I wear size 16 or 17 depending on company (adidas Supernova Glide currently-now) Love the idea of boost and some of the other new ideas. I am looking forward to FLAT ( zero-drop shoes ) because I have been running .
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Looking forward to fun stuff in my size.

I agree – I think the benefit will be very much individually based if there is any. It would also seem to me to be of limited benefit to have energy returning material under the heel since propulsion comes when the heel is already off the ground.

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Pete Larson’s Web Links:
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I wonder if they’ll be bouncier than Z-coils?

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I largely ignored the video with the steel ball, it’s just entertainment. I find it less offensive than the majority of the crap spilled out shoe manufactures touting their latest bogus innovation. The video still is silly and should be treated as goofy marketing.

On a technical note, all shoes loose more energy on first half of stance than the return on second half of stance, so the net energy is always negative.

The only time a shoe can provide an overall improvement in efficiency is if the runner compensates for the extra vertical travel provided by cushioning by stiffening their body on stance and reducing it’s own energy losses associated with the hysteresis of muscles and other soft tissue.

So it’s very much a case of is the spring in the shoe more efficient than the spring in your legs. And if it is more efficient does does this provide greater gains than the weight of the shoes increases losses?

I have now doubt that a more efficient overall sole material (the total of out-sole, mids-ole and insole and socks) will improve efficiency if weight does not increase over a similarly spec’d shoe with less efficient sole material. However, I can’t imagine that it’ll significant enough of an effect that it would effect race rules, we aren’t talking about anything in the order of efficiency that blades provide. Using a different mid-sole isn’t going to endanger life like performance enhancing drugs, and if there is advantage competitors will simply move to that design on mass and avoid any issues of unfairness.

Overall I think one needn’t be as skeptical of this new mid-sole material as the majority of the “recent” shoe innovations, it is at least plausible. I suspect the gains if any will be very modest and if Addidas are lucky one might be able to spot differences in running economy if a study is carried out.

One aspect not touched on is whether a material that is more efficient won’t absorb so much energy through the gait cycle and therefore won’t heat up as much. Less heating might also mean less wear, or should I say it the other way around, less friction within the materials will result in less wear and less heat.

Propulsion horizontally is provided entirely by the runner, any horizontal shearing in the sole on landing will absorbed and when loading is reduce oppose forward motion. So for propulsion sake you want perfectly rigid sole.

However, horizontal propulsion forces are far smaller and less important to a runner than size of the vertical forces that the runner has to generate on stance. Here a sole that provides greater energy return can indeed help, it’ll even help with pushing the heel off the ground – just a tiny tiny bit :-)

The amount of energy absorbed by the sole is an integral of the force over distance of compression, the amount returned is then dependent upon properties of the material. The amount of energy return is always than put in, so it’s really a game of how much energy the sole absorbs through the whole cycle.

If this sole is more efficient then it’ll be in reducing the vertical energy absorbed by the sole.

How do you think these new Addidas will compare to the Asics?
Art
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Yeah, makes you wonder about the legitimacy of the video…

—-
Pete Larson’s Web Links:
-My book: Tread Lightly: http://ow.ly/bdUO0
-Blog: https://runblogger.com
-Twitter: http://twitter.com/Runblogger
-Facebook Page: https://www.facebook.com/Runbl…
-Discussion Forum: https://runblogger.com/forum