So I got my foot x-rayed and my recent suspicions proved true. Apparently in mid-December I suffered a stress fracture of the second metatarsal on my right foot. It was healing well, but needed more time and was re-aggravated during the Manhattan Half Marathon on January 22nd.

Doubtlessly, I’m going to be dealing with a lot of “this is why you shouldn’t run barefoot” comments, so this will be something of a pre-emptive refutation.

Is barefoot running a failure? No.

As described in Essentials of Surgical Specialties, “Stress fractures are the classic overuse injury.” Stress fractures were originally identified in the feet of army recruits resulting from long marches (while wearing boots). Wikipedia’s March Fracture entry precisely described my injury: “mostly occurs in the second metatarsal of the right foot.” Yep. My exact fracture is on the bone’s shaft, towards the base (proximal, meaning towards the body).

The American Academy of Family Physicians Common Stress Fractures page describes this injury as “among the most common sports injuries” with “track and field sports” acounting for 50% of stress fractures in men and 64% in women. One quarter of all stress fractures affect the metatarsal bones of the feet. Runners are exceptionally well represented among stress fracture sufferers.

Yes, there are apparently a number of Vibram FiveFingers runners who’ve suffered stress fractures. But clearly, shod runners get them too. The clinical literature notes that changing equipment can lead to stress fractures, but much more blame is assigned to increased amount and intensity of excercise.

Barefoot and minimalist runners are running more because it just feels great. When I switched to minimal shoes my running distances more than tripled, I was having a blast and my knees, hips, feet and back didn’t hurt. I know I’m not alone in blowing past my previous physiological limitations.

Am I just weak? Probably.

Our bodies stop stop automatically adding bone mass at around 35 years old. That’s not to say we can’t strengthen our bones through exercise, but the process is slower than it was–and bone growth is already much slower than muscle growth.

My skeleton seems to be in pretty good shape, with the distinct exception of my feet. Having spent most of my life in stiff, over-cushioned and inflexible shoes, the bones in my feet are doubtlessly weaker than they might have been.

This leads to what is probably the most difficult question:

Am I simply too old to recover from a lifetime of shoe-weakened feet?

I’m inclined to say no.

Ten months might have been long enough to build up the muscles and tendons in my feet and legs, but seemingly wasn’t nearly long enough to make up for 39 years of under-use and weakness in my foot bones.

Much more on this idea: Barefoot running stress fractures: A theory

So is the VFF Bikila blameless? Maybe, maybe not.

My fracture is basically directly aligned over the unnatural flex-point of the Bikila’s forefoot. That doesn’t mean anything, but the correlation is troubling.

Consistent with my previous observation about limited toe dorsiflexion in the VFF Bikilas, a suspected cause of stress fractures is muscle fatigue. Tired muscles fail to absorb shock and transfer mechanical stresses direclty to the bones. Here’s how Sports Injury Bulletin describes the causes of a stress fracture:

The ‘fatigue theory’ suggests that during repeated efforts (as in running), the muscles become unable to support the skeleton during impact as the foot strikes the ground. Instead of the muscles absorbing the shock, the load is transferred to the bone. As the loading surpasses the capacity of the bone to adapt, a fracture develops.

If my extensor muscles were exhausted by trying to flex against the restrictive toes in the Bikila, then it’s completely possible that fatigue could have contributed to this injury.

Additionally, the VFF Bikila muffles ground feel much more than thinner-soled VFFs or Soft Star RunAmocs. Reducing feedback from the ground can result in harder foot-strikes.

Ultimately though, this happened after my third (non-consecutive) 100+ mile month–which is a lot for me. That last month also coincided with colder weather and increased use of the Bikilas–often with socks, further reducing ground feedback.

What’s next?

I’m off the roads for a few weeks but I’m not planning on sitting still. First off, I’m going to learn to swim better.

This is also a great opportunity to fulfill the volunteer requirement for NYRR’s 9+1 guaranteed entry to the 2012 NY Marathon. I can’t run, but I can still help.

Accepting my potentially not-yet-sufficient bones, it’s possible that the reduced ground feedback of cold weather running presents a hazard for me. I may just need to accept that when I can’t feel the ground my feet still need a bit of padding to make up for weakness in my bones. Whether that will prove a tradeoff for pain everywhere else remains to be seen.

I’m not sure what to do about races. They’re ridiculously fun and while I’m not “racing” racing, I do tend to run much faster during races than I would normally. Maybe I need to wear a more forgiving shoe, or just train better.

I’m not about to stop running or give up running barefoot. The first thing I did after the doctor confirmed the white fuzzy spot in the x-ray (bone callus, a sign of healing) was to mark a date in my calendar. Unless there’s some clinically compelling reason not to, on the first Saturday in March, I’m going running.

I’ve been reluctant to post this because there’s a weird sort of stigma among barefoot and near-barefoot runners that injuries should be a thing of the past. For the most part, that’s been completely true for me, but something is going on with my feet and I felt it was important to write about.

The pain is focused on the Extensor Digitorum Longus and Extensor Hallucis Longus on top of my feet, mostly behind the smaller toes, but with some sensitivity over the joint between the first metatarsal and first cuneiform bones. These muscles and tendons are responsible for lifting the toes–which is why I’ve become suspicious of the Bikilas, but more on that in a bit. There is no discoloration or swelling. Pain is most noticeable during the toe-off phase of walking, running mostly feels fine. It is very difficult to raise up on the toes of one foot at a time.

As seems to be tradition with running injuries, I’ve been spending a lot of time theorizing about what could be the cause.

In November, following my post about bad running form, I ran about 65 miles completely barefoot (and LOVED it). I spent a good amount of that time on Barefoot Ken Bob’s advice about lifting the entire foot, especially my toes. But December has been too cold for bare feet with only a few days above freezing, so I’ve been running in the Bikilas which are warmer than my open-top VFF Sprints.

I ran three races in December. The first two were MUCH faster than I normally run. By the third race, my feet were still sore from the previous week and I just wanted to finish without limping. Despite my growing suspicions, all three races were run in Bikilas.

What’s wrong with the Vibram FiveFingers Bikila

One of my first reactions to the VFF Bikilas was that the toes felt stiff. In this video, I demonstrate the differences in toe-flexibility between VFF Sprints and VFF Bikilas.

Toe dorsiflexion is severely limited with the VFF Bikilas. I suspect that trying to lift my toes against the stiffness of the Bikilas either pulled or strained my extensor muscles or caused some tendonitis where they attach.

I’d also considered the possibility of simple overuse or the switch to heavier winter shoes, but I’ve become convinced that the toe-stiffness of the VFF Bikilas is the culprit here. I’m taking some time off to heal, but I’m not planning on running in the Bikilas again for a while. When I do, I’ll be paying very close attention to how my feel are feeling.

I recently bought a pair of Vibram FiveFingers Bikilas to replace my VFF Sprints which had developed a hole on the bottom of the left fourth toe. The Sprints probably only had about 150 miles on them, but I attributed the wear to some time on especially rough pavement.

But now, after less than 30 miles, the new Bikilas are showing serious wear on the same toe.

People normally get well over 500 miles out of pair of VFFs, so I must be doing something wrong.

Advice from Barefoot Ken Bob:

The purpose of so-called “transition” footwear…is to protect you from the pain of becoming aware that you have not, yet, learned how to run barefoot.

His point is, you can’t learn to run barefoot until you’ve actually run barefoot. Near-barefoot helps, but it’s not enough.

What I had to do was get over my mostly-social anxiety about going barefoot and put down some miles sans-shoes. Whatever I was doing to shred my shoes would be immediately apparent. Even if it turned out to be painful, my body would naturally adjust before I tore the skin off my toes.

If you’re a VFF runner and haven’t yet tried running completely barefoot, do it. It’s impossible to explain just how wonderful it feels.

After the initial euphoria wore off, I settled in and focused on my form, especially my left footstrike. Right away I felt a hot spot under my toe and then noticed the expected change in my landings.

I’m pretty sure the abnormal wear came from a combination of the following:

1. Pushing off too much with my toes.
2. A small skid on footstrike from being too far up on my toes, this skidding causes the toes to push down and try to stabilize.

When I first switched to minimal shoes, I think I mentally overcompensated for my heelstrike by running up on my toes too much. There’s a big difference between a forefoot landing and a toe landing. Landing too far up on the toes introduces a slight amount of sliding or skidding before the heel comes down. VFFs let you get away with this, but when it’s just your skin on the ground your body won’t let you. The goal of a barefoot footstrike is kind of a patting motion. The foot lands, the arches absorb energy and the foot is immediately back up. There’s not much toe-springing and absolutely no “sliding into” a landing.

Overdoing a toe landing also redirects a lot of impact stress through the metatarsals, which then pound into the second and third cuneiform bones right over the arch. Coincidentally, I had been having some soreness across the top of my feet, something Barefoot Ken Bob previously attributed to “running up on your toes.” Since making an effort to flatten out my landings, that pain is gone.

Still more from Barefoot Ken Bob, something to work on during my next run:

And finally (at least for now), lift the entire foot – most people just lift the heel, and the toe or ball of the foot, just kind of drags behind – so put a little effort into lifting the front of the foot, at the same time as the heel, so everything comes up, about the same time.

When the barefoot luminaries say to ditch the shoes and learn barefoot, listen to them.

Related: I took my brother Mike out for a short barefoot run (actually I pushed him way too far, but he said he enjoyed it anyway). That was the first time I’d ever gone completely barefoot. I was fine, but he developed a small blister on the exact same toe in the exact same spot as my VFFs. Genetics?