Episode 23: Dr. Irene Davis

Welcome to the Movement Movement, the podcast for people who want the truth about having a healthy, happy, strong body. Remember, your body was meant to move. Now here's your host, Stephen Sashin. How can someone who not only makes orthotics basically for a living but teaches other people how to do that, have a change of heart and become the preeminent expert in minimalist footwear and natural movement?

You're about to find out on today's episode of the Movement. Movement the podcast for people who want to know the truth about what it takes to have a healthy, strong body starting with the feet first since those are at your foundation. And on this podcast, you know we get rid of the mythology, the propaganda, sometimes the outright lies that people tell you about what it takes to run, walk, dance, play, hike, whatever it is you like to do, enjoyably and more effortlessly. I'm Stephen Sashin.

I'm your host for the Movement Movement podcast. I don't know why I said that. You want to go ahead. But more importantly, if you like what we're doing, you know the drill, subscribe, like, share, review, go to www.jointhemovementmovement.com to find out all the places where we are and all the places you can interact with us and if you have any questions or suggestions or complaints or just want to share a poem or pay palme some money, you can send that all to move at jointhemovementmovement.com.

So let's jump in. I want to introduce to you my dear friend Irene Davis. Actually, it's more fun to say Harvard's Dr. Irene Davis.

You know, when I say that I have to clarify or I have to add, you weren't always at Harvard. You started out at my sister's on the monitor of the University of Delaware where she was a fighting blue hen. I think the only mascot less intimidating than the Montgomery County Community College slightly annoyed Farrett. And right now you are not at Harvard.

You are doing something really wonderful. You're vacationing. So thanks for taking the time to chat. No worries.

Happy to be here. And how else would you like to introduce yourself? I hate introing people because it always sounds too ridiculous. So if you're on an elevator and someone says, what do you do?

What do you tell them? I tell them that I am, I was first a physical therapist and I'm always a physical therapist. But I'm also a bio-mechanist. So if you put physical therapists and bio-mechanists together, I'm a clinical bio-mechanist.

Okay, that works. That works. That works. That's a good one.

Actually, before we jump into things, I always like to start this podcast since it's about movement and about creating the whole, well, the movement movement is because we're trying to make natural movement the obvious, better, healthy choice the way natural food is. And so we always like to start with something moving. Would you give anything you want to share with humans? Sure.

One of the things I like to think about, this is called active standing. And so if you are standing, you can either stand very slouched or relaxed, which is what most people do, or you can actively stand. And once you start to actively stand, that starts to become your habitual standing pattern or posture. And then you have to think about it in the beginning, but then you eventually have bitchely adopted.

And what active standing is, is you stand, obviously you're standing, your feet from straight ahead. And the first thing that I think about is doming my feet. So for those people who don't know what doming is, you press your toes, you straighten your toes, stiffen your toes, press them down into the ground, and then pull the ball of your foot back towards your heel. So you're basically shortening your foot, sometimes called short foot exercise, and contracting those muscles of your arch.

So you start there, and then you tuck your butt in a little bit to get a neutral pelvis. You tighten your abdominals. You pull your shoulders back a little bit. Slide your head back a little bit, and then stand there.

And it's a very different stand. If you take that stance and then relax everything, you'll see the kind of your habitual stance posture. So I want everybody to start thinking about incorporating active stance into their day. And I want to add the first instruction, take off your shoes.

Exactly. Yeah. And I also want to add that Irene, the framing that you have in the camera is in part because since you are at the beach, it just looks like you're doing this semi-naked, which I think is awesome. But no, which right now you're framed here, which is great.

It's sort of proof that you're not naked. That's my kind of thing. I only have one question that I plan to ask you, and it's one that I know the answer to because you and I talked about it before, but it's one of my favorite stories. And that is, what was your moment of awakening from being someone who was showing physical therapists how to post people's foot put them in orthotics to what you're doing now, which could not be more diametrically opposed to where that all began?

No, there wasn't a moment, Steven. It was really an evolution of thought. And I really encourage people to keep their minds open because sometimes the truth that you have today is not the truth you're going to have in five years from now. And the truth five years ago is not the truth of today.

And we have new information. We gain new perspectives. I think what happened is I had started doing my work in understanding impacts. And I was looking at strike patterns, thinking that forefoot striking was sort of the unicorn.

Only small percentage of people do it, but understanding just the differences between forefoot striking and forefoot striking, understanding also the relationship between the impacts that you have as a rear foot striker and different injuries. And that's kind of how I started my career, started out looking at impacts and to be a stress fractures, and then kind of continued to other injuries like plantarfasciditis and the patellofemoral pain syndrome, some of the really common injuries that runners sustain. And then also, this is kind of at the time, it was sort of at the time that Born to Run came out. And Chris McDougall came to visit our lab.

I didn't know he was writing a book at the time, so this was before Born to Run came out. And he wanted me to look at his ground reaction forces when he ran barefoot and was shoes. And it started to make me think about barefoot running and what an article had come out, oh, gosh, and I think in the 80s and looking at barefoot running, but I never really paid much attention to it. But then when we started talking about this, and he'd been down with the Tomlomara, he was talking about how these individuals tend to run on the ball of the feet.

And so now I'm thinking, okay, I did this work in forefoot striking. Forefoot striking has less impacts. Barefoot runners typically run forefoot striking and less impacts seem to be less injurious. And then I kind of connected with Dan Lieberman and he gave me an evolutionary biologist kind of perspective, which was me and I started thinking about that.

And maybe this is really the way we adapted to run. And so it really was a slow process. And honestly, probably over the course of five years, three to five years of thinking about it and sort of coming to it. There was a study that came out in 2010, a series of studies by Joe Knappock in which he was looking at different shoes and looking at the motion control shoe, the cushioning shoe, and questioning whether these shoes actually prevent injury.

So what he did is he took half his recruits and he did this in the Army, the Marines, and maybe the Air Force and they combined it all in one big meta-analysis. And so there was something like 8,000 altogether. Half of them were prescribed a shoe based on their foot type. So if they had high arch rigid foot, they got the cushion shoe, if they had a flat sort of hypermobile foot, they got the motion control shoe.

And then if they had a neutral foot, they got the neutral shoe. And then the other half all got the neutral shoe. So what he did is he followed them for, not exactly sure how long, I can't remember how long, but maybe through their recruit training and found that there was no difference in injuries between those who were prescribed footwork based on their foot type. That made me question because I was teaching scores of physical therapists this sort of approach to footwear.

And after seeing that, I thought there's 8,000 subjects in the study who are still not finding anything. Maybe we should question this paradigm. Maybe everyone should be a neutral shoe. So that was kind of my first kind of thought about footwear.

But then when I started looking at how footwear affects foot strike, it started making me question even neutral footwear because footwear basically, if you put a conch over rubber underneath the heel, people are going to land on it. So I'm making notes because there's a couple things you brought up that I definitely want to bring up, but okay, got it, keep going. So for those who, if you put a hunk of rubber underneath the heel, people are going to land on that heel. That's a good question, but I think in part, if you land on your heel, people tend to stride out for giving teens, you can go faster in a sense.

I mean, there's a payoff for that, but there's also a cost in that you get to see more. That's what made me start to question footwear. And then footwear and foot strike, we can go into that maybe a little bit later, but there's definitely an interaction between the two. It's funny you say that because, so you and I last year were the American College of Sports and Medicine's annual conference.

And both the guys from Brooks and Adidas started their presentation by, let's use the phrase in quotes quoting Ben O'Nig, researcher from Canada, by saying that everyone has a preferred movement pattern and footwear doesn't matter. And I was biting my tongue because there was not an opportunity for me to counter that. What I think I might have said is I was in the lab with Bill Sands, who formed head of a biochemistry and Olympic committee, where what he would do when he got in his lab is he would have you wear your favorite pair of shoes and then go barefoot and then try on every other pair of shoes that you brought in with you and film you on his giant treadmill that could go up to about 30 miles an hour at 500 frames a second. And what he saw was the exact opposite that every different shoe you wore changed your gait unless you were like a super super elite athlete where you could pretty much put cinder blocks on their feet, nothing changed.

So I was amazed that they started with that idea that footwear didn't matter. Yeah. And footwear matters a lot. Well, and then similarly, I actually, so it seems like one of my, I was going to say jobs or goals.

I'm not sure which it is, is to annoy the CEOs of major footwear brands. And I had a conversation with the CEO from Brooks, who they have their run signature program where they put little dots around your knees and watch you squat and then have you run in socks. This is an important thing. They don't want you to think you can do this barefoot in socks on a treadmill.

And then they somehow come up with some conclusion about which brook shoe you're supposed to wear. And I just asked Jim the simple question, well, where's the evidence that that improves performance or reduces injury? And that was the end of the conversation. There is none.

I wanted to pick up on when you're coming about how footwear doesn't matter, not that you think that, but that other people think that. You know what made me really, really believe that is when I came up to, to found the Swag National Running Center, we've now seen over 700 patients and every single patient has come through our center. I watch them in slow motion, run close up of their foot, right, right, on the backside, barefoot in their shoes, which 95% are in traditional shoes and in a pair of minimal shoes. And what I see is what really convinced me that footwear really matters.

I mean, the changes, it's not always, I mean, in the change of- No, but significant. And the majority of people, footwear changes the way they start. Yeah. Well, when I was in Bill's lab, we did a little pilot study where, because we were, what he saw when I was running just in our original sandal, which was just a piece of rubber strap to your foot, which we still sell, he noticed that my running was basically the same when I was in nose compared to when I was barefoot.

So we did a little pilot study. We brought in people and we had them run either barefoot, well, all four of these conditions, barefoot in a pair of sandals that I made for them in a pair of five fingers because we got people who all owned five fingers. Actually, no, we even brought some. I don't think people owned them or whatever their regular shoe was.

I don't know why that's four. That's what we were waiting for. There we go. And what we saw was two things that were really interesting, actually three.

One was that, like you said, almost everybody when they switched to barefoot or in our sandals, gate changed in really, really positive ways for about 90% of the people. The second thing is that, and it was very consistent. The second thing was that when some people who were accomplished barefoot runners, when they were running barefoot, they looked great. And when they put on the five fingers, let alone their minimal shoes, they often started over striding heel striking, but here's the kicker.

They didn't know they were doing it. And that was because they were wearing one of those shoes that had more padding than the others because they were made for running big air quotes. And then there was, oh, and the third thing was the people who didn't have an automatic gate change in some way to something where, and when I say better, what I mean was getting their feet underneath their center of mass, landing four foot or midfoot, in that case, just not pawing at the ground. Just things are kind of seemingly obvious at this point.

But at that time, this is 2010-ish, we're sort of radical. It took very, very simple cues to get them to do something different where they suddenly felt better. It was just kind of giving them the idea that they could do something different instead of trying to run the same way. And they did.

It was really spectacular to see. And what cracked me up, of course, is how surprised everybody else was. Yeah. Yeah.

You know, you mentioned midfoot striking. And it is something I want to bring up because I knew you would. Yeah. I mean, it's kind of like partial minimal shoes, minimal shoes, and traditional shoes.

Well, I'm going to pause you there because this is something I know if you know that I do this. So I know you break things down into traditional shoes, partial minimal shoes, and I'm going to ask you to find that versus minimalist. And I say that when you say that you're just being politically correct and I redefine it as minimalist, fake minimalist, and normal. I buy that.

But the studies that have been done in the partial minimal shoes show that people run pretty similar to when they run the traditional shoes since not until you get to true minimal shoes that you really start to see the changes. Yeah. And so this idea, and I used to think part in the beginning thought, well, this is a nice compromise. People like compromise.

They don't like to be on the edge. And then people do like to find something in the middle. But part of that is when the whole minimalist thing kicked in. The first response from big shoe companies was don't do this.

You're going to kill yourself and you're going to get Ebola and you're going to step on hypodermic needles and the turtles will die and dolphins will come reaching into your house, whatever it was. And then by the end of 2010, they're all coming out with partial minimal shoes and saying that those products gave you the same benefits as being barefoot, not even compared to other real minimalist products. And then the companies that weren't willing to go there, I mean Adidas is the one that pops in my mind first and foremost, like, oh, here's a whole transition program. Go from here to here, to here, lower, lower, lower.

And everyone's going, well, yeah, that makes sense unless you think about it when it makes no sense. So yeah, the idea of partial minimalist is definitely, or fake minimalist is definitely catering to people thinking that, you know, maybe I can't make such a radical change right away, which is ludicrous. Well, I mean, you can't make a radical change right away. I don't think that's ludicrous.

I think you do need to gradually transition. Well, yes, that doesn't mean you have to, you know, gradually drop the height of your shoes. You have to make a gradual transition. Your moves.

You don't really need to change this until you don't until you're in a minimalist shoe. So obviously we do try to transition people really slowly. That means the dosage that you get as well is building the capacity because it doesn't look like you're probably differently. It loads the calf differently.

So I do think it's smart to transition, but we don't do it that way. We don't go from a thick, we do the other way. But I started the conversation with talking about midfoot strikes. In the forefoot, yeah.

That was another compromise that I always thought was the way to go. And I actually, before really studying it, said, okay, midfoot striking is a nice compromise. You don't have to work on your calf so much. It doesn't look like a calf.

You don't get the impacts. Well, once we started looking at our data and we have data from the ground reaction force data as well as Kibil Shock. Right. And one is that when you look at Kibil Shock or load rates, which are an indication of, we've shown to be related to injuries.

So it's how fast your body is being loaded. You tend to be higher near foot strikers who have an impact peak. Those load rates are actually not statistically different between rear foot strikers. But foot strikers look like they're a little bit odd, but they're not at all significantly different.

And the same with Kibil Shock. They're similar to rear foot strikers. These are people who are bitual midfoot strikers. And this is what I think we have to do is we have to study people in their habitual states.

Taking someone and making them a forefoot or a midfoot striker or whatever, taking a forefoot making is not going to be their habitual state and not the end or not as valid. This is an argument that I've had with Roger Traum here at CU, where he takes people and has them, switch to something barefoot and shows, hey, their VO2 max is worse. It's like, well, yeah, they're doing something brand new. They don't know how to do it.

So I was listening to him. I love Roger. I love him. I think he's awesome.

But I've had that same conversation with him. It's even though he's done a stride length and oxygen consumption. I've asked him that question too. So once somebody is accommodated, then that might be there.

You may shift. Well, and I similarly like Roger very much and we see each other at Track Meats every summer. And I made that comment. I've also said, look, when you're studying barefoot compared to whatever, you're bringing in people that you're calling a accomplished barefoot runners, I know all the barefoot runners in town.

I'm one of those barefoot runners in town and nobody that I know has been in your lab for those studies. So I don't know who you're studying. And it's people who do some training on grass in bare feet, which is just not the same. It's not the same.

Yeah. One of his studies was actually he took a treadmill where he put 10 millimeters of foam that he got from Nike on it, which was interesting. Of course, no Nike shoe has 10 millimeters of foam for one. And the other was, again, it was, I don't know what it was, but the whole reason for doing that, or one of the reasons for doing that was looking at VO2 Max as an analog for performance or as an analog for efficiency.

And I thought that was an interesting bit of hand waving because no one in the barefoot world ever claimed that if you run in bare feet, it's more energetically efficient. And of course, nor is there any correlation between VO2 Max and performance? Because if it was, we would have to see who had the biggest VO2 Max that day and give them a trophy. So there's ways around that.

So I thought that was very interesting. And like I'm not trying to rush her under the bus when I say this, but over a beer, I said to him, we know that studies or that meta-analysis of studies of pharmaceutical drugs show that if the pharmaceutical company is paying for the study, the results tend to err in their favor more often than if it's an independent study. And I said, your lab is Nike sponsored. So don't you think there's anything in there that might be problematic?

And I'm not surprised that he said no. And I don't know that there is, but it gives me some pause. Yeah. It's hard because when someone wants to fund your lab, right, that's why it's not that.

But it also does, it gives an apparent conflict of interest. I mean, I trust Roger. I think he's very, is a lot of integrity. But yeah, I find it difficult.

I've tried not to take but wear money for that reason unless I offer, so for example, our Boston Marathon study, we went to every footwear company, everyone, and the only people that were willing to support it. And the study wasn't about footwear. It's about running out on it, but it was Vibrum. So Vibrum did support one of those studies.

But we offered it to Adidas. We offered it to everybody. We went to all of them. So in that case, it's a little bit different, but it is hard.

I mean, I understand why people do it. I mean, Joe Handel has had a lot of commercial support as well as well as Benonig and all of those folks. But it does give at least an apparent conflict. Yeah.

I mean, we're concerned about that from our side. Elena in particular really wants to fund some studies, assuming we have the cash to do that, which right now our cash is going inventory. But it's something that if we raise some extra capital, she wants to fund some studies. And I said, it's inherently problematic because people are totally going to say, well, you know, of course, it showed that whatever you're doing is better because you put up money.

It's funny back up to the ACSM thing. This is something I quote often. I don't remember. I think it was the guys from Adi who said, you know, well, we say that we're all about producing injury and improving performance.

We don't have any studies to show that because doing that would be very time consuming to take a long time, cost a lot of money, have a lot of compounds that would make the results sort of suspect. And again, it wasn't my position to say anything. My thought was, dude, if you could make a shoe demonstrably scientifically better than the guy sitting next to you and that's a guy from Brooks, that's worth billions of dollars a year. And you're saying you haven't done it because it's difficult.

I mean, you know, I know that there, I've heard rumors of studies that have been done internally from larger companies where it did not prove what they wanted to prove and those studies have not seen the light of day. But I mean, it couldn't be more clear that, you know, that if a shoe was significantly demonstrably better, people would be shouting that from the rooftops and there could not be more incentive for a lot of companies who have done that over the last 50 years and no one ever has. And in large part, because they're just reinventing the same broken wheel. I was just at, I suppose, big trade show in Germany and I said somewhat apolitically that because I kind of lost the urge to be politically correct or diplomatic.

I said, if you walk around this hall and just swap the logos for most of the shoes, you wouldn't be able to tell. There's maybe one or two brands where it would make a difference. And even then you go, okay, looks the same. It's just, it's shocking.

So actually, I thought of one other thing that I want you to talk about from a previous conversation of ours early on when we first started chatting. One of the things you said to me, which was very striking and frankly kind of both inspiring and sad at the same time and also riled me up. You'll see where I'm going with this as soon as I tell you what it is, was that one of your big hopes was that before you die, people understand the impact of what you've been discovering and researching and studying and sharing with people. I'm really curious what your thoughts are about why it's been.

First of all, why it is that we in the natural movement space need to prove anything because we're not the intervention. The intervention is what's been happening for the last 50 years. But then why it's so shockingly difficult to get people to hear it, understand it, try it, experience it, et cetera, when it is so screeningly obvious. Yeah.

So I don't think I exactly said what you said. Okay, well, that's the way I'm telling it. You talked with my work before I die. I guess what I really want to see is for us to revert back to allowing the feet to function more naturally in kids and then it becomes the norm.

That was part of it. Now part of the other thing that you said in that same conversation to the best extent of my memory, which I've never claimed as accurate, was, yeah, if we could just get kids to be doing this now in 20 years, we wouldn't be treating adults for all the problems they have right now. They're being conversation, right? And I would be very interested to know what the injury patterns would be like.

We all can say what we think and we can hypothesize what we don't know. But I did a search on the term running injury and the midline search from 1900 to 2000. Just to see the total last 100 years, there was nothing in the literature. I'm not saying there wasn't one study that didn't have running injury in its title but was still, but there was not one study with running injury in its title until 1977, right?

Not one. And then afterwards, there are thousands and thousands of them. Now from 1977 to present. When did Jim Fixx's book come out?

80? Was that eight? I think I was in high school. I graduated in 80s.

It's late 70s. So probably somewhere right around them, but certainly not. 77 is definitely not the time in which the running boom kicked off. So that predates that.

That's really interesting. Very interesting. And what that tells me, the very first running injury report that I could find was 1971, a newly minted runners world, put out a survey to its readership. It's about injuries.

And they found that the people who reported injuries, other people that replied, I think it was something like 20 something percent had gotten me. I used knee injuries as an example. And then they repeated it in 73, they had 800 runners in 71, and then 73, they repeated two years later. And they had 1600 runners, and then the knee injuries increased.

And so you can start to see that things were increasing just from that early injury study. But that wasn't published. That was something that was in the first published article. You have to think that if injuries were happening a lot, that they'd be in the medical literature, right?

I mean, medical literature's been around for a very long time. People have been running marathons for a very long time. Now, I don't think you can disassociate, though, the running boom with the footwear change. I think they kind of gave it together, right?

There is a lot of your relationship there. So more people were running, right, who were less fit. But they weren't as fit as we are today. No, because what the people, I mean, yes, it was a boom, but it wasn't like, you know, the boom happened on day one, and suddenly everybody started running regardless of their physical fitness.

I mean, the first people to adopt it were the people who already kind of hit the idea to begin with. You didn't start seeing, you know, really overweight people getting into marathons for a while. Yeah. But, you know, it's interesting because what happened is you had people who were not used to running running in flats.

And this comes from talking with Jeff Johnson, who was one of the early, he worked with Nike very early on. He actually came up with a Nike name, I believe. And I had a conversation with him. He doesn't have email.

I think he has one of those phones on the wall with a curly. He's got the sense of a, and he told me about, you know, how they were, he was running in the 50s on Plimsole. She was like, well, just a rubber sole and canvas on top. And he said they had very few injuries, very, very anecdotal.

But he said, what happened is when people started, other people started running, so people who were not used to running. And they were getting these reports from these sports podiatrists that they're having these injuries. Very well known sports podiatrists in. Dennis Vixi, Steve Savatnik, and Harry Hillebnik, I think.

Anyway, they came in and they said, look, you know, we think that they're getting injuries from hitting too hard, not enough cushioning and too much motion. And also because they were used to walking and shoes, typical walking shoes had two-inch heels. And so now they're putting a strain on their Achilles. So what they did is rather than have runners adapt to the shoe and the footwear that all the other runners were running in, which were basically minimal, they started adapting the shoe to the person.

What's this idea? This idea that you need to, you know, give them that relief and Achilles tend to snipe and elevate the heel, give them cushioning because that's a problem because they hadn't learned how to attenuate their low jet, give them motion control. Well, what happened is the very adaptations that they made, actually, I believe, further created problems. Well, Ben, one of those cycles.

Well, A, I agree. B, you and I have another mutual friend, Mike Friton, who says he was at a track meet. I don't remember with how many of those three guys and said, so, you know, your idea has become ubiquitous. And this is footwear design.

Now, what do you think? And the response was biggest mistake we ever made. Wow. And, you know, I mean, but the whole thing about heel strike, the thing with her, why it happens, it's funny, if you look at the, not funny, if you look at the videos that Lieberman brought back from Africa with habitual barefoot runners and you look at their foot strike pattern, I mean, their heel is like so close to the ground as it's coming through the swing phase.

And then at touchdown, it's barely off the ground. So if you just throw something that's more than a half an inch on their heel, they're going to hit their heel in front of their body because they are not unlike anyone else. They're not going to just change their movement patterns immediately. So if they don't change their movement pattern right away, they're going to land on the heel.

And then they have that padding. And of course, you know, calcaneus heel bone is a ball. So that's unstable. So now you need motion control.

And if you're landing with your foot, by the time your foot comes down with your flat, your planter fascia are in this weak position. And so if you're going to do anything to deal with that, you're going to put in, quote, arch supports. You don't need to use your arches. Put it all together.

And now you have something where you're preventing all sorts of everything, not letting the foot function in any way. And what a shock that we're getting having problems. I mean, it seems like this obvious evolution of errors. Yeah.

And so that's why it's hard for me to understand why people are so dug in. I mean, I know there's any sort of investment that's going to give you. I think some of it's similar. And you know, I'm going to sort of segue into something funny.

I got two notes of things I wanted to do. But the first one, I have to tell the story this way. Or I have to set it up this way or it's just too offensive. So about 10, 15 years ago, one of my best friends calls me and he says, you know what your biggest problem is?

I said, oh, this will be fun. And he says, your biggest problem is that you just tell people if they're factually incorrect or logically inconsistent or in some cognitive bias or anything like that, where they're not thinking clearly. And you do that because you find it really interesting when people do that to you and you think they're going to find it interesting and go, oh, but mostly they just think you're an asshole. And I said, oh my God, I've literally never put it together like that before.

And he said, see, you just did it. So which is true. So in a similar vein, I'm going to say I have a theory about what your biggest problem is. And your biggest problem, and it's not that it's your biggest problem, but I think this is an answer to the question why it's so hard is that human beings, when they come to a decision, think they've done it rationally.

They think it makes sense. And especially with all the marketing behind the footwear we're talking about, they get a lot of evidence for that despite the fact that that footwear hasn't worked for them and they keep changing over and over and over and the story keeps changing over and over and over. I've referred to this as the boy who cried or the shoe company that cried wolf. The only difference being that we keep showing up to see if there's a wolf despite the fact that there never has been for 50 years.

But because they made this rational decision, it's also energy inefficient, evolutionarily and energy inefficient to make up new ideas, to come up with alternatives and counterfactuals what you already believe. And what you're often doing brilliantly, I believe, is presenting more rational information. And there's a lot of psychological literature showing that when you present someone with information that conflicts with their existing belief, it actually makes them dig in harder because that's the way we're wired. And it makes me wonder, like, what's the way around that?

And certainly my experience has been that experience is one way around that. But I think there's got to be another way to encourage people to have the experience to begin with. It's beyond giving them all the data that shows that what they're currently doing isn't going to give them what they want. These have been showing that highly cushioned maximalist shoes don't reduce impact loading forces and yet people still buy them thinking that it's going to be cushy and make them feel better and be better for their knees when we don't see that.

So I think this is the conundrum that you may find yourself in is that you are both creating and discovering and inspiring all of this information, but information isn't going to be the thing that makes the change. Yeah. And I'm wired that way. You know, the...

You and me both. Evidence is my coin, it's my metric. I keep thinking that if we can demonstrate that, like, when people run in minimal shoes, it's been shown that the Achilles is stronger and stiffer. It's been shown that muscles are stronger.

Stronger feet are going to be healthier for you. It makes sense to me. But... But Irene, don't I need our support?

Yeah, I know. I mean, seriously, don't you get that as the follow-up? Like, but don't I need... One of the arguments I get, which is maybe not a bad argument, is that having some padding in their shoes allows them to run farther.

And there may be some truth to this. I'm not going to argue that one. But because there's, especially with ultra runners, where by the time they're in the last part of the race, you know, their form has degraded to complete crap and they just need to do something to get through the rest of the race, I'm all for it. But for the average recreational runner, it's like, just, you know, do a mile less and be healthy.

Well, so this is it. It's because people, I always tell them you're out running your capacity. Your body has a capacity to cushion and to control your fingertips. If you want to run farther than your body has a capacity for, then maybe you need that crush, so to speak.

You know what I mean? Yeah. So, I mean, there is a trade-off, I think, in terms of that. And the people choose to do that fine with it.

But I'm trying to promote it. If we got people and kids in minimal shoes, and that's all they ever wore, it had built over the years, the capacity to be able to run longer distances, there are people playing people playing in a marathon in minimal shoes with their foot. Not all people can. And so that's the argument that I get.

And I say to them, if you want to run a marathon and you don't have the capacity to do it, then you probably shouldn't. When I was in Germany, one of the guys that I was on the panel with was from New Zealand, and I brought up Arthur Lydiard, who for people who don't know was the coach of New Zealand runners. He was probably the most successful coach in history, especially if you think about the population he was working with, this tiny little country and the number of world champions and Olympic medalists that he produced. And there are a number of things that were interesting.

One is Arthur had people doing tons and tons of mountain hill training in the shoes that he made for them, which were super thin-sold. They look like mine, frankly. Even this guy from New Zealand who is now repping for a company that makes big-big-padded shoes, was saying, oh, yeah, that's what he did. And it was great.

He believed that having foot strength was really important. And he's saying this while wearing a shoe that does the exact opposite of what Lydiard did, while talking about how great Lydiard's methods were. And I heard a story that Lydiard and Bill Barriman from Nike had this knockdown dragout argument about shoe design after Nike started doing the L-A-ed at heels and padding. And Lydiard's saying, you're just going to kill people.

And Barriman's saying it, but they're selling really well. But it is interesting, related to the phenomenon of people outrunning their capacity, is, oh, wait, where that thought go. Oh, it's people using elite athletes as the example of what they should do. And I keep saying, you're not a 105-pound Kenyan guy who runs a marathon in 205.

You're a 200-pound, whatever guy who runs a 430. And so to think that what he's doing on his feet is what you should be doing, what you should be wearing is ridiculous. And of course, the other issue is that, I mean, so much changes when you're running at speed. People talk about who will analyze all this video data.

And look, this guy's heel is touching the ground first when he runs. It's like, yeah, yeah, but he's running basically 13 miles an hour. And by the time he actually loads his foot, it's a whole different story. So yes, his heel is barely touching the ground before he gets any loading.

And people just, again, like you said, people want a simple story. And ironically, I think we have the simplest story. Your feet are supposed to bend and move and flex and feel the world. And that's what you should be doing.

I know. You know, the other thing that I think we have to remember, too, is that if you follow like this whole mismatch leader of evolution and you believe that we should move the way we're adapted to move, we really weren't adapted, I don't believe, to run 26 miles relatively on a straight path on hard surfaces only. I mean, I think we were adapted to run on hard surfaces, soft surfaces, variable surfaces. Right.

We're running back then. What we adapted for was really stop and go, changing directions, a whole whole thing. So maybe we're setting ourselves up in that way for injury. It's just repetitive use.

Maybe people need that footwear to be able to do that kind of running. Well, I'm just talking. Yeah, that's interesting. Well, what's intriguing to me about that is thinking about the fastest-growing movement in running right now is trail running.

And I think that that maybe because it just does have that more variability. Yeah. That is helpful and feels good and is interesting and compelling and... It's injurious.

Yes. Well, yeah, yeah. And what's so funny, I went for a run up one of the mountains outside of Boulder with a woman a couple of years ago who I was in pair of sandals and she was doing a barefoot barefoot. And because she'd spent a lot of time practicing and got really good.

And what people think is that she has some massive calluses on her foot, but she's got really good at mapping the terrain and running with the terrain. And people looked at us like we were the crazy ones. And we were the ones that had this insane look on her face called smiling. Yeah.

Yeah. It's fascinating. Here's another question that's popped in my head backing up to you after you do your elevator page. I'm imagining that I'm not the only one who, when I tell people what I'm doing, they bring up the Vibram lawsuit and as seemingly proof that this whole idea is ridiculous.

How do you respond when people toss that one in your direction? I don't like that look. So the first thing I tell them is that the Vibram lawsuit was not about injury, but it was about false advertising because Vibram talked about how the strike and surfy. There had been a study with a Nike free showing that when you take away our sport, the arch muscles got bigger.

And they were kind of, I think, piggybacking on that. That's what they were sued on. So that's the first thing. Right.

And I tell people, but the other thing I tell people is if you went to the gym and lifted a hundred pounds, the very first time it got injured, do you think anybody would say don't ever go to the gym again? Or would they say don't do it that way? And that's exactly what's happening. You can't just take and put a pair of shoes on that now puts a greater demand on your foot, the medial lower leg, the posterior lower leg, primarily those of the areas that get loaded the most and run your regular mileage.

And think that you're going to be able to do that. It's like, why not play seven-plus of tennis when you've never played. You're going to injure yourself. You're going to be really sore or at worst you're going to injure yourself.

Right. Yeah. I also add that the lawsuit was settled out of court, which means, and for, you know, pennies on the dollar. And I think that I've had this conversation with Tony Pose, who was no longer CEO of Vibram at the time.

And Tony says he wouldn't have settled the case because of that Nike free study. And just, you know, I think there were some other dots that they connected where they just know that. I think, you know, they had shown that a shoe that does not have arch support results. And now there have been many more studies have reported that.

Yeah. Well, and back to what you just said about many studies and what I said earlier about the American College of Sports Medicine thing. So the guys from Brooks and Adidas, they both misquipped Ben on Nick. Oh, actually, I don't know if I told you this.

I had to talk with Ben on Sanro. And I was about to kind of read him the right act about this idea of preferred movement pattern and how it's just not the case from what I've seen in the lab and what I see with the people who come where's your issues. And before I could finish the sentence, he said, oh, what my dad was saying is that you have preferred movement patterns difficult to change, assuming you're basically wearing the same kinds of shoes, which every shoe is basically the same kind of shoe. But he never said that if you switch something truly minimalist or barefoot that you're getting the same, it's definitely going to change right away.

It's like, there we go. So but you know, completely taken out of context. But the reason that I bring that up is that when these guys said we don't have a whole lot of research to back up what we're claiming, I had a slide that was just little brief screenshots and I think 40 different minimal studies that I just found by searching on PubMed for minimalist shoes and just, you know, one after another showing the benefits thereof or the simple thing, it amazes me that we need to pull out studies that show if you use their feet, they get stronger if you don't use them, they get weaker. That's the part is it seems so simple to me.

Yeah. You know, I just think you're right. I think people, I think that they get, they get kind of stuck in a dogma. They really do.

It's like it's, it's the way that they think and it's hard to think differently. That's why I try to tell young scientists to keep your mind open because I was the person that made every orthotic, you know, in, when I was a university of Delaware, I was a person who was in the clinic doing footer, I taught it in the curriculum, I taught people motion control, I taught all that and I believe it. But one, I started to think a little bit differently and I started putting things together and reading different things. It made me think differently and you've got to be open to new ideas.

Well, I went back up to the first part of that. So what, how did you learn those things to begin with? From someone else who taught me who, you know, was basically, it was actually someone that I worked with and did my PhD with who was really very much a foot person, came from a really strong hospital that worked on feet. It was more diabetic feet, but had done a lot with orthotics and it's kind of what you taught.

I was taught some of it in school, I think. It was sort of from my peers and what I was taught in school. I think I just, you know, you kind of get that mindset. So that's why it's important that we get this back into the schools.

Well, you know, again, I want to follow it back in time. So they learned it from someone. Yeah. So, I don't know if this is when, because what I, I don't know if this is true, but there's two components.

One, just for footwear in general, we know that what's called the modern athletic shoe was a relatively new phenomenon, but now, you know, now it's been 50 years. And so we're past two generations. So parents are teaching to sit at her kids before they ever even walk into a shoe store. So the shoe companies don't need to do any of the heavy lifting anymore.

They can just say, hey, don't want to be like this guy. They don't need to justify any of their designs, although they try to. Now they do. They have the running up in the shoe store with really very little experience, how you're running and you pull out a shoe.

I think that's where it's coming from, a lot of those coming from the running shoe stores and marketing. Well, in the marketing because someone, because... Well, not much. Well, yeah.

But I think about, I don't know about the history of orthoses, but my hunch is that whoever came up with the idea of putting an orthotic in a shoe and posting it to the large and doing it or else they need to do, especially for runners, then realized that this is a way for practitioners to make a bunch of cash and created a basically marketing plan that once that initial push was done, the rest of it just rolled. And if people look back and found that initial event and saw that one, that might be a way of snapping people out of a bit of a 50 year old trance, or maybe not. I mean, I sometimes half jokingly say, it's a shame that we're doesn't kill people, because if they, if she was killed people, then we have tobacco situation on our hands where there would be a lot of incentive to do something about it. But it's like, yeah, it's shoes.

Yeah. It's interesting. I do think there's been a change in the podiatric world because I hear more and more podiatrists say, these shouldn't be permanent. Right.

To me, that's a big change. Huge win. Yeah. I mean, we're not exposed to three different pairs of people's shoes.

You need them and all of them, right? And honestly, it was not for money at all, because as a PT, we never charge the same as a podiatristic. And we didn't make a lot of money. I really believed it.

And I'm going to take the higher road, I mean, the higher road. I like to see the good people. And I think a lot of the podiatrists I know really believe that these really help. Oh, no, I agree with that completely.

I don't think that anyone's doing it explicitly for the money. I think that they are doing it because they believe that it's useful. The money doesn't hurt. The money locks in that belief.

And, but it's sort of like, I remember when I first got back into sprinting 12 years ago, or so I went to someone because of some problem I was having and he suggested that I wear an orthotic. I said, I'm a sprinter. You're going to put me in a three quarter orthotic. I'm never on that part of my foot.

How is it ever going to apply any forces to change anything? And you watch this guy's brain explode. And he spent like five minutes trying to figure out, tell me why it would still be useful. And then he kind of realized he was at the end of his rope and had nowhere to go.

And that was a real, and this was before I knew any of this. It was just, it seemed really obvious that I was going to be on my toes and the orthotic did not go to my toes. And that was the funny one. That's go to your menotageal heads though.

And it is supporting your arc so that when you land on the volume, but you do bring your heel down and you do get some support from that orthotic as even as a forefoot striker. Never, essentially, I never felt that there's a company that makes a somewhat concave or kind of expanding on which way you're looking at it. What's a carbon fiber insert that they say improves performance and you know, you get more spring out and blah, blah, blah. And I put it on, I ran with it.

I tried a few of them. I don't feel a thing because I'm never loading it in a way that it's going to do whatever it's supposed to do afterwards. And besides, it's physics. You're not going to get more energy out than you put into it.

But I mean, I literally didn't feel a thing. And I put one in one shoe and nothing in the other and switched them. And I did everything I could think of to see if I could feel anything and just got nowhere. I tell people, I think that it's important to support the arch if you have some kind of active plantar fasciitis.

You support anybody part when it's captured. Yeah. Right? But then you need to slowly remove that so that you can get that strength back.

Just like you would with a back brace, neck brace, shoulder brace, any other. Getting a cast off your arm. That's analogy I use. If you're on a cast, you take it out as a attribute.

You have two choices. Keep it in the sling for the rest of your life or use it again. And then it'll be fine. So what are you taking a look at now?

What's coming up in the wonderful world of Irene Davis research? So we have a lot of things going on. We're just getting a study off the ground looking at basketball players and looking at how they land and looking at TVL shock in basketball players and how that changes throughout the game, throughout the season, how it relates to injury, how fatigue affects how they land, how sleep affects how they land. So that's a big one that we've got.

So we made a demo basketball shoe. I put it on a WNBA player who sent me two emails that were interesting. The first was, I couldn't spray my ankle and these if you paid me two. And the second was, there's times where I come down from trying to block a shot or rebounding or something and I'm landing on my heel and with nothing under my heel, that's really a problem.

And so we're trying to find this interesting balance of giving them what they need for this specific use case without creating movement patterns that they believe and we believe are going to be not beneficial. And it's been an interesting thing trying to work that out, especially without a giant budget where we can just make 100 pairs of shoes for her to try and for other people to try. It leads me to another point. A lot of people ask you the question, okay, so I'm in one of those shoes for running or for walking, but what about for other sports?

And walking and running are things that we were adapted to do. We're adapted to ski, for example. And we weren't adapted to ice skate and play hockey. And so in the things that we weren't adapted to do, we sometimes have to have things that help us to do those activities that we're going to do.

If you don't have a stiff ankle boot and skiing, it's going to be very difficult, right? And so I could sing with basketball. Whereas walking and running, you can do those barefoot. You can argue though, there are people that play soccer barefoot.

When we go to Italy, the kids in the Piazza are playing on a concrete. Yeah, it's a barefoot playing soccer at a young age. So I think you probably could adapt to some of those things. But that course involves running, which is something we were adapted to.

Well, yeah, and there are just these specific situations that happen in some of these sports where you need to adapt to that in some way. But again, you don't want to encourage, you don't want to take that one adaptation or that one intervention and have that apply in such a way that it affects everything else unnecessarily. So I can't wait to hear what happens with that. What else is in the?

Well, we are looking at differences between forefoot striking and minimal shoes versus forefoot striking in traditional shoes. Ooh. I don't know if we talked about this one. This is something I started talking about recently when I started noticing that a couple of people running by me on the track who had good forefoot strike patterns, but they were wearing shoes like this.

So they just don't get any of that Achilles spring action going on. It's like they're limiting what their body can do for them. And I don't know. Have people been talking about that?

We weren't looking at that in particular. We did. We published a study in MSSE a couple of years back and a rice was the first author. And we found that when you forefoot strike in a pair of minimal shoes versus traditional let's do it the other way around.

When you heel strike in a pair of traditional shoes or forefoot strike in a pair of traditional shoes, your resultant load rate, that means the combination of vertical anti-poster unilateral is similar. So the resultant load rate is the same. And the reason for it is that vertical load rate is less forefoot strike in a pair of traditional shoes. Okay.

Into your posterior and medial lateral load rates are higher. It's a sense higher impacts in the anterior posterior direction and the medial lateral direction. So for human beings, so basically, so the anterior posterior forward and backwards, I'm guessing that what you're seeing is just more breaking forces because they're overstrawing and slamming on the brakes and then of course all that motion control stuff. Yeah.

And the medial lateral direction, if you've had a flare, you can land more inverted or more on the outside of your foot and then you're kind of pushing this way. Yeah. A larger lateral force that you're applying to the ground. So you have a greater braking force or braking load rate.

So that's the rate of loading. Right. And that is an indication of impact and a greater laterally applied load. So we also looked and found that people tend to planar flex more as well when they landed in a pair of traditional shoes.

When you put them in a pair of minimal shoes, forefoot striking, now you see a reduction in the total resultant forefoot load rate. Right. And you see reductions in each of the components. So it just gives you that indication that if you're going to tell people if you're going to rear foot strike, keep a hunk of rubber under your heel.

Right. Because you don't want to rear foot strike without that. If you want to, well that's fine. I'm okay with that.

If you're going to forefoot strike, we see so many people coming in like this when they land of the character to show shoes and too much flexion. If you really want to adopt a proper forefoot strike, you have to do it in minimal shoes. So this is that interaction of footwear and foot strike that I think is really important a lot of people miss. Agreed.

And well speaking of things that people miss, what you just highlighted was load rate rather than just total resultant load. That's something that people totally miss. In fact, that conversation that Lane is involved with now, this is the thing that part of the conversation was inspired by Alex Hutchinson's not great article in fact was outside about total load and not about load rate at all. Can you talk about why those two things are distinctly and importantly different?

I don't know if that article that Alex was talking about. That was he was talking about different concept. But let me just talk about it. My point is that they never brought up anything about load rate.

Yeah. So if you look at a vertical ground reaction force in a runner who's a heel strike, it looks like a glove. Right. You have a propelian peak.

Right. And so what happens is this peak here is twice the impact peak. And yet this peak here has at least in my readings in our research never distinguished who gets injured who does not. And that's because if you look at the rate of loading, this slope here is much more gentle.

It doesn't look like it by my hand than this slope. So it's that rate of loading. And this has been shown in other studies by like Raiden and animal studies very early on. That if you give a rabbit tibia sub-maximal impacts, but their impacts, right?

Not enough to fracture with one blow. So that's what I mean by that. If you do that repeatedly, then they end up getting a stress fracture. They did follow that up with another study looking at how joints.

And they started with a very rhythmic loading to the cow joint, no damage at all. Then they started to interject these impacts. Right. And they had a very quick rapid cartilage wear.

So the human body doesn't like impacts in general. We need some, ball needs some loading for sure. Correct. The studies that have been done with children and get increasing their bone loads have been done with jumping, which is a four foot strike pattern.

So I think broken striking and jumping does give you that stimulation that you need. But you know, I just think that there's a point, I think, that you have to do much load rate. And definitely some because some amount of impact force is what inspires increased bone density. And there's value there.

There's something else that it does, especially with jumping. Jumping increases nitric oxide production. And so that's a really interesting one that very few people talk about. I don't know what the real effect of that is.

But someone, I know there was some hospital where they realized this and for people who were bedridden, they had something that was just, while they were lying in their bed, it was just tapping their feet basically, because that motion increased nitric oxide, which was helpful for them. It's so funny. Again, there's all these things that just doing natural movement does that are valuable. And we have to prove it.

You think about somebody jumping off of a table or some kind of stand and they land. They're not going to land with their knees. No. Right.

First of all, they're going to land on the other foot. They're not going to land on their heels. Something went wrong. Right.

So that's going to give them that time to slow their center mass down through the dorsiflexion, because they're landing with their foot like this. So they get to that. The knee flexion, the hip flexion. So we naturally do that.

And if you're out on the trail and you're unsure of yourself, you land on the ball, you don't even if you're a no striker. And when you stop it, stop like, you don't stop and land on your heels when you're in your life. It is natural. Yeah.

So I just think, you know, to me, it seems like an easy argument, but there are some people that are very, very passionate about it. Well, I mean, we're in an interesting situation. Zero shoes is growing really quickly. We're getting a lot more attention.

And it's not just about us, obviously, I said on a podcast recently that if we went under and the whole natural movement thing took off because the big companies adopted it, I'm totally fine with that. I just want this to be a real thing. But I also know that the extent to which we continue to grow before or in lieu of any big companies deciding that they've got to figure out a way to do the same thing, they're not going to take it well. They're not going to just go, oh, oops, we were wrong and just change.

And they're not going to, I tend to work on the idea that, you know, the best idea wins, which is just not the case. And I'm kind of trying to figure out how to prepare ourselves as a company for the kind of response that frankly, I would never in a million years think to do that would be just some underhanded something or personal attacks or whatever it might be because people don't react well when they're back to a corner. And what we're trying to do is back a hundred billion dollar industry into a corner. Yeah.

I'm in favor of taking the high road and just getting as many people on board and the question is how to do it. Well, I agree. I mean, that's the only thing we can do. But at the same time, we have to be prepared defensively.

And it's something that's not natural to me. It's not the way I normally think. So it's really tricky. Yeah.

Yeah. But I'm hoping that, you know, you asked this question earlier on about how do you get people onto this? How do you get them to experience it? Because you have to, testimonial after testimonial, it's a fundamental issue.

As long as they haven't tried to do it too quick. I've had people giving up. I want you to do it. It's just, they love it.

You can't go back. Yeah. And once you are accustomed to minimal issues, all that question chooses is just weird. So how do we, Stephen, how do we get more people towards this minimal issue?

I think, you know, it just, it's just occurred to me and it never had before. I think that we need to stage more events where we can have the quote debate. And I say quote debate because we have all the evidence on our side, I would argue. But people think it's a debate.

So this is what I'm thinking of. I'm not trying to make a comment for this analogy. But I'm suddenly thinking about the whole debate series that went on with the new atheists. When Sam Harris' book got popular and Daniel Dennett and all the guys that are talking about is the new atheists.

And they basically went on tour. And they just did a whole, I mean, these guys made a career out of debating people who they knew they would never convince because their job was not to convince the person they were debating against. And not even to convince the people who were die-hards in the audience, but for the people who were new to it or on the fence. It just gave them a platform that they wouldn't otherwise have because a debate construct is inherently entertaining.

For whatever reason, watching people yell each other is entertaining. Maybe we need to start doing something like that. Just finding a good PR agency who can schedule these kind of conversations, whereas you and me against some designers from Pick Your Favorite Shoe Company or whomever it might be and making these things more publicly available. Anything that's going to get a conversation going.