see in hot sunny environments, uh, typically, so, uh, Los Angeles was, was famous for having really high levels of ozone in the past. And Japan has particularly high levels, but, uh, the reason that it’s connected to sunlight and heat is that ozone is a secondary pollutant, meaning that it doesn’t come outta the tailpipe of a car or out of a smoke stack. It’s actually is, um, you, you take, uh, all primary pollutants, like volatile, organic compounds or oxide of nitrogen and products of internal combustion. And then you convert them with ultraviolet light from the sun. Um, and that creates ground level ozone, um, which is one of the, the key gases that make up air pollution. And you talk about the mountain west. It’s interesting. Uh, one of my colleagues, uh, Dr. Nadine BWA dedicated, it always reminds me that in the winter in Utah, there’s high ozone levels

Corrine Malcolm (13:48):

And smog. And same in Chamonix.

Dr. Michael Koehle (13:49):

Yeah. Uh, yeah. Um, and the ozone, the Utah ozone has something to do with, uh, it’s some sort of petrochemical release during the winter coming off. And you’re right. Chamonix has horrible air quality, actually that valley, the valley leading up to Chamonix is apparently the worst in Europe in terms of air quality.

Corrine Malcolm (14:13):

Yeah. It’s like the thermal effect in the winter. It’s super, it’s super fascinating, but I know so many athletes in both those valleys who, you know, they, that’s what they’re stuck with. That’s what they’re dealing with. Every winter, yeah. Outside of salt lake city, like in the Chamonix valley, it’s, it’s not what people I think naturally think of though, when they think of air pollution, you know, I think that they think of the, oh, I’m, I’m running or riding around vehicles, or I live in an industrial or an urban area, or there’s a wildfire, and I can clearly see what’s happening. The wind has blown X, Y or Z part like particulate matter into our air. But I think it it’s important that we visualize all these different factors that can be present in our day to day lives.

Dr. Michael Koehle (14:57):

Yeah. And, and maybe that’s one of the biggest take home messages for your athletes and coaches just know, know your situation, right. Because you think Chamonix, it’s the Alps, right. It’s gotta be gorgeous and perfect. And away from mining, big cities, it’s gotta have low air quality, low air pollution levels. And it’s, it’s absolutely not. There’s a lot of industrial sources there. It’s trapped in the valley. And then there’s the, the tunnel to Italy there and the huge lineup of diesel cars, uh, up above town and through town all the way through there. And so, um, I guess it sort of, don’t take it for granted and same thing with, you know, Colorado it’s most of the time, it’s great, but for several weeks in late summer, every year, more and more frequently, uh, their quality is horrible cuz of the wildfires.

Corrine Malcolm (15:44):

Yeah. And some of these things I feel like are very visible. Like it’s, you can tell when our air quality is poor in a lot of these areas, um, it’s harder. My, my folks live in the Midwest, um, and the wildfires last year, um, I think particularly like in the boundary waters were below it in, in, I think up into Canada were cause like my, my folks in Northern Wisconsin for maybe the first time in my whole existence had horrible air quality in Northern Wisconsin, you know, just south of lake superior. And for them it’s like, they couldn’t tell because they’re in this big treat area versus here I’m in San Francisco right now you can tell when we have poor air quality, you can visibly see it in the air. Versus I feel like sometimes with ozone, you can’t necessarily recognize that it’s always there.

Dr. Michael Koehle (16:29):

Yeah, yeah. Ex exactly. Right. And, and ozone is also in hard to study because, uh, uh, or if you are doing observational studies, because it’s typically with the exception of these, these exceptions, we talked about to say Utah in the winter, it’s typically something we see on really hot, uh, sunny days. And when we talk about exercise performance, our performance is negatively impacted by the heat for everybody, no matter how acclimated you’ already the heat. And so on a hot, hot, sunny day, you, you do a, a race or a time trial or something like that you’re gonna perform poorly. And how much of that is the ozone and how much of it is the heat itself and the humidity. And so, yeah, so it’s a bit of a double whammy that we have to deal with.

Corrine Malcolm (17:18):

Yeah. Hard, hard to parse that. And I cannot imagine how stressful that was for everyone going into Tokyo and going into Beijing, um, where I think air quality was a, a really big worry on everyone’s on everyone’s minds. And now I’m excited to see kind of the papers that come out post Olympics, cause they always do. It’s always the, the research that’s kind of been held by, you know, the Canadian sport Institute or the Australian sport Institute that will slowly be released, um, kind of this like in the past six months and then over this next year. Um, but a question I think that’s interesting is that most of us, when we hear about these, these warnings, these air quality warnings, right? You get the notification that, you know, such and such population should be careful today or careful outside, or, or watch your activity level. And as athletes, most of us are, are very healthy humans. We like to move our bodies. Um, we see that warning and we think, you know, it doesn’t apply to us, but why in particular is exercise, you know, like why is why in particular, does exercise make your exposure worse in, in these, in these scenarios, right. As opposed to being out as a, a normal human out for a walk or, um, going about your day.

Dr. Michael Koehle (18:26):

Yeah. Yeah. And, but that’s in a really important question. And so, uh, exercise by definition, uh, means that your metabolism or your metabolic rate is increased, right? A and so, uh, to undertake work, which is what exercise is you need to, um, increase your, uh, oxygen intake through, uh, increased ventilation. You’re breathing more, and then you need to pump more blood to your exercising muscles. And so your cardiac output is more. And so all your bodily processes are increased manyfold. So sitting during this podcast, talking’m probably breathing, uh, uh, 10, 12 liters a minute, but at maximal exercise, I’m fairly tall. I could be breathing 180 liters a minute, right. And so just by pure dose, uh, could be 15 times the dose, uh, of air pollution coming into my body at that time. And that’s, uh, the other factor that’s really important is during intense exercise, we tend to breathe more during our mouth, through our mouth.

Dr. Michael Koehle (19:34):

Um, and our mouth has no innate filtration, whereas our nose is designed as both a humidifier and a filter. And so it could, uh, scrub out a little bit of the air pollution breathing just through your nose. So, uh, by increasing the dose of pollutants coming in, increasing the metabolic rate and the body’s, uh, the speed of the body’s processes, and then all the oral breathing over nasal breathing, we have many reasons to expect both the dose of air pollution to be higher. And in theory, the, the effects of air pollution to be greater on the body.

Corrine Malcolm (20:11):

Yeah. And we’ll talk, we’ll talk a little bit more about kind of what athletes should be on the lookout for in a little bit, but I guess kind of piggybacking off, you know, that we’re, we are at heightened, like we do have heightened exposure during exercise, particularly intense exercise. And then we’ve talked a little bit about particulate matter versus, you know, ground ozone air pollution. What, what is, is there one that’s worse for us? Is there one that we should be more concerned about when it comes to, you know, making these decisions about, do I run, do I not run? Do I run hard? Do I not run hard? That kind of thing.

Dr. Michael Koehle (20:46):

Yeah. And, and, and I think it’s always good to break it down into health effects and performance effects. Um, and so, uh, because they’re separate and, uh, and especially the health effects of air pollution over the long term are clear, right? Air pollution is, uh, one of the biggest environmental causes of mortality. Uh, it reduces our life expectancy. You live in, uh, an urban environment. If you live in an urban environment, you just have more risk of, uh, lung disease, including cancer, uh, even chronic constructive pulmonary disease compared to living in a low pollution environment your whole life. And so, um, uh, it’s really important to think of air pollution as bad for our health all day and night, uh, and not just during exercise. And so there’s, there’s really concrete, negative health effects of air pollution. Um, and, uh, the performance effects are a bit more nuanced and we’ll get to them a little bit later.

Dr. Michael Koehle (21:52):

So your question Karen was about which pollutant is, is, is, is worse for us. And I, I guess, acutely, uh, uh, during exercise, it seems, uh, that we react more to ozone than to, uh, the other pollutants, uh, the traffic related air pollutants and especially, uh, endurance athletes have symptoms like, uh, they feel the breathing more. So they get that more, more chest discomfort. And then we, when we actually measure their lung function, post exercise, um, with high levels of ozone, you may see a decrease in lung function in ozone that we don’t see say, uh, when we’re doing the particulate studies, we’re using diesel exhaust. People are actually breathing basically, uh, uh, really sciency exhaust from a Honda generator, uh, a diesel Honda generator. That’s what we have them breathe. And so, um, we don’t see, uh, huge acute effects in terms of health or performance from the diesel exhaust, like we would see from ozone. And so I, I, for athletes, especially, um, acutely the, the health effects of ozone are easier to detect. And, uh, there’s a lot of studies that back that up.

Corrine Malcolm (23:13):

Yeah. That’s, that’s super interesting. I think that, you know, I can imagine that it feels like an irritant and we know that irritants when you’re ventilating a lot, don’t feel so good in the lungs. So that makes a lot of sense, translating that from we’ve talked about, um, on the podcast here, before, and in, in a bunch of my writing about like cold, cold exposure in the lungs. And that makes, that makes a lot of sense. So that irritant would not, would not feel great. And you talked a little bit about the research there, and I kind of chuckled because I’m imagining trying to pass all this pass, like an ethics board or an IRB board. And I’m wondering, you know, yes, we do know that the longitudinal, like health effects of living in these environments, right. We know that children that grow up in urban centers are much more likely to have asthma. We know, you know, increased all cause mortality decreased life expectancy, all these things, but from a, so from a performance side, in, in the lab or in the field, I’m just kind of wondering nuts and bolts a little bit. Like how do you examine performance detriments in like, how, like, how does that get set up? And what does that look like as far as, like, how can we critically assess these changes in athletes when we’re either doing, I guess, field studies or like contriving something in the lab setting?

Dr. Michael Koehle (24:26):

Sure. So, uh, so we always have this debate, uh, uh, in terms of how best to assess performance. We typically, uh, I would say, I think every single one of our studies related to air pollution has used cycling as the form of exercise. Um, and it’s just because, uh, it’s, uh, it’s a bit more reproducible than running. And then with the equipment that we’re using measuring the, the gases that you breathe in and out, especially if we’re providing, uh, diesel exhaust or ozone to breathe, it’s just much easier on the bike. Now we always use a double blind design, meaning that the research participants, the athletes, they don’t know what they’re getting on that day, but at the same time, the researchers in the room don’t know either one person will know, you know, just in case something goes, goes wrong, but they’re separated from the analysis.

Dr. Michael Koehle (25:31):

So the actual researchers don’t know. So, um, that way, uh, we’re trying to minimize any, um, almost placebo effect, cuz if, if you’re expecting, uh, to feel worse in the air pollution, you’re gonna feel worse in the air pollution. And we always use a crossover design. So every participant does both the, the clean air and the air pollution, uh, exposure. And they do it in a random order and nobody knows which one’s first. And then when we analyze it, we’re always comparing them to themselves. And so typically it would be something like, um, uh, a time trial, um, and, uh, or we either do a, a time trial or a 30 minutes sort of constant load at, uh, 60% of the power that you can put out at your VO 2 max, which is, um, uh, a reasonably hard effort, uh, over that 30 minute period, pretty close to threshold for most people.

Dr. Michael Koehle (26:37):

Um, and then we look at things like, uh, how you feel, heart rate, oxygen consumption, uh, ventilation, um, and the rating of how good your legs feel, how your lungs feel. Uh, and one big limitation that I think is that the longest study that’s been done looking really at performance was 90 minutes, a 90 minute time trial. And that was done at the university of Sao Paolo in Brazil. And many of your, or most of your athletes probably are doing longer training efforts than 90 minutes, you know, four or five hour bike rides or long runs, uh, for your ultra runners. And there’s, there’s basically no proper research looking at air pollution effects over these long duration, uh, sessions. And so that’s, that’s a huge caveat. And, and that’s one of the sort of, uh, things that we would recommend during, uh, wildfire season or a high pollution about is to really avoid those prolonged workouts, just because that’s just such a high dose of air pollution for such a long time. So I think I rambled a bit there, but, uh, I <laugh>, uh, yeah,

Corrine Malcolm (27:52):

Yeah. And I think it’s like, it’s, you know, we can expect that’s not good for you, but we don’t know to what extent it might not be good for you. Um, which I think is a safe, a safe thing to hedge, right. Like I think it’s, it’s like the, the rest day is probably more important than, um, hosting your lungs so to, so to speak. Um, so in these studies, I think the, the one out of, was it Brazil, did they, they look at critical power. Was there any, like any other, I think they looked at critical power maybe on the bike, just like trying to think of like measurable performance decreases that you’re seeing with that exposure as far as, um, obviously there’s lots of like subjective things. Like how did your lungs feel? How did your legs feel that kind of stuff, but just kind of wondering from the objective lens to what, what we’re seeing change in those environments that would be concerning to a coach or concerning to an athlete that should be considered.

Dr. Michael Koehle (28:44):

Yeah. And so in that Brazilian study that, uh, Dr. ????? lab, they did look at power output. Uh, and one of the great strengths of their study is they use, if you, if you’ve ever been to Sao Paulo, you know, that they have really good high quality air pollution there. And so they used, uh, authentic, uh, downtown Sao Paulo air pollution and pumped it right into the chamber where the athletes were, uh, exercising. And then the control condition was, you know, perfectly filtered, clean air. And so, um, uh, so they did a really nice job there and having that longer duration, 90 minutes is good because all of our studies are only 30 minutes in the future. We really need to go much longer. And we’re designing a as a longer ozone study just to deal with that. Um, so yes, uh, looking at power output, this is why it always becomes a debate is if you do, uh, a time trial and say, Hey, ride 50 kilometers in both conditions, uh, then one of those may be slightly longer, let’s say in the clean air, uh, they do a little bit better and it’s five minutes shorter, or three minutes shorter over 50 kilometers, then there’s other differences, right?

Dr. Michael Koehle (30:03):

You have, uh, they’re breathing for a shorter period of time. The exposure’s shorter, the, the heat effects are different. And so, um, the advantage is you’re comparing power to power, but the disadvantage is the duration slightly off. And so we typically tend to go for a constant duration, uh, and then look at maybe softer athlete outcomes, like oxygen consumption, heart rate, and rating of perceived exertion, so that we can really, uh, get an equal exposure in both, uh, because with that double blind design, uh, it’s amazing how bad people are at telling which day was the air pollution day. And which day was the clean air day. Uh, cuz we use nose plugs on them. Uh, and uh, it’s about as good as flipping a coin so that the blinding is actually good. So it’s worth having them matched for time.

Corrine Malcolm (30:59):

And then you said you, do you look at post post ride lung function? Yeah. Like just like, right, like right away. Or is that staggered at all? As far as like when, when those readings are taken?

Dr. Michael Koehle (31:09):

Well, some of these things take time, so we like to go 90 to, to two hours afterwards. Um, and to just, uh, because the whole thing is another big take home message is exercises are so good for us, right? All your listeners love exercise hopefully. And one of the issues that we have with this research is the effects of exercise, especially intense exercise are so profound on the body, just exercise alone, opens up your airways of your lungs, increases your lung function. Right? And so we want to follow them post exercise until the beneficial effects of exercise have dissipated to see if we can tease out some negative effects of air pollution. And so, um, you know, ideally we’d have them stay in the lab for eight hours afterwards, but you know, some of these studies involve 18 visits by the participants, you know, half of them breathing air pollution. So it’s already asking a lot of them. Uh, so, uh, two hours is, is the longest that we’ve done with this particular study.

Corrine Malcolm (32:13):

Yeah. You have to get them back to their, their undergraduate classes or their real jobs or whatever else they have going on besides being a, a Guinea pig. Um, that makes a lot of sense. Yeah. I, I think sometimes I know this might be, that might have been like a long, a long researchy question for people, but I do think it’s important to understand like where, you know, we, we give recommendations based on research like this, both in the, the health and clinical space and in the athletic space. And I think it’s important for people to understand like what goes into trying to tease out these answers so that we can hopefully make positive change in people’s general health, but also in their athletic performance. So hopefully that’s getting the gears turning for, um, our listeners, I guess, from there. I think the biggest question I get every single year, be it when it’s super cold, be it when it’s wildfire season, whatever it might be.

Corrine Malcolm (33:06):

It’s my phone goes crazy. My email and box goes crazy with athletes saying like, okay, like what AQI is the cutoff? Like when, when am I not supposed to exercise? When am I, when do I need to cut my run short or my bike short, when do I, you know, bust out an N 95 mask? When do I say, you know what, I’m gonna exercise inside or I’m gonna take a rest day. Cause I know that’s, it’s really hard to be opportunistic for a lot of athletes who are not professional athletes, right. They have jobs and kids and, and everything else going on. So it’s hard to, to maybe move that long run to a different day in their week. So is there, I mean, maybe there’s no clear answer here and we’re all just kind of shooting in the dark a little bit when it comes to this, but is there, do you think there are any broad, at least, you know, health and performance recommendations that can be made for athletes who like wildfire seasons around the corner out west? For sure. I mean, it’s already raging in Arizona and New Mexico and Colorado. Um, like what can we tell them when, when the AQI becomes poor and they have to make that decision to move their workout, to cut their workout short, whatever it might be.

Dr. Michael Koehle (34:13):

Yeah. That’s, that’s the million dollar question. And the issue is too, is that when the wildfire season hits it’s two or three weeks sometimes, uh, that you’ve got this low quality. So, uh, you can’t just say rest for two to three weeks, uh, especially cuz you, you do that in middle of July. You know, your, a race is in late August, that’s gonna have, uh, huge impacts. And so, um, we, we try to make a, uh, it’s a, a bit, maybe it’s a bit of a harm reduction model or it’s a bit nuance, but when things are, uh, particularly bad, uh, we orient athletes towards shorter, more intense workouts, uh, because we have shown that, especially with the more part particulate air, uh, air pollution, higher intensity doesn’t lead to more acute health effects and so interesting. Uh, that’s, that’s sort of one in terms of pragmatic things.

Dr. Michael Koehle (35:13):

Number one is time of day is huge. And so, um, there’s, uh, apps, uh, the one that I, uh, have always used, it’s called plume P L U M E it’s a French one, but I think they just got bought by weather underground. So it’s, if you use the weather underground one, I think it’s integrated in there. And the thing about plume is that it uses historical data, a bit of AI and then weather forecast to predict the pollution going forward a day or two forward. And so, um, it’s really helpful even during, uh, a bad wildfire season, the pollution’s gonna vary during the day as the wind changes. Uh, and as time of day and rush hour traffic changes. And you can see when the optimal time of day is to exercise outside, to minimize your risk. And if you can make that work with your other commitments work and family and stuff, uh, that’s helpful.

Dr. Michael Koehle (36:13):

So I guess the, the recommendations that we give are, uh, use these apps or, or websites to, uh, find the training areas that are lower, uh, in air pollution. So here I’m talking to you from Vancouver. Uh, Vancouver is at the, I guess at the mouth of a valley, uh, at the base of some mountains, often the pollution gets trapped up against the mountains. So if you’re gonna go for a training ride, if you go south and along the ocean, you’re gonna have much lower air pollution than if you do some climbing in the mountains. And so you can make it, you can separate yourself from the air pollution or the worst air pollution by distance, and then you can use the forecasting, um, uh, functions of these apps to choose the best time of day. Uh, so those would be the first two things.

Dr. Michael Koehle (37:05):

The third thing would be on the really bad days, uh, prioritize intensity over distance or duration. Uh, and so, uh, that may be some time to work on obviously things like doing, uh, some strength workouts, some indoor get that neglected core and flexibility that you haven’t been doing. Uh, and if you have a good indoor environment, uh, which isn’t a given because, uh, it’s, there’s, uh, a lot of variation in how much of that air pollution gets indoors. If you do have a good indoor environment, then doing, you know, some, some of your workout indoors may be another, uh, suggestion as well. And then the other key one is if you’re in wildfire season, you’re exposed to two to three weeks of bad air, but you’re exposed 24 hours a day. And that air pollution is bad for you 24 hours a day. And so the key is outside of your exercise, you still need to reduce your exposure to, uh, air pollution.

Dr. Michael Koehle (38:08):

And so, um, finding good indoor environments in which to spend time, uh, when you’re not exercising is good. You, you mentioned a mask. So you also mentioned an N 95. And so by design that is designed to reduce 95% of the particles. And so particles are the big, uh, stressor in wildfire season. And so an N 95 is a, is very well fitting N 90 is really effective for that. It’s not realistic to do intense exercise with an N 95. Uh, you’re just not gonna get the volumes in and out. Um, some of them have, uh, an exhaust belt so that you draw in against resistance, but there’s no resistance when you breathe out, but still, I don’t think it’d be comfortable enough to exercise. So if you’re wanting to reduce your exposure with a mask, I would say wear it whenever you’re outside, outside of exercise. And so when we’re working with teams and stuff, we recommend, uh, if they’re in a high pollution environment that they consider wearing masks on the way to, and from training and to, and from competition, especially because they’re often in traffic in addition to the air pollution. So that, so reducing your non-exercise air pollution exposure is helpful as well. It’s bad for us 24 hours a day.

Corrine Malcolm (39:27):

I think that’s a big thing to note is that it is bad for us 24 hours a day. And we all became mask experts over the past two years. So I think it’s, you know, you can say N 95 and people are like, oh, okay. I know, I know what you’re talking about right now. Um, where we wouldn’t have, I think for, for many people, um, two years ago, but as a, as a California resident for the last four years with wildfire season, we, uh, we had our stash of N 95 S pre pandemic and a, and a very powerful air filter and bike trainers for that very reason, knowing that, you know, there was gonna be a, a period of every summer where we might be very, very trapped, um, in our homes, you know? So I think it’s, you kind of have to adjust on the fly and we’re all adjusting to that.

Corrine Malcolm (40:08):

You know, it seems like a, a longer fire season every single year. Um, and then I actually, the, the intensity thing kind of like to, I think that is counterintuitive counterintuitive and like very surprising, but also makes sense because your duration of total exposure would go down, even though your ventilation rate would go up for that kind of finite amount of time. There has to be, is there a limit to that? Or is there a cause I can see some athletes being like, okay, like I’m gonna not do my two hour run, but I’m gonna do, you know, X number of minutes of VO two max intervals. Is there any sort of practical recommendation as far as what what’s reasonable and what’s unreasonable as we talk to an, an ultra running audience who yeah. Are known for going a little above and beyond.

Dr. Michael Koehle (40:52):

Yeah. Fair enough. Uh, so ed, you’re a hundred percent right to say it’s counterintuitive. You know, when we did this study, we were expecting to see big differences between high intensity and low intensity exercise. Uh, what we looked at was a, a 30 minute exposure at, uh, 60% of your power at VO two max. So, uh, for some people, it was tough to finish that, uh, effort and then 30 minutes the same duration at 35%. And so even with the same duration, there was no increase in any of the effects during, uh, the high intensity. And so, uh, in terms of practical advice for your, uh, ultra audience, it’s, it’s still keeping the duration under control. Uh, so I, I really would recommend when the pollution is bad, get into your best environment and be doing sub 60 minute intensity workouts. I think it would be a good rule of thumb.

Corrine Malcolm (41:52):

Yeah. I think that’s something that people can, can reasonably get behind, right? It gives them their dose of endorphins and their dose of moving their body and sweating for the day without, um, without the, you know, the, the bad effects that we’re trying to avoid. Is there anything we’re gonna kind of wind down, I’ve got a couple kind of tangential questions before I let you go, but is there anything else kind of in this vein that you think it’s important for athletes and or coaches to consider as we look ahead to a, a hot warm potentially smoggy wildfire induced summer?

Dr. Michael Koehle (42:26):

Yeah, yeah, maybe, uh, a, a couple little minor tips. It seems that, uh, for the ozone air pollution, a diet high and antioxidants, uh, may help. And so hopefully a lot of your athletes eat quite clean, uh, for performance reasons and are already consuming lots of, sort of, you know, dark, uh, vegetables and blueberries and tart cherries and all that kind of stuff. Uh, but that seems to help at least with the ozone side of things and having enough vitamin C and vitamin E uh, seem to be helpful, uh, for that as well. Uh, often people are looking for a nutritional, uh, input and then probably one, the last other point that’s interesting, especially to, uh, California residences is people that are in a high ozone environment. If they go and compete in a high ozone environment, they do better than people from a low ozone environment.

Dr. Michael Koehle (43:31):

There seems to be for ozone, not for the other pollutants only for ozone. There seems to be a little bit of an adaptation process. It’s not worth, you know, moving to LA or Tokyo just to get O needed, so you’ll do better. Uh, but, um, if you are going to be competing in an area that has high ozone, uh, for your, your, a race, if you do get there a little bit early and do your heat acclimation, uh, at the same time as your ozone acclimation, cuz remember the high temperature high heat environments are also typically the high ozone environments, you may get a bit of, uh, a double benefit heat acclimation and ozone acclimation.

Corrine Malcolm (44:17):

That’s super interesting that, I mean, bodies are incredibly smart and we adapt to things that I would think are impossible, but we keep doing it. So, um, that’s super interesting that there’s this kind of adaptability mechanism at play. I kind of do you, is any inclination as to what, is there a mechanistic cause for that? Or do we have any, do we have any idea why that might be

Dr. Michael Koehle (44:39):

Not, not a clear idea yet? It’s probably has something to do with, you know, scavenging of free radicals or something. Uh, something like that. You know what the one, the one other point to make as we wind down is, uh, asthma is very common for everybody, but it’s more common in endurance athletes, which, uh, so the prevalence of asthma in your, uh, audience and in your clients is gonna be higher than the general population. And, uh, some of these pollutants, especially the ozone seems to irritate asthma more. And when your athletes are often in very remote areas away from, uh, rescue inhalers and that kind of thing, uh, for the asthmatic athletes, I think it’s worthwhile just, um, making sure their asthma is well controlled before their, their workouts and then having their, if they need an inhaler typically, have you have their rescue inhaler with them just to sort of, uh, manage when they’re in an austere remote environment?

Corrine Malcolm (45:42):

Yeah, that’s, that’s super important. There’s all sorts of weird breathing things that happens at these high, dry altitude, a hundred mile races that we don’t quite understand. And they definitely kind of fall into that asthmatic irritant exposure camp that we don’t quite fully, fully understand yet. Um, so we’ll let to keep that in mind. That’s a good note for anyone who does have asthmatic to keep their rescue inhaler on them, on these, on these runs. Um, okay. So to wind down, these are two questions that I’ve been asking everyone this season, um, and they’re kind of nice. They’re a little bit tangential, but I think they kind of round everything out well. And so the first one being, if they’re, I I’d like to know if there’s something that you’ve listened to read or watched, and it can be related to this field, it can be related to your field or just kind of adjacent to athletics in general. That might be something that you’d recommend to our listeners.

Dr. Michael Koehle (46:32):

I just started, uh, watching this, uh, podcast called I think it’s called upside strength. Uh, and, uh, I think that’s what it is. One of my grad students, uh, recommended it and it’s kind of like they’re short and they’re kind of just kind of like sport related thought experiments. Um, the, I think the one thing is about half of them. He does, uh, he’s a, he’s a Swiss French, I think so half of them are in French, but, uh, he does do some of them in, uh, or I think about half of them in English, but they’re just kind of short little thought experiments are related to sport. And, uh, uh, I found them kind of stimulating.

Corrine Malcolm (47:16):

That’s a good reason to have grad students. They always, they’re always listening to something that’s interesting. So upside strength will, will. That’s a good, a good recommendation. I’m gonna add it to my, to my list. And then the last question I’ve been asking everyone is, is there something that, you know, now as an athlete, as a physician, as a researcher, any of those camps, any of those hats that you wish you knew earlier in your career?

Dr. Michael Koehle (47:39):

Oh, geez. <laugh> uh, so much, um, you know, I think probably, yeah, definitely. Uh, I would say, um, I, I, you know, uh, early on, I think I chose to avoid goals because they sounded too hard, you know? Um, and I wanted to be an architect, uh, but it sounded really hard and I wanted to be a veterinarian and I heard it was really hard, so I didn’t kind of pursue that. And, uh, I think, uh, I’ve learned that, you know, what if, if, if you really wanna just put in the work and put in the time and, uh, you’re gonna, if you can, don’t achieve it, you’re certainly gonna learn a lot along the way anyway. And so, you know, I don’t regret that I’m not an architect or something that, but it just kind of, uh, it, things will tend to work out if you stick to it and put in the effort and, uh, work at it long enough.

Corrine Malcolm (48:52):

That’s great. I love that the architecture thing seemed daunting, but an MD PhD, it’s not a big deal.

Dr. Michael Koehle (49:00):

<laugh> I don’t know. I think I gotta get of luck there.

Corrine Malcolm (49:06):

We all, we all find a little bit of luck along the way, but I like that goals goals can be scary, but they make a lot of things worth it. Okay. Truly the last question now, and this one I promise is an easy one. Where can our listeners find you? Is there a best place for, for them to, to look you up? If they’ve got questions, ideas they wanna follow your research.

Dr. Michael Koehle (49:25):

Yeah. So I, you know, I’m crap on socials, but, uh, I am on Twitter at, uh, M S K O E H L E. So, uh, just, uh, my last name. And, uh, so we, we put up some of our studies on there and I guess that’s, uh, that’s probably the best, uh, place to find, uh, find me, I don’t have a good website or anything like that.

Corrine Malcolm (49:54):

That’s okay. Low tech Twitter, Twitter works just fine. Yeah. Even the least active Twitter. Twitter works. Okay. Um, we’re gonna link that in our show notes. So then people can definitely find you if they’ve got questions about pollution and exercise and all of that good environmental physiology stuff. Um, I wanna thank you one more time for joining our podcast today. This was a really fun conversation.

Dr. Michael Koehle (50:14):

Yeah. It was an absolute, a pleasure. Thanks so much and good luck to all your listeners. Hope you have a good season.

Corrine Malcolm (50:20):

Yeah. They’re gonna crush it. Thanks for joining us this week on the train ride podcast,

Corrine Malcolm (50:27):

We hope you enjoyed the show. Make sure to visit our website at www.trainright.com/podcast, where you can find social links and more for our guests. If you’d like to support the show, please subscribe to the podcast, share it with your friends and leave us a rating on iTunes. Thanks again. And we’ll see you next time.


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