I would also look into the barefoot running shoes (I know doesn’t make sense). They esentially have little to no heel cusion and allow you foot to flex as close to naturally as possible. You need to run with a different style though or you will kill your back. the Midfoot strike style is how kenyans run. It increases lower leg strength and mobility and once you adapt to it it is more efficient at absorbing shock.
Basically you turn your legs into shock absorbers and springs, instead of landing on the heel of your foot and letting the energy transfer directly up your leg into your hip girdle and lower spine, you land on the midfoot (balls of your feet) and the leg is slightly bent under you, you are leaning more foward. Then when pushing off, you have a greater stretch rebound in the muscles. Anyways, Try reading up on it, and maybe try practicing it in grass or something barefoot. It really is a neat way to run, and is definately how you should be running sprints anyways.