I trained this Summer with a mix of barefoot running and minimalist shoes. Some of this started with a workshop I did at a local running store where they took my shoes off and videod me running in shoes and without. Back when I was a personal trainer I used to have clients take their shoes off when I was doing a gait assessment, I'd have them run a bit and I always thought it was a shame people couldn't run without them all the time. Of course the truth is, the only reason I thought this was because I was missing something. Our bodies are actually very good at running without shoes, we just have to give them some time to realize the coffins are off for the first time.
I spent months researching barefooting, read 4 or 5 books on the subject and went from an 8 mile max long distance in 2010 to my first marathon in Oct 2011. I didn't run it barefoot but wore minimalist shoes which are designed to affect barefoot style running as little as possible. While I doubt there's a future where runners everywhere are barefoot on the streets of all the major cities, I want to make the point that the reason it seems to work is that there are major changes in your running form that are required to run this way. The amazing thing, is that your body will make many of these changes the second you take your shoes off. Peoples' form shifts almost immediately to one where they are landing flat on their feet, avoiding the dreaded heal strike, bending knees, landing more gently. It requires some serious work to refine your form but that's just the case with running anyway if you don't want long term injuries.
Here's me during my 6 miles today.
I've done up to twelve miles like this. There are lots of resources out there for figuring out how to start without tearing up your feet or getting injured. A slow careful transition is really really really important. The thing is, once transitioned many people find they really enjoy the sensation. It puts you in contact with the ground and keeps you engaged in the run, paying attention to your body. For me it has changed my relationship to running completely from dread to enjoyment. I wouldn't have run the marathon if I wasn't enjoying the training.
Like I said there are many places to go for scientific rationale on bareform but it basically boils down to this: Humans have been running for millions of years and wouldn't have survived a species without being good at it. Running shoes with cushy soles have been around since the 70's and while technology is fine, the shoe companies have screwed it up and are promoting injury rather than preventing it. I posted a short story on another running blog by barefoot Josh yesterday that I think makes the point very well.
When I was studying kinesiology one of my classes was a biomechanics course. In it we dissected a bunch of basic sports movements like vertical jump, throwing and running. In the throwing section we spent almost a full week talking about the forces and techniques involved. We broke the movement down into it's component parts, mapped all of the muscles that are working and how to maximize them, and applied basic physics to each section of the movement. The concluding statements by my prof were that doing x, y and z was the best way to get the fastest acceleration and therefore the fastest baseball pitch etc. Then he said that it was also guaranteed to destroy the rotator cuff muscles over time!! This among other things in that program ingrained in me the opinion that athletes are people who sacrifice their bodies for the sport and that in order to achieve the necessary performance will end up damaging themselves. That's how I thought of it at the time but now I see that as a misguided notion. Athletes should be able to achieve performance without destroying their bodies.
Bringing it back to running, puffy running shoes are supposed to allow you to run faster by elongating your stride. You would never land on your heal without that cushion, it would hurt. Take your shoes off and run half a block and you'll prove me right. The fluff heal was supposed to make people faster than they ever could be without it. The problem is that the fluff isn't absorbent enough to remove all of that shock, and your body isn't very good at running this way. The best way to mitigate the shock of running is to use your many jointed legs to run softly and without all of that impact.
You're always better off with less impact than more, and the best way to do that is not by increasing the amount of padding under your feet but by changing your form to decrease the impact you're creating. In terms of form tips this is a good place to start, and so is this.
Good Running and Good Living!