Intro: This is the TriDot podcast. TriDot uses your training data and genetic profile, combined with predictive analytics and artificial intelligence to optimize your training, giving you better results in less time with fewer injuries. Our podcast is here to educate, inspire, and entertain. We’ll talk all things triathlon with expert coaches and special guests. Join the conversation and let’s improve together.

Andrew Harley: Hey Folks! Welcome to the TriDot podcast! It’s a running show today! We’re joined by two run industry experts, here to give us an anatomy lesson on what makes a running shoe the shoe that it is. I have a few favorite run shoe channels that I personally follow to keep a pulse on what the shoe market is doing and what cool running shoes are coming out next, and one of those is called “Doctors of Running”. They are a network of physical therapists who love running. With their content they use clinical analysis to discuss the art and science behind running, and the stuff that we put on our feet. Our guests today are two of the doctors from Doctors of Running, Dr. Matthew Klein and Dr. Andrea Myers. Dr. Matthew Klein is the chief editor and founder of Doctors of Running. He is a residency- and fellowship-trained clinician and professor specializing in orthopedic, geriatric, and sports rehabilitation. Dr. Klein has been running for almost ten years, he was an accomplished Division III runner, including being the 2012 NWC 10k champion, and his 2:32 marathon PR is probably faster than yours. He has participated in and written research on footwear and running. He currently consuls with several footwear companies, helping with the development of shoes with appropriate biomechanics in mind. Matt, welcome to the TriDot podcast!

Dr. Matthew Klein: Hey, thank you for having me! I would like to point out that marathon PR was against my will. My wife signed me up because I was complaining about getting slower, and she was like, “I’m going to put him in the elite field at LA.” It was the most painful thing I’ve ever done, but I’m glad she did it. So, happy to be on here!

Andrew: Dr. Andrea Myers is a Doctor of Physical Therapy and Board-Certified Orthopedic Specialist. She provides sports performance and bike fitting services at Class Cycles in South Berry, Connecticut. Andrea completed her undergraduate degree in molecular and cellular biology at the University of Illinois at Urbana-Champaign. She graduated from St. Ambrose University in 2006 with a doctorate in physical therapy. As a cyclist, she has multiple topten placings in UCI competitions, and has numerous championship titles at the state and regional level. As a runner, she has a gnarly 3:04 marathon PR herself. Andrea, thanks for hopping on for today’s run shoe conversation!

Dr. Andrea Myers: Thanks so much for having me on! It’s great to join you!

Andrew: I’m Andrew the Average Triathlete, Voice of the People and Captain of the Middle of the Pack. As always, we’ll treat the show like any good workout. We’ll roll through our warmup question, settle in for our main set topic, and then wind things down with our cooldown.

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Warm up theme: Time to warm up! Let’s get moving.

Andrew: When we fall in love with a running shoe, there are usually a few attributes of that particular shoe that causes us to enjoy it so much. Many of us keep a few shoes in our rotation for different reasons and different types of training sessions. As our warmup question today with a couple shoe experts on the show, if you could take two shoes that you love and combine them into a new shoe that has the best of both of their attributes, having them make a shoe-baby of sorts I suppose, what two shoes are you combining? Andrew, what do you think here?

Andrea: Well, I’ve got the two shoes that I’d like to mate right here. First of all, the Saucony Endorphin Pro 3, my personal favorite racing shoe for basically any distance last year. Then a shoe that’s coming out soon, and our review is going to be out soon on it, the Topo Cyclone 2. This shoe is amazing for speed work, tempo runs, even for easy runs. I am a big Topo fan, I love the shape of their toe box, I just love the overall fit of their shoes. So if I could combine the fit and geometry of this shoe with the midsole bounce of the Endorphin Pro 3, I would be a very happy runner.

Andrew: Maybe the folks of Topo Designs are listening today and maybe they’ll be like, “Huh, let’s see if we can make that happen for Andrea!” Matt, what is this answer for you? What shoe-baby are you making today?

Matt: I’ve been thinking about this, that’s a tough one. I also love the Endorphin Pro 3, but if I had to really combine two shoes, just because I tend to need a little bit more stability it would be a combination of the Saucony Tempest and – I’m just going to toss this in there, because I did some crazy stuff in this a couple years ago – the Asics Metaspeed ORIGINAL Sky, not the new one. Sorry Asics, not the biggest fan. These two are probably what I would combine, just having a little bit more stable, faster racing shoe. But the Tempest has been really good for me.

Andrew: Is that Asics the one you set your marathon PR in?

Matt: No, the marathon PR – I can probably say this after this many years – was set in a prototype version of the Skechers GoMeb Speed Elite.

Andrew: Ah, you don’t say! I am a big Skechers fan. Skechers Performance, those shoes are great. I love the Hyper Burst. I’ve been in the Razor line for years now for my training sessions. So for me, this answer is the Skechers Razor 3 and the Nike Vaporfly Next%. Kind of like you, Andrea, the Vaporfly Next% is my race-day shoe, but the Skechers Razor 3 is my main goto training shoe, I use it for anything that has intervals, I love the way the Razor 3 fits my foot. On race day, I love the magic of the carbon plate and the high stack of the Vaporfly. You want that magic. You put that on, you start picking up the pace on race day, and you can tell there’s just something magical about those race shoes. So if I could take the magic of my race-day shoe but keep the lower stack and ground feel of the Skechers Razor 3, that would be the shoe-baby I would want to make myself. I know Skechers has a new carbon-plated shoe coming out, so I don’t know, maybe that’s the answer.

Matt: They might. Well see, we have not tested that yet, but excited to do so.

Andrew: Good to know! I’ll just make you my personal liaison to Skechers and see if you can drop some words in for me. Hey guys, we’re going to throw this question out to you, our audience. Make sure you are a member of the I AM TriDot Facebook group. Over 13,000 and counting triathletes every single day of the week talking swim, bike, and run. Today, the Monday this show comes out, we’re going to throw this question out to you: If you could take two of your favorite running shoes and make a shoe-baby out of your favorite attributes of each, what two shoes are you combining and why?

Main set theme: On to the main set. Going in 3…2…1…

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I really, really like buying and trying new running shoes. Social media ads have certainly figured that out, and they serve me up plenty of ads for the latest and greatest run shoes hitting the market. Run shoes come with all sorts of features, materials, and geometries, so knowing what makes our foot happy can go a long way towards having a good shoe experience. So here to guide us in sorting out what attributes make a shoe the shoe that it is are two of the doctors from Doctors of Running. Matt, you are the founder of Doctors of Running. It all started as a personal endeavor that you called Kleinruns DPT, and it’s grown into a network of physical therapists that use clinical analysis to discuss the art and science behind running and the stuff that we put on our feet. What was the origin story behind your blog, Kleinruns DPT, and how has it evolved into Doctors of Running?

Matt: It’s so funny when people bring up Kleinruns DPT, because to this day – occasionally when I’m going through the website to edit stuff and clear stuff out, I kept all those original articles – I just look at my sentence structure and grammar, and it was like a very angsty younger Matt, firing shots everywhere –

Andrew: How old were you back then?

Matt: Gosh, I was like 23 when this started.

Andrew: Bright-eyed and full of ideas, yeah.

Matt: Yeah, so this thing started during the end of my first year and beginning of my second year of PT school. Before that, I had been a runner. I’d run in college, a teeny bit in high school. But I’d been interested in shoes, I think because I was so sensitive. I was like, “I can’t find something that’s perfect, I want that perfect shoe.” So I started working at running stores, and I was really lucky to work with a couple phenomenal people at Fit Right Northwest where I started. Dave Sobolik and Robb Finegan, a couple of phenomenal people, were the owners at that time, and they took me under their wing. I would ask a billion questions, and they’d help me understand a lot more about shoes. What I kind of started realizing is, what I was learning wasn’t matching up with marketing, and what people were told, and what people believed and I was like, “I’ve got to figure this out, I want to know this.” So as a high-mileage runner – I was running like 90, 100plus miles then – I needed shoes, which was also one of the reasons I worked in running stores, the discounts helped. So I was cranking through shoes, and I had gotten in contact with a bunch of people on Facebook, and talking to people like Pete Larson and some of the other people who are doing RunBlogger and things like that. And some of them are like, “You should start your own blog and talk about some of the stuff that you’ve been learning.” I’m like, “That’s dumb, why would I do that?” Then they mentioned I might get free shoes, so then I was all in like, “Ah, if somebody could send me free shoes, that’d be great!” Which didn’t happen for the longest time. So I was learning, I was in anatomy, kinesiology, going through biomechanics in PT school, and I’m like, “I’m just gonna start sharing my thoughts on these shoes that I’m grinding through in less than a month, why not?”

Andrew: You’re already running, you’re already putting in miles.

Matt: Yeah, I might as well just share some thoughts. And it really started, as it has continued in my role as a professor now, I wanted to teach. I wanted to share with people what I had learned, and help people make better decisions. Because I had made a lot of mistakes with shoes like, “I’m told this is supposed to work. But it didn’t, it hurt.” I was given a high-motion-control shoe, and it made me hurt more, even though I was told that’s what I needed. And I was like, “There’s a deeper level here we’re not going to.” The whole purpose was helping people understand what they were putting on their feet, and also what worked better for them, because even then I knew this is very individual. There’s no such thing as a perfect running shoe, that doesn’t exist. There are shoes that are going to fit you better at certain points of your life. Helping people go down that and understand that is not easy. So that’s really where it started, and then about a year after that when I thought nobody would ever send me stuff, Skechers Performance was the first one who reached out and they’re like, “Hey, we like your stuff.” I’d won a pair of their shoes at a race and they’re like, “Hey, we liked your review, can we start sending you stuff?” And I was like, “Okay, sure,” never thought it was gonna happen. Stuck with that, kept going, somehow managed to barely keep it going through the end of PT school towards residency, which was intense. I just kept putting stuff out there, and slowly one or two other companies would start adding in. I don’t think it really took off until I had some amazing people come and join. Dr. David Salas went to Western, he was a couple years below me, and I knew him because he kept stealing my Strava segments in Chino Hills and I’m like, “Who the heck is this guy?” Then I realized he was also a PT student, so I brought him on, tried to send him a little stuff. Then Nathan, who I had met at the beginning of my fellowship program, we were taking a course together, we were talking and I was like, “Hey, would you want to do this with me?” He’s like, “Sure!” That’s where it took off. We started trying things, like it was David who said, “Hey, we should start a podcast.” Nathan is the ultimate when it comes to reaching out and getting companies to talk to us and send us stuff.

Andrew: That’s a skill set, yeah!

Matt: Yeah, he is the negotiator. I have lost privileges because I tend to send 40page emails explaining, so Nathan and Bach are like, “No, we’ll do this.” So everybody has their skill set, and we were super-lucky to add incredible people like Andrea, Bach, BJ. I’m really proud that Doctors of Running has evolved into this team effort that really still maintains the teaching, a little bit of the shoe geekery – you gotta’ have that a little bit – but diving into biomechanics and really trying to help people make better decisions, and also learn that there’s no such thing as a perfect shoe, but you can certainly find things that might be better for you. That exploration is what we like diving into. So it’s been a little crazy journey. If you’d told me back when this started like, “Hey, you’ll be working with a majority of the running companies out there,” I’d say, “You’re nuts, there’s no way.” Beyond all expectations.

Andrew: There’s definitely that moment when you’re starting to produce content, as a budding content creator, where you just don’t know how it’s going to be received. You don’t know who’s going to read you, who’s going to listen to you. I have just endless respect for anybody who will give that a shot. Some people are able to build an audience for themselves, some people it just doesn’t take off. And that’s fine, you tried. For you guys, it’s certainly taken off. It was cool for me, I followed your content for a while, and just researching for this episode and taking a look at the bios for everybody in your circle, just an incredible diversity of knowledge and talent and running abilities. Andrea, for you, to see the cycling in your background and see your story of going from a runner to a pure cyclist, back to running a little bit, tell us a little about your journey, where your scientific expertise brought you to Doctors of Running?

Andrea: Sure. So I’ve been a runner basically all of my life. I think I did my first race when I was four. My parents were both runners. Back in the day, my dad and I would get the running calendar from the local running store, and we’d pick which strawberry festival one-mile races we were going to do that summer. That’s just what we did. I got on a kids’ track team, I ran cross-country. I was also actually a swimmer, so I know that being on a triathlon podcast –

Andrew: You’re almost there! You got all the sports right there!

Andrea: I do, I just have to combine them! Actually, I have done one triathlon. I think I was seven or eight years old, so I’ve checked that off the list.

Andrew: Yeah, you’re a triathlete! That’s it! You just gotta do one!

Andrea: Totally! Yeah, and as I was getting into running, I had the same questions that Matt just talked about, like what shoes should I be running in? I didn’t remember what shoes I used to run in, we just went to the running store and I got a pair of shoes, and that’s what I ran in. I was 17, and that was fine. But as an adult, you have a better awareness of your body and I remembered, “Oh, these shoes that I think I used to like, these feel horrible!” I just felt like regular old 8- to 10millimeter drop, neutral trainers felt terrible. I felt like they were heavy, not flexible enough. So Doctors of Running helped me explore the questions that I had about shoes, and I really appreciated their reviews as I got back into the sport. Then one day I was like, “Gosh, I wonder if they need –

Andrew: “I’m a doctor, and I like running!”

Andrea: Yeah! So I just sent them a message on Instagram, and I’m pretty sure it was Bach who responded, and he said, “Yeah, we’ve actually been talking about bringing on more reviewers.” So I had an interview with them, and it’s such a great group of people to work with. I have so much fun with everyone involved, so thank you Matt for creating this incredible team of people. And it is fun, Matt, reading your original blog posts, because your writing style is definitely like that of a college student, but that’s what you were!

Matt: Yes! Firing shots everywhere, lots of grammar mistakes, it was terrible. I remember when we were first talking, we set up this interview, and I probably knew within three seconds. I’m like, “Yeah, we’re gonna bring her on.” I already knew, it was like, “I want to hear more about her,” but I already knew.

Andrew: Alright, so as we turn our conversation towards running shoes, most of the content produced by Doctors of Running really revolves around running shoes. Everyone on the team talks about shoes with the passion of a runner, which we’ve identified, and the precision of a scientist, because you’re all passionate runners and precise in your science. So as orthopedic professionals, what impact do you find the shoe to have on our feet and legs and body?

Andrea: Well, I think something we say all the time is that shoes are tools. Shoes can be used to help achieve a variety of goals for a variety of reasons. But I think one of the biggest mistakes runners make is that they say, “Oh, a shoe can injure me,” or, “A shoe can fix my injury,” or, “A shoe is going to make me run this time,” or whatever. “The shoe is going to do this for me.” No shoe can force or do anything. Shoes can be used to hopefully achieve certain things, but it’s hard to predict. Okay, you’ve got this person with these characteristics, what’s the perfect shoe for them? The only sure answer is, there’s no perfect shoe for anybody. It’s really about breaking down each person’s individual characteristics, injury history, any range of motion, strength, or biomechanical limitations, and then what we know about various features of shoes from research. And research is limited. Research doesn’t answer every question that we have about running, running-related injury, and running shoes. Then we have a lot of anecdotal experience and knowledge. Just as clinicians, I’ve seen a hundred people with these same characteristics, and a lot of them did well with this shoe. Well that can make it, not a sure thing, but a somewhat secure recommendation. “Okay, if I see another person with these characteristics, then this shoe might work for them.” But I think one of the big things that we really try to do at Doctors of Running is help people understand that shoes do not guarantee anything. Shoe marketing really tries to promise that it will guarantee something, but it doesn’t. Just because the shoe company says, “This shoe is going to reduce your knee pain,” or, “This shoe is going to make you 4% faster or 4% more economical,” that might be true for some people, but it’s not going to be true for everybody. Shoes are tools. That’s definitely the key thing to remember.

Matt: I would definitely jump on that same thing. The two phrases I would use are, “shoes are tools”, and what our students hate when say it, “It depends,” which we’ll say quite a bit.

Andrew: We hear that on the podcast quite a bit, yeah.

Matt: Yeah. Remember that shoes are basically the interface between your body and the ground. They will not eliminate forces. That is not a thing. They can certainly modulate and change them, but what that looks like is going to vary on the person. Oftentimes, having different kinds of shoes, they might put forces into different areas at different rates, but you’re still going to have that same amount. My example of that is, they did all this research on the maximalist shoes, and found that when you had a higher amount of foam under your foot, yeah it feels comfortable, but it doesn’t decrease force. Actually, people tend to land harder when you have increased internal joint forces, which may or may not be a bad thing when you have a higher shoe versus a less shoe. You tend to land lighter sometimes, and you may have decreased internal joint forces. But again, it depends on the person. There’s so many factors, but a shoe is an interface. How it translates between your body and ground is going to be very dependent on the person. We have some ideas about some ways shoes might facilitate or change things, but they do not eliminate. I think that’s the biggest key, and one shoe is not going to work the same for each person.

Andrew: A lot of very, very good guiding principles from what each of you said, to keep in mind as we navigate this conversation on running shoes, and to keep in mind that Matt is probably going to run differently from a lot of our listeners. And Andrea, the way you run and talk about shoes is different. I’ve encouraged people before, when you find a channel like Doctors of Running that have a lot of contributors – you guys do a good job of having people’s typical training paces on there, mentioning this person has a wider foot, this person has a more narrow foot, this person jives with this or that. So I’ve found other reviewers who like Skechers shoes, and seem to talk about certain shoes the way I experience that certain shoe, and it helps point you in the right direction. A lot of good principles there.

The first thing I want to get into here as we talk about the anatomy of running shoes – a lot of parts to the shoe we want to talk about, a lot of classifications of shoes we want to talk about – one thing that brands put out there when they’re marketing a shoe is they categorize it as either being a neutral shoe or a stability shoe. Many running stores, many brands categorize their shoes this way, and many running industry channels like yourselves will mention whether a shoe is neutral or stability in your review. What do triathletes and runners need to know about these two categories, and how can we tell if we need a shoe with stability features?

Matt: This is going to sound terrible, but the first thing that I would want everyone to know is that those terms are outdated. We’re starting to see shoes that would have been considered neutral or stability start blending and going the other direction. So there is a need to redefine and have better categories, or even accept that we can’t categorize this stuff. It’s hard, we as human beings certainly like to categorize and try to keep things organized, but it depends. You probably heard us talk about the concept of stable-neutrals, these supposedly neutral shoes – neutral being there’s no elements traditionally that we used to think about that are trying to influence foot motion, like a post or things that made it considered a stability shoe – these stable-neutral shoes have some new concepts that make them inherently stable, but they don’t have a post or use other methods. Versus a stability shoe is still getting defined as having something like a medial post, which is where you have a thicker or harder material on the inside that is supposed to help you control motion as you pronate, which just describes a motion. Pronation is not a pathology, it’s a certain amount of motion side-to-side. That’s not the correct axis, but it’s easy enough for people to understand.

Andrew: I can see the hand motions you’re making, so yeah, I’m following you.

Matt: Pronation is a natural thing that happens as we land and shock absorb. You technically need a little bit or a certain amount to facilitate shock absorption to a certain part of your foot, and then to be able to come back out of it and push off. So certain people have more or less control. Many, many years ago, that’s what was thought to be the major contributor to injuries, although we’ve now had a lot more evidence to suggest that that’s not clear-cut, that there’s actually just different injury if you pronate heavily versus if you don’t at all. You actually don’t necessarily have different rates of injuries, you have different types. So people that don’t, tend to collapse and have a lot of bone stress injuries, they tend to have a lot of shock-absorbing problem, because that’s shock absorption. Versus people that have too much motion there tend to have more muscle strain issues, issues with soft tissues that get irritated. You can obviously have them go back and forth. But we categorized this stuff for injury prevention, but now we’re finding that on the whole – there’s a great article that I just read this morning, and I’m totally blanking on the name, which goes, “Shoes don’t prevent injuries.” That’s how it goes. These tools are going to affect everybody differently, but they are not going to consistently prevent people from having injuries, so this category isn’t working. We know that trying to prescribe shoes based on foot shape doesn’t work. The military did a study with thousands of people, and it didn’t work, it didn’t tell us anything about their injury history. So what I would tell listeners and viewers is that these two categories are really telling you how much the shoe is trying to help you with side-to-side motion. Outside of that, there’s so many other factors that I think might be important to look at that this is probably not the best way to categorize shoes.

Andrew: I remember the days where, when you were shopping for running shoes, you would go into your local running store, and whatever young 20something employee was there would have you walk down and back, and they’d watch how your foot fell, and they’d say, “Oh, you need a neutral shoe. Here’s our eight neutral shoes we have in stock, which color do you like?” And that’s how we used to buy running shoes before we knew all of this.

Andrea: Yeah, and unfortunately some running stores are still doing tests like that, and still categorizing shoes and runners like that. But study after study has found that static tests like the footprint tests – like you get out of the shower and you step on the dry floor, and what does your footprint look like – that doesn’t tell you anything about what your foot is doing when you’re walking or running. What your foot does when you walk is going to be significantly different than what your foot does when you run. Matt said something that made me think. He was talking about categorizing stability by how much it controls pronation. But there are other ways that a shoe can provide stability or guidance, and I think that the Tempest is a really good example of that. Matt and I probably couldn’t be more different in terms of our personal running styles.

Matt: Yeah, the mechanics are very different.

Andrea: But both of us really enjoyed running in this shoe. There are some shoes that Matt and I both enjoy running in, but for different reasons. We both loved the Endorphin Pro 3. But the Tempest has so many features that not only help to keep you centered in that pronation/supination-type movement, but the rockers guide forward motion. It’s the forward motion like dorsiflexion/plantarflexion, or in the sagittal plane, that a lot of running shoe companies have completely ignored, and the researchers have ignored in terms of, “How does motion in that direction relate to injury risk or biomechanics?” So you see a shoe like this that has a significant rear foot rocker, significant forefoot rocker, it helps guide motion in that direction. It’s not really forcing motion, but it’s helping you progress from wherever you land. For Matt that’s back here, and for me that’s here, but both of us found that the shoe was really smooth, and helped us move smoothly forward.

Andrew: I even think to a shoe like the Asics GlideRide that has a very significant rocker built into it, and some companies are coming out with shoes that seem to be shaped to glide your foot forward through the strike. Is that helpful? Is that something that we should look into and see if it works for us? What are your thoughts there? While we were talking about stability side-to-side, now we’re starting to talk about front-to-back.

Andrea: Well, it depends.

Andrew: Of course!

Andrea: Another thing we like to say at Doctors of Running is that force and motion doesn’t disappear, it just gets shifted somewhere else. So if you have a shoe like the GlideRide, or actually a lot of the Asics shoes – the Magic Speed, the Sky+, the Edge+ – they all have a pretty significant toe spring, meaning the forefoot not only has a rocker, but the toes are actually pointing up in the shoe. So when you’re in the shoe, your toes are kind of bent up like that. That reduces the amount of work that your MTP joints have to do, especially your big joint, the first MTP.

Andrew: You guys are missing out on all the visuals that I’m getting, because they’re holding up shoes, they’re pointing at places on shoes, Dr. Matthew Klein just held up a skeletal outline of a foot and pointed to exactly what Andrea was talking about. This is why you should go check out the Doctors of Running YouTube channel to learn more from them after you listen to this podcast.

Matt: Just a disclaimer, these are not real bones, these are plastic. Just to not freak you out.

Andrea: That is an important disclaimer. Yeah, so if you reduce motion at your first MTP joint, you’ve got to get that motion from somewhere else, and that usually comes by increasing hip extension. Well, if somebody doesn’t have sufficient glute and hamstring strength, you may set yourself up for a high hamstring strain, glute pain from running in shoes with a really aggressive toe spring, or just too aggressive for you. Again, what’s aggressive for me isn’t going to be what’s aggressive for anybody else. So really, the only way to know what shoes work for you is to go try a bunch and see what’s comfortable.

Matt: That’s really the key. So Andrew, to answer your question on what do we need to know about these categories, and do I actually need stability. The biggest thing, one of the few things we’ve found about fitting shoes based on all this research that’s being done is, and I know we talk about this a lot, this thing called the comfort filter. We’ve found over time that shoes that tend to be very comfortable for the individual, tend to be the ones that are going to work better for that person. I remember this from working at running stores. There were these middle-age ladies that love the Asics Kayano, even though they had the most stiff, rigid foot on earth. I mean I was like, “This doesn’t make sense, you have a stiff foot and you would like a stability shoe, that doesn’t make sense.” They found it comfortable, and that’s what kept them healthy. I’m not saying that’s everyone, but comfort is probably the big thing. This is why, as Andrea said, you need to go try stuff. That’s exactly why this website started. You’ve got to go figure out, using some of the principles that we teach you in figuring out what applies to you, what’s comfortable and not. That being said, if you have a history of pronation-related injuries, things like Achilles tendon problems, some of the twisting and torque that happens can put you at risk for an Achilles issue. When you’re moving excessively and don’t have good enough control into pronation, or even sometimes into supination, either way. If you have anything like posterior tibialis issues, or anterior tibialis issues, if you have injuries that are associated with that motion, you probably will benefit from a stability shoe, because that’s all that we found in the evidence. And I can tell you from personal experience, sometimes that shoe works for me, sometimes it doesn’t. If you have a history of those, you might want to consider a shoe that helps control motion in that direction. It’s kind of the same thing for all these components that we talk about. If you have injuries in a certain area, and you’ve found that a shoe facilitates it and makes motion easier there, that might be something you might want to consider. An example being you have a history of Achilles issues. You might want to consider a more rockered shoe, because we know that rockered shoes tend to take a little stress off that area that might be beneficial for you. But again, that depends on the person. So going and thinking, “I know there’s these two big categories,” but you’ve got to be looking at the other things that are unique to you as a person, because the neutral/stability category doesn’t apply to a lot of people.

Andrew: Alright, so as we talk about the anatomy of a running shoe, great dive into the classifications of shoes and how much that does or doesn’t matter. Seems to not matter a ton, comfort on your foot matters. A lot of good takeaways there. But another thing that brands will promote is their foam. Every brand has their foam. It’s their secret sauce, their magic recipe, whatever it is. There’s different types of foam within those types of foam. Some are denser, some are more responsive, some are more cushiony. What are the notable foams on the marketplace today, and how do they influence our running experience?

Matt: Yeah, so the classic ones you’re going to see out there, the most common still at this point is going to be an EVA-based foam, which please don’t ask me to do the full word that those are, ethyl-vinyl-something. It’s a more traditional compound, tends to be a little bit more durable, a little more lighter. I’m trying to find an example. Ah, there we go. So it’s a more traditional foam, they’re not the bounciest, they tend to be fairly good, they tend to be a little bit lighter. That’s what a majority of shoes on the market have. In recent years, we’ve seen an explosion of different types of foam. Adidas was one of the first to mainstream a foam called TPU – which once again, don’t ask me to say the full name – which was used for years, but went out favor because it was heavier. It was durable and more bouncy, but it was heavier, so they found a way to keep it a little bit lighter by turning it into more of a pellet foam. Nike came out with a foam called Pebax. Pebax is actually the company, from what I understand, the type of foam is a PEBA foam. PEBA foams tend to be incredibly light and incredibly resilient, meaning they compress a lot, and they bounce back a lot. So you have these very, very bouncy foams that tend to be very light. It’s very interesting, some of them are very durable, some of them are not. So we’re getting these different foams on the market, and I’m just going to start out by saying, not all of these work for every person. That said, when it comes to some of these high-performance shoes, if you are looking for the most responsive thing, you’re probably going to need to find something with a PEBA-based foam. Because we’re seeing, especially in economy studies – which as I mentioned Andrew, not everybody gets 4% improvement. Some people get 10%, some people get NEGATIVE 10%, if you look at the original studies – but if you want the bounciest shoes, you’re going to need that foam. And I know you were just asking about the foams, but the plates in a lot of these super-shoes facilitate motion. They don’t give you a ton of energy return back, that comes from the foams. So I’ve got to shout out Laura Healey and Wouter Hoogkamer – thank you Laura – who cut a Vaporfly plate in half, and the running economy didn’t change that much. The plates have a place to stabilize the foams, but if you really want that soft, bouncy feeling, you’re going to have to look at changing the chemical makeup, and a lot of these PEBA foams really have that. So we’re still seeing companies that still have this really stiff EVA foams that are going, “Hey, these are bouncy!” But again, there’s other factors that go into this. Skechers had nitrogen-infused EVA, which turned into this really bouncy Hyper Burst stuff that people like, but it doesn’t last super-long. How you work with it and what you do with it is what really makes the biggest difference. That said, these new foams tend to be the bounciest. Is that the best thing? It depends on the person. Can you control the bounce, is the biggest question.

Andrea: I think another important thing, and I can’t remember which year the study was done, but they looked at the energy return from different foams. EVA returned about 60%, TPU – I think they specifically looked at that Boost foam – was like 70 to 75%, but PEBA – and they looked at Nike’s foam ZoomX – was a whopping 89% energy return. So Matt made the really important comment that people think it’s the plate that does the magic in these super shoes. It’s not. Like Matt said, they cut the plate and the loss in running economy was only, like 1%. It’s the foam, and specifically the energy return of the foam, in combination with the unique geometry of the shoe, and having the plate to stabilize that massive slab of foam. Often that is what the plate is for, is to provide stability to all that foam, and to help with forward movement. But the plate isn’t responsible for the 4% improvement in running economy, or 10%, or 1% depending on the person. It is important for people to know that there really is a significant difference in energy return between the types of foams. Another thing that’s important to point out is, one of the big differences between EVA and TPU is that EVA can really be affected by temperature. Shoes with EVA may feel very different at subfreezing temperatures as compared to normal spring or summer temperatures. I’m running in a shoe right now, the Brooks Hyperion Tempo, that I’ve read review after review that says it feels firm in the wintertime. I’ve only put miles on it in subfreezing temps and I would definitely agree it does feel a little firm, so I can’t wait to actually run in it when it’s not cold out, to see how it’s different. But that’s important to know if you’re buying a shoe with EVA and it’s wintertime. If you go out and run in it and you hate it, you could take it back, or you could save it for when it gets warmer, and it might be a totally different shoe for you.

Andrew: You can give it another shot, yeah!

Andrea: Yeah. So just keep that in mind, that your shoes are going to perform differently in different conditions, and EVA in particular is affected by temperature changes.

Matt: Since we were talking about injuries earlier, there is no evidence by the way that any of these foams decrease injury. Nobody has done that yet. I have seen some comments on Instagram where one person said, “Oh, with these new shoes we’ve seen an increase in injuries,” and somebody else said they decrease injuries. Nobody has found that. In the base of the evidence in general, injury rates in runners haven’t changed almost at all. It’s been super consistent no matter what shoe technology comes out, which suggests this doesn’t influence this in the way we think. That said, there’s been a lot of people who go, “Hey, some of these new foams are super fun, it makes running fun again, I’m feeling less sore afterwards.” So we do know that about some of the PEBA foams is there has been a little early evidence that people have decreased soreness. Whether that’s good or not, that’s the challenge, because you might be able to bounce back into being able to do harder training sooner, but also the problem is if you start doing harder training sooner –

Andrew: Are you OVER-training?

Matt: Exactly. We don’t know that yet. So on the question of these foams, yes, there is definitely difference in energy return and economy and stuff like that, but if you start asking us about injury risk and some of this other stuff –

Andrew: Very interesting. We will say that our listeners should be following their TriDot training plan, which tells them when to push and when not to push. Hopefully the right selected shoe for that day, plus the TriDot training plan, will keep people healthy. So once a brand has that foam, and they decided we’re going to roll with this foam and this shoe model, the next choice that they’re making of course is how much of that foam are they putting in? You referenced there are shoes now that are coming out that have ridiculous amounts of foam, and sometimes they have plates to help stabilize it. You’re holding up a few right now. The amount of foam that is in a midsole is called the stack, right? The stack height of a shoe. There’s a certain stack height to the heel, a certain stack height to the toe. What does a stack height do to influence how a shoe works for us?

Andrea: One of the most important things that increased stack height does is it can increase your functional leg length. One of the reasons World Athletics placed the 40millimeter limit on stack heights for regular running events –

Andrew: Which triathlon does NOT have to obey!

Andrea: That’s right! I’d say “Yet” though, because I read that they are considering. I think for IRONMAN maybe, not for like Olympic-distance or shorter. Your shoe becomes an extension of your leg, and if your leg is longer, your stride is longer. That makes you faster, it makes you cover more ground with every stride. In addition to increasing your functional leg length, the increased stack height also increases spring space. So the more foam you have, the more you can load that midsole, and then it springs back and then you forward. That’s not the scientific term, but it gives you that spring-back mechanism. One of the great benefits of foams like Pebax is that it’s so light, you can use 40 millimeters or more in a racing shoe, and not be negatively affected by the weight of all that foam, but you get this huge spring mechanism. Looking at Gustav Iden, who won Kona in last year in the Cloudboom Echo 3, I think that shoe has 50 millimeters of stack. This is Matt’s dream, to finally get to try that shoe, and he hasn’t. Actually, one of the things that I’m really interested in is how super-shoes can be used to help triathletes specifically, because of course triathletes are going to have different biomechanical needs than people who are just doing a running race. What features of a racing shoe are important for people coming off of a bike? I don’t think there’s much if any research on that right now, but I think that we should start seeing some of that soon. And I think it’s really telling to see what brands IRONMAN athletes are choosing to run in. There are definitely a couple of brands that you see the top athletes choosing, even if they’re not sponsored by them, so why is that? What features, theoretically, of those shoes are actually beneficial or theoretically beneficial for them?

Matt: The one thing I’ll say about stack height is, a lot of these shoes with the higher stack height, the more of this foam they put there, a lot of times – with the exception of when you start getting over a certain weight, then it sometime can get a little questionable –yeah, there’s more stuff to compress and bounce back. That said, you’ve got to remember that the further your foot is away from the ground, the more you lose something called proprioception, which is your body sense. Remember, a shoe is an interface between your foot and the ground. It can either facilitate, like some of the more close shoes, where you’re going, “Okay, I can feel where the ground is.” Your body has a better understanding of where things are, and can react better. Versus the farther away it is, the more delay there is in your body figuring out. “Where is the ground, how do I react to it?” Some people do very well with that, some people do not. People need to be aware, if you don’t have very good proprioception, some of these shoes with the taller stack heights may not be as good, and it’s going to be like, “I feel like a baby deer.” Some people don’t do well with that, some people do. You just have to remember, as an interface, it’s going to change your relationship with the ground, the higher the shoe is.

Andrea: One thing we were talking about recently on the pod is, depending on the course you might choose a different shoe, too. If you’ve got a course where you’re just running in a straight line the whole race, you could use a shoe like the Mizuno Rebellion Pro. But something David said was he wouldn’t use that shoe on a course that had a lot of turns, or even a lot of crowned roads, because he feels like it’s not very stable side-to-side. So more things go into ground feel and being aware of the changes in the ground than stack height. It also depends on the geometry of the sole, how much rubber coverage you’ve got on your outsole, how stiff the sole is. Stack height is one factor that influences ground feel, but it’s certainly not the only one. If you compare the Endorphin Pro 3 to the Vaporfly 2 – because that has a similar stack height to the Endorphin Pro 3 – the ground feel in those two shoes is very different. I do feel like the Vaporfly has better ground feel than the Endorphin Pro 3. Why is that? Is it because of the differences in the foam? Is it because of the differences in geometry? Differences in rubber coverage? It’s probably all of those things. Actually, I have a very good cycling anecdote regarding this. I ride all disciplines in cycling, and I got some new mountain bike shoes, Bontrager shoes fit me really nicely. I like the Bontrager XXX road shoe, so I got a pair of Bontrager XXX mountain bike shoes. I went out and rode them, and I was like, “What is wrong with these shoes? They feel bouncy!” They have a carbon sole, so there was no way –

Andrew: I’ve never heard of cycling shoes being referred to as bouncy.

Andrea: Right, and they really shouldn’t be bouncy. So I came back home, put my cross bike on the trainer, got on, and every time I got out of the saddle, the shoe just felt bouncy. I was like, “What is it?” So I took the insole out of my mountain shoe, and the insole out of my road XXX shoe, and I switched them. The insole in the mountain bike shoe is probably two millimeters thicker, and was a little bit squishy. When I put my road insole into my mountain bike shoe, the bouncy feeling completely went away.

Andrew: Wow, so that made that much of a difference.

Andrea: Yes. So people kind of disregard the influence that the very thin insole that comes in the shoe – what you called the sock liner – has on the performance on the shoe, but it can change the ride of the shoe. There are several companies who will put a slightly thicker or softer sock liner in to affect the ride, and that may or may not work for a person. So don’t forget about the sock liner when it comes to how the overall ride or performance of a shoe is for you.

Andrew: A lot of good stuff here. There’s one more major component of a shoe I wanted to talk about we shut the main set down today. This is the drop of a shoe. We’re talking stack height, we referenced very quickly that oftentimes the heel has more stack height than the toe box, that puts your foot where the toe is lower than the heel. That is the drop of the shoe. Now, most of our audience is probably familiar with this term, they may have even heard a coach or watched a social media running influencer tout that a certain drop is the best for runners or whatever. They might have a theory on that. Every brand obviously touts that their approach to the drop of a shoe is the best. Hit is with the science here, what does the drop of a shoe do for our foot while it’s running?

Matt: Andrea, can I take this one? Respect.

Andrea: Absolutely, I can see you’re wanting to leap out of your seat.

Matt: So yes, again, to define heel-toe drop or heel drop, there’s a difference between the stack height of the heel and the stack height of the forefoot, i.e., what’s the difference between those two? As you mentioned, people will tout, “This is the best for everybody, our specific number is the best,” whether it’s 12, 0, 6, 8, 4, 2, whatever. What we actually find is, just like everything else, there is no difference in injury rates between different drops. There are differences between injury types though, because different heel drops will place pressures in different areas. But the other big thing is, that number that you see has a huge asterisk after it, which really is all about, “It depends.” Because drops are measured statically. When you load the shoe, that number is going to change, and it’s going to change depending on where you land, how you’re loading the shoe, how hard you hit the shoe. So a shoe that has a 6 millimeter drop let’s say, a 6 millimeter difference between the heel and the front of the foot, for a certain person that might feel high if they load the front of the shoe more. They feel like the heel is not getting compressed, but the front of the foot is. That’s going to feel higher than that. Versus somebody that’s a very hard heel-striker is going to compress that heel down, and if it’s a soft foam that might feel like a zero-millimeter drop, like a flat shoe. So the answer is, you might see those measurements, but it doesn’t tell you always how the shoe is going to feel. For example, there are some shoes like the Mizuno Wave Inspire, the Wave Rider, the last holdouts that still have that more traditional higher drop. Some of those shoes with firmer foams, they tend to feel like, “Yeah, this is a really high-drop shoe.” With Mizuno messing with some new foams, a lot of them are not feeling that high, because the heel, for me anyway, as a heel striker, it’s compressing so much more, and it’s like, “This doesn’t feel like that.”

Andrew: It feels like an Altra!

Matt: Well, not that far usually, but sometimes, right? Versus those other shoes that use different densities of foam in the heel and forefoot, and it’s very common to go, “Wait, this is supposed to be a 4 millimeter drop shoe, but it feels way higher than that.” The Saucony Kinvara is a great example of that. For whatever reason, I’ve always felt that feels like a higher-drop shoe than 4 millimeters. Is that a bad thing? No, it’s just that’s how it feels. I would encourage people not to get hung up on that, because it’s a tool. It’s something you can use. If my calves are trashed, I’m going to grab a higher-drop shoe, because it’s going to take some pressure off them. A high-drop shoe tends to shift forces away from things like the calves, and up higher into the knee and hip, versus a low-drop shoe is going to require a lot more ankle motion, and you’ve got to go through a lot more calf motion, that’s going to require more work from your calves. For me personally, if I want to feel a little bit faster, I want to do something “over natural”, I might want to grab a lower-drop shoe. It’s not perfect, but again it comes back to your mechanics, what kind of calf length you have, what kind of calf strain, what kind of knee or hip strain. What’s going to work well for you, based on the fact that this drop may shift work at load to different areas, but also being aware that just because you see that number, doesn’t mean that’s how it’s going to feel on the run.

Andrew: With all that in mind, would you even say, as we’re building out our shoe rotation – if budget-wise you can only have one shoe, that’s certainly okay. You can be a triathlete, you can be a successful runner, marathoner, and have only one shoe – but if you have the means to have a rotation, is it good to vary what kind of drops we have in the arsenal? Or does it just not even matter because it’s just so different based on the foam and the drop, and what they claim and how it works with your foot?

Andrea: I’m going to hand this to Andrea, but I want to really quickly put that one of the few things we’ve found besides strength training – by the way, that does increase injury risk – is from a wonderful scientist over in Europe named Laurent Malisoux, who found that having a shoe rotation is one of the few things that actually decreases injury risk.

Andrew: Interesting, hey!

Matt: Which the shoe companies love.

Andrea: All the more reason to buy more shoes! That was the study I was going to cite. What I would like to add, in addition to how much the foam compresses affecting how the shoe actually performs in terms of what the drop feels like, I would say the geometry of the shoe also affects how it feels. I tend to like lower-drop shoes, like six and below is my sweet spot. But this is the Brooks Hyperion Max. It’s an 8 millimeter-drop shoe, and you can see it’s got a pretty significant heel bevel, where the heel is kind of cut away. So I land here with a pretty flat foot, so I don’t feel the heel when I land. Whereas I tested the Mizuno Wave Rider at the end of last year, that’s a 12 millimeterdrop shoe, and every time I landed, even though I landed on my mid-foot, it was like the heel of the shoe was just in the way.

Andrew: You couldn’t not hit it, I know that feeling.

Andrea: Exactly, then comparing that to the Asics Nimbus Light 3, which is actually a 13 millimeter drop shoe, that is a shoe I thought I was going to hate. But I loved running in that shoe. It must have just been the combination of the geometry and how the sole compressed when I landed, but that shoe was super-comfortable for me to run in, at slow-paces, at medium-fast paces. Again, Matt already said this, but don’t get it in your head that you can’t run in shoes with X drop, because just because that’s how they’re labeled, that doesn’t mean that’s how they’re going to perform. I do think people need to be careful testing out zero-drop shoes, because those shoes definitely run like zero-drop shoes, and there are specific biomechanical requirements needed to run in those. You need to have adequate ankle flexibility, specifically dorsiflexion rage of motion, calf strength, first MTP range of motion. With the exception of zero-drop shoes, if you love sixmillimeter drop shoes, don’t automatically reject a 10 or 12 millimeter drop shoe. Try it out! You might hate it, but you actually might find a shoe that you love that you never would have tried otherwise.

Andrew: We’ve had a fantastic conversation, and I feel like we really knocked down the most important parts, the things in a shoe that really make that shoe what the shoe is. I did have a question on here where I was going to get your thoughts on some things like toe boxes, tongues, outsoles, heel counters – you just mentioned bevels, some shoes have a bevel, some shoes don’t. So for our athletes that really learned a lot from today’s conversation and they want to take that deeper dive that I’m talking about, learn a little more from the Doctors of Running team, what is the best way for our folks to interact with you guys and watch your content? Where all can they go? Where can they find you?

Matt: Well, you can find us almost anywhere. I think the major sites you’re going to find us is obviously the website, doctorsofrunning.com. We are also on any media channel you can imagine, so we’re on Spotify and iTunes for the podcast, we also have a YouTube channel. We have a lot of our podcasts that come with the video, but also some really short subthree, two, and oneminute videos if you want quick little stuff that we try to get out that’s more digestible. Social media-wise, you can also find us on things like Instagram. Bach does a great job of trying to keep up with things like TikTok. You can find us, we’ve got a group on Strava. All kinds of places, so if you can think about it, we’re probably there.

Cool down theme: Great set everyone! Let’s cool down.

Vanessa Ronksley: All right everyone, this is the first installment of the podcast’s Coach Cooldown Tip. I’m Vanessa, your Average Triathlete with Elite-Level Enthusiasm, and I can’t wait to introduce you to our rock star TriDot coach, Kathy Hudson. Kathy is ridiculously passionate about coaching triathletes, has been a TriDot coach since about 2016, and she’s been newly appointed as a TriDot Master Coach in 2022. Her athletes range from newbies all the way to Kona qualifiers, who often have crazy schedules that most people would say triathlon would not typically fit into their life at all. Her first career was with the U.S. government, and she spent many years living abroad, but she now lives in Waco, Texas to be closer to her young grandchildren. Kathy holds many certifications, from strength and conditioning, to sports nutrition, and finding balance between triathlon and everything else that life holds, which I know is a huge struggle for many, many of us triathletes. One thing that not many people know about Kathy is that she worked for the CIA. Seriously, I’m talking to someone from the CIA, that is so cool! Welcome to the show Kathy!

Kathy Hudson: Thanks Vanessa! Wow, what an introduction! I really appreciate that, and thank you for having me today.

Vanessa: Great, let’s get started with that first tip. What is one tip that you would like to share with your listeners?

Kathy: Wow, it’s really hard to pick two tips, one tip, because we have so many as coaches. But sitting down and thinking about it, I really would highly recommend that when you sign up for an endurance event like a triathlon, you communicate with your spouse and with your family ahead of time. Give them an idea of what it’s going to look like. Maybe even go over your season planner. With TriDot it’s all spelled out for us, we pretty much know what our volume is going to be. So it’s helpful to sit down and show them that. Also perhaps communicate with them about, “Would you like to turn this into a vacation? Let’s maybe go to Florida or Arizona. Let’s make it a family event, and once the triathlon is over, we’ll participate.” I think this is very, very important. Also during your training, I would suggest that you're careful about how many times you tell your spouse and family, “No, I can’t go to that because I have this training or that training.” When I trained for my first full IRONMAN, I was not a coach, and I was not with TriDot. The training platform I used was crazy. I was training 24 hours a week, and my coach never said to me, “Hey, you can miss that session, it’s okay.” I thought I had to do every training session, it was brutal. So I did do my IRONMAN, I did finish, and then when I finished, my husband looked at me and said, “You’re done, right?” I was like, “What?” He was like, “You’re done.” I was like, “Mm, no.” Then I learned about this platform called TriDot. I trained with them as an athlete first, then became a coach, and the training was much more doable. And I was very careful when I told my husband and my family no. You want to be able to finish your endurance event and still love the sport. You don’t want to make it so that you don’t love the sport. Love the sport, have your family still love the sport.

Also, think about this. One of my favorite sayings, and I don’t know who said it, was “Perfection is the enemy of good.” Ponder on that for a moment. Your training does not have to be perfect. It has to be consistent, but it doesn’t have to be perfect. As a coach, I help athletes manage that. With TriDot there are actually three different volumes, there’s low, standard, and high. I’ve had great success with coaching athletes that are just super busy, so I will take their volume to low, and they’re still very successful. This is an aspect of TriDot that I love, and it works.

Vanessa: Wow, that’s incredible. I had no idea that there was a low, standard, and high volume of training, and I think that is a really wonderful piece of advice. Not to mention, I think the best part of that tip is the communication part, and talking to your spouse about potentially turning that race into a race-cation. Because then it seems like it’s more about the family, and the triathlon is just this thing that you're doing on the side. It gives the family an opportunity to be a part of not only the training, because they get to see all the training that goes into it, but they get to see you and be a part of that magic of race day, and then you also get to make memories with your family afterwards, which I think is really valuable and important. I love that tip so much.

Outro: Thanks for joining us. Make sure to subscribe and share the TriDot podcast with your triathlon crew. For more great tri content and community, connect with us on Facebook, YouTube, and Instagram. Ready to optimize your training? Head to TriDot.com and start your free trial today! TriDot – the obvious and automatic choice for triathlon training.

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