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HR zones not right

tenohfive
over 7 years ago
I've had on and off issues with HR zones with the 935 but I mainly dismissed it as being slight differences and trusted the Garmin; now I'm sure they're set wrong and I'd like to get them set right. I'm pretty sure the zones have changed on GC as previously runs at the same bpm would put me in zone 2 on the watch/GC.

During a recent run - 5km, flat, road - GC puts me in Zone 3, with a few minutes in Zone 4. Note - according to Garmin I was never in Zone 1; I gently jogged for about 1 minute before hitting record. Strava puts me in a mix of Z1 (a few minutes), Z2 (majority) and Z3 (a few minutes.) In terms of pace I was averaging 5:35/km - the standard pace I naturally slip into for easy and long runs. My 'run forever,' pace. RPE of 2, knocking on RPE 3's door occasionally on the odd gradient but not for long.

Both GC and Strava set my zones as a percentage of my max HR of 185 (taken from my 5K PB's within the last few months). Numbers:

Z1: Garmin - 93-110. Strava - <120
Z2: Garmin - 111-129. Strava - 120-149
Z3: Garmin - 130-147. Strava - 149-164
Z4: Garmin - 148-166. Strava - 164-179
Z5: Garmin - 167+. Strava - 179+

I've no idea how accurate it is but most LT tests or changes have put my LTHR at around 165-167bpm; but I don't know if that test is influenced by HR zones (which may be inaccurate) or if that's not something likely to affect accuracy.

Who do I believe? I don't buy into the Garmin version (and I'm sure it's changed) - but I don't want to blindly trust Strava either?

HR zones don't form a huge part of my training (I only really use it as a reminder not to creep into Z3 during long trail runs) but I'd like to have the data there and recorded accurately.
  • 0 over 7 years ago
    It's not a matter of who to believe, it's a choice. Heart rate zones are an artificial set of markers, whereas cardiovascular function varies mostly smoothly (up to the VO2max threshold).
    So you're set to:
    Garmin
    Z1 50-60%
    Z2 60-70%
    Z3 70-80%
    Z4 80-90%
    Z5 >90%

    Strava
    Z1 < 65%
    Z2 65-80%
    Z3 80-89%
    Z4 89-97%
    Z5 >97%

    If your lactate threshold is at 165-167, most people would set that as the boundary between Z4 and Z5, so Z5 is anaerobic, and Z4 is aerobic. That's not how Strava is set for you

    Where the lower zones are/should be is more a matter of debate. Lots of people go by zone 2 being 85-89% of LTHR, which for you would be 141-148 bpm
  • 0 over 7 years ago
    7bpm for Zone 2 sounds like a really narrow window - or is that the upper limit?

    The main reason I'm interested is because I want to stay at a state where I'm primarily metabolising fat rather than a mix of fat and carbs.
  • 0 over 7 years ago
    well, you're always metabolizing both, fats and carbs, there is no "only fat" or "only carbs" state to create ATP (energy used for cell transport, protein production, muscle growth and so on)

    while yes, lower intensity workouts have a higher usage of fats, vigorous exercises raise the overall amount of energy needed, and the total amount of fat burned will be higher than when training in a lower zone.. take as an example 75% of 100 units is still lower than 25% of 1000 units.. so if you're looking into fat-loss higher intensity is still more productive.
    this is not yet taking into effect that after more vigorous exercise the insulin levels will raise again, carb use will drop and fat use will rise, so you have a longer lasting fat-burning effect, which in the long run will be of importance if fat-loss is what you're after.. if that's not what you're after, then i apologize, then i have misread your question in between the lines
  • 0 over 7 years ago
    I know, there's a reason I said, 'primarily,' not, 'only.' And I'm not interested in burning fat for weight loss, I'm trying to become more efficient at utilising fat as a fuel source - the benefits for running long distance are obvious, and the studies suggest running at Zone 2 during long runs in order to train that adaptation.

    I've gone with Garmin's % of LT as a method for now - with a given LT of 169 apparently that puts my Zone 2 as 135-150, which loosely fits with the LT -20bpm figure I've seen elsewhere. I'll probably still try and aim to be at 135-145 for most of the run but at least I've got a bit of a red flag now if I get carried away.