A Breakdown of Acceleration Mechanics and Other Considerations
1) Stride Length = Short to Long Starts off short and increases until maximum velocity is reached (when the stride length is optimal)
2) Ground Contact Time = Long to Short Ground Contact Time is the amount of time each foot spends on the ground. It acceleration is longest at the beginning as the body is trying to overcome inertia, (the weight of your body fighting gravity) to try and create velocity through force application. This takes a great deal of strength.
3) Shin Angle with ground = Small to Large The shin angle is going to determine the force application to the ground and the projection angle that the athlete is going to drive out at (roughly 45 degree projection angle is ideal). The shin angle opens up and increases throughout acceleration and into maximum velocity.
4) Velocity = Slow to Fast Velocity is both the speed and direction that the body is moving. As the athlete accelerates, the rate and distance will increase with time.
5) Stride Frequency = Slow to Fast Like ground contact time, it starts off slower (though still quite high) and increases until stride frequency reaches optimal level at maximum velocity.
6) Heel Recovery = Low to High Heels should recover quickly, with limited backside mechanics and shouldn’t involve large amplitudes of motion behind the hips. During acceleration, especially the first 6-8 steps, you want to minimize your backside mechanics. Backside mechanics in sprinting, are movements occurring behind the center of mass. To put this more simply, think of the drill ‘butt-kicks’ as having a lot of backside mechanics and a drill like ‘high-knees’ will have little amount of backside mechanics but a lot of frontside mechanics. Coach Latif Thomas likes to use the ‘running on hot coals’ example to give people an image about how to quickly recover their heels to their butt.