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Another "Zone 5" Thread - Why is this possible?

RG
over 2 years ago

I am 45/M, in decent shape, and the Tactix 7 has been stalking me and my fitness activities for about a month now.
I am not an athlete but I exercise frequently. 

The watch (auto-detect) says my Avg. Resting HR is 47 (most recent update), and Max HR is 183.

Heart Rate Zones Heart Rate Settings

For virtually all of my runs (3-5x/wk), which vary from 2 - 5 miles each on the street or trails, I run at a pace that keeps my HR between 167 - 175, with occasional peaks up to 182.
I'm not necessarily targeting that range; it's just how I run and where I end up.  It is usually an uncomfortable pace but not even close to sprinting.

Yesterday, for example, my trail run lasted 50 mins and covered 4.42 miles. It was a very uncomfortable and difficult pace (and hot) but by no means my max or near max effort.

So, per the watch and HRM-Pro, I was in Zone 5 for 83% of the 50 mins, so almost 42 minutes in Zone 5!

HR Zones

Everything I have read about "Zone 5" says it is "unsustainable".  Even the Garmin User Guide says Zone 5 is "Sprinting pace, unsustainable for long
period of time, labored breathing".  I am not questioning the definition. 

Obviously, there are tons of threads here saying "well, you need to adjust your HR zones or HR algorithm or set a higher Max HR".

And that is not my point.  My point is, if Zone 5 by definition is unsustainable, then why doesn't the watch algorithm know that?
What doesn't it know that spending 42 minutes in Zone 5 would have killed a human (ie, no one can sustain a sprint for that long) and say "oh, that's not possible; this algorithm obviously needs adjusting for this individual!" and take some action?

So yes, *I* know the zone needs adjusting because it's common sense.  I was really in "Zone 4" more than Zone 5, by definition of the zone.  Question is, why doesn't the watch know the same?  It's algorithms are backed by lots of exercise science, after all.

BTW, this is not intended to be a bashing thread.  I'm truly trying to understand how these fitness trackers and Firstbeat Analytics have been around for a while and tracking so many folks, yet you keep reading these threads about Zone 5. 

  • 0 over 1 year ago

    That assumes that the watch measures the HR accurately, which isn't necessarily the case.

    As an example, two days ago I had a trail run when I first ran hard 4.5 miles uphill, then ran a few more miles downhill at a very easy effort. Despite running downhill at a very easy effort, the HR detected by my watch got "stuck" at zone 5. Even when I stopped to let the HR detected by the watch drop, which it did reluctantly, every time when I resumed running it quickly went back to zone 5. I know from my experience running with a chest HR sensor that at that time my HR was in zone 2 or perhaps low zone 3, about 30 bpm lower than what my watch was detecting. In fact, even when running uphill it is rare for my HR to go into zone 5.

    Interestingly enough, the next day I had another mountain trail run during which I took a much easier effort on the uphill part and hiked it all the way up. Then I ran the downhill part. That time the watch measured the HR correctly the entire time. So perhaps there is a sort of adaptive algorithm where the watch "learns" the level of effort and then tries to stick to it even when the actual HR drops.

  • Former Member
    0 Former Member over 1 year ago in reply to RG
    RG said:
    You're right, I can sustain an hour at the low end of the current Zone 5, but then by definition it isn't Zone 5.  More like Zone 4.8 (just a guess)?

    Maybe you don't know what your true MHR is.. You can run 5k at race pace, and towards the end give it everything you got until you feel like you are ready to pass out, then see what you HR gets up to.

    I'll be 66 in August, so according to the 220 - age formula, my MHR should be 155, but I have gotten it to the lower 170's a few years ago when I was running a lot.

    If you do this, please let us know what number you wind up with.

  • 0 over 1 year ago in reply to Former Member

    In my case, I do know my max HR well by experience and from several ramp tests (not the most pleasant experiences!).
    Never been chased by a bear, though.

  • Former Member
    0 Former Member over 1 year ago in reply to RG

    An ultra runner in another forum told me to get my HR up to as high as I can get it before passing out, then add 5 BPM to that number. He said it's because nobody can actually reach their MHR.

    I'm just an OldAssDude, so I just let garmin auto detect tell me what my MHR is, and use that. At my age, I just need to get my HR up for 30 minutes to an hour. lol