When compared to jogging in terms of technique, it would seem that fast running or sprinting, is considerably easier to maintain. However, there comes a point where we cannot physiologically run any faster. The key is getting as close to that boundary as possible. The responsible factors in increased speed are lean and cadence. Keep your focus on lean (fall) and cadence (pull, pull, pull) and avoid trying to over reach or overextend your foot forward to give yourself a "larger" stride. Also avoid driving the knees forward. Follow these simple rules and you'll be well on your way to running your new PR!