Hill training is designed to shock the muscles and central nervous by overloading them. The body will respond to a reasonable overload of this sort with faster leg movement and longer steps. A slope of ten to fifteen degrees is sufficient. Hill training consists of three phases: the run up, the run down, and the sprint at the bottom.
During the run up, run uphill 50 to 75 yards, while picking the knees up high and concentrating on a powerful feeling of bounding up the hill, pushing off with the toes with each stride. Strength and anaerobic, muscular endurance (the ability to perform at full speed, without rest) will be improved.
The run down is easier and quicker. The length of each stride increases, while at the same time forcing the legs to move faster. The central nervous system is overloaded by having to deal with the fact that you are "running faster than you can run," which resets its upper limits as far as speed is concerned. Relax and let gravity do the work but concentrate, it is easy to exceed your limits and fall.
During the bottom sprint, as you reach the bottom flat, carry your speed and even increase it for another 50 yards. Then gradually slow down to a slow jog. The bottom sprint convinces the body that it can go just as fast on level ground.