I have a vivomove lux which I have been using for 6 weeks. At the start of the 6 weeks I was a couple of weeks into the Couch25k, pretty unfit and the watch registered my VO2 max as 31 and my fitness age as 63 , over the weeks of regular running this went up to 32 and fitness age of 52.
I am now completing the last week of couch25K , and am running a solid 30mins . I have just run my furthest and fastest run yet and my VO2 has gone down to 30 and fitness age back up to 60. ??? I can say with absolute certainty that I am fitter now than I was 6 weeks ago so why doesn’t the data reflect this?