Balanced Runner Keys Series: Land with a Supple Leg to Optimize Your Footstrike

Two views of stiff vs. supple legs just before footstrike

For years – since roughly 2004, in fact – I’ve been telling people to avoid heelstriking and overstriding, and instead to aim for a midfoot/forefoot footstrike underneath you. In many quarters this is considered to be the very heart of good running form, especially since Daniel Lieberman’s well-known research supports it. For a quick overview of the basic principles, take a look at this video:

But today I’m here to tell you it’s time to move on. Years of subsequent footstrike scrutiny by researchers such as Lieberman and his team as well as people like myself make it clear that footstrike is variable for every runner, even experienced barefoot runners, depending on speed, terrain, fatigue, and probably other factors as well. I wrote about this from my personal experience here.

Why You Have to Overstride

Every runner overstrides to some extent. It’s a biomechanical requirement of running. Jay Dicharry explains this quite well:

“When running at a steady speed, your foot contacts the ground in front of the body, so from the point of foot contact until the foot is directly under the center of mass, you are in an energy absorption phase. Most folks call this the braking phase. Even though this is totally accurate, we are avoiding this terminology right now because runners get bothered by the idea that they might be braking when they are running. In fact, some of these new proprietary running styles have told runners that they should minimize braking at all costs and land directly ‘under their body.’ While minimizing braking forces sounds nice, it’s not exactly true. To run faster you actually need to store energy in the loading phase so you can release it later.

“Unless you are accelerating, your foot always lands in front of your center of mass, and in fact this is a very good thing. The whole point of landing in front of your body is to store elastic energy…If you struck directly under your body, your muscles would actually have to work very hard and produce more energy, at a greater energy cost to you… Contacting in front of the body stores energy inside of the tendons, just like pulling back on the rubber band stores energy in the slingshot.”

Jay Dicharry, Anatomy for Runners, p. 145-146

In other words, an optimal amount of overstriding for your current speed is essential, while overstriding excessively–more than you need to properly load your tendons–more accurately describes the overstriding Lieberman talks about.

The Sharp Spike of Impact

The main reason we’ve come to care so much about heelstriking and excessive overstriding is that they tend to result in excessive braking force and a sharp spike of impact that appears to be damaging to runners’ knees in particular. So let me emphasize, it’s not the heelstriking itself that’s the problem, but the sharp spike of impact it often causes.

Excessive overstriding also has the additional problem of putting your weight too far back relative to your feet for your whole gait cycle, so when it’s time to toe off the ground so you end up pushing yourself upwards more than you otherwise would. That can cause you to bounce excessively, which also increases your impact, creating a vicious cycle.

The thing you need to avoid is the sharp spike of impact. In trying to do this, though, it’s possible to go down a black hole of footstrike obsession, trying to figure out with every stride whether you’re heelstriking and/or overstriding. This is ineffective at best and counterproductive at worst, causing some runners to swap their habitual heelstriking for a prancing forefoot gait that doesn’t diminish the impact transient much but just shifts the stress from the knees to the Achilles tendons. It also drains most of the joy out of running.

In a paper entitled What Can We Learn About Running from Barefoot Running: An Evolutionary Medical Perspective, Lieberman writes this about the relationship between your footstrike, the impact peak associated with heelstriking, and leg “compliance,” or suppleness. (The abbreviations used are FFS for forefoot strike, MFS for midfoot strike, and RFS for rearfoot or heel strike.)

“…The other reason FFS and some MFS generate no marked impact peak is compliance. A RFS runner usually lands with a more extended and stiffer knee and ankle than a FFS runner, whose ankle dorsiflexes and knee flexes more during the period of impact, allowing the lower extremity to dampen forces more effectively…”

“…some runners who FFS had relatively stiff lower extremities and rates of loading that were higher than the most compliant shod landings. This variation raises the important point that a runner can alter lower extremity compliance in a number of related ways beyond using the elastic shoe heel, such as with shorter strides, more knee flexion, and less overstride (9). This point may explain why some barefoot runners sometimes RFS with no apparent discomfort (depending on surface conditions, speed, and other factors) and why some shod runners who RFS experience low impact forces.”

Lieberman, Daniel E. “What we can learn about running from barefoot running: an evolutionary medical perspective.” Exercise and sport sciences reviews 40.2 (2012): 63-72.

Stiff vs. Supple Legs

You don’t have much direct control over your footstrike. Your feet land where and how they must to prevent you from falling. In other words, your footstrike is determined largely by what’s going on above your legs, where most of your mass – and important parts requiring support such as your organs and brain – are located. In fact, your core action, or the movement of your torso, is the center of control for your footstrike (you’ll be able to read more about that in the upcoming blog post on Key 4, and you can also read this and this to get a sense of what I’m talking about).

Please stop worrying about your footstrike. If you follow all the Balanced Runner Keys it will take care of itself. Instead pay attention to the suppleness of your legs, which is an excellent indicator of an optimal footstrike, a healthy lean, and good core action.

Supple legs have softly bent knees and flexible joints. The ankles, knees, and hips are all relaxed enough to be able to bend immediately when the foot contacts the ground. Take a look at the image at the top of this post–the two pictures on the left are stiff legs, with straight knees. Those runners will feel a jolt every time their foot strikes the ground. Whereas the two pictures on the left are supple legs, with the knee at least slightly bent and the ankle more relaxed.

It’s also not a coincidence that the runner on the bottom left is clearly heelstriking and the one on the bottom right is poised to land midfoot, because the difference in tension between the two runners’ legs (and really their whole bodies) set up the foot and ankle positions. What I’ve found with my runner clients is that aiming for more supple legs, along with improving the core action, will also tend to optimize your footstrike without any direct effort on your part.

The original goal of avoiding heelstriking and overstriding was to reduce the impact peak and the damage it can do. If your leg is stiff when you meet the ground it doesn’t matter what part of your foot is touching down, you’re going to get a jolt. If your leg is supple and folds from the first moment you touch the ground, you are avoiding the harmful impact spike and using your legs like the springs they’re meant to be in running.

For more about landing with a supple leg, plus a demonstration of the difference between a supple leg and a stiff one, check out this replay of a YouTube livestream I did a few years ago:

And finally, to take action and learn how to land with supple legs and allow your footstrike to spontaneously optimize, try the free mini-course at the bottom of this summary page.


4 thoughts on “Balanced Runner Keys Series: Land with a Supple Leg to Optimize Your Footstrike”

    • A supple leg, as I describe above, is a leg that isn’t stiff and straight. The knee is bent and the leg is able to bend and absorb your impact. If that doesn’t happen naturally for you, drills won’t help much–they’re a weak tool for learning new things. Your first step should be to do my free Mind Your Running Challenge, which you can find by searching on this site. For more in-depth help, I’ve got some great options, including my online running camp and online 1:1 work. Look for that under “Get Our Help” in the menu above.

  1. What advice would you give when leg suppleness changes during a run? I often feel fine running, but if I stop (to cross the street, tie a shoelace, etc) my knee hurts and prevents me from landing with a bent knee when I start running again.

    • In that case, Rachel, you’re running in a way that stresses your quads and patellar tendons (I’m guessing about the part of your knees that hurt, but this is the most common one for the scenario you’re describing). You’re not stressing them so much that it changes the gait cycle while you’re running, but just enough that you can’t begin again the way you first began. Try this free mini-course and see if it helps:


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