It probably means you should push the steps through a full range of motion; meaning the ankle, knee and hip will be in a straight line when fully extended. The gradual transition into upright position, where top speed is reached and maintained, will then come naturally ??? without effort or change in rhythm.
(1): You could try to focus on your arm drive, so that you fully drive them down & back (without giving away the arm-angle too much thou).
(2): You could delay your ???blast??? from the blocks with a step or two: Try to come out as fast and relaxed as possible (leaving the actual clearance from the blocks to the reaction when the pressure against the blocks is released), and starting your ???conscious??? drive on the second step out of the blocks. Personally, I think trying to push as hard as possible from the blocks will often result in stiffness that is hard to get away from in the later parts of the sprint. If you start stiff, you???ll finish stiff.