I agree, I always worry a bit about trackway studies. Major limitation, as well as force plate targeting. Tough to avoid that as much as you might try I think.

We see the same thing with clients in our Feldenkrais/running form practice. My way of describing it is that the left leg is the stability (or standing) leg and the right leg is the mobility (or gesture) leg. The right foot is much more likely to be turned slightly out and the right side of the torso is more likely to be muscularly shortened from hip to shoulder. The glutes are likely to work better on the right. I’d always assumed it was due to driving but I started checking with my clients and many of them (in NYC) didn’t drive, so that’s not it. I recently discussed it with a podiatrist and she said she and her colleagues noticed it too, it’s a bit of a mystery. The only reasonable hint I’ve come across is that it may be related to the liver — the heaviest organ — being on the right side, and therefore having to be shifted to the left slightly through a contraction of the right obliques (stand up and try it and you’ll see what I mean). Doing this with your trunk will make the left leg your stability leg, bias you towards the heel in running, and put you more on your forefoot on the right. Chek practitioner friends of mine have noticed this asymmetry improves when people remove the most common allergens from the diet, which points again at the liver, and a stressed liver being perhaps larger or heavier or having some other effect on movement. All speculation, but at the very least it does show that this pattern has been widely observed!

this theory makes a ton of sense. When I was still doing PT we would see a ton of R sided injuries from driving: piriformis, calf, heel pain, etc…

Peter, your observations about shoe preference, soft heel/firm forefoot, and exaggerating heel strike, suggests to me an issue of force vs pressure.

The force, at any instant, being applied by the body through the shoe to the ground is equal to the instantaneous pressure x contact area. If we apply the force over a small area of the heel via an exaggeration dorsaflexion of the ankle we may be reducing the area of contact and as the pressure sole can push back with is governed by how much it’s compressed it’ll have a similar pressure profile as it compresses, but the force generated will be less. This means it’ll take longer to the force to peak. The shoe will feel to the runner less stiff.

If you land more flat footed then you rapidly distribute the loading across the a wider area, the compression of the sole will be less, and less localised pressure, but the overall force can be greater. The amount of compression of the sole will also be less, and the runner will perceive the shoe as being more stiff.

This is all with the same shoe, just a slightly different foot-strike.

A runner that lands with the ankle rolled so the outside edge of the foot will like reduce the contact area and like the exaggerated heel strike case in effect make result in a lower effective stiffness of the shoe.

For myself, my default landing is a mid-foot one, going uphill or sprinting it’s often a pure forefoot, when descending it’ll vary between forefoot, mid-foot and heel strike. I also have a preference for firm zero drop soles.

For a bit of variation in my shoe rotation I recently bought a pair of Nike Kiger’s, they are soft in the forefoot and even softer in the heel. Initially I really disliked the feel of softness of the sole and found it quite unstable, but now with 60 miles in them I’ve tuned into them more and am less put off. It also took me quite a few miles to recondition my leg muscles to handle the instability of the soft sole.

One thing I don’t notice is the soft heel though, I believe because I’m still running with a mid-foot strike so by the time my heel touches down I’m spreading my weight over a large area so the effective stiffness is higher. If I deliberately heel strike it feels mushy and unstable, yuk!

Going back to my F-Lite 232’s on my new X-Treme 178’s the soles feel firm, but after a half a mile I dial in and they disappear on my feet. I don’t know how much this is down to me adjusting my gait sub-consciously or my brain just dialling into what pressure patterns are normal, safe and don’t require any conscious intervention.

Depends on which classification scheme is used. Strike index is pretty standard in force studies, for video simultaneous contact of the heel and ball of foot is the typical definition. What’s new with the atypical heel strike I think is the ability to describe exactly how it differs using pressure patterns under the foot.

I’ve always been curious about whether working a gas pedal with the same foot every time we drive might have some influence, particularly for those who commute to work every day. Lots of work for one lower leg and not the other.

Will running in a very minimal shoe change foot strike? In some people yes, in others no if we are talking about say a discrete change from heel to mid/forefoot. Some interesting studies on this coming later this year.

I know it’s not cool right now to still be talking about minimalism, but there is something to it.

Eric- Thanks for putting in that insight from the cycling world. My first thought was the same as Andy’s, that the discrepancy had to do with which side is dominant. Has Steve offered up any reasons for why riders might tend to protect the right side, irrespective of “handedness”? Or do you have any ideas?