Vibram Transitioning → Bone Injury

Via Runner’s World, there’s a new study out that looks at people transitioning from regular shod running to running in Vibram FiveFingers. The study is Foot Bone Marrow Edema after 10-week Transition to Minimalist Running Shoes. It will appear in Medicine & Science in Sports & Exercise.

And it shows quite a bit of injury to foot bones.

First, a bit of background.

With the advent of MRIs, it was discovered that bone injuries could be seen long before they became stress fractures. MRIs allow one to look inside the bone and see what the marrow is doing, and when the bone is injured, what they see is a build-up of fluids. This is called “Bone Marrow Edema”. From the study:

Although some overuse injuries, such as stress fractures and callus, can be seen on x-rays, a more sensitive measurement tool is necessary in order to detect early changes that may indicate the development of a stress injury. Magnetic Resonance Imaging (MRI) makes it possible to detect bone stress injuries of the ankle and foot weeks before radiographs would demonstrate osseous abnormalities.

It actually happens whenever you start stressing bones. There was a 2003 study, Can bone marrow edema be seen on STIR images of the ankle and foot after 1 week of running? in the European Journal of Radiology, that looked at what happened to feet when you started sedentary people running. These people ran in regular shoes.

Here are before and after MRI pictures of one subject’s foot.

Before:

Pre-running MRI

After:

Post-running MRI, with Edema

The edema is pointed out with the arrows.

But, you say, wouldn’t we expect some mild stress to show up? Isn’t that what promotes new bone growth to strengthen our bones? After all, I’ve talked here before many times about how those who regularly go barefoot have thicker and stronger bones. See, for instance, Lack of Support for Support.

The answer is that yes, some mild stress does show up. As a result, they’ve developed a grading scale, from 0 to 4, to rate the degree of stress. “0” is no stress at all; “1” is called “Remodeling”, and is exactly what I am talking about: the body working to build up the bones. However, “2” and “3” indicate too much stress, where the body is not keeping up with it. “4” indicates a stress fracture.

So, what did this new study do?

It took 36 runners who regularly ran shod (normal running shoes) and took half of them and had them transition to Vibram FiveFingers. It did MRIs on all the runners beforehand, and then did MRIs again afterwards and looked for any differences.

(Actually, they started with 43 subjects, but 7 dropped out for some reason. I should also add that I was quite impressed with the care with which this study was done and written up. The runners were also supposed to keep running logs, but some lapsed, or didn’t do it at all. The write-up tells us exactly how often that happened, and warned us about how that might affect the results.)

Here’s what the study says about selecting the runners:

To qualify for participation, runners had to complete an average of 15-30 miles/week for the 6 months prior to the start of the study. Subjects were excluded if they had ever run in Vibrams prior to the study or if they had suffered a lower body injury that kept them from running at least 3 days/week at any time in the previous 6 months.

Interestingly, the protocol for transitioning to using the Vibrams was the one from the Vibram website. Even more interestingly, they note that that protocol was changed sometime between the start of this study (January 2011) and today. I was unable to find a cached version of the Vibram webpage from them, so I don’t know just how they changed it. But it does seem to me that the change will not reflect well on how they do in the lawsuits against them. See, e.g., DeFalco v. Vibram and Lawsuit Against Vibram Survives Motion to Dismiss.

Side note: at one point, the study talks about minimalist shoes:

Minimalist running shoes are designed to allow runners to employ the same mechanics as in barefoot running without the risk of injury due to contact between the bare foot and the ground.

We’ve seen the same sort of comment in the lawsuits. Look, even a Vibram sole is not going to protect against a nail or large piece of glass. Most shoes really don’t protect all that well against such puncture wounds. (However, eyes, which are used more when you are barefoot, can be quite effective in that regard.)

Back to the study . . .

Here are the instructions to the runners.

Participants in the Vibram group were instructed to run one short (1-2 mile) run in the VFF during their first week of training. During the next 2 weeks, they were to run in the VFF for one additional short (1-2 mile) run each week, thus during week three, they would run at least 3 miles in the VFF. After the third week of running, subjects were advised to add mileage in the VFF as they felt comfortable, with the goal of replacing one short run per week in traditional shoes with a short run in the VFF. The flexibility of this protocol was chosen to allow the subjects to transition as they would if they had just bought the shoes and were not participating in a research study.

The results were actually fairly dramatic. The control group, who continued to run in their regular shoes, showed no changes. The Vibram group, however, showed a marked increase in bone edema. Half of them showed an increase in at least one bone. Two of the subjects got stress fractures. By the way, while soft-tissue injuries also show up on MRIs (like tendon injuries or plantar fasciitis), running the Vibrams didn’t seem to make a difference in that regard.

Here is their Table 3 that shows all of the Marrow Edema Scores (MES) for the different runners.

Table 3. Number of bones with marrow edema scores greater than or equal to 1 during the post-test MRI for commonly injured bones in runners.

To interpret that, when it says “5b/3s” that means that 3 subjects had an MES of 2 on a total of 5 bones.

Frankly, that’s pretty damning. All of the significant changes happened with the Vibrams.

One other item of note: most of these poor results came from women. As they point out:

Of the 11 runners who had MES scores of 2 or greater in this study, 8 were female. This may suggest that female runners need to focus on a slower transition to VFF running shoes even more than male runners.

To some extent, that is buried by the lede. I don’t know what it means (and neither do the authors). But it has to mean something.

So, what should we take from this?

What I want to take from it is that, as usual, Ken Bob Saxton really knows what he is talking about.

The problem with “minimalist” shoes like the Vibrams is that they remove the all-important sole-to-ground feedback of real barefoot running. When you start running in a minimalist way, your entire foot is unprepared and unconditioned. But if you are truly barefoot, your soles will tell you when to stop (not some Vibrams website). Your soles will tell when when enough is enough.

But when you have the Vibram’s artificial sole, you get nothing. You can go way too far without realizing it, and then the next day, go ahead and do it again. And next thing you know, you have a hidden bone edema, and then after that, a stress fracture.

Another thing that this study didn’t get at is whether the Vibram runners were running correctly for being minimalist. The protocol had them running sometimes in regular shoes and then occasionally in Vibrams. That’s practically guaranteed to ensure that you are running incorrectly—maintaining an odd landing. See, yet again, How Barefoot Running Works (or at least how it is supposed to work). I really doubt that one is going to learn to run barefoot correctly given all these handicaps.

I’m not saying that real barefoot running would absolutely protect you, but I’m sure it makes a real difference.

And I would love to see these people repeat their experiment with real barefoot running and with real feedback from the soles.

[H/T to Fiat Lux for the suggestion to look at this study in this comment.]