Heart rate zone vs FTP on the bike | 80/20 Endurance

Heart rate zone vs FTP on the bike

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  • #9236
    Williamson1971
    Participant

    Morning David,

    I’ve a question regarding heart rate zones on the bike.
    I’ve done my LTHR and FTP test on my direct drive turbo, and will use this consistently over the winter.
    The issue is that my zones don’t really match up. I tend to be at the top end of the power zone when my HR is at the bottom end of the corresponding zone. Therefore I have crossover into zone ‘X’ for power when HR zone is firmly in Z2. Which metric should I use to avoid being in the wrong zone?

    Hope you can give me some guidance!

    Regards,

    Chris.

    #9241
    David Warden
    Keymaster

    William,

    Were the LTHR and FTP done within the same test, or separately? If done separately, there is a good chance they won’t align.

    If done at the same time, they *should* align. In fact, they really *must* align, right? If you do a 30-minute TT and capture HR and Power in the same test, that intensity represents the same LT/FTP for both Power and HR over a fixed period.

    But, even if you did them together, HR can be affected by multiple factors. Sleep, temperature, when you last ate, stress, time of day… The intensity that HR represents one day can be different the next.

    So, regardless of whether the test captured both at the same time, I would defer to Power over HR at any given time.

    David

    #9248
    Williamson1971
    Participant

    Hi David,

    Yes I did them at the same time.

    So last night I did a recovery turbo. I purposely did it at the middle of Z1, 180 watts for my FTP of 300. My HR averaged out at 95bpm and was more or less steady throughout. The HR table says it should be between 112 and 126bpm for this power output.

    I do have a low resting HR of 44, but this isn’t hugely unusual.

    Can you give me some guidance please as I’m wary of investing heavily into the training and being in the wrong zones.

    Is it a case of working out HR’s to zones now I have both top and bottom end of my HR range?

    Thanks for the reply yesterday, I really appreciate you taking the time out to answer my query.

    Regards,

    William.

    #9249
    David Warden
    Keymaster

    William, I can’t explain that discrepancy. The next time you perform Zone 3 intervals, report back here as I’d like to see the results of that as well. Something either set your HR either artificially high during the test, or artificially low since then. I also assume the test was done indoors.

    Additionally, reports of a delta between Power and HR are almost always the opposite: HR higher than Power (in fact, this is the first report I recall of Power zones being higher than HR).

    It’s another example of HR being an unreliable indicator of intensity and totally unique per athlete, per my often-used example which I’ll include here. I recommend that you disregard HR and use Power exclusively.

    David

    There are four ways to measure intensity: pace, heart rate, power, and perceived effort. The testing protocols for all four types are listed below. Each metric has different applications among the three triathlon disciplines. Each metric also has certain advantages and disadvantages. Power is an output, pace is an outcome, and heart rate is an indicator. Let’s use an automobile as an example. Horsepower (power) is the output, and represents actual work performed regardless of terrain, grade, or environmental factors. Your speedometer (pace) indicates the speed, or outcome. Your engine temperature (heart rate) represents how the car is responding to the output and environment. During a hilly ascent, the output (power) might be high, but the outcome (speed) might be low. On a hot day, the engine temperature (heart rate) might be very high even when stopped at a light with almost no output and zero outcome. For this reason, power is considered superior to pace, and pace superior to heart rate to measure intensity. There are some exceptions, such as hills, where HR can be superior to Pace to measure intensity. The recommended best-practice is to use Power or Pace as your primary measure, with HR as a secondary measure.

    #9250
    David Warden
    Keymaster

    Actually, this is bothering me…

    Can you attach yourself to my TP account and let me look at all your workouts, just tell me the date of your FTP test.

    Attach here: https://home.trainingpeaks.com/attachtocoach?sharedKey=OKYJVWHNFAPPG

    David

    #9252
    Williamson1971
    Participant

    Ok, I’ve added you as a coach. I did the FTP on Nov 12th, and the recovery on the 13th. I only did the 20 minute FTP test, and for that reason have had to estimate the LTHR to a point. At minute 10 my HR was 153, at minute 20 it was 157. I averaged 315 watts for the 20 minute test which gives an FTP of 300 watts. I worked out that my HR would have averaged out at 156. This may have been a little lower had I done the 30 minute test at 300 watts. If this is the case and say my average HR was 150 it would still put me out on my Z1 expected HR.

    I’m more than happy to do a full 30 min (well, when I say happy 😵) if that helps, or any other field tests.

    All tests were done indoors.

    Regards,

    Chris Williamson.

    #9256
    David Warden
    Keymaster

    William, thank you. Test looks good, done correctly, I agree with your threshold results. Power is right on at 300, and LTHR I’d put closer 153. Still, it is a crazy low HR for an FTP test. Think of it this way: your outdoor ride today for 3 hours averaged 130bpm (Squarely in Zone 2 HR). So the difference between your easy 3 hour ride and all out for 30 minutes is just 23 beats. Or, look it another way, your Zone 1 ride averaged 93 but your Zone 2 ride averaged 130: a full 37 beats between Zone 1 and 2? Something is amiss.

    We’ll need more samples to figure this out. Use Power as primary for another week, ping me again, and I’ll look at another week of cycling.

    Calibration an issue? Possible that the calibration between the last two indoor rides is off?

    David

    #9259
    Williamson1971
    Participant

    Ok, I’ll be in touch with more data in a week or so. I’ll do some efforts in different power zones and collate the HR data. Just for info, the ride you looked at yesterday was a run, think it’s down as navigation.

    Thanks for your help David, I’ll be in touch.

    #9303
    MWILLS
    Participant

    Just to add to this, my FTP both indoor on the turbo and outdoor are identical (280w). However, my HR tends to be lower indoors than outdoors. I assumed it was down to outside variables such as wind resistance, elevation, bike handling, rolling resistance, etc.

    #9331
    Williamson1971
    Participant

    Hi David, hope you’re well.

    So, this week I’ve done some 20 minute steady state mid power zone sets to map my HR, these are all on TP’s.
    The concise data is:

    Z1 180 watts Average HR 100 Max HR 106 (suggested HR for power Z1 is 110 to 124)
    Z2 230 watts Average HR 116 Max HR 124 (suggested HR for power Z2 is 124 to 138)
    Z3 286 watts Average HR 133 Max HR 140 (suggested HR for power Z3 is 145 to 153)

    Regarding calibration of my turbo, looking back at my history, HR vs Power are fairly constant with nothing to suggest that there is an issue with repeatability.

    Just to recap, FTP is 300 Watts with a LTHR of 153.

    Just something to ponder on – I do have mild asthma which is controlled with a preventer. This does restrict the amount of air produced when doing the forced expiratory volume test (we get tested periodically at work). I’m not new to training, I’ve been active all my life so dealing with this isn’t anything new, but it could be the cause of my low HR at high efforts.

    If you’ve time to have a look into this and unpick it that would be great, then I can set my zones and get started for Austria IM 2021 (Covid allowing!!)

    Regards,

    Chris.

    #9345
    David Warden
    Keymaster

    Chris, I can’t explain it yet. Again, your upper end Zone 3 of 300 watts was 153bpm, but just a couple of weeks later 14 watts lower at 286 is an entire 20 bpm lower at 133. That’s 13% lower HR for 4% lower power. Your HR is just inconsistent.

    It’s an example of why not to use HR. It’s just unreliable. We can keep tracking your data, but I’ll be surprised if anything changes. I just don’t think your HR and Power will align.

    But, they don’t have to, just user Power. HR is an appropriate secondary measure for when HR goes to high. But if HR is too low, there is no need to use it at all. Use 300 watts as your FTP and set zones accordingly.

    Once you get outside, you may see a change in that HR is often 10-15 units higher outside… but so is power! So, I’d again expect to see the same delta. It’s possible that once you get outside power will remain float but HR will jump by 10-15 beats.

    For your medication, I don’t think that is an issue. If it was an issue of oxygen transport, your power would also be low. Your power is actually great,

    David

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