What Your HRV Numbers Actually Mean (Resonance Theory) | Ep 288
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Confused about what those HRV numbers mean on your wearable device? Or if they even matter?
Learn how Resonance Theory, the same science behind musical instruments and bridge collapses, reveals why focusing only on heart rate variability (HRV) numbers misses the bigger picture of what's happening in your body.
Main Takeaways:
Your absolute HRV number matters less than changes from your baseline
3 key factors affect your baseline HRV
Daily factors like sleep, alcohol, and stress can push you away from baseline
Looking for patterns over 2-3 weeks is more valuable than daily numbers
Understanding your body's natural frequencies helps optimize training and recovery
Episode Mentioned:
Interview with Dr. Peter Martone [Episode ###]
Timestamps:
2:01 - What is resonance theory?
4:08 - Interpreting HRV numbers and using data effectively
10:43 - Tips to improve HRV
Remember, to submit your question for a future episode, go to witsandweights.com/question and you'll get a personal reply from me plus a shoutout on the show!
What Your HRV Numbers Really Mean and How to Use Them to Improve Recovery
Heart Rate Variability (HRV) is one of those health metrics that pops up on your fitness tracker, but what does it actually tell you? You might see numbers jump from 25 to 65 overnight and hear that “higher is better,” but is that really true?
In this article, we break down what HRV really measures, why the absolute number doesn’t matter as much as trends, and how resonance theory explains your body’s natural rhythms. By the end of this article, you’ll know exactly how to use HRV to optimize your training, recovery, and overall well-being.
What Is HRV and Why Should You Care?
HRV measures the small variations in time between your heartbeats. Unlike a steady drumbeat, your heart isn’t perfectly rhythmic—it adapts to what’s happening inside and outside your body.
A higher HRV generally means your body is in a more relaxed, adaptive state (parasympathetic nervous system is dominant). A lower HRV suggests higher stress, fatigue, or poor recovery (sympathetic nervous system is dominant).
But here’s the key: HRV is highly individual. What’s low for one person might be completely normal for another. Instead of focusing on an arbitrary “good” number, the real value comes from tracking your personal trends over time.
Resonance Theory and Why Your Body Functions Like a Tuning Fork
To really understand HRV, let’s talk about resonance theory.
In engineering, resonance happens when something vibrates at its natural frequency. Think about a tuning fork that hums at a precise pitch or a child swinging higher when pushed at the right timing.
Your body operates on natural rhythms, too:
Your heart rate beats around 60 times per minute at rest.
Your breathing rate is about 12-20 breaths per minute.
Your sleep cycles follow a predictable pattern.
When these systems sync up, your body operates at peak efficiency. But when stress, poor sleep, overtraining, or bad nutrition throw things out of sync, HRV takes a hit.
What Your HRV Numbers Actually Mean
HRV scores range from below 20 to over 200 milliseconds, and here’s what really affects them:
1. Age
HRV tends to decrease with age, but it’s not just about getting older. The bigger factor is lifestyle—lower muscle mass, less movement, and more stress cause the decline, not just aging itself.
2. Fitness Level
Better cardiovascular health usually means a higher HRV, but you don’t need to run marathons to improve it. Strength training, walking, and general movement all contribute to a well-functioning nervous system.
3. Genetics
Some people are just wired to have higher HRV than others. That’s why your personal baseline matters more than any universal standard.
How to Interpret HRV Trends
Instead of obsessing over daily changes, look for patterns over weeks and months.
A sudden drop (20% or more) – You might be under-recovered due to poor sleep, alcohol, stress, or a tough workout.
A consistent downward trend – Overtraining or chronic stress could be wearing you down. Time to reassess training volume or lifestyle factors.
A gradual increase – Your recovery habits are working, and you’re adapting well to training.
Extreme daily swings – Your body’s rhythms might be out of sync due to inconsistent sleep, erratic training, or stress.
HRV is best tracked overnight with wearables like the Oura Ring, Whoop, or Garmin since that’s when external variables (movement, food, etc.) don’t interfere as much.
How to Use HRV to Optimize Training and Recovery
Breathe Your Way to a Better HRV
Deep breathing exercises like box breathing (inhale 4 sec, hold 4 sec, exhale 4 sec, hold 4 sec) can help regulate HRV by calming your nervous system. The key is slow, controlled breaths—around 6 breaths per minute tends to match the body's natural rhythm.
Train Smarter, Not Just Harder
HRV trends can help guide training intensity, but don’t let them dictate every session. Instead, use them as one piece of the recovery puzzle. If HRV is tanking consistently, it’s worth adjusting your volume, sleep, or stress management.
Sleep and Nutrition Matter More Than You Think
Poor sleep wrecks HRV. Alcohol, late meals, and inconsistent bedtimes disrupt your body’s natural rhythms, leading to lower HRV and worse recovery. If you want a stable, higher HRV, sleep should be your number one priority.
The Bottom Line
HRV is a useful tool, but it’s just that—a tool.
Instead of chasing a higher number, focus on creating balance in your body through sleep, strength training, daily movement, and stress management. Use HRV to guide recovery adjustments, but don’t overthink it.
By understanding resonance theory and tracking your HRV trends over time, you can make smarter training and recovery decisions to keep your body performing at its best.
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Transcript
Philip Pape: 0:01
you've seen those HRV numbers pop up on your fitness tracker or aura ring 25 one day, 65 the next. Maybe you've heard higher is better, but you're wondering what the numbers really mean for your health and performance. Today I am getting into why HRV metrics only tell half the story. Using a principle called resonance theory the same science that explains why bridges collapse and musical instruments sing You'll discover how your body's natural rhythms affect everything from stress to recovery. By the end of this episode, you'll understand not just what your HRV numbers mean, but how to actually use them to optimize your training, sleep and overall well-being.
Philip Pape: 0:52
Welcome to Wits and Weights, the show that helps you build a strong, healthy physique using evidence, engineering and efficiency. I'm your host, Philip Pape, and today we're uncovering what heart rate variability, or HRV, really tells us about our bodies by looking at the science of resonance. I want to give a special shout out to Aubrey in our Wits and Weights Physique University, who asked a question related to HRV and she said quote I am not clear on what good, normal, bad numbers might be for HRV. So not only will we answer that question today, but you'll learn why focusing solely on those numbers might be for HRV. So not only will we answer that question today, but you'll learn why focusing solely on those numbers might be missing the bigger picture of what's happening in your body. Before we dig into HRV and resonance theory, I want to let you know that if you have questions like Aubrey did, and you're not already in one of our communities and you want to have a topic covered on the show, you can head over to witsandweightscom slash question witsandweightscom slash question link in the show notes as well, where you can submit your question to me. You'll get a personal reply. I will answer your question, usually within a couple days max, and then you'll get featured on a future episode and I'll even give you a shout out if you prefer.
Philip Pape: 2:01
All right, so I want to start with a concept of resonance as the background and in the world of engineering, resonance occurs when a system vibrates at its natural frequency. Now, every physical object has a natural frequency. That's the rate at which it wants to oscillate when it's disturbed. So if you strike a tuning fork and then it vibrates at its specific frequency, it's going to create a pure musical note, right? People can use that to tune instruments, for example, If you're pushing a child on a swing at just the right timing and then they go higher and higher. This harmonious timing creates what we call resonance. The opposite happens when frequencies clash right, A marching army is going to break step when they cross a bridge because their synchronized footsteps could match the bridge's natural frequency and cause it to collapse. I don't know if you knew that this isn't just theoretical. It actually happened to the Broughton Suspension Bridge. I think I'd say it pronounced Broughton Broughton in 1831, when 74 soldiers marched across it. Broughton Broughton in 1831, when 74 soldiers marched across it. And you may know the famous Tacoma Bridge that tore apart as well. Kind of an example of frequencies gone wrong.
Philip Pape: 3:13
And this is where it gets interesting when it comes to health and fitness. Your body operates on natural frequencies as well. Your heart beats around 60 times a minute at rest. These are averages, okay. You breathe about 12 to 20 times a minute. These are not random numbers. They are your body's natural oscillations, and when these systems are synchronized, they create what engineers would call constructive interference, which means it amplifies their effects. When they're fighting each other, you get destructive interference, and so this is why HRV numbers alone like let's be honest just about any metric by itself isn't going to tell the full story. If you have an HRV of 50, it might be fantastic for you but very concerning for someone else, and so it's not about hitting a magic number right. In this case at least, it's about how well your body systems are resonating together.
Philip Pape: 4:08
So I want to address Aubrey's question directly about interpreting HRV numbers. I don't want to remain theoretical here. For you guys, your HRV can range anywhere from below 20 to over 200 milliseconds. The crucial thing here that I've already alluded to is that these numbers are highly individual. I have clients with average HRVs in the 30s who are incredibly fit, and others with numbers in the hundreds who might struggle with recovery. So think of HRV kind of like your body's check engine light as opposed to your speedometer right, the absolute number matters less than how it changes from your baseline. So when you understand something like resonance theory, this makes sense. Just like the tuning fork has its specific frequency, your body has its natural rhythm. So three key things affect this natural rhythm your baseline HRV.
Philip Pape: 5:02
The first one is age. Hrv generally decreases as you get older. Okay, and like many things when it comes to age, my big caveat here is a lot of things that happen as we age are actually tied to other variables like a loss of muscle mass, a loss of fitness, lower activity, higher stress, and we need to make sure to separate the two. But generally, if you live the average typical american's lifestyle, which is fairly sedentary not at all what we are going for here a lot of these things will just simply get worse with age. But we're trying to defy age, aren't we anyway? That's age. The second of the three is your fitness level, so it usually increases with cardiovascular fitness. Okay, and remember, cardiovascular fitness isn't just from cardio. In fact, it's predominantly because you are generally active, you walk a lot, you move and you lift weights. It's not just because you are a runner or endurance athlete. In fact, for many people like that, they actually have issues with stress.
Philip Pape: 6:00
Keeping that in mind, Number three is your genetics, and that's kind of your starting point, and that's why the absolute number isn't as important as you seeing your trend over time and then making the changes to nudge it in the direction you want. Now, daily factors can then push you away from your baseline and this is where it's kind of a chicken and egg. It's like do you want to react to the HRV or do you simply want to recognize that what you do is going to affect your HRV and change your behaviors? I mean, I would argue they all work together, but just keeping that in mind, poor sleep is the first one, and big one, that is going to knock your systems out of sync and going to cause your HIV to drop. Alcohol huge disruptor to your natural frequency, Anybody who has an aura ring. If you eat too late or you have too much alcohol, you're going to see your HRV be worse the next day or overnight. High stress that creates dissonance in your autonomic nervous system and then even things like room temperature can affect how well these resonate together. It's why we talk about having a really calm, dark, cool environment for sleep.
Philip Pape: 7:04
So if you want to actually use the information because I know a lot of you you see it and you're like okay, that's great, what do I do? Instead of chasing just a higher number, which was the chicken and egg thing I mentioned I want you to look for patterns. Okay, Patterns First. You're going to establish your baseline. So you've got to. You've got to be tracking your HIV somehow with some sort of wearable over about two to three weeks and you notice that many things that we track when it comes to human body. It's like you've got to do it for at least two to three weeks. It just takes time to understand these things. Um, so, two to three weeks of your normal routine, your normal living. You're going to track your HRV during sleep, because that's when external factors are adding noise to the system, adding extra variables.
Philip Pape: 7:44
Hrv during sleep is a really reliable indicator from a day-to-day trend, and then you're going to look for significant deviations, For example, a sudden drop of 20% or more below your baseline. That usually says that you have excessive stress or poor recovery. That's a sudden drop. And do we always have to be worried about that? Eh, I mean, if you know why, if you, if you, if you, you know, got drunk last night, then that could explain it. Or if you had like an extra 2000 calories late at night, right, and you know what causes it again, chicken and egg it's like, okay, I know that happened, move on, Um, but it's good information to know why that the HRV dropped is because your stress level just went up because of what you just did. So it's a good way to correlate those things. That's a sudden drop. Now a consistent downward trend over several weeks. That could indicate, for example, that your training load is too high. Maybe you're overtraining and you're getting fatigued, assuming nothing else is pushing it up like some new source of chronic stress or some anomalous situation like travel. But again, that's why it's good to understand, it's good to take these measurements when you're in your normal routine so that you can isolate variables.
Philip Pape: 8:58
Multiple days of elevated HRV actually could be a good thing. It could indicate that you're adapting really well to training. It could also be that you just improved your sleep, Like I just started using a new pillow sleeping on my back. And I'm monitoring my HRV. It's only been a week. I've seen it go up, I've seen it go down. I don't know if the trend has is is has moved in one direction or not yet, Cause you can't tell just from a few data points, just like can't with scale weight or anything else. And then if, however, if, however, you have large day-to-day swings, so we're talking about huge ups and downs. Okay, and this is different than scale weight, because the scale weight, that's actually pretty normal With HRV it could mean that your body's natural rhythms are being disrupted somehow and that itself, even though it may not deviate to a certain value.
Philip Pape: 9:43
The fact that it's fluctuating so much could be a red flag. So, going back to resonance theory, where this becomes practical, and remember the analogy of pushing the kid on the swing just at the right time, well, you can kind of work with your body's natural frequency to optimize your HRV and if, for those of you who caught my episode with Dr Peter Martoni, he actually talked about the fact that if your HRV is higher and you're adapting well and handling stress well, it also could represent a more distinct gap between your parasympathetic and sympathetic nervous systems. There's a healthy separation and distinction between the two. They're not overlapping and conflicting with each other. So it kind of goes with this whole frequency resonance thing where we don't want them to clash, we want them to actually be more in sync and not interfering with each other. So if you want to optimize your HRV, a lot of this has to do with stress, but it's also recovery and training. It's the things that you're doing in between the recovery.
Philip Pape: 10:43
So, breathing practices you know we'll get talked about a lot, but they're they're actually kind of underrated. I think even just taking 30 or 60 seconds to stop and breathe it could be very helpful. Um, people with anxiety, whether it's chronic or acute bouts of anxiety, find that breathing practices are extremely helpful because it forces you to become mindful and it also makes your body feel safe. It feels like, hey, there's not a threat here, because I'm able to focus on breathing like this. How would that even happen if I was under threat? Therefore, activate the parasympathetic nervous system and relax. And it's like six breaths per minute tends to match your cardiovascular resonant frequency. So there is this theory that breathing in sync with your heart rate can be helpful.
Philip Pape: 11:30
Now, don't overthink it. This could stress you out. Just using a typical like box breathing technique, chances are your heart itself will also match your breathing, so it kind of works that way. There's also your training. So some people are actually using the aura ring data to schedule their workouts when they know the HRV is at or above baseline.
Philip Pape: 11:51
Now the problem, the only problem I have with this one is like, if you wait till the day of and you wake up and you're like, oh, my HRV is good today, Now I'm going to train, I'm not, as I'm not a big fan of that, because I'd rather you have a training schedule that is preplanned and sometimes, when your HRV isn't great. You can still train really well and actually you might need the training to kind of get you out of the funk, so to speak, and help you out. Um, it's just more of the intense training where you might be dealing with things that are exacerbating your existing fatigue. I think it's good to pay attention. And if your HRV is like totally shot because you just like whatever you did last night was not pretty normal routine, I mean yes, then you've got to consider seriously whether it's going to be most effective to train.
Philip Pape: 12:31
But for a lot of people I'll tell you what just going by feel is not always the best indicator of how effectively you're going to train or whether it's good for you. I'm sorry to say so. I usually recommend people just get in the gym, warm up, see how you feel and, you know, modify the lifts if you need to like, if low back fatigue is an issue or whatnot, but don't necessarily let your HRV tell you what to do. And then recovery protocols as well. Hrv is a good indicator of how you're recovering and so if you are pushing or backing off, or you're in fat loss or you're in a gaining phase, it's kind of nice to see the patterns and correlate them with how hard you're pushing and how much you're recovering, you might find that like an extra training day in between your training weeks, like two days off instead of one day off, for example, is exactly what you need to get your HRV to have a much better trend over time. But it's gonna take a while to kind of figure that out.
Philip Pape: 13:29
So I guess my point with this whole episode is to not really overthink HRV and use it as more of a lagging indicator of the stuff you're doing. Maybe it'll give you some surprise insights. A lot of times it's not really surprising why it's lower. But if you're trying to tweak something to improve recovery or your training, adaptation or stress, it's great to have a baseline and then see like three weeks later oh yes, it actually improved. So it is likely that what I did helped me. Again, the only caveat there is if it didn't improve markedly, that doesn't mean it's not beneficial. Whatever you're doing, it could take longer to reveal itself through your HRV, or it may not really reveal itself through your HRV, and that's why I don't want you to put too much stock in this one number.
Philip Pape: 14:15
All right, so tying this all together, this principle of resonance. It doesn't just explain HRV. It actually it reveals why certain practices feel almost magical. All right, so I mentioned box breathing. That is a technique used by Navy SEALs and most people think it works because you're you know, quote unquote calming down. Right, You're calming down, but there's actually a lot more to it. There's science behind it, because when you breathe in for four seconds, you hold for four, out for four and hold for four. You are creating a 12-second cycle and that is five breaths per minute. That is actually remarkably close to the resonant frequency of six breaths per minute I mentioned earlier. So I kind of buried the lead back then.
Philip Pape: 14:59
And then I recall that I had a note on this and wanted to share why that, um, that system, why there could be some uh magic behind this, behind the mathematics of our bodies and our heart rate and our breathing. I mean it's pretty cool, I mean it almost sounds woo, woo, right, but it really is mathematical if you think about it, Um, and then you're literally like tuning your body, like an instrument, bringing your whole system into harmony. And that's why some people do get really great results from breathing work, Um, but others don't, because you, your resonant frequency might not match up with that breathing, and so that is something to think about. In other words, try box breathing and if you can experiment with different numbers of seconds, you may find something that's closer to your resonant frequency. Cool stuff, Whether you buy into it or not, it doesn't hurt to breathe and to relax, guys.
Philip Pape: 15:51
Okay, as we wrap up, I want to recap the key points so you don't forget all this. Okay, HRV, resonance theory. Your absolute HRV number matters far less than how it changes from your baseline. Remember that, Like a tuning fork, your body has natural frequencies that work best when in harmony. If you can understand the patterns through both HRV, through your breathing, through your training, recovery, all of your health practices, it's just one more thing in the toolbox to help you improve and optimize the way you live your life. And then simple practices like the controlled breathing can sometimes help you even find your resonant frequency. Isn't that cool? All right, the beauty of viewing HRV through the lens of this theory, through resonance theory, is it transforms something that just seems like this random, complex number into potentially an intuitive tool. You know, you don't have to obsess over the number, Just learn to work with your body's natural rhythms and then the numbers will follow. All right, If you have questions about today's episode or any other health or fitness or nutrition topic you want me to cover on the show, head over to witsandweightscom slash question.
Philip Pape: 16:56
Witsandweightscom slash question. I'll throw a link in the show notes and then your question might and I'll say might, but almost most certainly will be featured in a future episode. I mean, I need a lot of topics, folks. I never run out of episodes to put topics into. So today we answered Aubrey's question. Yours can be in a future episode. Go to witsandweightscom slash question. All right, until next time, keep using your wits lifting those weights and remember, just like a well-tuned instrument, your body performs best when all systems are in harmony. I'll talk to you next time here on the Wits and Weights Podcast.
