DB can you please post vid?
What you are saying seems to support not using any resistance in sprint training. Stating that increasing stride length and frequency is going to create acceleration is pretty obvious and I doubt is going to be disputed. What is being disputed and discussed is which method(s) are going to create the best transference (and perhaps, which are best in certain situations). Without a video to understand what your point is on relation to THIS, it’s difficult to really advance the discussion in any way.
No it’s not. If Carl’s athlete acceleration pattern doesn’t match this which it doesn’t seem to do after the first 5 or 6 steps. Then stiffness is compromised especially if the stride is rate adjusted instead of stiffness adjusted for increased acceleration. This happens because we go from zero stiffness in the blocks to maximum stiffness at max velocity.
The use of sleds is to alter the stimulus for acceleration. It has it’s purposes especially for those who have the trouble of standing up. The best possible use of sleds is pulling them no longer 5-15m and have the force of the pulling the sled below the original center of mass. This forces the athlete to use more strength with decreased stiffness.
Acceleration is about pushing therefore I would say Nick’s suggestion about longer strides is correct in what you want in the outcome, but it has the flaw of being somewhat misleading as your steps should be shortened while pulling a sled, but it is more inline with improving the initial impulse. This is were the increased step rate of Carl’s athlete shows what should happen when pushing a larger mass is the best way to accelerate the added load.
Therefore a video shows nothing, but a series of photos showing a sled pull layered on top of a regular acceleration at ground contact at the same step should show you what is needed.