Question about Maximum Heart Rate Calculation

Garmin has "recently" improved the max HR detection and several users, including me, have been reporting very good results. So, after having ignored that auto-detection for months, it is now back on the watch. From public research, there are ways to estimate Max HR from age plus HRV and it might be the method used here (Garmin doesn't say).

The first thing you want to do if you care about the metrics is to wear an HR strap or a good quality arm band optical HR. There are too many risks of erroneous data with wrist HR.

Note that the watch can give you a Max HR that is higher than the peak HR of your last or any activity, or lower (if it has disqualified the peak HR data for some reason). Note also you can get a cycling Max HR after doing a run, if you have different sports zone.

The typical formula of 220-age comes with a standard deviation of 12bpm. This means that on average, "only" 68% of people will have their actual max HR within 220-age-12bpm, and 220-age+12bpm.

If you are a runner, here is a simple test for Max HR. Run your best 5km ever, take the peak HR of that run and add 5bpm.

Otherwise, just perform a field HR Max.

Another way to approximate is to divide your LTHR by 0.9. This has its limitations because the LTHR detection is (quite) influenced by the Max HR value you set: the watch is looking for certain changes in the relationship between HR and pace around 90% of Max HR. So, it is a bit of chicken and egg, but it could give a ball park estimate to start with.

Once you have max HR, run a new threshold test to make sure the LTHR is detected right.

Wrt to LTHR, it is best to rely only on the built-in test. These tests are "calibrated" ramps that helps to build the right data set for the relationship dynamics described above. The Auto-detection might by triggered during intense short intervals and be biaised by the work vs rest dynamics.

You are right to worry about Max HR is that is the single most important input from the user, aside from wearing a chest strap and provide good pace/power data.

This is one of the best posts I have read on this topic and just wanted to let you know I enjoyed reading it Etupes25.

Does the watch ask if we want accept the new HR max like it does for new FTP’s? Otherwise at least for me, would be useless.

Tks 

Yes, after new MAX HR detection, watch showing you prompt with new value and ask for acceptance.

Is that actually asking or is it informing?

For me it just says, "new Max HR detected", and there is a little line up near the start button that implies you have to press to accept...but pressing it doesnt really seem to do anything, and the only way I can get out of that screen to view my just completed activity is to wait a long time or press 'back'.

If I look, it DOES seem to accept these new Max HR detected announcements irrespective of what I click.

Thank you for all this information :-)  Admittedly some of it I need to learn more about to fully understand.  So in simple terms, if I take a look at a recent run (3.4miles / 5k) and see that my max HR was 174 (tho another one was 179), and to add in 5bpm, then ill have 179 - 184 as a new max.  Maybe split the difference and say 181?  

Because now, at 190bpm, I just think that is way too much?

It says in the app my LTHR is 170bpm.

- How do you perform a field HR max?

7828711 said:

So in simple terms, if I take a look at a recent run (3.4miles / 5k) and see that my max HR was 174 (tho another one was 179), and to add in 5bpm,

Wait… it needs to be your maximum effort 5k ever. If you are not going after personal bests in 5ks, then perform a field Max HR test. 5k PB and field tests are brutal and should take you to your maximum ability. If you are not used to maximal efforts over long periods of time, get your doctor’s blessing.

7828711 said:

If I were to manually input a lower maximum heart rate based on my age, how might this affect the calculations and dynamics of other metrics tracked by the watch? Loading, vo2max, everything really.  So, I need to learn on this so I can ensure I have it setup correctly. 

MaxHR directly affects some thresholds like the one between low and high aerobic, for example, or the ideal target for Tempo/Threshold training effects.

Pace is still an important variable as it can overtake the HR, in certain situations.

On the other side, LTHR looks like just a way to customize better your zones but it doesn't affect Garmin's metrics.

Thank you for that.  That might be a good idea (the Dr. part).  Maybe I can go and do a stress test and they can tell me what my max HR should be?  But, I am also going to look at your advice on how to do it on my own.  Thank you so much!  So, my max HR now in the Garmin system at 190, might not be that far off then.  I am SURE if I did a 5k at max effort my peak HR would be in the mid 180's...  so, if I added 5 to that, it would kinda make sense to be at 190.   It's just when I think about 190, and my age, etc..,  I just feel like that is death LOL.