Sounds like perhaps you have what is called ‘muscle imbalance’ where if you naturally use the wrong muscle for an exerise/action, then it will take over from the correct one and become stronger that it should.
Looking at your running style, I think you your find Dr. Mann’s book very interesting. Particularly the part on frontside and backside mechanics.
To achieve maximum efficiency while sprinting, your foot should always contact the ground behind your centre of gravity, yours is too much infront so each step acts as a brake for a short time before pushing back.
You can see here the technique used by the worlds top sprinters in slow motion…