Does Health app use Nike Run Club data for VO2 max readings or should we only use the preset Apple Outdoor Run workouts?

Hi - don't fully know the answer to this. I do get VO2 max readings after using Nike Run Club provided my iWatch is connected to my iPhone during the run. (If it is not connected and I upload the data later then I do not get a reading.) However, when I look at the data I see the VO2-max data is being measured after the NRC run has finished and has been uploaded to Apple Health. (If you look at "all data", you can see the timings of when runs are started, finished and uploaded and the same for VO2-max.) So my suspicion is that it is not using the NRC data but making a reading shortly after I have finished my run. I do not know how that works since I am usually not moving very fast though my heart beat is high as I recover. I thought apple was computing VO2-max from a combination of speed and heart rate (see https://www.firstbeat.com/wp-content/uploads/2015/10/white_paper_VO2max_11-11-20 142.pdf).