Notes
10 minute warm-up, then
10 cycles of 3 min Fast (9.0 mph), 1.5 min Slow (6.0 mph, with some 3.3 mph walk/water breaks),
then jog to complete 8 miles.
My peak HR in each cycle (other than the first) was about 164.
Did not seem like I was pushing it all that hard. I could have maintained the 9.0 (6:39) pace for quite a bit longer than 3 minutes.