Rhonda: When you're measuring, so, uh, the, the, using the zone to, you know, lactate threshold training to kind of measure mitochondrial function. Um, how, so buying the lactate meter Nova diagnostic, Nova biomedical or something like that.

Peter: It's like a yellow purple one.

Rhonda: I got it per your like recommendation, but, uh, for people listening, uh, if they want to, to get one, but also knowing like how, you know, because there's, when you, when you go to like any sort of, if you were to go talk to an exercise physiologist and you say lactate threshold, like they kind of know.

Peter: They're going to push you up. They're going to lactate threshold is a different number.

Rhonda: Right? So this is like lower level. This is lower. So, um, how do people know, like, like let's say they have a Peloton at home and they get on their Peloton and they want to do a zone two test. Okay. Do you, can you somehow use a, you know, percent max rate, a heart rate, sorry, max heart rate, uh, like proxy to kind of know, like,

Peter: yeah, there are lots of different ways to estimate this. And to be clear, like I'm one of the very few people that is checking his lactate every, you know, every day that he's on his bike, which is four days a week for me. And by the way, I'm also doing it while using all the other metrics that I'll explain in a moment, mostly just in an ever never ending quest to just have as much data as possible to understand when is lactate the best predictor? When was RPE the best predictor? When was heart rate the best predictor? When was absolute wattage the best predictor? Like there's a lot of stuff going on here. So first thing I always say to people, namely my patients, when they say, I don't want to get that lactate meter. I don't want to be poking myself in the finger. I'm like, great, don't, you don't have to. There are like other ways that you can pretty much approximate your zone two output. And the only reason I brought up the whole lactate testing is it is the gold standard and it is the most objective way to do this. And therefore, if I'm trying to really understand the impact of say metformin or a statin, that's what I want to do. But let's put that aside for a moment and answer the relevant question, which is, hey, how does someone exercise in this zone? I think the most important tool for virtually anybody is rate of perceived exertion. I think that will almost never let you down. In fact, I would argue that for a really, really out of shape individual, rate of perceived exertion is even better than lactate. And the reason for that is you take somebody who's got, for example, type two diabetes, their resting lactate may already be at two. So in those patients, we actually never use lactate until you get somebody to a certain level of fitness. We only use rate of perceived exertion and we will provide heart rate guidance. So here's two ways to think about it. RPE, rate of perceived exertion, we give people the test, which is the talk test. So when you are in zone two, you should be able to speak to somebody, but it should be uncomfortable and not something you want to do. If you can't speak, you're out of zone two. If it's really, if you can't speak in a full sentence, you're not in zone two anymore. You're, you're, you're North of zone two. If you can speak the way you and I are speaking now, you're, you're not working hard enough. You're too far below it. So there is that sweet spot where if you're on that Peloton and the phone rings and you answer it, the person knows you're exercising and you're going to let them do most of the talking. But if they ask you a question and you have to answer it, you'll, you'll answer it and you can speak in a full sentence, but you're not that comfortable. That's the single most important thing people need to understand about it. As far as what heart rate guidance comes with it, Phil Maffetone uses a test that I think is a pretty good starting place, which is 180 minus your age. Now, the fitter you are, the less relevant that becomes. So I'm 51, so that would put me at one 30, but I can tell you my zone two is above one 30. So if you're fitter, you may add five to 10 to that. I, uh, my, my, I use another app that checks my HRV every single morning and it predicts my zone two as a result of my HRV. And so every day what I'm doing is I'm looking at the heart rate predicted by the app, which can vary by as much as 10 beats per minute based on how much I slept, the quality of my sleep, how sore I am, a subjective measurement of how much I want to train that day and my HRV. So it, it's a, it's called Morpheus. Yeah. Um, so I have no affiliation with or anything like that. So, so basically this morning I got up, my HRV was, I don't even remember, 78 milliseconds, slept seven hours, 15 minutes, good quality sleep, not sore, felt good. So I actually had a pretty high target today. My target today was 141 was the heart rate on a day. That's about as high as it will predict me to be on a, on a day when everything sucks. It might tell me as low as 129. Usually it's about 136, 137, 138 is where it's predicting. And that's generally aligning with where my lactate is, where what that'll generally put me in a lactate about 1.9. Um, and then on top of that, I'm paying attention to the wattage. So I kind of know where to be. But again, for somebody just starting out, RPE is all you need to know, 180 minus your age is good. And then the, if a person is fit enough that they truly know their maximum heart rate, we tell them to start at somewhere between 75 and 80% of that number.

Rhonda: Great recommendations. If so, if a person is specifically trying to do this functional mitochondrial test, how long should they be in that zone 2, before they can measure their lactate?

Peter: We like to see people there for 30 to 45 minutes before we do it. Yeah. So a true, true steady state.