Really, what I care about more are the outcomes of what I’m doing. And so the proof is in the pudding to me when it comes to, is this working?

What my heart rate does is not a reflection of me compared to you or compared to somebody else. It’s simply a reflection of me.

Welcome to the Strength Changes Everything podcast, where we introduce you to the information, latest research, and tools that will enable you to live a strong, healthy life. On this podcast, we will also answer your questions about strength, health, and wellbeing. I’m Amy Hudson.

I own and operate three exercise coach studios. My co-hosts are Brian Saigon, co-founder and CEO of The Exercise Coach, and Dr. James Fisher, leading researcher in evidence-based strength training. And now for today’s episode.

Welcome back to the podcast. Hey, do you have a heart rate monitor? Do you have an Apple Watch? Do you have a Fitbit or some kind of tracker where you can see your heart rate changes throughout the day. I know that they have grown in popularity and I know that I’ve tried some of these. Dr. Fisher, have you tried any heart rate monitors?

I have, and I wear a Garmin watch, although other heart rate tracking watches are available. And I wear a heart rate monitor when I do most exercises as well. So yes, I do use heart rate.

Yes, yeah, they’re all over the place. I mean, there are so many ways that we can track this now. And so today’s episode though is all about heart rate and what that actually means to us and is that meaningful? Is it a meaningful way to understand the efficacy of the exercise that maybe has raised our heart rate? So really what is heart rate telling us as we see a different heart rate that we have at various times? Should we look at that and are we able to really draw conclusions based on what heart rate we have at a given time about what the activity means in terms of our fitness results and all kinds of other stuff related to this topic. How that reflects our cardiovascular fitness as we age, should we expect a different type of heart rate range, what’s healthy, so all kinds of things.

It’s a deep dive today about the topic of heart rate as it relates to exercise and our fitness outcomes. So I’ve got some rapid fire questions for Dr. Fischer today. Are you ready?

We’re ready.

Let’s dive in.

Okay. So first of all, you know, we already mentioned at the top of this episode that it’s kind of cool to track our heart rate. We can see different times where our heart rate is changing. I just want to know, what does that mean if I see my heart rate go up, what does that mean to me in terms of what I am accomplishing?

Yeah, for, well, I should have said when you said you’ve got some rapid-fire questions is I’ll try and keep them to rapid answers but they’re not going to be very rapid answers. So heart rates are really interesting, really interesting thing to monitor. Effectively what we’re looking at is how we can move oxygen around the body and that’s done by pumping blood around, oxygenated blood, where the oxygen is then transferred into muscle cells and our active muscle. So, you know, everything in our body that’s happening at this level is really about moving oxygen around ourselves and getting rid of carbon dioxide. So, we can of course monitor heart rate and we can monitor at rest or we can monitor it during exercise and I think it can be a really really really useful tool if we track it over time. So for example if I track my resting heart rates overnight then I can see that if it comes down and is progressively going down over the course of say a year that can be indicative of a good fitness level or improving fitness level or if it has sudden spikes it could be indicative of maybe being ill or being a bit sleep-deprived, it could be indicative of stress or dehydration or even lack of sleep or things like that. Now when we come to exercise, heart rate is a little bit different. We typically think about there being heart rate training zones, there being sort of fat burning zones and so forth. The reality is whenever we are exercising below a certain intensity, we’re using fat as our main energy substrate anyway. We’re almost always in a fat burning zone effectively until we go above a certain intensity and then we’re in a carbohydrate or we move to more carbohydrates. It’s not a switch from fats to carbohydrates, it’s predominantly fats or predominantly carbohydrates. But heart rate can certainly be indicative of that to some extent.

Interesting. Okay, so you’re saying that the higher the intensity of the exercise, that means that we shift from a fat burning for energy state to a carbohydrate state, I would have guessed it was the opposite.

It’s kind of been pitched a different way by different organizations, but yeah, as soon as we move into the higher end of our heart rate, we’re certainly in the carbohydrate burning zone. What’s really interesting around all of this is that when we get to the higher end of exercise, it’s not so much about, because of course we do want to have intervals of a very high heart rate. We can’t sustain a very high heart rate and we sort of know that by if we’ve done any interval training or any strength training or so forth. Whereas if we go for a light jog, a moderate steady state jog, our heart rate might be relatively high but not too high. So we might think of that as our fat burning zone. But what’s interesting is it also prompts different hormones as a response and this can almost be the undoing of our exercising in certain heart rate zones. So we have two hormones called ghrelin and leptin and ghrelin is a hunger hormone and leptin is a satiety hormone. What that means is if we have a ghrelin spike or a ghrelin response then it makes us hungry. We simply, we’ve got this intermittent urge to go and fuel our body. If we have a leptin response then we’re effectively saying we don’t need to eat. So if you have a meal you should have a response of that hormone that says you don’t need to eat anymore. The reason this relates to exercise is when we do strength training or interval training our ghrelin doesn’t go up, it doesn’t increase, so we don’t have a hunger response. But when we do moderate or lower intensity steady-state exercise that’s sort of below a certain heart rate zone, we actually have a spike in this hormone. So there’s almost this intention for our body to go and refuel itself and we are constantly fighting that. So if you’ve ever gone for kind of a light run or a swim or a bike ride and felt hungry afterwards, that’s exactly why you might not necessarily even be hungry, or you might not need to refuel or want to refuel the calories you’ve just burned, but your body is telling you that you should.

Holy cow. Okay. So if if weight loss is a goal. For somebody and they go on a light run and they get that hormone secreted telling him to go eat man. Is that going to be counterproductive?

Well, I mean that we’re going to get that hormone response. So it’s counterproductive if they then go and eat. But one of the problems with this is that they are, if they engage in moderate intensity exercise for prolonged durations, then they are almost certainly going to have that hormonal response. So they’ve got to kind of combat that.

So, you know, sometimes it’s hard enough to get yourself out of bed in the morning and go for a run. But imagine somebody’s, you know, finally got the willpower now to kind of go through the process and they’ve set their goals and they’ve got out of bed at 6am and they’ve gone for a 30 minute or 40 minute run and they’ve got home and they feel great for going for a run. But this hormone is now saying, refuel, refuel, refuel. So instead of them having their normal kind of oatmeal for breakfast or whatever they might have normally had, they now feel the urge to have oatmeal and a muffin, or they have an extra glass of orange juice, or they have extra pancakes, because their body is saying, you’re hungry, you should replenish the calories that you’ve had, that you’ve burned.

And with strength training you’re saying that that doesn’t happen as often or at all? Yes with strength training with interval training very very infrequently and we’ve probably both experienced this and know clients that have experienced this. If people don’t finish a strength training workout and feel they should go and eat. They almost you know sometimes when you say to somebody you know you should have a know, you should have a protein bar, you should have a protein shake, or make sure you try to get some protein in the next couple of hours, they almost, the response is almost, oh my gosh, I don’t want the last thing I want to do right now is to go and eat or refuel and that’s because their body simply hasn’t had that response to the exercise that they’ve been doing because in part they’ve had that higher spike in heart rate or that higher spike in the hormone of leptin. Wow, I think that actually just unlocks something for me about my history. I’ve mentioned before on this podcast about before I found the exercise coach I really didn’t know how to effectively exercise. And so I would run, just run for 45 minutes, a few five days a week or so. I was not losing weight and it didn’t make move the needle for me. And I had baby weight. So this is where I had two kids by then.

And I wanted to, that, that was one of my reasons for exercise was weight loss and it wasn’t working. And I’m sure I was hungrier because of that. And looking back, it explains why after I started strength training, I really became leaner, not to mention stronger.

And of course we understand there’s other reasons too with an improved metabolism by adding muscle mass and strength and things like that

It’s all connected, but that really explains that and wow is that important information for people to know? Yeah, so I mean, I don’t know. This is a divergence from the topic of heart rate You know the idea of should we monitor our heart rate during exercise? We absolutely can monitor our heart rate during exercise I think it can be really useful But it’s not the be-all and end-all of a workout and it’s not indicative of the quality of the workout Which is key based on the themes that we’ve discussing in the last few podcasts and the key when you look at heart rate certainly during a strength training workout is that First of all an exercise sets may only be a couple of minutes. So you’ve only got a couple of minutes for your heart rate to actually elevate. Now, for some people, it will take longer than that to truly reach the indicative kind of effort level that they’re working at. Their heart rate simply can’t get high enough. And therefore, they actually have what’s called EPOC, excess post-exercise oxygen consumption, and that means that they feel really out of breath after the workout. And that simply means that their heart rate couldn’t get high enough during the exercise set for their body to move oxygen around well enough, so they’re almost in what’s called an oxygen debt during that exercise set. And people have probably experienced that with multi-joint exercises like chest press or leg press and things like that. But there’s also the amount of muscle mass that’s being used and our posture can really influence our heart rate as well. So for example, I often joke that if I really want to get my heart rate high, for me personally, standing tricep extensions will really jack up my heart rate. We often think of this as being quite a small muscle at the back of the upper arm. It’s not a big muscle. It shouldn’t really have a big heart rate response. But because I’m standing and because my posture is very active in trying to keep my trunk straight and keep my good posture, my shoulders back and down and my back straight and so forth, there’s actually a lot of muscle working during this exercise. So because of that, my heart rate personally for me will always get that bit higher during that. And then for example, I might get on the leg press. So my heart rate will almost seem to come down a little bit. So it’s not truly a representation of even the amount of muscle that’s being used or necessarily the intensity of the exercise, it’s a product of kind of a number of different factors, including those, including the exercise, including the effort level, but also including things like posture, including time under load and so forth.

That’s really interesting. That really helps to explain it. So then talk to us about interval training. Interval training is, you know, in very simple terms, a more intense stimulus, very challenging, followed by an opportunity for your heart rate to drop, so a lighter effort picture like an interval bike.

What should we be looking for and what are the advantages of really like temporarily spiking my heart rate up and then letting it come

back down in an interval type fashion. Yeah, when we get that real high end heart rate, we are working, we’re certainly working in a carbohydrate burning zone, in fact we’re actually working anaerobically, so we’re working typically without oxygen and that’s kind of our body’s energy production methods. We’re also prompting some response of things like lactate dehydrogenase, so that’s an enzyme that helps our body clear blood lactate. So as our body works at these very, very high effort levels, we accumulate blood lactate and that’s thought to cause the kind of burning sensation within our muscles. It’s not necessarily proven that that’s the case but what we we certainly know that that can be the cause for cessation of high intensity exercise. So we’re improving our fitness level and our ability to work at that very high end by improving our ability to produce the enzyme that removes that byproduct of that type of energy production. So we absolutely at certain times want to really push our heart rate into these absolute peaks. We shouldn’t be fearful that my heart rate is nearing 100% of its maximum if we work to something like age-predicted maximum heart rate.

We can absolutely push to our maximum heart rate. We can absolutely push to our maximum heart rate for certain intervals. We can’t sustain it and that’s okay because we’re not meant to be able to sustain it. We need to let it come back down again and then of course we can repeat. So the only thing to be cautious of with interval training is if we’re doing it based on heart rate, then it takes our body a certain amount of time for our heart rate to respond. So the interval has to be long enough. So for example, if I say to you Amy, let’s do 30 seconds at 95% of your maximum heart rate, then is 30 seconds long enough for your heart rate to get to that marker and actually measure it? Or is that marker too high and you won’t quite get there in 30 seconds or in 20 seconds or in 10 seconds?

So sometimes it’s actually almost easier to forget the working to a heart rate and actually just see what happens to our heart rate when we do an all-out maximal effort. So for example, if we get on something like a carol bike or we do interval training, we might do a six or a 10-second sprint. Well, we just give our maximal effort and then we look at what our heart rate was afterwards rather than trying to work to a certain heart rate. So one of the last things I want to ask you about this is resting heart rate. So one of the last things I want to ask you about this is resting heart rate. Is a lower resting heart rate usually indicative of somebody’s fitness? Yeah, typically. So what it is with our resting heart rate is the more efficiently our body can move oxygen around the body into the working muscles and the organs where we need it, then the lower our resting heart rate will become because effectively we’re pumping more blood with each contraction of the heart.

So our stroke volume effectively stays the same, but we can move more oxygen around the body with each heartbeat and we can transfer the oxygen into those muscles more efficiently. So yeah, so our heart rate can come down and a lower resting heart rate is generally indicative of somebody’s cardiovascular or cardiorespiratory fitness. We should be a bit cautious because heart rate will certainly be influenced by caffeine, it will be influenced by stress, it can be influenced by dehydration, illness, lack of sleep as we said, and things like that. Heat, humidity, so these are all things that can impact heart rate. And of course, if they can impact heart rate at rest, they can impact heart rate when we exercise as well. So if we’re in a very humid environment or very hot environment, our heart rate might go higher than the normal. If we are, you know, more sleep deprived and we’ve had caffeine, then our heart rate might go higher than normal and so on. Okay, got it, got it. All right, so then just to wrap up, you know, this episode, what would you say to somebody who is really focused on tracking their heart rate in terms of trying to draw conclusions from the changes they see in their heart rate about their fitness?

Yeah, so the first thing is when we first start tracking anything, we’ve got to remember it’s just a snapshot.

It’s a, it’s a real, it’s just a moment in time.

And we like to have data. We like to have feedback. We often compare it to other people and we really shouldn’t. Um, what my heart rate does is not, is not a reflection of me compared to you or compared to somebody else is simply a reflection of me compared to you or compared to somebody else is simply a reflection of me. So I’m not trying to be better than somebody else I’m only trying to be better than I was on the previous day. And of course that’s where data is really only meaningful when we have over a long enough time span. So for example I can look at my resting heart rate and typically my resting heart rate overnight will drop to low 40s in beats per minute. And I know that because I’ve worn a heart rate monitor overnight for multiple years so I’ve seen the kind of trend in that way. So I have that long term data.

If I buy a brand new heart rate monitor and I put it on overnight and it says I have a heart rate of 48, well there’s a natural variation in different monitors anyway. So that doesn’t suddenly mean that I’m unwell, it just might be a different heart rate monitor giving me a different reading for one. But it’s also important to sort of recognize that once we’ve got that long term data we can start to see trends.

So if I wear a heart rate monitor for a month and I can see my resting heart rate and I can see that it’s starting to come down, that’s great. If I go to a workout and I can look at my heart rate after the workout and I can say, oh, hey, my heart rate spiked at, I don’t know, 90% of my max today and prior to that I’d only got to 85% of my max. Then that’s a good thing. That shows that you’re working hard.

It shows that your, your effort level or your heart rate certainly is, is getting more elevated and that’s sort of matching your effort level and so forth. But it’s really about looking at trends over time. And I, and I personally think that it’s looking at heart rate after the fact, not looking at heart rate during the event.

Yeah. If anyone out there is kind of like me, I mean, when I think about exercise, I really think about it as a means to an end. So there are sort of like inputs that we have, like time spent exercising or, uh, you know, amount of steps I took or how frequently I exercise. And that’s one thing, right?

That’s sort of like what I’m doing. But really what I care about more are the outcomes of what I’m doing, you know? And so the proof is in the pudding to me when it comes to, is this working? When it comes to the changes that I feel. And we talked about that in a previous episode. When you ask yourself if your exercise is working, ask yourself why are you exercising?

What are your goals with it? Are those goals happening? And if not, you might need to try something different, right, in order to achieve those outcomes. But that really, really helps me understand. Do you have any other closing thoughts on this topic or anything we didn’t mention about this that you want us to know?

Oh, I think it’s an interesting topic, so happy to discuss it.

Awesome. Thank you, Dr. Fisher. We will see you next time. Hope you remember, strength changes everything. Thanks for listening. If you enjoyed today’s episode, please share it with a friend. You can submit a question or connect with the show at strengthchangeseverything.com. Join us next week for another episode and be sure to follow the show on Apple Podcasts, YouTube, or wherever you get your podcasts so that you never miss another episode.

YouTube, or wherever you get your podcasts so that you never miss another episode. Here’s to you and your best health.