The Research: Studies have clearly shown that as runners become faster, their stride length decrease. Therefore, the way to get faster is to increase turnover of feet and legs. Even those who lack a fast bone in their bodies will benefit from turnover drills because they teach the body to find a more efficient motion.
The Drill: After a slow mile warm-up, select a level and traffic-free stretch of road, trail or track. Without picking up your speed, count the number of times either your left foot or you right comes down in 30 seconds. Jog or walk for a minute or so and run back, counting again, with the goal of increasing the count by one or two. Repeat this four to six times, with the same projected increase each time but without a significant increase in effort.
How Often? If you do this drill once a week, you’ll intuitively learn to stay low to the ground with an increasingly lighter touch of the foot. You’ll see more progress when doing it twice. But you’ll lose two weeks of progress if you miss a week.