A sprint race, or even a rep in a workout, can be broken down into 3 phases. This is especially true if you use the 100 meters as an example and if you examine the technical components of elite sprinters. There is a start/drive phase, an upright running/max velocity phase, and a maintenance/minimization of deceleration phase. At the elite level over the 100 meters, that roughly divides the race into thirds.
The phase changes are not robotic and are barely noticeable. There are several elements which are critical in each phase.
As you come out of the start, the drive phase requires a gradual change in horizontal to vertical force application. This is reflected in a subtle rise over 15-30 meters (depending on the athlete and distance raced) toward the upright running form. We go from big, pushing steps to fast, snapping strikes as the body transitions from a 45 degree angle relative to the track to almost 90 degrees.
Once you are into upright form, this is where you really hammer the speed. It's where you want to hear those crisp sounds of your feet hitting the track and everything is in sync, (arms, legs, trunk) moving as quickly as possible.
In the maintenance phase, we are trying to maintain that max velocity. In reality we are hanging on, keeping everything together, and trying to minimize the inevitable slowdown. Here, it's important to learn to apply effort in the presence of mounting fatigue. Avoid straining and stay as relaxed as possible.
It's incredibly fun to explore these concepts. The net result is that you will get faster. Sprinters are like gunfighters. Smooth is fast. Fast is smooth.