Hi all, thanks for considering my question. I have a late model phone (iPhone 13) on which I use the Nike Run Club app. Lately I have been doing a number of training runs on a good quality treadmill. If say I set it for 12 minute miles, slightly uphill, and I run for an hour, the treadmill says I ran 5 miles, but the Nike app says I ran 6.1 miles (varies slightly). I know the late model iPhones have hardware/software to detect pace, movements, etc., and the Nike app has an "Indoor" setting specifically for treadmill running. So which is accurate? I have to say there was no calibration on the treadmill, so I guess it knows how far I ran by running 5 miles of tread material across the rollers? But is there a way I may be running - in air longer, longer stride, etc. - which makes the Nike app more accurate? I do see my pace varies on the app, by mile. I thought about trying to calibrate by running outside, but the terrain is so varied I don't know that it would be an accurate comparison to what I am running on the treadmill.
Does anyone have an idea on this? Thanks!