Notes
First attempt at a Fartlek run, and I tried to do it on a Treadmill. I may have overdone it when I ramped up a "hill" to the max incline of 15% and "bounded" up the hill the way it's shown in the Lydiard video. HR went WAY up (over 180?), and my achilles felt a bit tight for a little while.
Overall, it was fun to do some "fast" running. I had a few 2 minute bursts up to 9.5 mph (6:18 pace), and those felt great!