high aerobic problem

You have correctly set the HR Zones and FTP if it's related to cycling? On the forum already exist few threads talking about this if this is the case.

nhorner said:

but not high aerobic which drops to zero

What do you mean by "which drops to zero"? When does it drop?

nhorner said:

Do you know why ?

It can depend on the type of workout. What was it? running with GPS? biking with a power meter? or something else?

Sorry, I meant that the high aerobic remains at zero despite the workout that is treadmill

On the treadmill, are you using a chest strap? Just want to make sure your HR is captured correctly.

How is the watch getting the pace information? Through the watch itself (no HRM Pro chest strap)? Or through a foot pod? Or through the HRM Pro strap?

Hint: using the watch alone (no GPS since indoor) is making it much harder to get an accurate evaluation of the trainign effect which relies heavily on the HR/HRV data, and also on the pace data (in particular for higher efforts like threshold, VO2 Max, Anaerobic, Power Max/Sprints)

This will definitely give you much better HR and HRV information for all your workouts. On the pace or running power side, the HRM Pro Plus will be calibrated automatically as you run outside with your best GPS settings. Then, you will get pretty accurate pace for indoor running.

The other 3 key benefits of the HRM Pro Plus: the ability to record the HR offline and then download to the watch (for cases where you cannot wear the watch during a workout. Eg.: martial arts), the true up of HR outside an activity through Garmin Connect mobile, and the count of intensity minutes when your device (eg Edge series) doesn't support them.

Etupes25 apart from the fact that the HRM PRO+ can record information on its own, is the accuracy very different compared to the HRM Dual?
For now I use the HRM Dual and it has given me good results, mainly in cycling and I think the other additional features of the HDRM PRO+ I wouldn't use since I always use my FR955, but I don't know if I'm overlooking something. Maybe when I upgrade my band I'll keep that in mind. Thank you very much.

G141592653589793238 said:

is the accuracy very different compared to the HRM Dual?

Check-out DC Rainmaker review here where he compares with other straps

HRM Pro

https://www.dcrainmaker.com/2020/09/garmin-hrm-pro-chest-strap-depth-review.html

I don't think you would upgrade because of additional accuracy. Once you avoid the limitation of wrist optical HR, any armband optical or chest strap that supports HRV will give you enough accuracy for good HR and HRV data.

In the OP case, there is also the need to capture good pace data indoors.