I recently finished an English version of the DFB-UEFA B Course in Berlin. 24 “American” coaches traveled to Germany and took part in 2 and a half weeks of learning followed by exams. I put “American” in quotes because other than myself and the one female participant who live in Germany, one Polish guy who lives in England, and a Brazilian who lives in Brazil, the rest of the coaches who live in American were mostly not from America.
If soccer players want to run quickly, then they need to be producing a lot of force against the ground. There are two ways to do this; firstly, we can produce this force via our muscles when our foot is on the floor, or, secondly, we can have our foot moving at a very high speed once it hits the floor. For elite sprinters, it is, of course, a combination of the two. So, ideally, you want to have a large range of motion in which to accelerate the foot towards to ground (requiring good front side mechanics); you want to be able to accelerate the foot downwards (requiring good hip extensor strength); you want to contact the ground in the optimal position (requiring good sprint mechanics), you want to be able to absorb and reuse much of the force you apply (requiring good foot and ankle stiffness), and you want to be able to produce force quickly (requiring an optimal level of strength and power).