212. How Much Cardio Do You Really Need? Zone 2, VO2 Max, HIIT, and the Minimum Effective Dose (Training Series, Part 3)

0:00 Welcome to Medicine Redefined. I'm Dr. Ultima Sharajah. And I'm Dr. Darsha. Let's put the hell back in healthcare. If you're a high performer who wants a clear plan for longevity, performance, and staying active with fewer setbacks, and you want to work with me directly, you can book at refininghealthrx.com. All right, let's jump in. All right, back here with another module talking about building our holistic exercise program. That word is cringe. Holistic? You know what? You don't like it? I went into osteopathic school because I used to love that word. And I think now it's one of those words that has been really muddied.

0:43 Don't you think? It's true. It has been muddied. I don't know. It's funny because one of the nurses just, today, she was like, my whole adult life, I've been seeing DOs because you guys are holistic. So it's just one of those things. It's appropriate. But because it's misused so much. And language is such a funny thing that way. I mean, maybe it is. Okay. Maybe we can say all encompassing. Comprehensive. Comprehensive. I like comprehensive. No, I'm kidding. We'll use holistic. It's 80 still. We'll use holistic. All right. Love it. All right. We're going to do a holistic, comprehensive overview and break out each component. So today we're doing cardiology. Sorry, guys. Sorry. Cardio.

1:23 Wow. There we go. That's where my mind's at right now. Just because I sent a text out about cardiology right now. Cardio. It will be cardiology. Yeah. It'll be cardiorespiratory fitness. I think that's a crucial point. So last would be a talk a lot about strength and hypertrophy. And when we're looking at some of the key components in the order that we looked at the overview, strength, hypertrophy, and the next question that people are always asking is like, how do I make sure... Engine is working with a lot of capacity, right? So B02 max is something that people got really excited about looking at the data. maybe a little bit more attention has been paid to VO2 max, or at least on my social media feed, I have some theories why people get so excited about VO2 max and don't pay attention to strength.

2:08 But I think really ultimately this comes down to which lens we're looking at this longevity problem from, as I said before. So maybe we'll start with the floor, right? So this, when I went back and I'm always looking at to see like what the ACSM, what the CDC guidelines are. For most things, the guidelines are... the floor and say, that's not enough. That's not enough when you look at the literature. And again, it's kind of the case with this, but it's actually better than when it comes to strength and other things. So the CDC recommends at least 150 minutes of moderate aerobic activity per week or 75 minutes of vigorous. I think I said last episode I said, or the first episode I said, moderate to vigorous, but really it's 75 minutes of vigorous activity.

2:48 exercise, plus strength training two or more days. What they do say is some activity is better than no activity and more brings additional benefit. So here's something that I posted about in August. And this came... Like I think I get this weekly updates on MSK and in 2026, earlier this year, you had Lang and colleagues. They followed about 17,000 folks from the UK Biobank study and for nearly eight years. And what they did was they measured activity for these folks on a wrist device and they estimated their fitness with baseline fitness was measured on like a bicycle, a cycle ergometer. to see where they were at. And they wanted to see how many people were meeting that 150-minute guideline and how many people were going well beyond that.

3:31 Some folks were going all the way up to 610 minutes of aerobic activity, moderate to viracid activity per week. What they found was that meeting 150 minutes a week gave about 8% to 9% lower cardiovascular risk. So that's pretty awesome. But they modeled some of that reduction of about 30% benefit when you get all the way up to 560 to 610 minutes a week. But only about 12% of those people were there. Now, what was interesting about this, man, was that your levels of baseline fitness really shifted the dose. That 150-minute benefit held at every fitness level, no matter if you're low levels of fitness, high levels of fitness, but the least fit people needed 30 to 50 minutes more a week than the fittest to reach the same level of benefit from cardiovascular.

4:21 Say that one more time. The people with the least amount of fitness needed 30 to 50 minutes more moderate to a vigorous activity per week to get that same outcome, same cardiovascular risk reduction. Any thoughts on to why that might be the case? Lower floor, right? I mean, if we're looking at like aerobic capacity zone two, I don't know if it's maybe just when you look at that pyramid, right? We talked about building that base. That would be my hypothesis is they kind of just need a raise that floor a little bit higher, but I don't know. Yeah, I think so. I think that, yes, what you're trying to say. So like, here's what we know.

5:01 It's like a correlation causation or chicken egg situation. So what I didn't talk about in this post on social media, and I didn't have space for it. It's like they also ran a genetic analysis in this, right? And what they wanted to see is like people who had genetically higher fitness levels They were the ones who were linked to lower heart failure risk, reduced cardiovascular. So it's again, it's cardiorespiratory fitness, whether it's just genetically you're more fit, right? You picked your parents wisely, or it's because you've acquired that levels of fitness over time, it's protective against all cause mortality, right? Not a shocker for people. So unfortunately, not a lot of people have the luxury of picking their parents, but what do we have under control, right?

5:42 Now, here's another one. So now we're looking at all cause mortality. So we're looking at the most important, right? So we're looking at death. And this is a 2026 paper that I came across where they looked at nearly 600,000 U.S. adults Potter and colleagues is the paper in the show notes. And they counted each a vigorous minute as two and found that just five minutes a week was associated with about 13% lower mortality compared with none. So the biggest gap here is going from nothing to something, just five minutes, dude, five minutes of intense activity, right? At 115 minutes, which is the CDC guideline that we talked about. you're getting to about 19% lower all-cause mortality. At 300 minutes, it's about 24%.

6:24 At 600 minutes, it's about 26%. So there's this plateau that you continue getting benefits. Again, there's going to be a standard deviation of this, right? But- right, you're continuing getting. So the most benefit you're going to get is from nothing to something. Like, I think that's the biggest take-home point for this. A 2022 paper on my research pretty much came across the same thing. Far less people when they looked at that. But I thought that's what was the coolest thing about this is like just the amount, the minimum effective dose to get some is so low. That bar is so low, yet there's still a lot of people who are just not achieving this. How do we define mild, moderate, vigorous exercise that heart rate-based exercise? Yeah. Yeah. Most of the time it's going to be about like where you're getting.

7:04 I know a lot of time people when they're looking at zone two, they're talking about, okay, well, can you have a conversational pace and stuff? We're going to come back to zone two, but typically it's going to be heart rate based. Like anytime you're above 70%, you're probably in that vigorous 75% or higher, you're going to be in that vigorous. Moderate intensity exercise is going to be, again, this is your absolute maximal heart rate. which for simplicity reason, there are a lot of different variables out there. I would do 220 minus your age. That's kind of the simplest way to get that. I forget who, I think this is the Phil Maffetone had talked about this. They said, if you're on some type of chronic medications, just reduce, you do 220 minus your age, then maybe reduce 10 beats per minute. If you're on top of have chronic illness or chronic medications as well.

7:47 So like you can just do that. It doesn't always, because you could be on some type of chronic medication from primary prevention standpoint, which is what you and I are at this point, right? And I don't know how that comes into that. So I haven't gotten a chance to ask him these follow-up questions, but I think that's one way to look at it. But I think 220 minus your age, if you've done a VO2 max, you will know what your max heart rate is. Also trainable. Also, you can, something you can push. I think moderate would be somewhere between, I would probably say about 40 to 70% of your max heart rate. How do you, when you're tracking, because you do a lot of this steady stuff, you talk about zone two, you're doing your threshold running. How do you track where you are, how hard you're pushing?

8:28 I use the Morpheus heart rate strap. So I use that for all my strength training and then as well as... Which it doesn't. So it's good because, you know, it's Joel Jameson's company. But when you do the strength training, it doesn't actually record it. You're just using it as data so it can affect your HRV the next day. But for anything I log as cardio or mixed cardio strength, it will log it for me. But that in itself will test out my max heart rate and then based off that, give me the percentages and then tell me what my dose should be for that week. Yeah. And then, sorry, the percentage, is it the same percentage that we were just talking about in terms of where you are? So zone two would be like 60. You're talking about the heart rate or you're talking about how much of each getting per week? According to your heart rate.

9:09 60% zone two. And then it'll be like 61 to probably 80 for like zone three, four. And then zone five will probably be like 80, 85 plus. Yeah. And it goes in different colors, right? It's like blue, green, and red. And Lunaban will do the same thing. Okay, okay, okay. Yeah, I haven't used that in a while. But I do, yeah, I do like that as well. Sometimes when I'm on an Airdyne bike and it's charged, I'll throw that thing on. One thing that's worth mentioning is even in... Fellowship training, we had talked a lot about this. I had the privilege of working with a really awesome sport cardiologist who was a really avid cyclist. And so we were talking about a lot of this data that James O'Keefe had talked about. This scary J-curve that people would think that we would have is like at higher levels of training, actually, it would be more detrimental.

9:57 Really, in the general population and in most active individuals, it's kind of been debunked, right? So for those who don't know, you quickly use J-curve of aerobic exercise. It just basically says, so the numbers that I had talked about all the way up to 600 minutes, you're getting benefit. For most people, that actually turns up being the case. I think what was scary was that in younger athletes below the age of 55, there was a slightly higher incidence of AFib. So atrial fibrillation, the initial study was this 2015 flawed paper that looked at 40 athletes and two of them ended up dying. But the confidence interval was really low, so it really didn't mean much. But a more recent meta-analysis in 2021 where I think Newman and colleagues had looked at that, okay, yes, about 2.5 times higher odds of AFib.

10:41 What was interesting was that There's this Venn diagram, right? So you have people who are highly fit, who are training at high levels. And then most of these are actually men and they're training in sports like soccer more than pure endurance sports. But then you also have these folks in the other sides of the Venn diagram, which have some type of coronary artery calcification. So they have a significant calcium score. And maybe they're not checking. And so when that Venn diagram overlaps, if you can think about it, there are going to be people in there who are going to have some calcium, some atherosclerosis, and are also going to be training at really high levels. So that's, I think, some of where that comes from, that you want to be aware of that. Does that kind of make sense? Yeah, because I definitely heard that too. Most marathon runners, they've been training their whole life.

11:22 They're going to develop AFib. And then that's where that scariness comes from. Am I doing too much aerobic training to eventually get that way? Yeah. Yeah. So when it comes to just the biggest things that the concern about the J curve for death that I think that I talked about, really, there's really no J curve in the big data. But for AFib, there's a real signal at the far end. So I think that those are two things that people want to look at from an arrhythmia perspective. Yes, I'm concerned about, but I think just globally, most people who are choosing most actually most people aren't choosing between training three to 600 minutes. I don't think that's a problem that we're seeing, even at the high level. you're training for really high levels. You might be, it might be 300 minutes and stuff if you include all your high rocks training. So I think this is really elite athletes who are maybe some more marathon runners.

12:04 We can talk about that. And so you really have to kind of figure out what the dose is yours. But I think the take-home point is there. It's like going from nothing to something is you're going to have the biggest effect, the biggest positive effect anyway. All right, which brings me to zone two because you had sent this message as well. I have a question for you. Why do you do a zone two? So I wonder, for me, I guess it's twofold. One, if I'm looking to improve that BO2 max and just... my stability and stamina throughout, that would be one reason too, right? When you're looking at that floor, being able to sustain a heart rate for that long, whether it's 20 minutes plus. The second, if you're looking at it physiologically, when it comes to mitochondrial density, biologically speaking, when you look at longevity, people talk about how zone two helps with that type of system efficiency from a fat burning, right?

12:55 Metabolism perspective compared to when you're at zone three and above where you're using more of those carbohydrates as fuel. That's kind of why. I have heard the same. And this is the part that when my reading of literature and when I talk to my exercise physiology colleagues on this, I'm not really sure that's actually the case. Right. So while researching this, right, there's a 20-25 paper by Storch-Schirke and colleagues. We talked about the current evidence that did not support zone 2 as the optimal intensity for improving mitochondrial or fat burning capacity. Higher intensities produce larger improvements in VO2 max. And the authors tell us that people who skip hard work in favor of zone two, they're actually probably limiting their benefits of exercise.

13:37 I think this is one of those things that has been said on enough podcasts and social media. And we've talked about how to measure zone two. And look, zone two is important. I like it. I think probably from a performance-based standpoint and when it comes to athletes, it's probably more of a recovery-based tool and probably more for something, again, when you're building it hours and hours. So you already are training seven, eight, nine, ten hours a week. And you're thinking about, well, where else am I going to add volume? Instead of adding junk volume, you're going to add in zone two because it's going to be helping build recovery. Right. If you again, we know this when we look at the literature of how exercise helps from a mental health perspective, helps improve your sleep quality.

14:18 Well, yes, all exercise is going to do that. But if you're already training 10 hours of high intensity and you need to add in more of that aerobic efficiency. Zone two may be a good place to do that without exceeding that recovery capacity like we talked about the last episode. Right. And so that's a good place to add it. This is not most people. These are not the people you're seeing in clinic, dude. It's not the people that I'm seeing. Absolutely not. And so I think this infatuation of zone two has probably gotten a little bit out of hand. And if you think about it, you actually pay attention to those who are talking a lot about zone two, the importance zone two. They have a really strong background from being aerobic athletes and endurance athletes. I don't think Usain Bolt is doing a lot of zone two training.

15:00 And I'm pretty sure his VO2 max is pretty darn good. Maybe not today, but at least when he was. Johan Blake is probably fine with his VO2 max. And I don't think he's doing a lot of zone two stuff. And so that's the other thing. I heard John Barty talk about this a long time ago. When you look at the literature, you dig into that. high intensity interval training, or probably longer intervals is just as good, if not a better way to do that. Which brings me to the other thing that people get really excited about. The Norwegian 4x4. Is this something that you've gotten excited about? You've tried to do? I've done it. I've done it. I'm not like the biggest fan of it. And nor am I of Zone 2.

15:41 So what you just said is kind of music to it. Why are you not a good fan of it? It's just not my type of training. Like, I... Maybe I'll do it, but in terms of running and sprints, right? But then my fatigue is different compared to an airdy bike. If I were to do like sprints, I was just sprinting. How, what would be the interval or the length of the sprint? I'd probably go 30 seconds on, two minutes off, but I'm, yeah. So I think that's the good news. I think there's one takeaway for you. Like this is the good news for you. I'm the same way. I think that growing up, played sports. I think it sounds like we played similar. We both ran track, right? And so we were both sprinters in track. And yeah, when we ran 200s, run a bunch of 200s with a one to three work ratio and tell me your VO2 max doesn't improve it.

16:25 Or run 400s and tell me your VO2 max doesn't improve it. But a 400 meter at 60 seconds is pretty slow, right? Yeah, sure. Like even if you run it like 80% or whatever, like you're going to run 65, 70 seconds. Yeah, run three 400s and tell me your VO2 max doesn't improve after that. So I think that when we look at that, the Norwegian 4x4, what is it? So this, again, it's a lot of the group out of the same lab where you do four hard minutes. You're getting anywhere between 85 to 95% of your max heart rate. And then you have three easy minutes of a cool down. And then you go for another four intervals. So it's four by four, not four minutes of work, four minutes of rest. It's four minutes of work, three minutes of rest. And you're doing four total intervals.

17:05 And there are a bunch of trials on this, again, pretty much out of the same group where they looked at that, hey, this has been really beneficial, but it's not the only thing that looked at this, right? And so, or when we look at, again, like I talked about, so my aerodynamic sprints are actually 30 minutes, 30 seconds, excuse me, on, and I'll do 60 seconds off. So it's a one to two work to rest ratio. Now I'm doing a two minutes warmup. I'll do maybe six to eight sessions of really hard on that. And then I'll do a two-minute cool down. The entire workout takes me about 15 minutes on and off the bike, right? And I can do that pretty quickly. I don't have to have an extended warm-up because I'm done bike. I can really go hard with low risk of injury.

17:47 If you're on a treadmill or something, you might need to do a little bit more time. Stuff that you're doing, you might need to spend a little bit more time. So you really have to think about that. Now, in an ideal world, I would probably want to stress that out. When I was digging into my program and your program against this, it turns out probably what we could if we were thinking about ideal for us, turns out that probably work or at least the intervals for work. two minutes or maybe a little bit longer than two minutes seems to be probably better if stretching out the view to max is your main goal. But yeah, the four by four, again, it's another thing that's really pushing you towards that mile and mile repeats.

18:30 And I'm not sure that's the best way to do that. But from an efficiency standpoint, it's really hard. And not to mention 85% or 90% sustained at four minutes. I don't know. Like this is one of those things. Like if you love getting into the cold bath in the morning, by all means, go to the Norwegian four by four. Like you are the person to do that. Right. But like sitting in a cold bath for four minutes on, four minutes off like type of situation. Yeah. Then this, you're the type of person. But most people that I'm seeing in clinic that I think we're just working across, even elite level athletes, that's a level of intensity that they just, they're not able to sustain. Your elite cyclists, yeah. When you have that much lactate buildup, that's something that they like.

19:13 But most people don't, especially if you're a power anaerobic type athlete, like somebody like you, somebody like me. I think that's my issue with it is that when you're going four minutes, it's hard to gauge like how much you should push in that first 30 seconds and then minute and then do you back off. But the way my heart rate's dropping into it, but like it's hard to actually gauge in those four minutes how much intensity you need. And then again, you add in, let's say those allostatic load of the next time you're training for it and you're like, wait, why is my heart rate so high when I'm not? So I just feel like there's too much variability within the four minutes, which is why I like to condense it because it's 30 seconds treadmill or not. I can, I know what I have to do in that. I know what miles per hour I can run at. and just get after it that way and still get my heart rate jacked up.

19:53 Yeah. The other thing is like with these specific protocols, when they actually looked at that, a lot of these studies, they actually had multiple sessions per week. So this, I think, paper that I came to the small 2007 trial with Helger Ed and colleagues, they had three sessions a week for eight weeks, which raised VO2 max by 7%. in that group, but then the other control group, but I think that it may be 15 seconds on, 15 seconds off. It was like 5.9%, right? So it's not that significant in the interval group that they had, if I'm remembering the data correctly. Not all we'll plug. So again, it's not that impressive of protocols. So really, again, it comes back to anything is going to be better than nothing. That's going to be your biggest leap. And then find something that allows you to be consistent and come back to that.

20:36 And you're going to build towards that. So I think that was like the biggest takeaway. Because I used to think, I'm like, oh, man, how do I? I've been hearing a lot about this 4x4. I got to do this 4x4. And then now after... doing a little bit of studying for this in preparation for these episodes, I'm really not interested in that at all. It's something that, again, to go back to James Clear, like in the last episode you had talked about is, what do we say? Yeah, what gets rewarded, gets repeated. And I guess the inverse of that is the more friction you create, the less likely you are to do that, right? So if you absolutely hate the four by four, it's I guess my message for my PSA for people would be is like, if you're listening to a lot of podcasts like us and you're reading and you're watching social media and people are telling you, you got to do this.

21:20 This is the ideal way to do it. That is absolutely false. And please don't get caught into the trap that I did as recently as a couple of months ago. Have you looked into the 12-minute run test for VO2 max? Like you just run the farthest distance you can for 12 minutes and then use that as a proxy to predict your VO2 max if you're not actually getting it officially done? We did that in high school track. I remember that. Yes, we did that. I don't know if you had any thoughts on it because for me, running 12 minutes for this distance, like... Again, I mean, is it true then that the best VO2 or the people with the highest VO2 max are these people who run 800 meters, right? Or a mile and are trushing it versus a sprinter who, again, will not have the type of muscle density or even that type of cardio respiration.

22:05 I don't want to say cardio respiration or fitness, but that type of mechanism or advantage to run two miles in 12 minutes. Like I know I can't run two miles in 12 minutes anymore. But you can run a mile under six minutes, right? Exactly. I haven't in a while, but I probably can. Yeah, but I remember at some point you could run a five something mile, right? So yeah, no, I agree. Look, the reality is, yes, people who are running miles and two miles or distance runners are probably likely to have a better view to max on average than your sprinters. Like that's just because you're training a different system like we talked about. Again, it's like, what game are we playing? Are we playing the game that's get your VO2 maxes high? Because if that's the case, then let's get your VO2 maxes high. This is to go back to my proxy point, right?

22:46 Right. If we're going, if we're in the game of, I want to be a great high rocks athlete, or I want to be a good tennis player, or I want to be a healthy person who is getting a deep life, as Cal Newport would say at 80 years old, then VO2 max is just a, it's a surging. Yeah. So I think that's like the really important point about this. Yeah. I think what's interesting too, when we talk about wearables, a lot of these wearables are now starting to predict VO2 max, which is interesting. Again, not super accurate, but again, just like anything else, if you see a trend. That's probably the most important thing. Yeah. On that note, I actually came across this 2025 validation study by Lam and colleagues where they found the Apple Watch. I'll bring that up. It caught my attention because I was wondering if I'm going to upgrade from my Series 8 to my Series 12, which I could get with Verizon, but decided not to.

23:31 It actually underestimated VO2 max by about six points on average in mostly fit people with errors around 13%. Now, probably whoop. Morpheus and stuff. I don't know what the data around that shows. I know that I think with heart rate straps, probably you're going to get better data than you are going to get with the wrist straps, right? Because wrist straps, it gets a little bit tricky as you're moving your arms and stuff. And that's looking at like just activity and how that's behaving. Yeah. And so probably the closer you can get to your actual heart, you're probably going to get better data in that regard. Well, the way it does it, Apple Watch, they use GPS tracking too. So they're looking at the distance you're traveling and whether there's like elevation and stuff, and then your heart rate during that.

24:11 And then it'll trend it over time based off similar activities. So yeah, that's what I read too, is that in fitter people, it'll underestimate, but in low fitness people, it'll overestimate. So if you're kind of in that middle sweep, but again, I'll use it as a trend if anything. So yeah. That's awesome. The last thing I think it's worth mentioning because this was actually something new to me. This was something that was testable concept on our sports medicine board. So it was like, how do you, as you get people back to running, well, one return to running program from an injury, but also if you are building on your running, right? So we talked about run clubs a couple episodes ago. Maybe you could apply to your high rocks training or maybe the next games that you end up doing.

24:53 The rule that we used to tell people is as you're building volume, you don't want to exceed the 10% threshold. So the classic rule was 10% on total amount of miles. You've heard this too? Well, it turns out the case, that's probably not as important. The newer data points somewhere else. So this 20.5 paper that we came across, friends and colleagues, they looked at 5,200 runners for 18 months. And really what they were looking at is overuse injury, right? That's the number that we're cautioning people against. The overuse injury rates in this study, there rose when a single run was more than 10% longer than the longest run in the previous 30 days. So if you had a small spike, right? So what that means is just to make it more tangible for people, if you went for a five mile run and then the next week you end up going for a eight mile run on your longest run, that's more than that 10% threshold.

25:41 So if you have a small spike, it's about a 64% higher risk for injury. If you double that, go from five to 10 the next week, just because you're like, oh, I'm going to catch up. because I'm going to be able to run less because I'm traveling. So I'm going to do a 10 mile run as opposed to the five mile run, which has been the longest in the last 30 days on my marathon training session or half marathon. Your injury risk goes by about 128%. Interesting. Wow. But last 30 days, no more than 10% of the most miles you've ran. In one single mile. In one session. Yeah, one single session. Yeah. So, I mean, again, this is one study that I came across, but I think this was different than what we had historically thought because we would think, oh, just look at your weekly mileage.

26:21 Yeah. Yeah. And increase that. I think there's probably something to that. We don't completely pivot our practice based off of one thing. I do. I did think that this was injury. This is more of an acute to chronic type of ideas. As you're doing this progressive overload, you need to be aware of not just the cumulative weekly dose, but also just in that one session, how much can your body actually handle? So I think that for me, look, it's cross country season now. We're seeing more injuries and people getting back to that. Seen already a couple of stress injuries as I'm guiding them back to a return to run program. I'm actually hopeful that I'm going to send this to a couple of the physical therapists that we work with, but their return to run program that we're also going to caution to not have that one single bout to exceed too much.

27:03 So yeah, I think that's the biggest takeaway for me from this, the return to running example. No, it's good, man. Because again, down here in Tampa, man, I'll see Strava's of 16 miles on a long run. And then the other days will be like two, three miles, right? Of like short runs. So everyone here, for some reason, has one day of just an extra long run. But no, it's interesting for me too. I mean, again, we have different mechanics. I'm sure you've done long distance. I don't know if you do anything for it. But being a sprinter to running long distance, it's just a whole different ball game. And so me being used to... running, let's say, two, three miles at a zone three, zone four, kind of has the same mechanics to a sprinter. Whereas now if I'm going to go do a 15K, yeah, I'm going to, like, my stride lane is going to be very different once I cross that three-mile mark until now I'm feeling it in different places, trying to compensate and whatnot.

27:48 So, yeah, it's definitely a real thing. Yeah. And it's not even to account for just pre-existing injuries that people have. Most people, certainly in our age cohort, you got some aches and pains. It just happens. And it was... Laughing with my residents the other day, I was like, yeah, I was 37. I was scanning my own medial elbow and he was like, oh, you got some stuff going on. I was like, oh, how old are you? He's like 30. I was like, yeah, wait, seven years. You'll have it. You know, it just happens. It's just, it's just, it's part of life. And especially if you have a lot of mileage that, no pun intended, built up throughout decades of training and running and. just being a crazy person in the gym, you're going to have some aches and pains. So you have to account for these things. So I hope that is digestible for people and we're actually given some actionable data.

28:31 But yeah, I think this one was probably one of my more enjoyable ones because I learned a lot. It's not an area that I consider myself to be really well-versed in the literature, nor do I enjoy doing it. So some validating stuff, some reassuring stuff. The one thing I'll say about to come back to the shorter intervals that we had talked about. Another reason it gets a little bit harder on the things like Morpheus that we use is that heart rate lags much more when you're doing shorter intervals. So for instance, like we both like doing 30 second sprints, right? Or if I'm doing like 20 second absolute airdyne or doing a 20 second treadmill, by the time your heart rate catches up, it's much longer, which is why another, another reason like this is a little bit hard to pick that up.

29:14 And actually when you look at the studies, they actually commented on that caveat as well. So sense makes sense. All right, man, we're chipping away. So Anton, if you're listening, hopefully you are listening to all these episodes one by one. If you're not, I don't know. At least I learned, man. Now I'm like good with vote too. So we'll come back up and we'll pick up speed and power next week. Sounds good, man. Thank you. Thanks for listening to another episode of Medicine Redefined. If you enjoyed this episode, please be sure to check out some of the additional resources in the show notes. Please also check out our social media platforms where you can find more content like this.

29:55 You can follow us on Instagram, Twitter, and TikTok at medredefined. We also want to thank our team for the production of this podcast, specifically Ethan Ju on video, Harita Yaporian on social media, Zanab Lugmani on research, and Saira Khan for newsletter. Oh, and if you want to get similar bite-sized information delivered to your inbox every Sunday, please be sure to sign up for our newsletter. Also, if you enjoy this show, please be sure to subscribe, review, and share with anyone who you think will gain value from this as well. Now, time for the ever-so-important disclaimer. We'll see you next time. This podcast is intended for general public use and is for educational purposes only. It does not constitute the practice of medicine, nor should be construed as medical advice.

30:36 No physician-patient relationship is formed, and anything discussed in this podcast does not represent the views of our employers. We recommend that you seek the guidance of your personal physician regarding any specific health-related issues.