Training speed prior to the speed phase of training shifts momentum building, pickup and reinvestment speed and well coordinated power application which is key to running the longer sprints well.

The philosophy behind this is simple. It's easier to run at a slow sprint phase for the 200m and 400m than trying to run faster after a lof of pace running. The latter is the cause of many injuries simply because the motor units and muscles are not adapted to the rate of force the athlete demands to run faster. This leads to muscle confusion, cramps and tight muscles due to sudden overloading of theneurons connected to the muscles.

For example: A guy lifting moderate weight in the gym and looking to lift heavy at a power lifting competitions. You will crumble under the pressure due to lackof exposure to the amount of weight and the subsequent adaptation.

Thanks,