This post is part of the The Balanced Runner Keys series.
If you’ve given even a moment’s thought to your running form in the past two decades, it was probably either to your footstrike or to your core. My previous two posts in this series on The Balanced Runner Keys addressed the issue of footstrike; now it’s time to talk about the core.
The conventional wisdom of this era is that core stability is critical for runners. The Oxford English Dictionary defines it this way:
However in my experience most runners and even some fitness/movement/coaching professionals interpret “stable” to mean “still.” (If you are a professional who doesn’t make this error, good for you! I know there are many out there, so please don’t take this personally.)
In my training to become a Feldenkrais practitioner I learned the fundamental necessity for the pelvis to move to accomplish any well-coordinated action. This includes walking and running. Once you can clearly feel and see the pelvis moving it becomes difficult to imagine not being aware of it. However, the current preoccupation with core stability has hidden this movement in plain sight.
Core stability and pelvic stability are not necessarily the same thing — many of the traditionally defined core muscles are around the abdominal wall, attaching onto the top of the pelvis. But any time the pelvis moves, the abdominal region moves, so I’m going to use the two interchangeably for this post.
We are generally unable to hold our pelvises entirely still when moving but we can substantially interfere with the movement, making it smaller, timing it poorly, and restricting it in specific directions. In addition, any injury that makes it uncomfortable to walk or run will cause you to alter how you move your pelvis to avoid putting weight on the painful side, and we tend to continue using this movement pattern long after we have healed, thus interfering with healthy, comfortable, and enjoyable running.
Why is it necessary to move your pelvis? Because we have two legs (usually) and neither is in the middle, so if you want to balance first on one leg, then on the other, you will have to change the shape of your trunk to enable you to shift your weight and keep from falling over. Remember how those “posable” action figures or barbie dolls you played with as a child were almost impossible to stand upright? Usually there was just one arrangement of limbs that would allow them to balance, and any other one resulted in a tumble. That’s because they couldn’t shift their pelvises (and in fact entire torso and head) to balance on different arrangements of legs.
Now what about the evidence? In this study, researchers looked at the movements of volunteers’ lumber spines and pelvises in walking and running at different speeds. They found that they moved in all three planes of motion, and furthermore:
“…there is a strong correlation between the amplitude of transverse plane lumbo-pelvic rotation and stride length during walking and running.”
In other words, to increase your stride length you turn your pelvis more. Since each person has a preferred stride rate which they stick to regardless of speed, the difference between one running speed and another for you will be your stride length. If you’re working hard to prevent your pelvis from rotating when you run, you will be restricting your stride length and thus limiting your top speed.
So that’s a pretty concrete reason why transverse plane movement (or rotation) benefits you. How about the frontal plane?
Movement of the pelvis in the frontal plane, meaning if you’re facing yourself in a mirror you’ll see your pelvis tip side-to-side like a seesaw, is part of your spring system. Between footstrike and midstance your free hip (the side of your swing leg) sinks, causing that side of your waist to stretch and your stance side to compress. Through late stance towards toe-off this reverses so that your swing hip begins to lift upwards and the stance hip pushes downwards, directing force into the ground. In tandem with the straightening of your leg, this raises your center of gravity and moves you towards flight.
Here is a video of me walking on my butt to demonstrate the kind of movement your pelvis makes in running. Note that the size of the movement is not necessarily the same as in running.
Here’s an animation of a skeleton walking and running showing the pelvic movement. Unfortunately this video is a demonstration of animation software and also shows reaction to external forces, so a ball keeps getting chucked at the skeleton during walking and running. Obviously that’s not relevant to the current discussion, please ignore it (particularly since it’s stressful to watch!)
These movements of your core should not be done intentionally when you run, and definitely not forced in any way, but should be allowed to occur and be regulated spontaneously by your nervous system as needed for your speed, effort, fatigue, terrain, etc. in any given moment. You also should not try to improve how you do these movements by trying to restrict anything, and especially not by trying to prevent your pelvis from tipping forward. As the study I linked to earlier showed, the pelvis also has to move in the sagittal plane, and furthermore the muscles that you would use to try to make your pelvis more upright are also muscles that need to work to create movement. They can’t hold and move at the same time, and especially not when you’re trying to control these actions consciously.
However you can optimize your ability to supply these movements by doing core training and movement learning experiences (a.k.a. Feldenkrais lessons) that help you feel how to coordinate them better. In my ten+ years of experience helping runners from beginner to Olympian, I have found this is the most important thing you can do to improve your running. Here are some of the key effects:
- Because it uses both the flexors and extensors to perform, this action of your core balances the effort in those muscle groups and thereby regulates your footstrike, preventing you from landing with an exaggerated heel or forefoot strike or overstriding excessively.
- Because it shifts your weight properly from leg to leg, it helps increase the support and power you get from your legs, improving your speed.
- Because it allows you to shift your weight to wherever your legs need to be (within reason) it improves your versatility and especially your ability to run on uneven terrain such as trails.
- It also makes your running at least subjectively more economical by reducing the efforts you make to fight yourself.
- For all the above reasons, it generally makes you feel fluid, free, and fantastic when you run.
When I use Feldenkrais lessons in workshops to help runners feel how to move their cores better they tend to PR in their next race. I’m not kidding, it’s that powerful. So forget about stability and get your core into action!