When I run out of doors I use GPS (like everybody). At the same time, I have an old time Garmin foot pod on my shoe. I can see that my 945 recognizes the foot pod as it shows up on the start screen before I start a run. Would seem reasonable to conclude my foot pod is accurately calibrated for distance. What about indoors? On an indoor track I select 'Treadmill" as an option. The screen acknowledges both my heart monitor and my foot pod. Is the foot pod measuring my distance on an indoor run? Is there some sort of an accelerometer in the watch measuring my distance on an indoor run? Second part of the question. If my old time foot pod is working on my 945 will it still work when I start running on my soon to be delivered 965? Thanks to everyone in advance for your comments and opinions.