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Uploading treadmill runs with calibration-based estimated distance (no GPS)

  • September 6, 2026
  • 2 replies
  • 25 views

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Hi everyone,

We’re developing TreadSpeed, an iPhone treadmill app that estimates workout distance from a measured treadmill calibration profile and user-entered speed changes, without GPS or continuous speed sensing during the workout.

We’re exploring a user-initiated upload of completed indoor runs to the user’s own Strava account via the API. The integration is not implemented yet.

Has anyone implemented a similar indoor-running upload to Strava? What upload format and activity settings would you recommend, and how should we clearly identify the distance as estimated?

Thanks for any guidance!

2 replies

Jan_Mantau
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  • Hub Powerhouse
  • September 6, 2026

If it’s without sensor data the simple “Create Activity” endpoint would be sufficient. Else you have to upload a file with the “Upload Activity” endpoint. You could use i.e. the tcx format, but that depends on whatever is easiest for you to build.

There is no flag for an estimated distance. It’s not really needed anyway, treadmill distances are often if not mostly only estimated.


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  • Author
  • Hub Rookie
  • September 6, 2026

Thanks, Jan — that’s very helpful. Create Activity sounds like a sensible starting point for a workout summary.

If we later want to preserve interval speed changes and pauses, we could generate timestamped cumulative distance and estimated speed from our calibration profile and the user’s inputs. These would be model-derived values, not continuously measured sensor data, and we would make that clear in the activity description.

For an indoor run without GPS, would you recommend TCX or FIT for this? In particular, how should pauses be represented so Strava handles elapsed time, moving time and the pace graph as intended? Are there any required fields or common pitfalls we should be aware of?

Thanks again!