Is a good stride a matter of many disparate elements coming together or one underlying virtue?
Running form is still a hot topic these days. Countless articles about running form have been printed and posted within the past couple of years, long threads on form keep appearing in online running forums, experts on running form are touring the country talking about it, whole books on running form have lately hit the presses, and running coaches all over the country are now teaching running form, whereas in the past they ignored it.
With all this communication going on, we must have a very clear idea of what good running form is, right? Not really. In fact, all of this communication about running form is going on precisely because we don’t yet have a clear idea of its proper definition. If we’d figured it out we would have fallen silent on the topic and moved on to another.
If you ask any given “expert” on running form what it is, you’ll likely get a response that consists of a laundry list of seemingly unrelated characteristics: a midfoot or forefoot footstrike, a slight forward lean, relaxed shoulders, eyes focused straight ahead, and so forth. To improve your running form, you must instill each of these characteristics in your stride. They will somehow add up to speed and efficiency.
Perhaps it’s the Plato in me, but intuition has always told me that, whatever it is, good running form must be a single thing, not a grab bag of things. And if you take a close look at the research on running form, you will find some pretty solid evidence that good running form may indeed be one single thing.
My current favorite researcher on running form is Stephen McGregor at Eastern Michigan University. McGregor uses three-dimensional accelerometers to measure various stride characteristics and plot them against running economy, as measured the old-fashioned way, through oxygen consumption in relation to velocity. In his research, McGregor has found only one stride characteristic that truly matters with respect to running economy: sagittal plane accelerations. In plain English, McGregor has found that the most economical runners slow down the least between strides, and the least economical runners slow down the most.
Other researchers have arrived at more or less the same place from different entry points. In a 2007 study, Finnish scientists measured a long list of stride characteristics in 25 trained endurance athletes and plotted these against running economy and maximum running speed. They discovered that only one stride characteristic was closely associated with both economy and maximum speed: ground contact time. The less time a given runner’s foot spent in contact with the ground, the more economical — and faster — he was.
A short ground contact time and minimal sagittal plane deceleration are more or less the same virtue. Or, perhaps better put, they are different ways of measuring the same virtue. The quicker you’re able to get your foot off the ground, the less you will decelerate. And the less you “hit the brakes” when your foot lands, the less time your foot will spend in contact with the ground. Short ground contact time and minimal sagittal plane deceleration are sort of like high club head speed and long driving distance in golf.
Now, a running form expert with a conventional perspective might grant that this virtue of short ground contact time/minimal sagittal plane deceleration (SGCT/MSPD) is the be-all and end-all of good running form, but he will likely say that this virtue is achieved through the usual assortment of good technique elements: midfoot or forefoot landing, slight forward lean, etc. He will say that these elements came first and have added up to speed and efficiency.
But the evidence suggests that this is not the case. The relationship between SGCT/MSPD and performance is much stronger than the relationship between the standard elements of good technique and SGCT/MSPD. In other words, you absolutely must have SGCT/MSPD to be fast and economical, but you don’t necessarily have to have a forward lean or a forefoot footstrike to have SGCT/MSPD. True, most runners with SGCT/MSPD will exhibit this characteristic, but not nearly all. The late Sammy Wanjiru, for example, leaned backward, not forward, when he ran. And 2009 New York City Marathon winner Meb Keflezighi is a heel striker.