Fixed Pace Training

14 Miles on Treadmill.
Did a 2 mile w/u, then 12 miles at a 7:30 pace for 90 minutes. Average HR 139.
132,134,134,133,133,137,138,142,143,144,146,147.
Felt like a recovery run until about the 7th mile. There was a distinct point at the end of mile 7 where the effort level went up a notch. Then, again at the end of mile 10, I felt the same distinct change in effort; this one felt more like I needed some fluids.
Felt good about this test; I expected by HR to be higher after the Fixed HR test I did last week. But, a treadmill is different than the measured 1/2 mile I was running on outside on a windy day last week. I think I'm seeing evidence that I can run some of my long runs at an average HR in the 130's instead of the the upper 120's that I've been doing. Since the race I'm doing in Feb. is a 40 miler I still want to work on "mastering the distance." Maybe I could do some 20 milers in the 130's HR area and keep increasing my 30 miler at the very cautious pace I've been going for those runs...