Yah Nick, I'll still prioritize the ol' listen-to-one's-body approach, but if there's science justifying what our bodies have been telling us, so much the better, right? Tomorrow I'm going to try a 7.5-mile run at 10-minute pace. It'll be my first completely steady pace run in a month or so. On shorter runs I'm already close to a 9mm pace, and can do 8mm for 1/4 t0 1/2 mile intervals. Hopefully within 6-12 months I'll be able to run an hour at 8mm pace. That would feel good, very good. (I also like how redefining myself as a FT-kinda guy justifies my resurgence in strength-training, now that my left shoulder seems to be about 95% normal. I've been especially getting into the military press lately. I'm also switching more and more from 30 minutes of easy-to-moderate rowing to 10-15 minutes of high-intensity rowing. It's great rowing for shorter periods of time because rowing on a machine inside can be pretty tedious at times.)
Overall I'm just loving the variety of hills, fartleks, and steady runs. The last piece of my reworking of my workout regimen over the last year will be finally scheduling the workouts first thing in the morning. It'll be a mental challenge at first, so I'm allowing myself potentially one or two weeks of reduced workouts just to help me ease into it. I know my long-term ability to consistently exercise depends on making the switch to early morning workouts. There's just too much that can come up later in the day.
Anyway, here's something else of Magness's that I found on fast-twitch (FT) versus slow-twitch (ST) for runners:
http://www.scienceofrunning.com/2008/11/hs-training-neuromuscular-and-speed.html
Scroll down a bit to the section on: "FT athlete-Types of anaerobic development"
And be sure to check out all the red-lettered topics to the right of the articles. There's a lot of useful info there, and I've only been able to tap into a bit of it so far (I'm trying to reduce my weekly time spent on this stuff, now that I got 80% of what I need to know).