cTHR and zones

Hello I am new to training and want to use heart rate for some type of structure during outdoor rides. I don’t have a power meter for outdoors yet and I ride MTB so I think heart rate zones will give me some type of structure. I am new to structured training and I would previously just ride as hard as I could the whole ride.

I did the full frontal test using wahoo kicker and heart rate monitor and got a 167 cthr score.
A few weeks later I did an XC race outdoors using the same wahoo heart rate monitor and element roam and had an average heart rate of 184 (max 193) for 31 minutes. I’m competitive so in a race situation I know I gave it my all. On the trainer I tried to give it my all.

Setting cTHR at 167 vs 184 creates very different zones.

Anyone have any insight to this?


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Welcome to the forums @Dave399 ! You’ll likely hear a lot how indoor training and outdoor training differ but, here’s a couple of thoughts. It is my understanding that cTHR of 167 as calculated during FF implies that would be your threshold HR for an hour. Do you think you could have maintained the 184 HR you got during your XC race for a full hour? I’m guessing not.

So, my 2 cents as a rank amateur, not a coach, not a sports scientist …is go ahead and use the 184 outdoor average as your threshold rate for training outdoors and if you find yourself struggling at those training zones, knock it down a notch or two. HR is a trailing metric and not ideal for training when power is available as power measurements are instant. In your case though, without a power meter, HR and your perceived level of exertion will be your best training tools.

There’s some GREAT info on using RPE and a recent The Knowledge Podcast on it here:


Sounds like you went too easy on the full frontal 20minute test, or you were I’ll/fatigued, overheated. I’ve got a good idea of my cTHR from trying to beat my pb up a local 45min climb and judge my effort during the FF 20 min test on that.

Have you done the Half Monty ramp test, that also gives an estimate of cTHR?

Thanks Glen I’ll give that a listen.
I don’t think I could have held that 184 for an hour but I do believe 167 is too low for me. Somewhere in the middle might be the correct number

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I have done the half Monty, but again it was a low number somewhere around 167.
I’m new to indoor training so motivation might be the problem.
Maybe I’ll try half Monty again and really give it my all and see what happens now that I know outdoors I can hold 184 for over 30 mins

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There is also this:

and this:

Soooo many resources here from people who, unlike me, actually know what they’re talking about. :rofl: :rofl: :rofl:

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Hey Dave, also just a thought for structured outdoor training qithout a PM. Often intervals can be a wee bit short to be able to use heart rate as a target. I’d recommend reading through some articles on RPE. There’s a recent podcast as well I believe.

The reason is that HR can be a wee bit slow in dialing itself up and down and is often responding to what you did minutes ago. As you get fitter, HR seems to react even more slowly to an increase in effort and more quickly to a decrease as well.

For longer intervals or endurance style outdoor workouts, HR is brilliant.

Agree with both @Glen.Coutts and @DameLisa : heart rate is a poor metric for intervals because it lags so much. While better for long (>5 minutes) intervals, it is still problematic. HR is highly sensitive to you hydration level, heat, and just how your heart is beating on a given day. Also, it drifts up over time on even longer intervals even if your effort doesn’t change.

While without a power meter HR may be the best objective measurement available, I’d teach myself to pay close attention to RPE (perceived effort). Many riders learn to judge effort by how it feels with high accuracy. You can use the RPE targets in STSTM to help teach yourself the scale and train yourself to recognize RPE. That will give you the confidence to realize when HR isn’t really telling you the right answer outdoors.

Thanks everyone for the insight.
RPE might be hard considering a technical downhill section will be low effort spinning the legs but my heart rate will likely be maxed.
I basically want to learn and understand my zones so I can stay zone 1-2 for a warmup, Be able to a trail that is 6-8 mins long at my max heart rate. Hit a few trails in my tempo for 30-45 mins and not over exert myself. I feel like knowing my zones for a trail that takes me 45 mins to complete will give me a good idea of what to shoot for regarding heart rate…and if I see my numbers getting out of that zone I know to dial it back a little.
Coming from motocross to mtb, in the past I would just hit the head of a trail and go as hard as I possibly could for about three minutes before dying and then struggling for the remainder of the trail. I have recently dialed it back and it’s far more enjoyable and even faster
I have some reading to do and some podcasts to listen to thank you for pointing me in a good direction.

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Also with technical mtb riding during climbing you have to go 100% at certain sections of trail in order to properly clean the section. So it may be more tricky to calculate RPE then smooth Xc trail or road riding?
I guess it just comes from experience

Welcome Dave, I trust you will have a productive time in SYSTM. Enjoy the journey.

It seems the last The Knowledge podcast has stirred some sense into training and keeping it real. The knights above have been quick on the draw to guide you to using RPE.

It’s not always about the gadgets. Trust your built in ticker to guide you. A device is only as good as at the point of measuring, and an optical wrist HR will measure differently to a chest HR strap just as an example. Devices will incur error, your ticker will be the most reliable to tell you your effort.