New data on running shoes

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Jennifer Leigh sent me a pointer to this article suggesting that running shoes put more stress on your legs.
Sixty-eight healthy young adult runners (37 women), who run in typical, currently available running shoes, were selected from the general population. None had any history of musculoskeletal injury and each ran at least 15 miles per week. A running shoe, selected for its neutral classification and design characteristics typical of most running footwear, was provided to all runners. Using a treadmill and a motion analysis system, each subject was observed running barefoot and with shoes. Data were collected at each runner's comfortable running pace after a warm-up period.

The researchers observed increased joint torques at the hip, knee and ankle with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus torque were measured when running in running shoes compared with barefoot.

Seeing as hip, knee, and ankle are major running injury sites— in fact, practically every major running injury I've ever had has been either at the knee or the ankle—this seems like it's something to pay attention to. The authors recommend that "Reducing joint torques with footwear completely to that of barefoot running, while providing meaningful footwear functions, especially compliance, should be the goal of new footwear designs." I already wear a relatively compliant shoe, the Inov-8 295, and while I don't have any data, it seems to have had a positive impact on a persistent ankle injury that has plagued me for years. I'd be interested to see this study repeated with a shoe deliberately designed to be as barefoot-like as possible like the Inov-8.

I do have a pair of the Vibram FiveFingers shoes, and while the advertising literature clearly suggests that you can run in them, I haven't really been brave enough to try it. There seem to me to be two issues here: First, the soles provide some protection but they're pretty flexible; I'm not sure that if you stepped directly on a rock it wouldn't be unpleasant. So, it seems like you would have to be a bit careful on trails. By contrast, asphalt is so unforgiving you would really need to have ideal form in order to avoid having some pretty serious impact forces. I'm still planning to go for a short run on a trail at some point, but I figure on taking it slow.

3 Comments

I don't do much running in the 5fingers (I get rubbing/blister problems pretty quick) but they seem to work well on grass if you are reasonably careful. Compared to other thin-unpadded-rubber-soles I've worn they are a little thicker, so to some extent rocks and such aren't quite as much trouble as you might fear. I don't go pounding along on pavement much, but it is surprising how comfortable that is. You'd think it would be just huge impact, but you do seem to naturally adopt a sort of running form that works ok.

One does wonder if the ideal running surface wouldn't be manicured clay or grass rather than asphalt. However, perhaps there is some sort of good middle ground between the modern shoe and the vibram that would work well on modern engineered surfaces -- maybe something that is much like a vibram but with a thick yet very flexible rubber sole.

I've got two standard runs around my neighborhood (2 miles of asphalt or 4 miles split between asphalt and crushed cinder) that I do regularly in my VFF's.

Observations: you run with your weight forward a bit, so initial contact is on the front of your foot, not the heel. You don't need to be on your toes, like a sprinter. You're somewhere in the middle.

When running this way, your lower calves and Achilles tendon take on shock absorber duties. They need time to adjust to their new duties, so start off with very low mileage and work your way up. (In the beginning, I thought I felt great and overdid it, resulting in not being able to comfortably descent stairs for a few days.)

Around my neighborhood, there are a lot of old oak trees, and the acorns are hazardous to your health. You start dedicating non-trivial cycles to selecting your path to avoid stepping on acorns, rocks, and so forth. Again, we're hard-wired to do this already, it just takes some practice and it internalizes pretty fast. And if you do step on something sharp, it hurts and you pick your foot back up again quickly. Not really all that big a deal.

Chaffing over a four mile run doesn't seem to be a big deal, and I'm running without socks. What is a big deal is if you get a small pebble or something into the *top* of your shoe. When that happens, you have to stop and pull it out immediately. This happens infrequently, but it's annoying. Once I wear out my current VFFs, I'll replace them with the KSO version in the hopes of reducing these issues.

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