VO2 Max and Race prediction are tremendously off overnight

9552419 13 days ago

Hey everyone,

I had to send in my old Forerunner 245 because of dead pixels and used an unused fenix 2 for a week before getting a new Forerunner 245. After connecting the Fenix 2 my VO2 Max dropped from 47 to 30 overnight. It told me I had the physical fitness of an 80 year old. The training status also disappeared, and the race predictions increased tremendously overnight. It went from a 22 minute 5k to a 48 minute 5k. I thought I’d give the new watch some time to adjust. After 3 weeks the new Forerunner has barely adjusted. The VO2 Max has increased by 1 and the watch continues to tell me crazy race predictions, even though I ran distances like 5k in 25 minutes and 10k in 53 minutes in these 3 weeks. Generally, I don’t care too much, but the watch cannot give me the correct training status and is completely off with calorie data, which is annoying.

I have deleted both my old Forerunner and the Fenix I used for a week.

Can someone help me?

0 Scott12345 11 days ago

Can you verify that your HRMax and HR zones are accurate have not changed with the new watch? VO2 Max estimates depend on how they are set (e.g. an 8:00 pace at 90% HRMax will give a much lower VO2 Max than an 8:00 pace at 60% HRMax). You may want to increase the HRMax setting and see if your VO2 Max improves. Also check that weight, height, etc. are correct (this would affect calorie calculations).

Does the heartrate data also look ok on your runs? Are you using the optical sensor on the watch or a chest strap? Are there any spikes or does your heartrate get stuck near your running cadence (cadence lock)?

VO2 Max estimates also require running outside with GPS, for at least 10 min continuously, at an HRMax of 70% or greater, according to Garmin.

Barring all that, there are some sites (such as runalyze.com which is free) which will calculate an effective VO2 Max for every run based on your pace and heartrate data, and will predict race times from that.