Use Functional Threshold Power to Determine Workout Intensity

From Slowtwitch

Rich Strauss from EndruanceNation.com:

I don't work with aerobic threshold. I think like this:
* Establish FTP
* Work at percentages of FTP to achieve certain adaptations:
o To lift FTP (get faster), do intervals at 95-100% of FTP
o To rack up a lot of TSS/hr (train time-efficiently), ride at 80-85% a lot. This is also HIM specific intensity, roughly
o To focus on IM specific stuff (intensity, positional adaptation, and generally get good at all the stuff you'll do in an IM bike), ride at 68-75% of FTP.
These go into a training mix and think of it as the ingredient slidersorwhatever on the Infinit site. Depending on where you are in the season, time avaiable to train, how close you are to your race, you move these sliders left or right.
I'm not very concerned with what's going on in the body. Focus on what you can do, express everything as a percentage of what you can do, and if you want to get better at a thing, do that thing. Life, not a spreadsheet, dictates how much time you have to do a thing.