05-20-2025 00:57
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

05-20-2025 00:57
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
We started with requesting the Cardio Load, but it looks like the Web API doesn't return the correct values. For a test device we see vo2Max range results on days that we didn't use the test device (for example May 10 and 11), we see a vo2Max range for the current day, while the Fitbit app shows that there is no cardio load (yet) for the current day (May 20), and we see wrong values, for example on May 18 we see a cardio load of 82 in the Fitbit app, but a 45 - 49 range via the API.
We are sure we retrieve the data from the correct Fitbit account, other data from this test account can be read properly from the API.
Is this a known issue? Do we need to provide more information? (showing the JSON result of the request doesn't work here, too many not permitted data items in the JSON like dates and ranges)
05-26-2025 16:31
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post



05-26-2025 23:40
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

05-26-2025 23:40
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
Hi @IncaFitbit ,
Thanks for your response. For these cases there is no run with GPS data. But the Fitbit app shows a VO2 max value, like 82, but we receive for that day a range of 45 - 49. We can't explain to users why the user sees in the Fitbit app a VO2 max of 82, while we show a much lower value range (in this example we will show 47 as the average value for the range).
I assume that without run with GPS, there should not be VO2 max data visible in the Fitbit app for that day (and we should not receive any VO2 max data for that day through the API), or the VO2 max data should match between what Fitbit shows and what the API returns.

06-25-2025 08:28
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post



06-25-2025 08:28
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
Hi @Hielko
While there could be an issue with the mobile application or endpoint showing mismatched data, it would be important to show us a picture of the user's mobile app showing the data and the VO2 Max value, and your VO2 Max endpoint response so we can compare. If you can get this information from your user, please submit a support ticket, https://dev.fitbit.com/build/reference/web-api/help/, through issue tracker so we can investigate.
Thanks!
Gordon

