Is heel striking bad when barefoot running? Rather than rely on research, I'm experimenting with my own body.
But first a bit of background. I've been teaching yoga for 20 years or so. Plus I've been studying anatomy. And my focus is on feeling and controlling (as well as understanding) my body. And part of the reason for all of the following has been to fix problems I've had with my knees, hips and feet so that I can do the things that I love, like running.
One basic idea or assumption that I'm going by is that ligaments are active structures. They are affected by muscle tension. And one reason for this, the main reason, is so that they can pressurize the fluid within the joint capsules they work on so that bones of that joint are kept from butting against each other.
(Read The Architecture of the Connective Tissue in the Musculoskeletal System (by Jaap van der Wal) for more on this.)
If ligaments are viewed as passive structures, then they are only tensioned at the end of a range of motion of a joint. With active ligaments, ligament tension is affected by muscle tension. This means that ligaments can have tension even when the joint isn't at an end of its range of motion.
If each joint is suitable tensioned then the force from an impact can be transmitted past each suitable tensioned joint capsule.
The trick is making sure that each joint is stabilized (tensioned appropriately.)
Now before going into running it might help to talk about kicking and punching.
Kicking with the heel can feel a lot more solid that a forefoot kick. Though if the foot is suitably rigidized then a forefoot kick feels pretty solid also. But what do you imagine kicking down a door with, a heel kick or a forefoot kick? Personally, I imagine a heel kick would feel stronger.
Barefist punching a bag or wall, if you gradually increase striking force you soon realize that the hand has to be rigid when striking. And if you've ever punched with boxing gloves on, it's easy to fuck up you hand because it's hard to line everything up properly, at least that's my limited experience.
I much prefer bare fist punching because it's easier to get the alignment right on striking. And the last thing you want is any sort of rolling to absorb shock. It's the solidity of the joints that absorbs the shock of impact and it often feels quite good, not a pain at all.
So even if the idea of active ligaments doesn't grab you, the idea of having a solid punch or kick might, and a simple idea is to apply the same principle to running. What are you doing when you run? Kicking the ground, sort of. You could be forefoot kicking or your could be heel kicking or you could be flat of the foot kicking. In all cases, if your knees and hips are braced sufficiently then you should be able to strike with impunity.
At least that's the theory.
Does this mean you should just go out and start barefoot heel running on hard surfaces?
My own goal is to be able to switch between the three main modes (heel strike, forefoot strike, mid-foot strike) without a problem and still have feet that are flexible and strong enough to do everything else that I want to do. Plus, in the process of working through knee and hip and foot problems, I've got pretty good awareness of all of those plus the muscles that control them so I feel like I can heel strike with relative impunity.
So if you think you can approach heel striking intelligently, even scientifically, then go for it. But it might help to understand what you are trying to do when you heel strike.
The idea then is that with a heel strike (and for me it's the outer edge, more specifically the outer back corner) of the heel that strikes, I don't roll my foot inwards or outwards as I transition to the foot. Instead I maintaining foot posture as well as knee and hip posture as I pass through the support phase.
Do note, I've got something to prove. If ligaments are active structures, then proper muscular tension (since muscle tension affects ligament tension-that's what is meant by "active ligaments") should be able to protect the joints in heel strike running. So me going out and heel striking while barefoot running is an attempt to test the theory on myself first.
The first few times I tried heel striking while barefoot running on a hard surface (pavement), I hadn't worked out all the kinks in my foot and hip control and so had some problems. And my method was to run a few steps (sometimes as little as three steps, sometimes as much as ten) then walk, each time taking a brake to monitor hip, knee and foot mechanics before proceeding. And i stopped when I got too tired to maintain good form, which in my case was something that I was focused on feeling.
Anyway, this experiment is still in its early stages. But so far my own personal experience is that with body awareness in the right places, and the necessary control, it is possible to heel strike comfortably on a hard surface while barefoot running with relative impunity.
Now apart from being able to switch between three basic modes at will one possible advantage of heel striking while barefoot running is that if ligaments are indeed active structures, then heel striking while running barefoot might be one method of strengthening the feet, knees and hips, assuming that they are all working correctly in the first place.
If you've got problems in any of these areas, heel running or any sort of running may make the problem worse. But once you've got the problems sorted, then the barefoot heel strike (even on concrete) is just one more way of experiencing your body while running.
I should point out that in my experiments so far I'm not going super fast. Some might say I'm going super slow.
It may be that with faster speeds, the force of impact increases and so the natural tendency is to take up a more full footed landing or a forefoot landing to either spread the load or absorb the load.
But more on that as the experiments progress.
Here are some of the articles I found most relevant. Bear in mind I'm more biased towards more flexibly minded writing versus those who say "you must do this" or "you must do that".