Written by: Dan Empfield
Date: Tue Mar 15 2011
The following are exact quotes taken from Dan’s article on the slowtwitch.com website. This is a very good article. Please read his entire article in the posted link above, so that we do not take something away from the hard work and writing of Dan. We take zero credit for this work, it is all Dan’ Empfield’s. Thanks for the great work Dan and www.slowtwitch.com Visit them both !
What we’re talking about here is the distance your heel sits off the ground versus your forefoot, when you’re standing in the shoe. In order to calculate an angle, you’ve got to solve a right triangle equation, specifically, in a size-9 shoe, the distance from the heel to the forefoot is a right triangle’s long arm, the delta between heel and forefoot height is the short arm, connect these two arms via the hypotenuse, the slope of the hypotenuse is the ramp angle (or, just look at the image furthest above).
Who wants to calculate that? Not me.
So, let’s just talk about heel height, forefoot height, and the delta between them. Typical of today’s conventional running shoes is a 24mm heel and a 12mm forefoot. The delta between them is 12mm. This number is much easier to get one’s arms around, so, from here on in I’m going to talk about Ramp Delta (a metric of my own invention—if you’ve got a better term, lay it on me, maybe I’ll abandon mine and adopt yours). The complaint with a large ramp delta is this: If I’m a midfoot striker, can I midfoot strike without that propped-up heel getting in the way? Probably so if we’re talking 10mm, maybe 12mm, but 15mm? (Which is not by any means unheard of.) That’s questionable.
A bigger problem yet: Once I midfoot strike, the heel will touch down almost immediately—how much will the rear of the shoe compress? If it doesn’t sufficiently compress, am I plantar flexing (pushing off) with an achilles tendon not sufficiently elongated?
Part of this depends on how firm the shoe is in the heel. If the midsole is less dense, the shoe may compress to a point where the shoe functions as if it had a smaller ramp delta.
Are traditional shoes made for heel strikers?
This is a contention I hear over and over again, with greater regularity. The running boom has spawned a lot of runners who didn’t get the proper running technique memo (the narrative goes) and companies like Asics and Brooks have accommodated their overstriding, heel-striking, overpronating technique with shoes perfectly made for this inefficient method of running.
I buy this line of reasoning up to a point. I have some problems with this line of thinking and we’ll get to these, but, here’s an experience related to me by a shoe designer, Dave Jewell of Zoot, from a bit earlier in his career:
"We cut all the competition up with a band saw. We wanted to see what the midsole heights were. What we found was rather astounding. Yes their stated midsole heights were fairly correct but their overall height was rather outrageous. We found shoes that were stated as 25mm heel and 13mm forefoot. The total height was 34mm heel and 22mm forefoot. People were still buying them but it seemed to us like they were too tall.” Dave does not rail against companies that make shoes with a taller heel, or a larger ramp delta. Rather, he offers this observation from the latest Hawaiian Ironman:
“The race up front is won by folks who can run in anything but choose the shoes with the smaller delta—say, 10mm or less. But those finishing the race from 3 hours behind to 10 hours behind tended to run in a shoe that has a 12mm delta. Are all of these people running in the wrong shoe? Clearly they are running in what’s most appropriate to their running style. Running shoe companies for years have offered different shoes with different deltas. In the past the shoes with the low delta were racing flats.”
Does a low ramp delta require a low overall shoe height?
Some believe ardently that a firm connection between the foot and the ground is a must. Danny Abshire (founder and owner of Newton Shoes) believes this and offers the following rationale: There are thousands of nerve endings in the foot responsible for proprioception, and a loss of communication between the ground and these nerve endings interrupts the proper interaction between nerves and muscles. Adding distance between the foot and the ground interrupts this communication.
Newton’s shoes are known for an exceptionally low ramp delta as well as generally low shoe heights. Still, Dave Jewell notes that, “Now there are shoes with a low delta and thicker overall midsoles that are getting some traction.”
Does a low ramp delta necessarily mean a neutral shoe?
This is where the natural/barefoot/minimalist guys lose me. Yes, no doubt you’ll overpronate less if you don’t overstride. But in my experience, it’s dangerous fiction to flatly state that an overpronator can, and should endeavor to, “teach” himself to run in a neutral shoe through engaging in exercises to strengthen his feet.“