It is short to long, but 75-80% is tempo, not special endurance. In the IAAF article linked earlier, Mills talks about training (one of the 3 zones) in a 40 second/325 meter zone, which would be specifically intensive tempo. I take it he’s now talking about running the long part of short-long harder, as you are certainly not going to be running 60s at 80% and consider it speed.
Turning up the volume AND intensity for an athlete that has been injured the last 2 years? hmmmmm.
Anybody know when in the course of a season that Mills starts training speed? Talking about 50-80m, not 30 meter starts or sleds.