We are comparing sled pulls with near 10% load to the sled marches stated in my blog post. I do hops for stiffness but working on isometric action instead of teaching yielding allows the the athlete to accelerate better….we are trying to shift qualities to become better not be perfect as it’s impossible when doing any sled work. We know we are compromising things when you choose to do a drill or derivative as “nothing beats the real thing.”
Attached is the research showing that step length is shortened and swing times decreased when using the sled. Those kinematic differences are what we want to bleed into our running mechanics as the differences are what we need more of to get 8 steps in from blocks to take off point.
Many athletes have that problem and other problems popping up.