Some very interesting videos and links on last weeks weekend sports article. One theme being that running barefoot is much more natural than in shoes, and some interest from folks in making the switch. The latter could be a problem.
Update: Sorry for leaving off the links.
And, a shorter video
If you watch the longer video, you'll see that a person who was used to running in shoes their whole life, when running in shoes, had a big spike in landing forces as you go from the first instant of touching the ground to the first instant of the foot being off the ground. It hits near maximum forces almost immediately on touching down, which is bad news for your body as it means a shock to the systems. Someone who has never run in shoes doesn't have the big spike. There's a smooth rise to the maximum, and then smooth fall to takeoff. Clearly this is a better thing to do, hence the interest in barefoot running.
But there's a third profile -- what happens when someone who has always run in shoes starts to run barefoot. They have exactly the same spikes in forces barefoot as they did when running in shoes. Except that now there's no shoe taking up some of that force for them. This is a recipe for injury -- your body will be experiencing new forces, and be unprepared for them. The one person I know personally who tried the minimalist shoes went promptly to injury (stage one in about a week, stage four in a month). She did an abrupt change to the new shoe, not a transition.
More to the story of course, and it touches on my current rehabilitation.
First, though, injury stages. The idea is that there is a progression of injury. If you catch them all in stage 1, you need never miss any of your good, healthy workouts. Stage 1 is where you notice an issue while you're doing the workout. You can still carry out the workout. Stage 2, you notice the issue during the workout, and have to start backing off (run shorter, lift lighter weights, etc.) Stage 3, you have pain even after the workout is over and cannot do your normal workouts. Stage 4, you cannot do even a light version of your workout and have pain well after the workout.
Corresponding to those stages is an increasing length of time to recover. In stage 1, you might just need to take a couple of days easy, but still be getting your workouts in. In stage 4, you'll need to take weeks to months off for a recovery. Since I'm in the exercise for the health benefits (my days of looking towards a 4 minute mile are long past :-), months off because of injury are a very bad thing.
Once you've recognized the injury, there are two things to do. Rehabilitate it. Find out why you got it in the first place and then figure out how to prevent it recurring. Last year I had a recurring calf/achilles problem. Rest and stretching (the latter having been recommended by my doctor) and some heel drop (Alfredson) exercises (recommended by an MD friend who is a runner and has similar problems to mine) didn't do it. So at long last I went back to the doctor and got sent off to physical therapy. The leg is definitely improving with the therapy, so that's progress.
The second part, though, is to figure out what caused the problem. I don't have a good smoking gun for this. My strong suspicion, which strike the physical therapist as reasonable, is a change of shoes. It's an unfortunate reality that you can't run in the same pair, or even the same model, of shoe forever. I did run in the same model for 12 years, which was pretty good for duration. But spring of 2008 I did a lot of racewalking (not in a global sense, but compared to what I had ever done before). That lead to a stress fracture. The podiatrist said to lay off the racewalking (I'd figured that part out myself :-) and to go to a particular store that had the technology to match me up to the right pair of shoes for my running form. The technology said that I was definitely a neutral runner. That means that my weight moves pretty straight down the middle of my foot, as opposed to veering towards the inside (overpronator) or outside (supinator). I'd actually been running in shoes more for an overpronator than my (observed) neutral form. So the new shoes were for a neutral runner.
And there, perhaps, is the injury source. After 12 years of running in one type of shoe, even though a different type is more natural to my running mechanics, I'd become adapted to the other style. That might mean that, for example, some of my lateral stability muscles in the ankle/foot are weaker than they need to be in order to run consistently in the neutral shoes. It happens, I'm sure not a coincidence, that the rehabilitation exercises are working on those lateral stability muscles.
My current answer, checked with the physical therapist (it's not just in my field that I think people should check with those who have studied more of the subject at hand!), is to work on the rehab exercises, and to get a pair of shoes that is more in line with my former style. (The exact model is no longer available, but something of the same sort is.) I may alternate between the new style and the old style. The new style do feel more comfortable, which is a good sign in a shoe.
The lengthy bit there about my own injury/rehab is also by way of illustration of injury that you might expect from a sudden change to minimal or no shoes -- a much larger change than I made. A true minimal shoe, for instance, has no heel. That's one of its virtues, eventually. But it also means that your achilles tendon will be stretched more than usual, and that makes for big new stresses.
A second thing is that in order to run in minimal or no shoes (I've run barefoot off an on since childhood, quite often so in childhood) you must land with the front of your foot touching down first (forefoot landing). If you've been slamming your heel in to the ground first for years (as flatmates of one commenter last week do), you are quite possibly going to rapidly head to injury, as my acquaintance did. On the other hand, you can start practicing forefoot landing even in your usual shoes. Better, perhaps, is to start walking around the house or flat without your shoes on and practice bringing your forefoot down first.
On yet another hand, one of the more certain ways of creating an injury is to try to make a rapid change in your running mechanics, even if the form you're trying to change towards is generally better.