Different default heart rate zones for general training and running. Why?

FYI - maximum HR isn't really a good/bad metric, 'great MaxHR' isn't really a thing.  It is just part of genetic makeup, a elite athlete can have a max of 205 or 190.... it isn't an indicator of ability to do more work/speed/power.   Although now that I remember (along the lines of your 'great maxHR'), there is some evidence that good training, will often reduce or remove entirely the trend of losing 1bpm from your max every year or three.

Resting HR on the other hand is often pretty indicative of fitness (although there is a solid genetic component as well).

JazzRunnerDP said:

've not experienced auto-detection "wreak(ing) havok in the percentages of zones

It seemed your standard percentates got messed up in your original post, though... Typical of new auto-detection messing up the zones. Maybe there is another reason...

JazzRunnerDP said:

I see using auto-detection as a big positive with little negative consequences.

I woudn't have agreed last year, but now I am 100% in agreement, especially for people who can/t/won't/shoudn't push to their physical limits and still count on the training metrics.

I have the auto detect on and I trusted it 'cause it gave reasonable numbers between 2020-2022, when I started running and then I bought my 1st Garmin watch. in 2022 I had my 5k PB, and at the time my max HR was set to 191. Then I had some problem with my shoulder that 1st made me stop running and then even walking and I really haven't do any meaningful sports activity for over a year. During this time my max HR stayed as it was from Garmin's perspective.

3 months ago I started running and related other training again. My fitness was of course noticeably worse than 2 years ago, but that is expected. And at the beginning I thought: ok, so maybe I'm now 2 years older, so my max HR is 2-3bpm lower than was, but my HR zones should be more or less OK, so I didn't change anything. But then I realized that most things the watch calculates are based on the max HR, and that it makes no sense for me compared to my current fitness (most notably runs that could be easy jogging 2 years ago, but felt hard now were in zone 1) so at one point I decided to reset my max HR and zones, and let the watch auto-detect them again, and improve them from now on. I don't know if it is the right thing from the medical point of view (aka maybe my max HR in a lab test would be 189 or maybe even 195 [I never had a lab test in my life]) but it seemed to be the right thing to do to match Garmin's calculations to my current fitness level.

However then strange things started to happen. 10 days ago I had an interval training where my actual HR during the activity was recorded to be 178. However at the end of the activity the watch offered me to update my max HR to 158. THAT DOESN'T MAKE ANY SENSE TO ME AT ALL!? This for sure is some bug in Garmin, so I reported it, but it doesn't seem they care a lot.

Today I realized that the max HR is again set to 191, even though I haven't have any activity recorded since where my max HR was higher than 178, nor did I receive an offer from the watch to update my max HR. So I reported this today, they checked it and have no idea how it came to be. Disappointing, but I'll follow up with support as they requested, though I'm not too optimistic.

As for the advice of "disabling auto detect": I have no way of knowing my max HR (I won't do a lab test, as I'm not an elite runner, nor have any know medical reasons to test me - I was tested last year on some "yearly" checks, for the first time, but all it did was sitting 20 minutes with a Polar H10 (similar to what I use on my runs) on my chest and then some app told me I'm OK and shouldn't be concerned) but as someone who's relatively new to running (especially after the long break, I consider myself to be more-or-less like someone who started to run for the 1st time in his life 3 months ago) I always had the following questions in my mind:

1. I see I'm improving for now, but when will I reach and how will I know that I reached my potential? What will my max HR, LTHR, and my PB-s be then?

2. At some point (I guess it already happens, as I'm 47 y/o) all these numbers will start to decrease every year. How will I know if I have auto detect disabled?

Also someone mentioned that the watch ic now capable of giving you max HR that is higher than what you actually reached. I also saw this, because before I reset my max, it gave me updates like 190, 189, even though I haven't reached even 180 in the past 3 months. So while I don't know how accurate these "higher than the HR you actually reached" max HR calculations are, they seemed realistic (one could also argue that maybe some of the updates were just based on the past max HR and my age, so it decreased it by one). So I didn't care much and I always accepted them. That was until I got the 158bpm maxHR during a run when I reached 178, that was when I understood something isn't right.

Someone also mentioned the Resting HR. I wear the watch 24/7 so I assume it's accurate. Now for the HR zones: how to decide which one is the best for me: based on maxHR, LTHR or HRR%? If one would have accurate maxHR, accurate LT, accurate RestingHR, then what would be the order of preference between these to base the HR zones uppon? (Also, am I correct that HR Reserve is maxHR-RestingHR?)

flocsy said:

How will I know if I have auto detect disabled?

flocsy said:

it gave me updates like 190, 189

At this point, the estimates of your Max HR are pretty consistent, except for the fluke at 158. Since a new max HR has a change of changing your % of heart rate zones, you can choose to disable it and re-enable it 12 months later to see if anything has changed. Or you leave it on like me. I am using % of HRR for zones (more on this later) and they survive nicely my auto-detections (I check everytime).

For other users who see a big change in Max HR (>= 5bpm), I recommend they perform a new LTHR test, as one value influences the other's detection. 

flocsy said:

If one would have accurate maxHR, accurate LT, accurate RestingHR, then what would be the order of preference between these to base the HR zones uppon

First, let's be clear that the choice has no impact on your training metrics. LTHR and pace @ LTHR are criteria for a sub set of the rules used to determine your training effect label, but not for the training effect itself.

% of  Max HR is very common and simple to use. When you know that your Max HR is correct, it works well except that it seems to be prone to be "new auto-detection" bug. The workaround is to reset your zones after a new Max HR detection.

% of LTHR is also very common and makes a bit more sense from a physiology perspective. Anchoring zones to the 2 ventilation thresholds gives you a 3-zones system essentially, and seems to be the preferred way to go. Except that Garmin doesn't give us VT1. Maybe in future models since the technology exists based on HRV detrended fractal analysis. It goes give us VT2 only (a proxy for the blood lactate threshold).

% of HRR has the benefit of being close to the way EPOC (in the context of level of intensity) is calculated and the % of HRR are close to the % of VO2 Max (not the same though). Because Rest HR is included, the approach adapts slightly to your fitness level. So, these zones tend to be the most aligned with the way the watch is estimating intensity, EPOC and all its derivatives. It is not a key advantage and the zones are less intuitive less common. 

See a comparison and a discussion here:

https://winklercycling.com/2020/10/13/training-zones-hr-maximum-reserve-threshold/

https://www.ncsf.org/pdf/ceu/relationship_between_percent_hr_max_and_percent_vo2_max.pdf

https://pubmed.ncbi.nlm.nih.gov/9139182/

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My recommendation: if you train on HR, use LTHR based zones. If you train on power, use FTP/CP zones for power and % of HRR for HR. You won't get anything wrong by choosing a system of HR vs another.

OK, thanks, you, this is very useful (and a lot to ingest:)

I don't know much about power, I don't have a power meter for my bike, and my main sport is running. I do see now, that on my relatively new fr965 there are running power measures, and I started to look at them in the past 2 weeks (even added a field to my running layout), but I have not read about them yet, so I have no idea why one should or shouldn't choose to go by either HR or power. Though given that 90% of the youtube videos talk about HR and less than 1% about power, and that I am a casual runner, and that older watches don't even have running power, I am pretty sure that for me, now the HR is the right choice.

That brings me to the next question: I assume that my maxHR detected by Garmin up to the point when I stopped running was close to the real value (191bpm), but I am less confident about my lactate threshold. I never had a dedicated test for either of them, but when you run in races and you look at your max HR, you know it's at least as high :) and on some races (or even training sessions) the watch gave me LT updates, but less frequently than maxHr updates, and I have no way to know how accurate they are. (Maybe this is mostly because I don't know enough about lactate threshold, certainly not about how the watch can estimate it, and even though I think I do understand the meaning and why that is an important number for long-distance running, it's harder to say if whatever number the watch give is close or way off [like in case of the maxHR it is obvious that 158 is crap, if I reached 178 just minutes prior to that])

So given my not too high confidence level on Garmin's estimations, should I go with LTHR (that was last updated according to garmin connect 3 weeks ago on a random run: HR: 167bpm, pace: 5:21/km, and power: 293W or 4.33W/kg from a week ago) or with maxHR (and if yes, should I set it to 178, which would give me the max for the last 6 months, or 191 that I last reached 2 years ago?)

And one last thing: I saw videos explaining how to do all kinds of test runs (for lactate threshold, EPOC, Cooper's, etc) and I never did a proper one. The main reason is that even though I live on the shore it's not easy to find a place to run on a plain field. The other reason (that unfortunately was always true for me) is that I tend to have knee problems. I even went to physiotherapy in the past, and I know the importance of strength training, and I wish it was just the will power to do enough of it, but I still don't know what really causes it (when the physiotherapist asked where it hurts it wasn't the "usual" area for runners, more to the outer side) so I don't know which excersises are best for me (though I guess all of them are better than nothing, and none should do any harm) so I am a bit hesitant to do these tests as I know it would be like after a hard training or race, that I'll loose some days after it because I need some recovery (not just based on what the watch would recommend, but on the knee pain) But maybe it's really time to do one proper test, and set the maxHR, LT manually for the next 12 months...

flocsy said:

should I go with LTHR (that was last updated according to garmin connect 3 weeks ago on a random run

I recommend you (a) set 191 as your Max HR, (b) perform the built-in guided threshold test for running (running settings/training/workout library, with a chest strap. The test is challenging, but doable for a person used to various efforts in running. If you are not quite ready, just use 90% for LTHR in the zone definition and don't worry too much about treshold pace.

flocsy said:

Though given that 90% of the youtube videos talk about HR and less than 1% about power, and that I am a casual runner, and that older watches don't even have running power,

Even if you train with HR, power and running FTP is useful. Whether for intervals or tests, it is important to keep the effort steady during the interval. In theory, if you run in power zone 2, your HR will raise to HR zone 2, stay in it until it starts drifting up (maybe after 90mn)?.

The built-in test takes you through increments of HR targets from zone 2, to zone 5 in 5 steps of 4mn (3mn for the last one) and can/should get the detection before the last interval. You can use the power zone to help target the HR with a constant effort for each interval of the test:

- warm up

- interval 1 4mn: target steady 50% of power zone 2

- interval 2 4mn: target steady 50% of power zone 3

- interval 3 4mn: target steady 25% of power zone 4 (assuming FTP/CP is in the middle of zone 4)

- interval ...4 4mn: target steady 75% of power zone 4

- interval 5 3mn: target steady 25-50% of power zone 5

flocsy said:

But maybe it's really time to do one proper test, and set the maxHR, LT manually for the next 12 months...

Once you have your Max HR set, fine tuning with LTHR based zones and power is nice. You could keept it simple with % of Max HR zones. Alternatively, you could decide to use LTHR zones depending on how your training plan is set up. For training purposes, you will be just fine if you use LTHR zones aith LTHR = 90% of Max HR. After you have recovered and got the blessing of your doctor, you can do a test if you look for confirmation!

All this sounds like chicken-egg problem. No matter which one I try to do, it seems to somehow depend on something else. Either I need to open a new Garmin account and reset my watch or find the one test that doesn't depend on anything but the things it measures during the test itself. I hope the guided lactate threshold test is such. I'll try to do it in the next few weeks, maybe I'll get to a proper 400m track once.

Flocsy,

I'd suggest that what you experienced when you got a heart rate of 178 and the watch set your maximum heart rate to 158 was some sort of anomaly regarding the 178 heart rate. I've had a similar thing happen. On a recent run, my 965 showed a one minute heart rate above 180 with a peak at 192. Quite impossible, particularly considering that I was running at a moderate pace going downhill. Obviously there was something wrong. Not sure what. But I chose to ignore it and believe my assigned maximum heart rate of the low 170s.

If you set your maximum heart rate to 178 and use the suggested workouts, I think your watch will give you suggested workouts that are either at the high end of your capabilities or perhaps even beyond them. For instance with a 178 maximum heart rate, I would estimate that the watch will give you a Base run at about 135 beats per minute. In contrast, if you allowed your watch to set your maximum heart rate to 158, your Base run would likely be at about 115 beats per minute. Quite a difference. Do an experiment and try both maximum heart rates and do the Base runs the watch will give you with each one. See what works for you. Tempo and Lactate Threshold runs will require substantially higher heart rates. Let those workouts be the judge of what your maximum heart rate really is. When my watch adjusted my maximum heart rate lower, the prescribed runs became much more doable with less strain.

I agree that a 20bpm difference in the max HR setting is huge and it's important to set the one that's closer to reality. However:

1. my HR was really 178 during that run. We did uphill intervals. It wasn't just a bad reading it was what I felt also compared to similar intervals in the past.

2. My previous max hr was 191. It was from 2022, but then I had more than a year with an injury that stopped me from running. I restarted running 3 months ago so my problem was the opposite of yours: my fitness wasn't anywhere near to what it was 2 years ago, but from Garmin's point of view my max HR still was 191, thus my hr zones were high. So what happened was that I tried to run in zone 2-3, which I know would've been an easy jog 2 years ago but now I could hardly breath and I was still in zone 1 or below. That's when I thought: ok, I'm kind of someone new to running, like I just started 2 months ago. I need to take it easy (also what my trainer and my body said) but having 191bpm max hr makes it impossible, so I reseted my max hr and hr zones and hoped that it'll be set by the watch gradually (just as it was in 2021-22) and I thought that while my actual max hr could be 191 (or 189 'cause 2 years passed) I'll let the watch reach it when I'll get to these heights (let's say in my next race)

So now you understand that my problem wasn't between 158 vs 178, but rather 158 vs 191 (and opposite sign)