Some kids are fast.
My son plays 10-year-old soccer. A few boys on his team are quicker than others, and the speed is easy to see and does not escape parents' attention.
One of my friends wants to help his son run faster, and he thinks his son needs physical fitness. I was intrigued because his son seemed as physically fit as the other boys. Last night, I found my friend at the soccer fields. His son was fully immersed in a private coaching session with an instructor legendary for drilling physical fitness. The boy was running hill repeats. “The coach is building his physical fitness so he runs faster.” I nodded but wondered if that was what was happening.
Running Speed = Stride Length x Cadence (Steps per minute)
Running is simple. If you want to run faster, you must increase stride length, cadence, or both. Differences in running mechanics seem to be the principal difference between the faster boys on the soccer team. Some kids figure out how to make their bodies move efficiently sooner than others. The fast boys lean forward when they run, not wasting energy and stride length on unproductive vertical bouncing. (I see this often with adult runners. There is an evident hopping in their running stride instead of a drive and push forward.) The fast soccer boys have a high knee drive, which opens their hips, leading to greater stride length.
Cadence is the second part of the equation. You will run faster if you take a bigger stride length more quickly. Cardiovascular fitness now becomes the limiter. Think of when you sprint. You know the feeling of chewing up massive ground with a powerful, quick stride. Why can’t you do this forever? Your cardiovascular system cannot keep up, delivering oxygen and blood to your rapidly firing muscles. Your muscles fatigue and stop firing from the strained workload. Your body runs out of energy, unprepared to burn stored fuel at such a high rate. We train to improve all these systems: cardiovascular, muscular, and energy.
Hills are speedwork in disguise. Yes, hill repeats are explosive efforts taxing cardiovascular fitness and building anaerobic strength. But that is not the foremost benefit of running hills. Hills force good running form. You cannot run up hills with incorrect form. You must lean forward with a high knee drive and quick turnover. Hills teach your body correct running mechanics, which inevitably translates to flat-ground running.
Next time you encounter a hill in your run, embrace it. Lean forward, drive your knees, and increase your cadence. Feel the forward propulsion of each step. Remember this form and keep going when you crest the hill to flatter ground. Your next mile might yet be your fastest.