March 18, 2013

Paleo footwear

At the end of the summer I decided to try out running shoes as everyday footwear for the first time in I can't remember how long -- maybe ever. Got two pairs of ASICS '81 or something, mostly because looked nice and felt comfortable in the store. Right away I noticed how cushion-y they felt, but thought that might be a nice change of pace since I walk so much on paved surfaces.

Something else never felt quite right about them, though it was hard to tell without switching back to uncushioned shoes. Your leg muscles don't seem to do as much flexing or whatever when you're walking around in running shoes, or other shoes with lots of padding (seemingly most shoes these days). Especially the muscles on the back of your thigh. I think they've gotten smaller over the period of wearing cushioned shoes.

Before that, my sneakers were slightly upscale Chuck Taylors, and your feet feel the ground more in those. More of a grip against the surface, and your muscles pushing you off of it. Yesterday at Urban Outfitters I saw some bright yellow canvas sneakers, and figured they were worth $18. Hardly any cushioning at all.

Man, I'd almost forgotten what it felt like for your feet to really contact the ground, the back thigh muscles flexing, and your toes gripping the surface and pushing you forward. I don't think I'll be wearing cushioned, arch-supporting shoes ever again.

Here is a great article (with references) on how modern athletic shoes cause running injuries. Injuries are in the tail of the distribution; presumably the bulk of the others suffer from milder screw-ups that don't land them in the doctor's office. Here is a report on a more recent study about running barefoot to regain a normal healthy gait or stride, not landing so squarely on the heel. And here is a report of an article about shock-absorbing shoes being bad for people with arthritic knees.

It's a familiar theme -- trying to pad the body prevents hormesis, where experiencing lots of little and not so little stressors signals our body to improve itself to meet these challenges. Take away stressors, and your body starts to atrophy. When it inevitably does encounter a stressor, it'll be too much too soon, and the system will be overwhelmed.

Imagine someone who, for years and years, never lifts or carries anything of substantial weight. Now give him a 50-pound load to move from point A to point B, hardly an impossible task -- unless he's weak from inexperience. Probably won't be able to, or he'll be straining too hard if he does.

With cushion-y shoes, the information about the impact of the ground doesn't reach our nervous system, being wiped out by the shock-absorbing materials. So we underestimate how much impact we're truly experiencing, leading us to walk or run in a more heavy-footed way. A weaker system that ultimately gets put to a greater stress means it'll get overwhelmed, whether the injury is mild or severe.

Before, I showed that a rising crime rate causes stronger bones, and a falling crime rate weaker bones, using data on the incidence of forearm fractures across four decades. Rising-crime times feature more rough-and-tumble play, especially in the outdoors (and up in trees), and that spurs development. Young people are so fragile today because they didn't get banged up at all as children, so their bodies never got the signal to build up stronger bones to compensate.

I bet we'd see something similar with foot defects like having flat feet. (I searched for studies on incidence over time but couldn't find any.) South Asian children who don't wear shoes hardly develop flat feet at all, while those who wear shoes do get it. The arches of the foot develop in response to walking and running barefoot on the ground. Yep, I remember that.

Back in the '80s children mostly wore shoes if they had to go to the store with their parents, and even then they weren't cushioned. (I know because about a year ago my mother showed me all of our baby/toddler stuff that she's kept, including shoes.) Around the house, running around the back yard, at the beach, at the park, wherever -- it was acceptable to not wear shoes or even socks. It must have been uncommon, but I still vaguely remember occasionally walking around stores barefoot.

And we always took our shoes off on a car ride of more than 30 minutes or so. Somehow it's become rude and crude to have your bare feet touch any part of the car, even hanging out the window, as though you were propping your feet on some imaginary coffee table.

I'd mostly been following the minimal footwear thing ever since, and it sounds like it's time to go back. No more moon bouncy shoes.

1 comment:

  1. For normal wear, eschewing the moon shoes is good advice. For running, I'd still recommend wearing running shoes to cushion the shock load to you knees and other joints. Over a period of decades, the shock and fatigue can take a toll.


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