The Time-Crunched Cyclist Podcast by CTS

Power vs Heart Rate vs RPE: Which Metric is Best?

• CTS • Season 5 • Episode 249

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OVERVIEW
Power, heart rate, or RPE (rate of perceived exertion or how you feel)? Which data point is best for gauging intensity during training or a race, and which is best for monitoring training progress? Coach Adam Pulford tackles these frequently asked questions in Episode 249 of "The Time-Crunched Cyclist Podcast". Although ALL THREE metrics have their place, Coach Adam reveals the hierarchy for what matters most and what metrics are used for context. 

TOPICS COVERED

  • Power vs Heart Rate vs RPE Hierarchy
  • How to keep HR from drifting up during intervals
  • Why HR might drop during intervals
  • Why prioritize Power first, then RPE, and HR last
  • Training at the top vs bottom of power zones
  • All about Rate of Perceived Effort (RPE)
  • Why three data points are better than one

ASK A QUESTION FOR A FUTURE PODCAST

LINKS/RESOURCES

  • Eston, R., & Connolly, D. (1996).
    Use of Ratings of Perceived Exertion for Exercise Prescription in the Elderly.
    Validates RPE as a tool even without heart rate monitoring.
    Shows strong correlation between RPE and physiological markers like VO2 max and lactate threshold.
  • Faulkner, J., et al. (2008).
    Rating of perceived exertion during isometric and dynamic exercise is influenced by the duration of exercise.
    Indicates how fatigue alters perceived effort.
  • Garcin, M., Fleury, A., & Billat, V. (2002).
    The correlation between RPE and physiological variables (heart rate, lactate) in cycling.
    Found strong correlation between RPE and lactate threshold, especially in trained cyclists.
    Source: International Journal of Sports Medicine.
  • Seiler, S., & Kjerland, G.Ø. (2006).
    Quantifying training intensity distribution in elite endurance athletes: is there evidence for an "optimal" distribution?
    RPE used as a monitoring tool for training load in elite cyclists and runners.
    Source: Scandinavian Journal of Medicine & Science in Sports.
  • González-Alonso J, et al. (1999). Influence of body temperature on the cardiovascular response to exercise. Journal of Applied Physiology, 86(2), 599–605.
    https://doi.org/10.1152/jappl.1999.86.2.599
  • Berntson GG, et al. (1997). Heart rate variability: Origins, methods, and interpretive caveats. Psychophysiology, 34(6), 623–648.
    https://doi.org/10.1111/j.1469-8986.1997.tb02140.x

HOST
Adam Pulford has been a CTS Coach for nearly two decades and holds a B.S. in Exercise Physiology. He's participated in and coached hundreds of athletes for endurance events all around the world.

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Speaker 1:

From the team at CTS. This is the Time Crunch Cyclist podcast, our show dedicated to answering your training questions and providing actionable advice to help you improve your performance even if you're strapped for time. I'm your host, coach Adam Pulford, and I'm one of the over 50 professional coaches who make up the team at CTS. In each episode, I draw on our team's collective knowledge, other coaches and experts in the field to provide you with the practical ways to get the most out of your training and ultimately become the best cyclist that you can be. Now on to our show. Now onto our show. Heart rate versus power which one should you monitor during your training session? Which do you prioritize during a hard training session versus an aerobic ride, and why would your heart rate drift or shift between zones? Or is there something else that we should all be paying attention to? My answers power, it depends, and RPE too. Welcome back Time Crunch fans. I'm your host, coach Adam Pulver, and if you like short, concise answers, that's what this podcast is all about. Today, we'll be answering more audience questions in detail, like the ones above about power and heart rate. Now, heart rate can be tricky, but it's an important metric to monitor during exercise. We need to remember, though, it is much more variable than power, so we need to observe it with that in mind and not get too emotional when it's a little higher or a little lower than normal. Additionally, wattage from your power meter is consistent and accurate day to day, so long as the power meter itself is calibrated and you take care of your equipment and your technology. Finally, rate of perceived effort, or RPE, is by far and away an overlooked key metric that should also be considered when monitoring a training session. So let's read the original question, then I'll recap my answers with a little bit more detail and nuance as it pertains to training zones, and we'll wrap things up with a pretty bow to end the day.

Speaker 1:

So here's the original question coming from an audience member from the show. Hi coach, I recently discovered your podcast and I'm relishing Well, thank you, uh, the the the learning journey. So thank you for sharing your knowledge with us mere mortals. Thank you, uh, yeah, thank you for that. This is Mark. Here's the question.

Speaker 1:

Uh, something that has long perplexed me with zone-based training is whether to prioritize heart rate or power metrics. For instance, I sometimes drift into heart rate zone five whilst executing threshold power intervals and or, conversely, I may drop into tempo power if targeting zone four heart rate. I know power is absolute, but not surely shouldn't ignore heart rate as it factors into my training readiness, slash, recovery state, et cetera. I'd be grateful for any insight that you have to offer. Thanks again and keep up the great work, mark. Yeah, thanks, mark. I really appreciate those kind words. Really good question as well. So here's my answer, again a little bit more unpacked, but in my opinion you want to prioritize power first. Rpe is like a close second, but it's almost like a 1.1, if that's a thing, and then there's heart rate coming in third.

Speaker 1:

The main reason why you want three data points to check yourself and monitor over time is to ensure that you're on the right track. In the words of Dr Steven Seiler, power and pace, heart rate and rate of perceived effort are the holy trinity of monitoring exercise and performance. Now it's normal for your heart rate to drift up a bit into zone five. If you're doing some zone four work and without looking exactly at your data, mark, this usually means you either need to better pace at zone four, you need more training time at zone four, or you might need more volume to have more aerobic capacity to handle the zone four work. Okay, now, that's just if it's drifting up into zone five. Now you also made a nod to maybe my heart rate is drifting down when I'm in zone four and it's like going into tempo and it's a little all over the place. Now I'll get into the reasons as to why that happens. But I think more common is that heart rate drift up into zone five. So I'll kind of address that a little bit more Now.

Speaker 1:

Assuming you have done all the field testing, you have accurate FTP ranges, here's my advice if you don't want to see the heart rate drifting up on that zone five is keep on accumulating more time in zone at zone four and lengthening the intervals out to help you be more durable and kind of have that higher aerobic capacity going. So let's just say I'm making something up here, but you're doing eight minute intervals and you have some drift going on. Extend them out to 10 minutes, then 12 minutes, then 15, then 20, and try to accumulate at least 30 minutes of total work per session. When you're aiming for zone four training Now you can go up to 60 minutes of time in zone as well. What that means is three by 10, three by 12, three by 15, do the math and we're kind of in that 30 to 60 minute window.

Speaker 1:

Generally, with my time crunched athletes, 30 to 45 minutes of time in zone at zone four is about the limit time-wise. But on a weekend you could definitely rattle off a three by 20 as one of your biggest workouts in this threshold set, or threshold block, I should say, with maybe a total ride time of two to two and a half hours of that ride time on the weekend. Now just to throw this in here, mark, sometimes if you see the heart rate kind of drifting down a bit too, it could just be the terrain that you're riding. So if it's an aerobic ride or maybe you chose some interval where you're just not on the pedals as much, that could be because the legs just aren't under load the entire time, as opposed to a hill climb where you could be riding at a 4% gradient for those 10 minutes and the heart rate will build and build, and build and maybe go into that zone five. That time under tension is really important when we're looking at what's going on with the power and what's going on with the heart rate. So when it's a little bit more rolly.

Speaker 1:

I tend to find the heart rate coming down a bit or lower than like a steady heel climb effort, of which try to hit that power but keep the perceived effort in mind. So if it's a little bit more rolly, I'm going to say push the art like, match the RPE. These should feel like a seven or an eight out of 10. For when I'm coaching somebody to do threshold work, that's the RPE. These should feel like a seven or an eight out of 10. When I'm coaching somebody to do threshold work, that's the RPE range that I'm encouraging them to do. They have a power range, they have their perceived effort range. Then they're looking, checking their heart rate to make sure it's up there.

Speaker 1:

If it's going down a little bit, just push on the gas a little bit more, maybe a little bit of pop on those rollers and that'll drive the heart rate you know up there they'll drive the perceived effort up there. It'll make the effort more squiggly, but that's not bad Okay, especially if you're prepping for a race or something. A squiggly effort is more race specific versus a steady effort. So take that for what it is. But that is the other part of your question. If the heart rate's slipping a little bit. That is the other part of your question. If the heart rate's slipping a little bit Now, we could just leave it there. But if you have more time to listen to me here and you're curious as to why I say power first, then rate of perceived effort, a very, very close second and heart rate third, here's my rationale. Heart rate is more variable than power.

Speaker 1:

I'm going to get a little philosophical here for just a second. Our bodies are brilliant, complex and smarter than we give them credit for, and this is what we want, primarily because all the checks and balances in place seem to be there to help us not die when something is out of balance, like when we get sick, like me right now, which is why I feel so congested and I'm coughing in between talking points or we have an injury, or when we're pushing to our limits during training and racing. And because we have these checks and balances, our physiology is not as precise or as predictable as we always want it to be, especially compared to the tools we use to monitor it. Therefore, I encourage you to think of your physiology as a continuum from resting on one hand to max effort on the other, you're never truly off and you're never truly maxing out or to the point of death, at least not yet. So in other words, humans are not binary. Don't think of your physiology as such, don't think of your training zones as such. Each zone picks up from the other and carries on to the next in that spectrum of things. Okay, I'll get to that here more in a second.

Speaker 1:

But these complex systems that regulate or give our checks and balances in the body, like the autonomic nervous system, it's going to regulate us and it's going to regulate our heart rate. 24, seven and everything in life will influence that heart rate. That's life stress, accumulated training stress, hydration, dehydration, depletion of glycogen and electrolytes, caffeination or how jacked on caffeine you are excitement, depression, mood states, heat, cold, altitude, in-laws and lots more. So when things are normal, heart rate can be a predictable normal. However, when things are not normal, heart rate is the first thing to change or have variability to it. And most of my time crunched athletes don't have normal days always.

Speaker 1:

Therefore I tell my athletes and to you, mark, to monitor training with a power first approach, then perceived effort, not a heart rate first approach. Another, or the second point to my rationale here is. Wattage is not variable. Most power meters these days from bigger, reputable brands are accurate and they're consistent. You definitely want to monitor training with an accurate and consistent tool like a power meter, but for many reasons that I'll get into here in a minute, the precision of this tool is almost too much if you overemphasize this tool is almost too much if you overemphasize the number more than you should. My suggestion here is to measure everything but don't latch on emotionally to the number.

Speaker 1:

You also need to understand that there's a broad range to stay in to get the benefits of zone training and that can be on the higher side or the lower side of the range for any given day, depending on how you feel. I tell my athletes if you're feeling good, don't waste a good day right on the upper end of that zone. Give me what you got. Maybe you actually do another interval, but stay in the zone. On days where you're not feeling as good, just hug the lower end of the zone. If we're doing threshold training and I've got four by 10 in there and you just you're not feeling, you're not tanking on the workout, but you're not feeling great, maybe we did intervals a day before, but hug the lower end of that zone, try to get at least three in, because, again, right around 30 minutes of total time in zone is going to help move the needle forward. So let's try that.

Speaker 1:

So you're always kind of checking yourself and balancing with these three metrics rate of perceived effort, power and heart rate. Now this leads me to the rate of perceived effort, and this is probably the most important factor in monitoring training. But my opinion, and this is why we can't put it first, in my opinion we need something like power or pace to help us get to the perceived effort or help us ground in something. The scale of one to 10 needs a power or pace associated with it to help us understand the perceived effort. Now, this is why I call it a close second, if not like a 1.1. In order of priority, it's first but kind of second until you know where 250 is at, or threshold pace, or your time trial, effort, things like this.

Speaker 1:

Whatever the effort that you're doing, I try to drill this into my athletes as best I can to get them highly aware of their efforts as it relates to the number that they're seeing on their power meters. I use a scale of one to 10, 10 being a max effort, one being almost nothing and each zone has a corresponding rate of perceived effort to it. Sometimes the zone will have a range of perceived effort as well. So endurance miles, or zone two, with CTS methodology, will have a rate of perceived effort of four to five Okay, very medium. Now I'll provide a link to the CTS zones with rate of perceived effort scales to it. I'll put that in our show notes.

Speaker 1:

This brings me to the final point here, and this is the holy three in one, the holy Trinity of monitoring exercise. So really, mark my answer. If it's one thing I'm going to tell you, it's the holy Trinity. That's what Dr Stephen Seiler has kind of popularized, these three elements as to be the most important thing to monitor. And you say why? Well, like I said, power, rpe and heart rate in that, or in my opinion, is the best way to monitor. And I'll put it in like maybe simpleton coach Adam knowledge here, but there's probably statisticians listening that could do more justice to this.

Speaker 1:

But three is better than two and three is better than one, why? Because three data points lets you see more of a pattern. It can cross, check and verify the other data points and give you better feedback, or more like holistic feedback, of what's going on during the session, right then and there. It also gives that same, like a kind of quantum feedback to the coach who may be looking at the training afterwards. And with two points you don't get that. You may only see things linearly and with one point, let's face it you could just be shooting in the dark and you don't know exactly where you're aiming. If you want a more super in-depth explanation of that, check out my podcast I did with Dr Steven Seiler. Just search for his name and time crunched in the Apple podcast or wherever you get your podcasts and you'll find it there.

Speaker 1:

But real quick, what about breathing? Breath rate and breathing are getting pretty hot again right now and there is some new tech coming out soon about new breathing devices to monitor these things. That could be helpful, but for right now I wouldn't get too excited about it. Consider it a curious companion along with heart rate that could tell us perhaps how cooked you may be on hard intervals or if something could be off at sub max other than your legs just being a little tired. I'll keep you posted as I learn more, but in my opinion it's not something super useful yet, and certainly not more useful than the holy trinity of monitoring exercise.

Speaker 1:

So, finally, to bring this all home, back to zone training, your training zones are ranges or spectrums of intensity on this continuum that I talked about before, and those zones are somewhat in the middle right Of resting on one side and maximum effort on the other. There's not an exact wattage or beats per minute or anything else that's going to pinpoint the end of zone two or three or threshold versus VO2. And even if you have a power meter in the highest end metabolic cart and you go in and you do an LT test, you'll still have a range of power that you will be at for threshold, because on any given day it will be plus or minus, a little up or a little down due to a number of things in life, all stuff that I mentioned, including how you're improving over time. So keep that in mind You're, you're, you're always kind of in flux. There's, there's never a homeostasis, really Okay. So I want you to to think about your physiology as that continuum and everything is always, always a range, and I think that's going to be the most helpful to answer your, your full question mark.

Speaker 1:

So, in closing, if there's one thing to monitor during an exercise training session, it's the Holy Trinity, which is power, rate of perceived effort and heart rate, which is a cheeky way of saying there's actually three things. Right, that's what I've been saying this whole time. Now, that's assuming that you have all the thresholds and devices accurate and calibrated, and that also includes your awareness of your effort, that rate of perceived effort that we're talking about. So if you want to learn more about how to do that, or if you have any other questions about all things endurance training, you can head over to trainrightcom backslash podcast and click on ask a training question. Those get sent directly to me and my little pod team here at CTS and we'll do our best to answer it on an upcoming episode.

Speaker 1:

Thank you again for listening and be sure to share this show with your training partner. So they get faster too, as they improve. So will you Thanks again. Or two as they improve, so will you Thanks again. Thanks for joining us on the Time Crunch Cyclist podcast. We hope you enjoyed the show. If you want even more actionable training advice, head over to trainrightcom backslash newsletter and subscribe to our free weekly publication. Each week you'll get in-depth training content that goes beyond what we cover here on the podcast that'll help you take your training to the next level. That's all for now. Until next time, train hard, train smart, train right.

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Adam Pulford

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