Low HR, but high intensity?

I’ve only been riding for about ~2 months now, so apologies if this question has been asked and answered (I didn’t find anything in searching) but I’d like to understand what I need to work on based on this type of data.

Coming from completely untrained, couch potato to current state in those ~two months, my FTP is only 215 watts per the ramp test I took when I joined TR a few days ago, but when I ride outdoors, in a HR for me that’s in “Zone 2” and sustainable over distance…and I would classify as a moderate effort, I’m already almost at my FTP. I wouldn’t say this pace is uncomfortable, but I know I’m near my max aerobic HR as if I push too much harder it’s not sustainable for any significant duration.

What specifically should I target in training if my HR says 99% at “Zone 2” but my power meter has me at .96-.99 intensity?

How are you measuring power in each instance? Same power meter, or are you using a smart trainer indoors?

Smart trainer indoors (Kicker v5), Stages Gen 3 left side crank power meter outdoors.

Also, I’ll add that I’m a typical middle aged male. I realize HR isn’t comparable between folks, but mine (outdoors) averages ~130 BPM in “Zone 2” +/- a few bpm. Much over 138-140 I can’t sustain for significant distance, but at something like 133 bpm I can ride for several hours.

It may be worth checking your Kickr against your stages, and at a range of power levels (easy, moderate, hard, very hard). Power measured on different devices can vary.

Just ditch the HR monitor. I used to wear one when I MTB and when I did a structured vo2 max workout. Otherwise, I don’t need the data. Follow your power meter and let RPE guide you

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Ah, that’s probably it. You can see significant differences between two different devices, so your FTP and subsequent power zones aren’t necessarily the same for both.
If you’re looking to train to power both indoors and outdoors, your best best is either to use the same power meter for both using Powermatch (probably simpler) or perform a separate FTP test for each.
If you’re newer to indoor training it’s also probably worth looking into cooling if you haven’t already done so (most people need a lot more than you think!), and I’ve also found the mental aspect of both being inside on a trainer and pushing yourself to failure on an FTP test to be something that improves a bit with experience.

In any case I’d make sure the conditions and measurement methods are as consistent as possible before making big changes to your training, especially if you’re seeing improvement in other areas.

How are you determining your HR zones?

HR and power zones often do not match up that well, but z2 at threshold doesn’t sound right.

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Thanks for the replies. I’ll try Powermatch and see what difference I can find.

I set my HR zones as age minus 220. We don’t have good hills here, the whole state is flat so max HR test outside is difficult. I do know from (many) years ago when last I cycled mine was within a few beats of what the formula recommends.

The advice to set HR zones from 220 minus age has generally been discredited. This article from British Cycling is a really good introduction to HR zones and includes a HR zone calculator:


Yeah, don’t set your HR zones by age, they’re most likely wrong.

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Adding to this, a protocol to follow to find your heart rate threshold is linked in this article:

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I would start by taking all power from your Stages so you get consistency indoors and out.

I get the best readings out of my Stages by calibrating it when it’s at outdoor operating temperature. For example, if the bike is stored at 70F but you go out and ride in 90F, wait ten minutes until after your power meter has warmed up. Or, set your bike outside 10-15 minutes before you plan to pedal off.