If we bend the pogo stick in the middle it's very difficult for the stick to work to it's maximum potential. Step down to the ground - We should apply force away from the direction that we want to move. To move forward we push backward, backward we push forward, to go left we push right, and right we push left. A lot of coaches tell athletes to lift their knees when they run but they are missing half of the movement equation. Half of running is lifting the leg up the other half is stepping back down to the ground.
Speed is a result of stepping down to the ground with greater force.
This means to basically cock and load the ankle joint so it is ready to respond to the ground by only pushing against the ground. Technically as soon as the foot leaves the ground we want to focus on pulling the toes up toward the shin putting the ankle in a cocked position. If athletes land with their toes hitting the ground first the foot acts as an absorbsion tool, not a projection tool. If this is done correctly the ground becomes the triggering mechanism to tell the foot to push off the ground immediately upon contact, thus increasing force and speed. Arms - Speaking specifically about linear speed, arms are critical for generating greater speed.