What is the ideal ‘drop’ for a running shoe?

holy grail

Straight to it: based on my understanding of the current knowledge, the evidence and discarding all the logical fallacies, I can find no evidence and no rationale for any blanket recommendations for any ideal drop in a running shoe. Yet, everywhere you go there are some pretty strongly held opinions with lots of the typical rhetoric and propaganda as to what it should be. Given the strength of those opinions I was surprised to find how little evidence backs it up.

‘Drop’ has become the populist term for what the footwear industry normally calls ‘pitch’ and is the difference in the height of a shoe between the heel and forefoot. Some call this the ‘gradient’. To avoid confusion, ‘stack’ is the actually height of the heel and forefoot in the shoe, so heel stack, minus forefoot stack = drop. I probably should be using the more correct term, ‘pitch’, but will use the populist term ‘drop’ here¹.

Typically the drop of the vast majority of running shoes have been around the 10mm mark. I could find no research, rationale, theory or arguments as to why 10mm is the standard that has been used for a very long time by virtually all the traditional running shoe companies. It just appears to be what most runners are comfortable with. Historically, I am aware of a couple of anecdotes from industry insiders in which they did experiment with changing, but it was not accepted in the market.

Obviously, more recently with the minimalist trend, the term ‘zero drop’ has entered the vernaculum. I did a lot of searching and reading to see just what underpins the belief that this is better than a 10mm drop. I could find the very strong opinions, but no research evidence to back it up. I checked the websites of running shoe companies that market zero drop shoes to look for their evidence or rationale as well as the usual books (eg) and websites and found nothing substantial. A lot of them did mention the word “science”, but I could not find any science! To paraphrase what I found: the basic reasoning for zero drop is that it is more ‘natural’ and facilitates a more ‘natural’ running form away from a heel strike whereas a 10mm cushioned shoe tends to encourage the “unnatural” heel strike. That is all I could find to justify it. Anyone with a basic understanding of the ‘critical thinking’ or ‘logical argument’ fallacies will immediately recognize the flaw in that reasoning. It is the natural fallacy and is used all the time to argue that something is better because it is natural. Its a false argument. Just because something is natural does not make it better. Something may or may not be better for you because its ‘natural’, but to use that as an argument is a logical fallacy because there are plenty of natural things that are bad for you and plenty of unnatural things that are good for you.

I also came across a lot of use of the wishful thinking fallacy in regard to this as well. This is simply stating that zero drop or 10mm drop is best and just wishing it to be true. Those kinds of arguments are easy to deconstruct.

So basically, at this stage, nothing really underpins the concept of zero drop except a logical fallacy and nothing underpins the 10mm drop other than most runners are using it and we been doing it for a long time, which is also the logical fallacy of ‘appeal to popularity’ which also does not mean its right. It may or may not be right, but popular things have turned out in the past to be wrong, so no one can use that argument either.

(As an aside, while reading forum posts, blog posts and comments sections on this topic in the crankosphere blogosphere, I was surprised how often I read comments that could be interpreted that as though the 10mm drop was one great conspiracy by the running shoe companies to injure runners and affect their running form in a negative way! … go figure that out, given that the injury rates between traditional shod vs barefoot/minimalist and forefoot/midfoot vs rearfoot are pretty much the same ).

What evidence touches on this? While there is really no direct evidence (unless I missing something), there is some indirect research that can shed some light on this. There was one recent undergraduate project that found no differences in running economy between omm and 4mm drop running shoes. Another study did show running in a shoe with a 7cm or 4.5cm heel raise vs 1 cm is more uneconomical, but that hardly contributes anything to this discussion. Clarke et al in 1983 found no effects on rearfoot motion with changes in running shoe heel height (it would be good to know if there are any kinetic differences here, rather than just kinematic differences). Probably the best bit of research to inform this was by Reinschmidt and Nigg in 1995 in which they looked at changes in ankle joint moments with different heel heights in running shoes and they basically found no systematic differences, but they did report that “However, single subject analyses indicated that for two subjects the plantarflexion moments decreased with increasing heel heights“. For those two subjects this hypothetically, theoretically and overly simplistically means running in a 10mm drop would have less load to plantarflex the foot. This hypothetically and theoretically means that those 2 runners will have less load in the Achilles tendon (ie decreased injury risk for the Achilles problems) and the calf muscles do not have to work as hard (ie improved economy).

That last section points to what is probably the answer to what is the ideal drop: Its subject specific. Some runners are going to do better in a 10mm drop and some are going to do better in a 0mm drop (or the 4,6 and 8 in between), and don’t forget we are talking about very small differences of a few millimeters of a compressible material here. I have not touched on those issues of compression and drop and a cushioned zero drop shoe, may even be a negative drop shoe under load.

There are plenty of anecdotes of runners transitioning to zero drop running shoes and doing just fine and claiming to get less injury. Similarly, there are also plenty of anecdotes of runners not doing so well and claiming to get more injuries. But these are anecdotes and we know from the evidence just how unreliable anecdotes are when it comes to making blanket recommendations. This is the anecdotal fallacy.

For those who managed to understand what I wrote in the post on why one size does not fit all, its just as applicable here. Just look at the picture in that post showing the variation of the location of the subtalar joint axis; imagine the differing effects and lever arms that a 10mm vs a 0mm drop will have at that joint (let alone all the variations in the other joint axes across a group of runners!). You can then start to appreciate why the ideal drop is probably going to be subject specific.

Unfortunately, all we mostly have at the moment to determine this subject specific need is trial and error. We certainly need more work. What was it about the 2 subjects on the Reinschmidt and Nigg study above that changed? Was there anything “clinically” different in them compared to the others to help predict that they hypothetically and theoretically would benefit from a 10mm drop shoe? In the comments section on the post I did on supination resistance it was also speculated that those with high supination resistance probably should be in a higher drop shoe (and that speculation was based on extrapolating some research). It is more work, preferably more than just thought experiments along these lines that are going to help get to the bottom of determining in advance what the subject specific response is more likely to happen with different drops, so better recommendations rather than trial and error can be made. There is probably never going to be any research showing that one drop is systematically better than another (and I am sure this will disappoint the conspiracy nutters who think running shoe companies are deliberately trying to injure runners and affect their running form in a negative way).

On a personal note, I have drifted away from doing some of my runs in the NB Minimus (0mm drop) to the Saucony Kinvara’s (4mm drop). But that is my personal preference. Its what just feels right for me. I just don’t feel motivated and arrogant enough to evangelasize that because it works for me, that I have found the final solution and the holy grail and everyone should do it the way I preach.

While researching this, I was surprised to find a forum post I made 2yrs ago on this topic and had forgotten I made it:

“All we have is the nonscientific pseudoscientific propaganda from the ‘one size fits all’ school.
I don’t think there is a systematic ideal height. There is probably a subject specific ideal height … all we need is a way to determine it.”

… nothings changed! All we need is a way to determine it.

As always: I go where the evidence takes me until convinced otherwise,  and thou shalt not commit logical fallacies when trying to determine it.

logicalfallacy

1. Sorry, David

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About Craig Payne

University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger, dad. Follow me on Twitter, Facebook and Google+

13 Responses to What is the ideal ‘drop’ for a running shoe?

  1. Tim Litzinger December 1, 2013 at 7:04 pm #

    “On a personal note, I have drifted away from doing some of my runs in the NB Minimus (0mm drop) to the Saucony Kinvara’s (4mm drop). ”

    Ok, but with this switch you have also added more padding, so even you don’t know if its the 4mm difference or not when it comes to your own preference.

    While I agree with most of it, I also have a small issue with your logic.

    “To paraphrase what I found: the basic reasoning for zero drop is that it is more ‘natural’ and facilitates a more ‘natural’ running form away from a heel strike whereas a 10mm cushioned shoe tends to encourage the “unnatural” heel strike. That is all I could find to justify it. Anyone with a basic understanding of the ‘critical thinking’ or ‘logical argument’ fallacies will immediately recognize the flaw in that reasoning. It is the natural fallacy and is used all the time to argue that something is better because it is natural. Its a false argument. Just because something is natural does not make it better.”

    True, but it is also logical to start with the assumption that natural is better unless otherwise discovered. I’m going to assume that a chicken breast from a farm where the chicken was free to roam, is better for me than a chicken Mcnugget, whether the science is there or not. Yes, it is possible that this assumption is wrong. Likewise, it is completely logical to think that zero drop is better for you than shortening your achilles chronically. Of course, it is also completely logical to think that switching from a 12mm gradient to a 0mm might cause problems if you have been wearing the 12 mm all your life (again shortening the achilles chronically). So again, logic WOULD dictate that a 0 drop (or natural) is better for you but the same logic does not mean it is better for you to switch. Or certainly not an immediate switch.

    • Craig Payne December 1, 2013 at 7:17 pm #

      but it is also logical to start with the assumption that natural is better unless otherwise discovered

      Why is it? You just applied the natural fallacy to your argument!

      Likewise, it is completely logical to think that zero drop is better for you than shortening your achilles chronically.

      Nope. How many runners do you know who have always worn 10-12mm drop that can’t get their heels to the ground? I have never seen one. A high drop does not chronically shorten the achilles. If it did, then why can runners still get their heels to the ground when going barefoot? Its not logical at all. Simply making that statement is an eg of the “wishfull thinking fallacy” – you are just wishing it to be true. Mind you, I read that kind of statement all the time. Its simply not true, and those making that statement just wish it was true as it suit their purposes and if it gets repeated enough then people might start to believe it.

      Can you see the problem that I keep constantly bringing up?

  2. Droichead December 1, 2013 at 9:15 pm #

    Craig,

    Your counterargument for “shortened” or less flexible achilles tendon by stating that touching the ground when barefoot means equal flexibility and dorsiflexion ability in your ankle lacks the same level of scientific rigor that you accuse those that make statements about what is better. If we are going to be strict and serious in an argument we have to apply the same rigor to all approaches. Muscles and tendons are flexible, a minor reduction in flexibility does not mean that certain positions or angles cannot be reached, it means that they are done at a slightly higher stress in the tendon.

    In relation to the drop issue, can you please tell me what is the advantage of 10mm or any other drop at all? Because if that parameter was not there in the very first place, I think that the challenge is in demonstrating the advantages of the introduction of the drop itself than the other way around. And no, this does not mean that I support the “natural” fallacy, but I still think that it is more to explain from the benefits of the addition of drop (because it wasn’t there in the first place) than the other way around.

    I have been reading your excellent site for a long time and I agree with you that cherry picking is a common disease, however when you mentioned as counterargument “For those two subjects this hypothetically, theoretically and overly simplistically means running in a 10mm drop would have less load to plantarflex the foot.” Is this not cherry picking? so it is plantarflexion the only parameter that matters, what about other parts of the whole chain where the effect of drop is reversed? (i.e. lower drop reduces certain torques or stresses).

    • Craig Payne December 1, 2013 at 9:35 pm #

      Your counterargument for “shortened” or less flexible achilles tendon by stating that touching the ground when barefoot means equal flexibility and dorsiflexion ability in your ankle lacks the same level of scientific rigor that you accuse those that make statements about what is better. If we are going to be strict and serious in an argument we have to apply the same rigor to all approaches.

      You missed the point! Simply stating that a high drop shortens the achilles is simply not true as those who wear high heels can get their heels to the ground. How is that chronic shortening? If chronic shortening happened, then women who wear high heels and runners who wear 10-12mm drop will mostly be walking around barefoot with their heels off the ground! Do you see them doing that? No scientific rigor is needed to show those claims are wrong. BUT, rather than ask me for that are you also going to ask Tim to produce some scientific rigor to back up his claims?

      can you please tell me what is the advantage of 10mm or any other drop at all?

      That is my exactly point. I can see no systematic advantage of one over another. The fan boys seem to see it, but no one else is. I suspect (theoretically and hypothetically) that a higher drop will be of more benefit to those with high supination resistance and a medial STJ axis as there is some evidence and rationale for that and that will reduce loads in teh tissues; but apart from that I can see no other reasons for any other recommendation – maybe one day we will. That was the point of the last part of the post.

      There probably is going to be an advantageous drop for the individual eg the two in the Reinschmidt and Nigg study clearly got an advantage in one parameter and would benefit from a higher drop if that parameter needed altering in the direction that it was.

      What we need a is whole lot more parameters that different drops impact on; some ‘clinical’ indicators to predict that, then we can start making recommendations based on individual needs and what parameters wee need to change.

      Is this not cherry picking?

      That is not what cherry picking is. Cherry picking is when you pick one study that supports you and ignore another study that does not support you (the fan boys do that ta lot). I just used those two subjects to illustrate the subject specific response to different drop.

      The plantarflexion moments were the parameters that changed in those two subjects in that study and if that is the parameter you need to change in those two subjects (could be for any one of a number of reasons), then a higher drop would have done it.

      To be clear: I am not systematically advocating one drop over another as I can find no reason to. I would like to find indicators that can be predictive of when one drop may be better than another for an individual. We don’t have that yet.

  3. Craig Payne December 1, 2013 at 10:01 pm #

    WTF!!! If you want to email abusive emails to me, at least show me you can read. I NEVER said there was anything wrong with zero drop! I run in zero drop shoes myself!

  4. Droichead December 1, 2013 at 10:13 pm #

    Craig,

    I am not stating that a high drop shortens the achilles. I am stating that the fact that people that wears high drops have exactly the same flexibility in their achilles just because can touch with their heels in the ground when barefoot does not prove that the achilles is not shortened (tendons and muscles are flexible, its the neutral point of no tension what matters). Of course it is up to those that make the “shortening” statement to prove it, but your, in my opinion, over simplistic counter argument does not prove that ankle, achilles and calf flexibility is exactly the same just because can land their heels in the ground when barefoot.

    I mean cherry picking in terms of mentioning a particular study with a particular reduction of a measurement in an argument which is very general, i,e “ideal drop”, ankle joint moments is a small part of a much larger equation, the fact that in a particular study decreases with the drop does not mean anything, other moments might increase in different areas, etc. I understand that you are deconstructing the fallacies stated by others that defend the benefits of zero drop with no scientific arguments, but I think that the danger of mentioning specific cases can always be taken as cherry picking.

  5. Tim Litzinger December 1, 2013 at 11:14 pm #

    Craig, your responses and lack of knowledge regarding the issue you at hand really put into question any trust and integrity regarding this web site. Unfollowed!

  6. Dana Roueche December 9, 2013 at 8:57 pm #

    Craig, good post. I’m just glad that the shoe companies are offering many more models that have a drop other than 10 or 12mm. Until they started marketing trail shoes with lower drops in the mid 90′s there weren’t many shoe options that didn’t have a 10 or 12mm drop other than racing flats or cross country shoes.

    Now a runner can try shoes with various heel-toe differentials and find what feels and works best for them. I know what works best for me so between that and a few other variables, I can quickly sort through the running shoe jungle and get to the models that best fit my requirements.

  7. Mark Richard January 31, 2014 at 7:59 pm #

    No evidence for pitch in shoes.
    People adapt to it. (Not ideal)
    Nature will adapt a part to a feature imposed on it! In other we get used to it.

  8. Golden March 14, 2014 at 8:33 pm #

    Craig,
    You are correct in that there is no science to support ANY claim, by any running shoe company, ever. With that said, I would love to send you a pair of cushioned Zero Drop shoes for an experiment of 1 for you. More importantly, they have a foot-shaped toe box, which is a much bigger deal than Zero Drop anyway. Send me your info and we’ll get something out to you.

    Thanks,
    Golden Harper, Creator & Founder
    Altra Footwear
    http://www.AltraFootwear.com

  9. Kaycee August 14, 2014 at 3:44 am #

    There is, however, science straight from my podiatrist’s office stating that if you have peroneal tendonitis (which feels like someone stabbing you with a knife under your lateral ankle bone) DON’T WEAR ZERO DROP SHOES! 7 years of trying to get my feet as level as possible believing I shouldn’t be wearing any kind of height in my heel because my foot/ankle hurt, I go into the podiatrist, he takes one look at my flat, zero drop shoes and says get rid of those–they’re killing your feet. I would guess that zero drop shoes might be good for some people with certain types of feet/problems, but I will never go near them again. Thank goodness Brooks makes a 12 mm drop shoe–it’s the minimum for me.

  10. Frank August 15, 2014 at 9:09 pm #

    Here is a link I found of an interview with an Asics consultant who states that Asics had done double-blind studies which concluded that most people prefer a shoe in the 10mm drop range:

    http://www.sneakerfreaker.com/articles/simon-bartold-the-bullshit-detector/

  11. Frank August 15, 2014 at 9:15 pm #

    So it seems, there is some “science” behind the idea of a raised heel, whether or not the science came after the heel was raised.

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