This post is the tenth in the series on The Balanced Runner Keys.
Today I’m zigzagging back to Balanced Runner Key #7: aim for a cadence of 170 steps per minute or higher. If you’ve worked on transitioning to more minimalist footwear or barefoot running, or have sought to learn from the natural running movement, you’ve encountered this recommendation before.
But in case you haven’t, let me start with a couple of definitions. Your cadence, or stride rate, is the number of times a foot touches the ground per minute. In most discussions on the subject each footstrike is counted separately, so you count both your right and left feet.
Research into barefoot running consistently shows that habitual barefoot runners naturally run with a higher cadence than people who are used to running in conventional cushioned trainers. The barefooters are above 170 and the shod folks often run with a cadence of 150-160.
Research by Lieberman et. al also indicates that overstriding and heelstriking, brought about by reaching in front of yourself with your foot, cause a sharp spike of impact that particularly stresses the knee. Running with a higher stride rate tends to decrease your stride length, preventing you from reaching your foot out in front of you and causing this problem, so in that way it helps to reduce running injuries.
This excellent brief article summarizes the research-supported benefits of a higher running cadence. The writer counts a whole gait cycle (landing with right foot and left foot) as one “stride,” so double his numbers to avoid confusion with my blog post and many other articles on the subject.
However, beyond considering injury risk and impact forces, there’s a more fundamental reason to aim for a stride rate of 170 or above, and that’s the elasticity of connective tissue. In each running stride, up to 50% of your energy comes from energy stored by your connective tissue having been stretched by your previous landing. However, tempo matters, and your tissue won’t spring back very well if you’re moving too slowly. At slower stride rates, below approximately 170, you don’t benefit as much from this property of your body and have to use your muscles more to generate energy. And who wants to do that unnecessarily?
The explanations I’ve encountered about this have always used rubber band metaphors – if you stretch a rubber band and let go quickly, you can shoot it across the room. But if that same rubber band stays stretched too long, say, wrapped around a big stack of envelopes for a year, when you take it of you’ll find it doesn’t snap back, having lost its elasticity.
That metaphor isn’t bad but leaves you picturing your whole body strung together with rubber bands, and considering how frequently rubber bands snap, and how skinny and overall unreliable they are, I’m not sure that’s such a positive image. Fortunately there is a much, much more accurate image, and I was lucky to stumble across it on my favorite podcast, the Liberated Body, in an interview with biotensegrity pioneer Stephen Levin, MD.
Simply put, our bodies are governed by tensegrity at every level from our overall structure to the level of individual cells. And our tissues’ viscoelasticity, or the ability to be either soft and yielding or hard and resilient depending on the nature of the force that’s applied is thus a basic property of our bodies. (This is a complex and utterly fascinating phenomenon I’m only just coming to understand myself, so if you’re intrigued I highly recommend you listen to Brooke Thomas’s full interview with Dr. Levin.)
And where in nature can we see this property at work and understand how it works in our bodies? In cornstarch. Forget rubber bands, cornstarch mixed with water shows you exactly why having a stride rate above a certain threshhold keeps you resilient and returns so much of your energy from the ground back to you. You can watch it at work in this YouTube video of people playing on/in a giant vat of cornstarch in a shopping mall in Kuala Lumpur.
My colleague Julia Pak kindly translated the video for me – the gist is that the white goo is just starch mixed with water, and if you move fast and hit it hard it is hard, pushing you back out. But if you move more slowly and let your weight sink into it you literally do sink. As Levin explains in the podcast, our bodies are exactly like this when we run (though he talks about landing on the heel, which in fact we don’t do that much of ) The impact forces of your landing, applied quickly, turn your tissues hard and resilient. Slow it down and it doesn’t work quite so well. Move very, very slowly and you’ll be flexible enough to do yoga (or closer to it, anyway). Same body, different forces.
As far as I’m aware, nobody knows for sure what the exact magic number of steps per minute that optimizes our viscoelasticity for running, or even whether it’s exactly the same for every person. Coach Jack Daniels observed 180 steps per minute and others have found something similar, the latest thinking is that the threshold is probably somewhere above 170ish.
On a practical level, when you start experimenting with this you’ll find the gooey 150s and 160s don’t actually feel so great and are tough on your body. Furthermore, you will find you end up running a bit faster with more frequent, smaller strides than with slower, larger ones.
If you’re used to running with a low stride rate, the simplest way to adapt to a higher stride rate is to get a running metronome – either a gadget that clips to your waistband or an app for your smartphone – set it for 170ish, and match your steps to it. But like everything else, don’t force this, because running with a higher cadence isn’t just a matter of turning up the speed on your usual biomechanics, it involves actually changing the rhythm of everything in your body, and this will take a while to figure out.
You’re more likely to be successful at it if you don’t just try getting it right, but instead experiment and play with it. Warm up and then, over the course of an easy run try 4 or 5 different cadences, some too slow, some too high, and switch among them several times. Then try to home in on a cadence at 170 or above that feels like you can settle into it. Another game you can play is changing your speed WITHOUT changing your cadence – try a couple of different cadences and speed up, then slow down while trying to hold the cadence. This one might be good on a treadmill.
Learning requires experimentation and exploration, so approach this with curiousity and a readiness to try a bunch of different things and don’t be in a rush to get it right, and you’ll likely end up with running that is more biomchanically sound and versatile in ways that go way beyond your stride rate. Have fun!