The difference between download heartrate and the heartrate direct from my strap?

I am not sure what exactly you mean. Could you post screenshots of the two different graphs? Also, which watch, and which strap model do you use?

When I use my Garmin Fenix 5x Plus along with my Garmin Triathlon heart rate strap for running (connecting it to my watch), I immediately read my data on the watch afterward. I can see my VO2 max and aerobic or anaerobic status.

Later, when I check the running activity: history - activities - today, and choose to 'download heart rate,' it retrieves the heart rate data from my strap. However, I often notice differences in VO2 max or aerobic status compared to the real-time readings on my watch.

Shouldn't these data be the same since I'm already reading my heart rate data with the chest strap? Why are the 'downloaded heart rate data' different than without the download?

Tamara1980 said:

Later, when I check the running activity: history - activities - today, and choose to 'download heart rate,'

Where exactly? In Garmin Connect? I am not aware of such option there. Or is it on the watch? If so, then you better ask on the Fenix 5 forum - there is a bigger concentration of people able to help with that model. On the recent models that I am familiar with, there is no download function either, the data is being transmitted from the strap to the watch either live (when dry and connected), or automatically upon saving the activity (at swimming/diving activities).

However, if you use the strap for swimming, then during swimming the strap is not connected to the strap (the connection does not work underwater), so the watch calculates the metrics using the wrist optical HR sensor, which is much less accurate than the strap, hence there may be indeed quite significant differences once you download the data from the strap.

Thanks! It’s on the watch after running. I’ll check it on the Fenix 5 forum. Thanks