When running on a treadmill, you can adjust the incline. Obviously, it will take more effort to run on an incline. You might find that your power will be reported the same as if you are running on 0% incline. The reason is that our device depends on elevation change rather than incline to adjust the power reading. Outside this works well, and we have a work around for running indoor. If you use the Stryd app to record your run, you can adjust the incline in to match the setting on your treadmill. That will adjust the reported power appropriately.
Note that Stryd is considering incline detection for future releases.
If you have additional questions, contact firstname.lastname@example.org.