I neither agree nor disagree with the basic premise of this post, but I do have an observation to offer on the upper/lower hamstring issue:
For maybe a month or three weeks now I have had self-diagnosed proximal hamstring tendinopathy--soreness in the hamstring under the "sit bone" of my butt. It still hurts to do things like hurdle stretches with the leg straight at the knee.
I tried running a 100 and a 200 on this ham, with disastrous times resulting--not only could I not go 100%, I couldn't stretch it out, and get that extra reach I need to hit top gear. It killed.
I have since experimented with different running styles, and I have found one that works: Kim Collins mechanic. Lots of recovery, stepping-over, and shooting the foot down rather than out and down, and landing the foot right under the body, using faster turnover.
How was I able to effect a Collins mechanic? By actively concentrating my hamstring efforts AT THE KNEE JOINT rather than at the hip joint.
How is this possible, you ask? I must admit, it's a pretty amazing thing to be able to do. It requires 2 things: 1) keeping the knee very slightly less than fully extended, and 2) slightly advancing the timing of the leg snapping down, by increasing arm turnover and letting the legs follow.
It FEELS like I'm using the lower hamstrings but not the uppers--it FEELS like the knee joint is more stable and that the knee joint is where the force is focused, and it FEELS like the upper hamstring tendons are painless, even relaxed--I know they're not, but what they ARE is they are carrying force at a very slightly different time, a time that does not produce pain due to the impingement or whatever is produced by the injury.
Using this I took a quarter-second off my 100 time, still going only around 90% effort, maybe less, and I am able to continue training.
Compare these two vids of Collins, who has quick turnover and snaps the leg down so that his foot contacts immediately below him, and a guy like Thompson, who extends the lower leg to a greater degree before sweeping the leg rearward at the hip:
Collins, around 8:05
http://www.youtube.com/watch?v=bXEMTyG37kg
Notice the angle of his lower leg as the foot is driven down to the ground--his lower leg barely, if at all, goes beyond vertical, except in maybe the very last stride, where he is extends and leans for the tape. (BTW, this tells you that his lean was timed absolutely perfectly...and it won him the race) The
Now Thompson, around 2:00
http://www.youtube.com/watch?v=SYHuylQcF8o
Notice that he achieves an angle beyond vertical with his lower leg (Frater in lane 1 is an even more exaggerated example, but he is difficult to see in this vid); but more than that, notice his timing, especially on acceleration: he first extends the lower leg, and THEN sweeps the leg rearward at the hip joint, rather than doing the 2 actions at exactly the same time, the rearward sweep is delayed, if only just.
I can do this, and it can be fast--but it KILLS the upper hamstring tendon...unlike the Collins mechanic, which doesn't bother it in the slightest.
Just an observation, that there are actions that can somehow emphasize, or de-emphasize, either the upper or lower hamstring, and any deficiencies present at these points.
Consider that Thompson has gone significantly faster than Collins, BTW, then think about what Francis was saying about upper and lower hamstrings.