dbandre, the trampoline sprints have nothing to do with ground contact or force absorption. It’s all about teaching one to relax more quickly and more completely during the swing phase so less energy is wasted.
This is a re-classification of what you previously wrote.
Well, in order to perform the exercise you’ll be cycling the legs faster than in a real sprint. This will require faster activation and relaxation, and it should carry back over. Similarly, there was a bit under the Functional Flexibility section of “Supertraining” that covered the best way to teach muscular activation was through rapid contraction followed immediately by instand unloading. Trampoline sprints provide this while keeping impact forces lower than sprinting.
What happens with more compliant surfaces is they gradually unload and less compliant surfaces like concrete instantly unload and instantly reload. In the whole leg spring/leg stiffness debate you will not get around speed being related to stiffness. How fast one cycles their legs is a proprioceptive response of temporal and spatial awareness to prepare the body for landing within the limits which body can allow. The CNS will not get involved unless the reactive systems (Golgi Tendon Organs and Muscle Spindles) cannot process with enough efficiency to keep the system in stability with what the rest of the visual/temporal systems are processing. Once you introduce the CNS system into an activity were it is overriding autonomous response to stimuli to keep the system balanced you are not controlling what you perceive to be controlling at the spinal level and below, but with visio-motor sensory at the brain as well. For a beginner at this exercise it is hardly a relaxation exercise and one if they spent enough time with will auto-regulate at the spinal level to become better at. This is akin to skill re-acquisition, like how astronauts learned how to move on the moon, it’s a re-acquisition of locomotive skills to a different environment. I am pretty sure the guys who really study and research dynamic systems theory could pick apart the IS reasoning behind such an exercise much more than I could.
Like I said, I think “IS” does a lot of things that I believe are proper and that I would do, but their backing it up with “science” is misusing the scientific literature. This is were I think “IS” starts to fall into the “Guru” grouping. However there are things that “IS” does that I wouldn’t do.