You mentioned before about a 12mm heel height being ideal? Why is that the standard?
Well, that's a very interesting question because it hasn't been settled on at all. With ASICS we've always worked on a 10mm gradient. That's the difference between the height of the forefoot and the height of the rear foot, so if you've got a cushion type shoe it might be 24mm and 14mm off the ground. A racing flat might be slimmer at 10mm and 20mm. We've done a lot of research on this and we understand that it actually puts your foot in a mechanically better position, makes it more stable, takes a load off the Achilles tendon... so there's a lot of positives. There's a lot of myths and all that sort of crap and the problem is that every time you add a little raise, people are going to say ‘oh but you're removing the foot from the ground therefore you're going to make it more unstable and you're more likely to sprain an ankle', which is complete nonsense. That's scientifically unsustainable. There's no evidence to say that happens at all.
Would the average runner notice the difference between a 10mm and 13mm raised heel?
We've actually done what's called a double-blind experiment which means that the researcher doesn't know which shoe the subject's getting and the subject doesn't know either. Across the board, runners prefer the 13mm in terms of performance and comfort. That was a pretty positive result.
Is it true that shoes which are completely flat can cause problems? There's a lot of those around at the minute...
You've got to be really careful that you amortise this to the actual situation. So the thing about kids these days is that hopefully they're pretty active, which means they will need some sort of meaningful midsole and elevated heel. Let's go back to the Kalahari Desert. If you habitually don't wear a shoe with any sort of midsole, you will adapt to that. But then you've got to think about what happens if that kid then wants to go and play tennis or basketball? They are certainly more likely to get injured. Kids have things called growth plates which is a plate of cartilage sandwiched between bone and it disappears by the time you're about 17. The growth plates are normally exactly where tendons insert so they tug on the growth plate. If you get impact on that, especially around the heel, then you are very likely to develop an injury.This is something we've looked at at length, especially in football boots which is why we've had a raise in our boots now for a long time. So yeah, I think walking around in completely flat shoes is less than ideal.
It's a bit off the topic, but are high heels particularly bad?
The simple answer is yes they are. If you're wearing them occasionally, I don't have a problem at all. If you are wearing them eight hours a day, six days a week you will definitely get adaptive changes that will be bad for you. You'll realign your spine and probably get an adaptive shortening of your Achilles tendon which is bad news. You will get a profound increase in loading through your forefoot which will probably affect the joints of your forefoot.
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