Notes
first 4 miles @ 7.0mph on the far left treadmill. Hot and HUMID in gym - went through 1 water bottle in the first 3 miles!
then for last 4 miles moved over to the "fast" treadmill with the fan - that helped a bit. Was able to up pace to 7.2mph and still keep hr below 150.
for the last 3/4 mile, turned on the speed - started at 8.5mph (7:03 pace), and gradually upped it to 9.5mph (sub 6:20 pace, I think). average hr for this portion = 168