I thought this might be of interest. It was to me at the time.
It is a result of my 1 mile repeats I have done since learning about CV/TP and this forum. what caught my eye was the 2012-08-08 lap 3:1 and the HR...compare that to 2012-07-10 and also see the speed difference. All these workouts (all my workouts are) on the treadmill, the only major consideration I can think off is my placement of the garmin footpod between two pairs of shoes. One is on top of the laces, the other in the Nike shoe cavity..
This is my last 28 days mileage and the Intensity Factor as per Training Peaks as a duathete.
Any other observations you can see. Let me know.