A Strong, Flexible Spine

If a genuinely new technique is to be discovered in running it is going to be important to challenge conventional wisdom and widely accepted thought. For example, I have been studying cheetahs and, most of the experts agree, cheetahs are fast because fo their flexible spine which adds spring into each stride. But in speaking of people, they say we do not have a flexible spine. Or do we... http://www.youtube.com/watch?v=6NckIdFl9Is
I found this video on youtube. Instead of saying we don't have a flexible spine, maybe it is more accurate to say we don't know how to utilize a flexible spine.
According to the following video (refer to minute 2:33), "runners need powerful leg muscles for long strides. The muscles bring the leg down hard launching the runner into the air."http://www.youtube.com/watch?v=S-zcA_mOa94
Ouch! Can anyone say, "Shin-splints?"
Yet in the same video, Scott Edwards, Ph.D., a professor at Harvard, says that cheetahs don't, and can't, get their power in the same way. He says cheetah's legs are too light and fragile to do it that way. He goes on to say cheetahs carry 60% of their muscle mass on their spine. In other words, they have light legs with a freakishly strong core that mobilizes their flexible spine.
(refer to minute 2:55).
I say, if cheetahs are faster than we are, maybe we should be trying to lighten our legs and load up on our core strength in order to achieve a power output from the flexibility of the spine instead of by "bringing the leg down hard." If a centralized spring helps the cheetah achieve 75mph, maybe it can help us break 35 or 40.