Connect misattributes activities and creates nonsensical suggestions

I do not know where the misinterpretations comes from, but I would double check the Max HR and the LTHR values. Since you have them measured in a lab, I suggest disabling the auto-detection, in order to prevent that they are set by the watch incorrectly.

You could also try master-resetting the watch to factory defaults, in order to see whether it then learns your level better. It may take a few weeks, though.

Using a chest strap is also highly recommended. Although you tell the HR measured by the watch looked OK, the watch (unlike the strap) is not at all reliable to read the HRV when you are moving. And it is the HRV that is used to detect your lactate threshold, and your respiratory rate. I highly recommend the HRM-Pro strap. Although it would work with much cheaper straps too, the HRM-Pro offers much more than just the HR and HRV. It also improves the distance and pace accuracy, adds detailed and accurate Running Dynamics, allows standalone use without the watch, etc.

It;s definitely weird.

My Max HR and LTHR are set by hand and correct. What's more is that the HR was detected accurately by my watch (I know my body and I was definitely running easy) and it was correctly placed in the right heart rate zones in the graphs, with 9% in Zone 1 (warm up), 87% in zone 2 (easy) and 2% in zone 3 (Aerobic) and 0 in any other zones. So, from this, to conclude this was a threshold run is just bizzarre.

But is the characterization of the run done by the watch, or by the Connect app once it receives the data from the watch?

I did notice that the watch estimates my Power threshold at 360, which seems very low. But then again, since HR is an objective measure and power output an estimate at best, it should not have any influence in this.

7789739 said:

What's more is that the HR was detected accurately by my watch

As I wrote, the HR is not all. The most important is the HRV, and that can be accurately measured only with a chest strap. So the advices I wrote originally still stand - either master-reset the watch to the defaults, and let it establish the baselines again in the next few weeks, or use a chest strap.

Ok, I will give it a try with the chest strap.

How does HRV enter into whether I am running close to my threshold or not? Isn't that just a matter of what percentage of my O2 carrying capacity I am utilizing? In general that works really well, for instance, to pace my races (I run a 5K, for instance half just below my threshold and the remaining half just above to incur some debt).

7789739 said:

How does HRV enter into whether I am running close to my threshold or not?

The HRV drops significantly when you cross the LTHR

... and another way that the HRV is used to detect the LT is the respiratory rate which is being detected with the help of the HR Variability too. Over the threshold, the respiratory rate rises too.

Interesting. I just ordered an HRM-Pro-Plus from Amazon. I'll try it over the next few runs and report back... I hope I don't have to reset the watch.

Thanks for the tips.

7789739 said:

I just ordered an HRM-Pro-Plus from Amazon.

That's definitely an excellent choice and you will not regret it. It's a must for any serious athlete. On the other hand, I am not 100% sure that the reset will not be needed anyway. Before doing so, try some runs with the strap for a longer time (1-3 weeks) before doing the reset.

BTW, to assure a long life to your strap, thoroughly rince it after each use, and do not bend it near the electrodes when transporting in a bag. I tend to wrap it around a rather large pack with a towel and some cloth, in order to prevent that it gets damaged by some bending. My HRM-Pro is 3 years old and serves still well (exchanging the battery once a year), while you can find plenty of complaints here on the forum from people telling it failed after just a year. The proper care is crucial.

... also when you get the strap, conduce the Guided LTHR Test with it. It is a workout that you can find in the Training menu of the watch. Once completed, see how well it matches the value from the lab, and choose whether you let the watch+strap updating the LTHR automatically, or whether you prefer keeping the lab value.