Over the past few months I've written several posts about the relationship between footwear and running gait, with a particular emphasis on how shoes, or lack thereof, affect our footstrike (here's one showing how various shoe types affect footstrike, and another on how the presence of a cushioned heel affects footstrike). I've received a number of questions about what is happening regarding pronation, or the inward roll of the foot that happens after the foot hits the ground. Given this feedback, we went back to the lab and shot a series of videos (of me) from behind a treadmill, which allows a very clear view of what the foot is doing after it hits the belt. Before I post the videos we shot, I wanted to provide a series of short "primer" videos from Runner's World that outline the difference between neutral, overpronated, and underpronated footstrikes (note: the "underpronator" in their example looks more like a midfoot-forefoot striker to me, but that's a whole different debate).
So here are my videos - they go in the following order - 1. stability shoe, 2. neutral racing shoe, 3. Vibram Fivefingers KSO, 4. barefoot:
Running in Asics Kayanos - Posterior View from Pete Larson on Vimeo.
Slow motion video of me running in Asics Kayanos, which are a high-end support/stability shoe. Looks like my feet are pronating quite a bit after footstrike despite the supposed stability features of the shoe (particularly pronounced on the left foot). Video shot at 300 frames-per-second with a Casio Exilim EX-F1 camera. Courtesy of runblogger.com/.
Running in Nike Lunaracers - Posterior View from Pete Larson on Vimeo.
Slow motion video of me running in Nike Lunaracers, which are a neutral, lightweight racing shoe. Looks like my feet are pronating quite a bit after footstrike. Video shot at 300 frames-per-second with a Casio Exilim EX-F1 camera. Courtesy of http://www.runblogger.com/.
Running in Vibram Fivefingers - Posterior View from Pete Larson on Vimeo.
Slow motion video of me running in Vibram Fivefingers, which are a barefoot-like, lightweight, non-supportive shoe. Looks like my feet are pronating quite a bit after footstrike - more pronounced on left side. Video shot at 300 frames-per-second with a Casio Exilim EX-F1 camera. Courtesy of http://www.runblogger.com/.
Running Barefoot - Posterior View from Pete Larson on Vimeo.
Slow motion video of me running barefoot on a treadmill. Looks like my feet are pronating quite a bit after footstrike. Video shot at 300 frames-per-second with a Casio Exilim EX-F1 camera. Courtesy of http://www.runblogger.com/.
My interpretation of these videos is that I would probably be classified as an overpronator by anyone who does gait analysis on a regular basis (and so I was by the salesman at the local running store when I first started running regularly back in 2007). I also show striking asymmetry, with much more pronounced pronation on the left foot (I already knew this, and it's confirmed by the wear patterns on my shoes). What's surprising to me is that I don't really see much of a difference among the videos in how much my feet pronate after hitting the ground - they roll inward in all of the them. Even in the stability shoes (Asics Kayanos), my feet still pronate to what seems like a similar degree as in the other shoes (or barefoot), they just do it inside the shoe. This makes me wonder what benefit stability shoes are actually providing - I'll have to hit the scientific literature and check out what data we have on the topic.
I'll finish by pointing out that despite my pronation issues, I've been wearing lightweight, neutral shoes and the Vibram Fivefingers almost exclusively since last May with no injuries, pains, or any other issues. I tend to think of pronation as a natural process, and am curious to get into the scientific literature a bit more and try to find data that actually links pronation to increased chance of injury. Unfortunately, a lot of that data is likely proprietary and held by shoe manufacturers, which is unfortunate since as an academic scientist I'm trained to think that if data isn't openly published through peer-review, then it's not of any value. I'll be back to post more when I'm done with a bit of research.
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