After reading the new research on unscripted interval training, I tried it on Sunday and then again today. Both workouts went very well. I went into each session with no plan whatsoever about speed, length of intervals, length of rest intervals, or total duration of the workout. I just did them all by feel, and it worked surprisingly well. You do end up moving at a higher average speed during the workout.
It also occurred to me that this is what I did back in 2001-2002. Back then I ran on a hilly trail at a local park. I did intervals of various lengths and intensity, all based on what I felt like on a given day. It's funny that such an unstructured but intuitive approach is now backed by some science.
