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Yet another study advocating shorter, quicker strides when you run has just been posted on the Medicine & Science in Sports & Exercise site. In this one, researchers at the University of Wisconsin had 45 recreational runners run on a treadmill at their preferred stride rate, then increased or decreased the stride rate by 5% and 10% (keeping speed constant, so a faster stride rate resulted in shorter strides and vice versa).
The results aren’t that surprising: Increasing stride rate by 5% or 10% reduced the mechanical energy absorbed by the knee joint by 20% or 34% for each stride. The ankle joint didn’t change much, while the hip absorbed significantly less energy only when the stride rate was increased by 10%.
Of note, the researchers point out:
[M]any of the biomechanical changes we found when step rate increased are similar to those observed when running barefoot or with minimalist footwear.
So you could read this as an argument for minimalism — or, alternately, you could conclude that you can get the benefits of going barefoot simply by shortening your stride.
Three caveats. First, if you shorten your stride, you’ll take more steps to cover the same distance. Last year, researchers from Iowa State used a computer model to predict that, for a 10% increase in stride rate, the benefits of gentler foot-strike outweigh the downside of taking more strides in reducing your stress fracture risk. Still, it’s hard to know whether this conclusion is generalizable to other injuries. Second, studies have found that deviating from your preferred stride rate makes running feel harder, though there’s conflicting evidence about whether it actually makes you burn more energy. So this tactic might be most appropriate, the researchers suggest, when you’re returning from an injury and reduced load is more important than efficiency. And third, the study — as with virtually all the studies in the ongoing Shoe Debate — is a kinematic one that makes big assumptions about the connections between joint forces measured in the lab and ultimate injury rates. No one really knows whether “a more flexed knee at initial contact with less peak knee flexion during stance” will translate into a lower injury rate.