I have a Garmin Footpod which has been calibrated via outside running. It tracks reasonably well with the displayed speed on the treadmill (+/- 0.4 kph). And I would also add that the RPE feels about right for the speed being reported.
However, my HR seems low compared to the same run speed outside. For example 4:45/k will be 126bpm on the treadmill (1% grade) and 133bpm outside (flat/windless/tarmac). Does this seem right?
I’m struggling to reconcile the ‘other’ factors that could be at play. Hills, weather, soft ground, etc.
And if this HR variance is right then the next question is, should I be running quicker indoors to compensate?