MR. KOJO NNAMDIIt's not unheard of to shell out close to $200 on a single pair of running shoes. You can't get the top of the line running kicks with the most cutting edge technology if you're not willing to spend some cash. But what if the most sophisticated, most scientifically perfect running devices on earth were the bare feet you were born with?

MR. KOJO NNAMDIThose mind numbingly complex combinations of bones, tendons and skin. It's an idea that inspired legions of runners across the world to ditch their cushioned soles for minimalist shoes or no shoes at all, including Christopher McDougall, a writer and author who famously joined the worldwide society of barefoot runners, after he watched the Tarahumara Indians in Mexico run with his own eyes.

MR. KOJO NNAMDIBut what does science have to say about the boom of barefoot running and what do world class runners who log thousands of miles a year really think about the idea of going barefoot? Christopher McDougall joins us in studio. He's a journalist, author and barefoot running enthusiast. He's the author of "Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen." Christopher McDougall, thank you so much for joining us.

MR. CHRISTOPHER MCDOUGALLOh, my pleasure.

NNAMDIAlso with us in studio is Michael Wardian. Mike Wardian is a champion long distance runner and ultra distance runner. He's a five time champion of the national marathon in Washington, D.C. and a three time qualifier for the U.S. Olympic trials in the marathon. Mike Wardian, just a pleasure to have you aboard.

MR. MICHAEL WARDIANThank you very much. It's a pleasure to be here.

NNAMDIChris, you were not always born to run barefoot. Do you -- only a few years ago, you couldn't run more than a few miles without your body breaking down completely on you. You had sworn off the sport and everything with it but that was all before a hidden tribe of Indians in the Copper Canyon of Mexico opened up your world to a completely new approach to running. Who are the Tarahumara and how did they put you on a path to becoming an evangelist for barefoot running?

MCDOUGALLI would love to answer your question, except right now I'm still processing the fact that I just found Mike ran a 2.33 marathon...

NNAMDIOh, yeah.

MCDOUGALL...pushing a jog stroller with his child inside.

NNAMDIYeah, he does that in Rock Creek Park from time to time a lot. I have seen him, as a matter of fact.

MCDOUGALLIt's mind numbing.

NNAMDIYes, yes. It is, it is.

MCDOUGALLSo I come from a perspective where I wasn't a runner at all. I mean, my approach was a punishment for whatever I'd eaten the night before. So if I ate some pizza, I'll go out and try and jog a few miles. I was constantly getting hurt. I was constantly seeing doctors who would look me up and down and say, well, you know, guy what do you expect, look at the size of you, you're the size of Shrek, of course you're going to get hurt. Running is bad for the body.

MCDOUGALLThe impact is bad for the body. And then I was down in Mexico on a magazine assignment and I see a picture of what looks to me like someone's granddad in a robe and some sandals. And the caption said he had won a 100 mile race through the Rocky Mountains. And I'm looking at this picture thinking, there's got to be at least three lies in this picture, 55-year-old men don't win races. Nobody can run 100 miles. And what are those ridiculous things on his feet?

MCDOUGALLI'd always been told you need to have specialty running shoes. And that was my first introduction to the Tarahumara, you know, a tribe that has essentially been running long distances, deep into old age for hundreds of years and doing it with a sort of joyfulness that seems absent for most of our lives.

NNAMDIAt what point did you become convinced that going barefoot was also the right approach for you? What do you remember from your first barefoot run?

MCDOUGALLI was a very slow convert. It's very hard to get me to do anything right. And no matter how many -- often you tell me, I'm going to resist. I saw the Tarahumara run and one of the first things that was evident was -- have you ever watched the finish line of a race? You know, have you watched the Marine Corp marathon?

NNAMDII do every year.

MCDOUGALLYou see 40,000 runners -- you're going to see 40,000 different running styles. Everybody's doing something different. You watch the Tarahumara and they're all uniform. They are all running almost identically, young and old, men and women alike, have the same running style. So that caught me off guard. The fact is, they seem to have all agreed that we're all going to do the same thing.

MCDOUGALLHowever, I thought I could do the same thing while still wearing my thick cushion shoes. What I found over time is you have such a loss of sensory input from those thick cushion shoes that once your technique starts to backslide, you don't know it. You're not getting any input. So what happened was, my technique may be very good for a while, but after a while, it would degenerate. And that's what dawned on me. I need to take the gloves off my feet and actually feel what I’m doing.

NNAMDIWhat kinds of routine do you stick to now? How many miles are you logging a week and how many of them are you running without any kind of foot gear at all?

MCDOUGALLYou know, that's the key word, routine. I was very routine based. You know, I have to do three miles a day and if I get to the red light, I'm going to keep running because, you know, you run, you run. Now, I'm the opposite. I go strictly by feel. I try to run exactly the way my six-year-old runs when she goes out the door. If it's fun, she'll do it. If it's not, she stops. And that's how I run. I basically just go by feel and go by fun.

NNAMDIMike Wardian, if any of us were born to run, it's people like you. You don't just run marathons, you win marathons. You run and win ultra marathons. And you've recently qualified again to run in the U.S. Olympics trials for the marathon. What's your approach to footwear and how do you take care of your feet?

WARDIANMy approach to footwear is I try to wear all different types of shoes, different models, different brands. I'm lucky I work with a company called the North Face and they make a lot of nice shoes. And so I get to try all different kinds of shoes. You know, I wear racing flats sometimes. I think, like Chris, sometimes I go no shoes when I'm walking around. I wear heavy cushion shoes so I can't feel anything on days where my legs are maybe more beat up. So it's nice.

WARDIANAnd then, I’m also looking for new shoes. So, you know, if a company is looking for feedback, I'm willing to work with them to try and help them develop shoes. But I think it's really interesting, to get back to the barefoot thing, to see how this whole barefoot running concept and movement has really spurned a lot of the companies. It seemed like everything was just getting more and more built up. And it's really neat to see everybody kind of really -- kind of come and look at things and say, well, you know, maybe there is something to this barefoot thing and maybe we'll try and make some minimalist shoes.

WARDIANI think New Balance has come out with some really minimal shoes and you see, like, the Vibram, five fingers, that have come out.

NNAMDIYeah, just this past Sunday in Rock Creek Park, I see a guy running on a trail that has a lot of pretty sharp rocks on it.

WARDIANYeah.

NNAMDIAnd I'm seeing these five fingers on him and I'm going, I wonder if that hurts? But apparently not.

WARDIANWell, yeah, and I was actually up in North Face 50 miler here in D.C. and I saw a guy with a pair of just, like, scuba boots on his feet. And there was just jagged rocks all over the place and the guy looked like he was in misery. I mean, I don't think he may have done as much training in those as he thought he had, but, you know, I think that it's pretty neat. I just saw Chris outside doing an interview with a little pair of Huaraches on that looked really cool, too.

WARDIANSo I think it's neat to see that, you know, there is this whole movement to try and shift everyone's mindset to try and run...

NNAMDIAs much as you run, Mike, have you ever suffered a running injury that you would've blamed on wearing shoes with too much cushioning?

WARDIANActually, I would say that I haven't -- I'm really blessed and I think a lot of people think that I'm a little bit abnormal and that I, unfortunately, like -- or, I guess, fortunately for me, like Chris, I can run a lot of miles and I don't seem to end up hurt. So I haven't really had any...

NNAMDINot exactly carrying his body weight either?

MCDOUGALLI'd be curious to ask Mike a question.

NNAMDISure.

MCDOUGALLAre you four foot striker?

WARDIANActually, I think that I do on my right foot, but on my left foot, I think I'm more middle to back.

MCDOUGALLRight.

WARDIANBecause I notice that I slap my -- and I'm really loud, actually, when I run. So I sound like, you know, like (makes noise) . So, like, when I'm running in the front, like we were saying, like, at the front of the Marine Corp with all the Ethiopians or Kenyans or something like -- I've heard you give a talk before where you've said, like, if you look at all those guys, they look kind of uniform. Like, I'm the guy, like, clopping in the back, like, (makes noise) .

MCDOUGALLBecause you know, Kojo, the question really comes down to, it's really not footwear, it's about form. I mean, Emil Zátopek, the great Czechoslovakian runner...

NNAMDILoved him.

MCDOUGALL...used to train in a pair of combat boots. The reason why was his biomechanics were so pristine and perfect. He used to train also by running on wet laundry in the bathtub, which is a foolproof way to learn perfect form. You make a mistake, you're in the hospital. But what he learned how to do was, you can't over stride and you can't land on your heel. You have to learn -- land to learn, right -- lightly and gently. You do that and you can wear any kind of shoes you want.

NNAMDIEmil Zátopek, who fell in the 10,000 meters at the Olympics and was able to come back and win the race anyway. That tells you just how old I am. We're talking about barefoot running. You could call us at 800-433-8850. Have you ever had a running injury that you suspect was the result of your running shoes? Did it make you think about the benefits of running barefoot or what would it take for you to give some thought to ditching your running shoes and going barefoot? Call us at 800-433-8850.

NNAMDILet me go to Steven who is in Boulder, Colo. Steven, you must be listening to us online. Go ahead, please.

STEVENI am, and I want to put in a word for people who went from injury to injury to injury as I did when I started running again at 45. And then switched to barefoot and I -- not only did all my injuries disappear, but, as Chris was saying, my form improved and now I'm one of the fastest guys over the age of 45 in America.

NNAMDIYeah, I like being one of the fastest over a certain age group. I'm way down in the middle to the lower part of my own age group. But you -- has -- how has -- have you noticed how your form has changed, Steven?

STEVENAbsolutely. Well, let me tell the worlds shortest version of a story. My first long barefoot run and I'm a sprinter by trade. So the fact that my -- that I ran barefoot for 5K was just totally shocking to me. I mean, the people I train with tease me that I don't even know what the corners of a track look. So the fact that I did a 5K was sort of stunning. And at the end of it, I ended up with a blister on my left foot only. And it wasn't lost on me that I had a problem with one foot that was doing something wonky and the other was okay.

STEVENAnd it was also not lost on me that it was my left leg that was getting most of the injuries. So I went out the next week and thought that if I could figure out a way to run and not do the thing that caused that blister, then I'd be on to something. And I didn't know what it was at the time. After about 10 minutes, something shifted and I started running faster, easier and lighter. And at the time, I was just grateful.

STEVENI wasn't clear what had happened. It's only after the fact that I realized I stopped doing the classic thing that everyone's been mentioning. I stopped over striding. I stopped pulling onto ground and pushing off the ground and instead was just getting my feet underneath me, lighter and easier and sort of lifting and then placing them. And that's what made the change. And that's how -- I think why I've been uninjured ever since.

NNAMDIIndeed, Chris, one of the things you noticed about the Tarahumara is that they take fairly short strides.

MCDOUGALLI should mention, by the way, I think I know who Steven is. Steve Sashen, he created a pair of Huaraches, Tarahumara style sandals, which I now wear all the time and are fantastic. So if that's Steve Sashen, you make a one fine pair of Huaraches.

NNAMDIIs that you, Steve?

STEVENOh, thank you. It is and thank you very much, Chris.

NNAMDI(unintelligible) …

MCDOUGALLOh, no, they're fabulous. Yes, that was what caught my eye about the Tarahumara. You know, I ran the way I ran. I ran with a big muscular stride, trying to, sort of, power myself. And I'm looking at the Tarahumara, there were guys in the 70s and 80s that are wafting right past me on mountain trails and doesn't seem like their working at all. And I think the key difference is there is a force much stronger than any human muscle and that force is gravity. All they're doing, is allowing themselves to fall forward and just plant the foot down under their center of mass to catch themselves before they hit the ground.

NNAMDIMike, it's my understanding that you didn't exactly start out your running career decked out in top of the line running gear, that you ran your first marathon and the Marine Corp marathon, 15 years ago, in a pair of long, baggy, lacrosse shorts.

WARDIANThat's true. Without any type of lubrication on anywhere and I know a lot better now. And I remember fighting my -- I guess I'm like Chris in a lot of things. Like, people tell me, like, oh, you should use, you know, running shorts and I said, I can probably do it with my old lacrosse shorts. And so, yeah, I did run my first marathon in a big pair of lacrosse shorts and a huge pair of trainers and just a cotton t-shirt and I suffered greatly for all those mistakes. And luckily, I've learned a lot since then.

NNAMDIBut, Chris, most people are not pounding the pavement like Mike, but there are a lot more people running than ever before. And you say that running shoes, the shoe industry, are to blame for a lot of the big spike in running injuries. That injuries are just as likely, even more likely, than the era in which people would've been out there in the canvas Chuck Taylor's.

MCDOUGALLExactly.

NNAMDIWhat's your case?

MCDOUGALLThis is the fascinating thing people have been looking for. They've started to study running injuries and they want to compare the incidents of running injuries prior to the creation of the modern running shoe. So my running shoe really developed in the mid '70s. And we know that somewhere between 50 to 80 percent of all runners have been injured every single year since the creation of the modern running shoe. So let's look back what happened prior to that.

MCDOUGALLThe thing is, there is no data on running injuries prior to the 1970s. They were so incidental that no one even bothered to count them. What I think happened is, with the creation of the modern running shoe, you created a new kind of running style. With a thick cushioned heel, you can now land on that heel. Without that cushioned heel, you have to land on your forefoot. So essentially what we did was we created these big mushroomy, marshmallowy shoes, is we created a kind of running that is new to our species and new to our lifetime.

NNAMDIBack to the telephones. John -- and Steven, thank you very much for your call. John in Washington, D.C. You're on the air. Go ahead, please.

JOHNHi, Kojo. Thanks for taking me. I just actually came in from a run in my Vibram Five Fingers about a half hour ago out of the mall. So I wanted to get back and make sure I could listen to your phone call -- to your show before it was over. I've been running in -- I'm not a true barefoot runner, I guess. I discovered the five fingers about a little over a year ago. And I've been up to about eight miles in them. The biggest thing for me, I was in Air Force. I ran in everything from, you know, heavy combat boots and just about every kind of environment, snow and rock and sand and all that kind of stuff.

JOHNAnd the best thing for me, I've found, is my agility has improved a lot. And it's been able to transfer into other, you know, athletic endeavors, I suppose. Mainly because, you know, when you're running on those things, there's a lot of sticks and rocks and things that you have to avoid, that you can -- you know, you definitely feel a little bit more and you're in touch with the earth quite a bit more. So, you know, honestly, I'd wear them all day if I could, if -- to work if they'd let me.

NNAMDIHow's it affected your technique, John?

JOHNWhile I'm naturally forefoot striker. I have been ever since I've -- you know, was running track in junior high, I suppose. So it kind of just facilitated what I was already doing. And also the best thing for me is, you know, it's a great social -- great conversation starter. You get -- my kids call them, my ugly monkey feet. So I get a lot of new friends every day who want to know about them.

NNAMDIThank you very much for your call. Mike...

JOHNThank you.

NNAMDI...to what extent have you experimented with minimalist shoes or barefoot runs?

WARDIANOh, I've done quite a bit of both. I haven't actually gone out and purchased any of the Vibram or the Huaraches, but Chris gave me a couple of good contacts that looks like -- earlier when I saw him before the show. And I think that's pretty neat and then, you know, working with some of the shoe companies and in particular, North Face. We've been really trying to -- they have a lot of really nice trail shoes that they're trying to scale down and make more minimalist.

WARDIANAnd so that's also pretty fun to be able to be involved in the evolution of the actual running shoes because, you know, I think, you know, for me running at the level I am, running in the five fingers is great but I think it's the pace that I'm running, it's at such that I'm striking the ground very, very hard and I need just a little more cushion just because I'm a bigger guy, like, you know, six foot and like 140. And so for me, I'm not like the 110-pound African runner that isn't generating that type of force, so I need a little more cushion.

NNAMDIChris, it seems that a big part of your beef is with the commercialization of running itself, a beef that goes beyond the high prices of health risk of shoes, and goes all the way to the commercialization of marathons and road races that go down every weekend. Could you talk about your philosophy in that regard?

MCDOUGALLRunning has become a gigantic money maker. And I think the difficulty with this is that it's become this moral imperative on people. If you tell somebody you run, they're gonna automatically say, have you run a marathon, how fast can you run a marathon? It's this sense of you gotta do more, you gotta go to New York City Marathon, you gotta, gotta, gotta. And I think it robs the fun and the playfulness from the activity.

MCDOUGALLLook at children. Children don't care how fast they're going, how slow they're going, how many miles they -- they're enjoying it. And I think what we've done is we've taken this thing and, you know, 26.2 miles is really far. It's not beyond human capability by any means, but it is if you haven't trained for it properly. And also, if you think by strapping some $150 pair of foam on your feet it's going to get you to the finish line.

MCDOUGALLI think what we need to do is get running back to where it was before, a sense of joyfulness, community, playfulness. Let people enjoy it first and worry about races later.

NNAMDIGotta take a short break. When we come back, we will be talking to the director of research at the department of physical therapy at Indiana University School of Health and Rehabilitation Sciences about the science behind all of this. But you can still call us, 800-433-8850. If the lines are busy, go to our website, kojoshow.org, join the conversation there. Have you picked up barefoot running? How did you get into it? You can also send us a tweet @kojoshow. I'm Kojo Nnamdi.

NNAMDIWe're talking barefoot running with Michael Wardian. He's a hero of mine. He's a champion long distance and ultra distance runner. He's a five-time champion of the National Marathon in Washington D.C., and a three-time qualifier for the U.S. Olympic Trials in the marathon. He joins us in studio along with Christopher McDougall. He's a journalist, author, and barefoot running enthusiast. He's the author of "Born to Run: A Hidden Tribe, Super Athletes, and the Greatest Race the World Has Never Seen."

NNAMDIAnd joining us now by telephone is Stuart Warden. He's a professor and director of research at the department of physical therapy at the Indiana University School of Health and Rehabilitation Sciences. Stuart Warden, thank you so much for joining us.

MR. STUART WARDENThanks for having me, Kojo.

NNAMDIStuart, you study the physiology that comes into play when people go out to run. How would you describe the impact that running barefoot has on the body?

WARDENWell, it comes back to a little bit in terms of what Chris is talking about, in that it's not barefoot running, per se, that we're talking about here. In terms of the physiology, we're talking about where people strike their feet on the ground. And like Chris was talking about, with the modern-day running shoe where there's a large cushion under the heel, it basically encourages or allows people to run carefree with land and bang their heel on the ground.

WARDENAnd as a result of that, you get an impact transient or shock that goes up into the body and potentially contributes to injury. Barefoot running, per se, doesn't change that, but what it does, it changes how you run. So if you run barefoot and you land on your heel, well, that's no better than running in normal shoes. It's actually worse. So going barefoot, per se, is not the main issue. It's when you convert to barefoot, you've got to be able to run with correct form and run correctly to really decrease the injury risk.

NNAMDISo Stuart, are you in agreement with the argument that growing up with shoes, learning to run with shoes, fundamentally changes how our bodies react to the impact of running?

WARDENI am. And, you know, with my own children, you know, I have a four-year-old son, and even before a lot of this barefoot work, well, I came across a lot of this, I didn't want him in shoes. I didn't want him to be wearing shoes running outside because once you put a shoe on, it changes your whole perception of the world, you know. That's your only contact with the world, physical really, when you're walking or running.

WARDENSo I wanted him to develop his feet and the muscles in his feet and his calves. And I get the impression, and from what I've read is, that once you put a shoe on and you wear a shoe, you basically adapt to -- you become a shoe wearer. You adapt to wearing a shoe. And so if you have a shoe with, you know, nice arch supports and a big cushion on the heel, well, the shoe does what it says. It's gonna cushion the impact.

WARDENWell, as a result of that, your body doesn't adapt. So you've now adapted to wearing a shoe, and to go from a shoe runner to a barefoot runner, you need to unadapt from being a shoe runner and now adapt to becoming a barefoot...

NNAMDISo what would you recommend to the person who has never run barefoot before and is thinking about giving it a shot?

WARDENWell, if I had say a patient, you know, in the clinic who is thinking about going barefoot, first I'd ask them, you know, why do they want to do it. If it's someone like you had on earlier, Steven, who constantly got injured and no matter what he did he couldn't rehab and he kept getting overuse injuries, then I would say, you know, definitely let's try barefoot running. Because it has the potential of decreasing injury risk because you're decreasing the load that you're putting into the body.

WARDENIf it's someone like Chris -- I'm sorry, like Mike who is, you know, runs long distance, really never gets injured, if he came to me and said, I want to run barefoot now, I'd be saying, well, why? You never get injured (unintelligible) ask why do you want to do this? You know, so if you have...

WARDIANIt's fun.

WARDENYou know, if you're optimally adapted to running, and you don't have any problems, I would stick with what you're at. But if you really want to do barefoot running or you prefer or you want to give it a shot, then you really need to go slower. You know, you can't just go from running in a shoe and then go, okay, I'm gonna run three, four, five miles without my shoes today and see what happens.

WARDENSo we try to advise people to build up slowly. You know, start by walking around their house with no shoes on, or if you're gonna (word?) shoes, put those on. Walk around, walk the dog around the block in those shoes. Do that for a week. And then before you start running in them, you know, walk the dogs for ten minutes. In that ten minutes, run for 100 yards or every few hundred yards just jog a little bit, and just start building up and get a feel for how does your body respond to running barefoot.

NNAMDIOkay. Allow me to go to the telephones starting with Barbara in Potomac, Md. Barbara, your turn.

BARBARAYes, hi, Kojo. I was calling because I've been a long-distance runner most of my adult life. I'm in my mid 60s. And a few years ago, I started to get knee injuries...

NNAMDIWelcome.

BARBARA…wearing traditional shoes like New Balance. So I've sort of had to give it up. I've taken up swimming, and I've been running along with my swimming, in the swimming pool, obviously barefoot, and just to kind of get a feel for it. And it seems like it's really strengthening, you know, my calf muscles and my feet. But I've been toying with the idea of getting the five-fingered running shoes, and I was hoping that in doing so, that it would help me to prevent knee injuries in particular.

BARBARAAnd perhaps, you know -- a lot of my questions, you know, have been answered by your speakers, but I just wanted to know if anybody had comments about knee injuries because I really would like to give these new five-fingers a try.

NNAMDIChris?

MCDOUGALLYes. Barbara, before you buy anything, let's practice learning something first. Inside your own house go barefoot, and just try to run in place for five or six minutes at a time. You can't run improperly when you're running in place. You can't land on your heel, you can't over stride, same as (unintelligible) in the bathtub. I wouldn't counsel you to go right to the bathtub in the soapy laundry just yet, but here's what I would suggest.

MCDOUGALLIf you can run in place in your house lifting your knee as high as your hip, and if you don't feel any heel -- I'm sorry, any knee pain, then you're on your way to injury-free running. I would say learn the technique first before you invest in any new toys.

NNAMDIEspecially a dog, which is what Stuart seems to think you should get to walk around the block. Barbara, thank you very much for your call. Stuart, what are the most common injuries that you run across from people who are running a lot in cushioned shoes, and how much do you figure these injuries have to do with footwear?

WARDENWell, the most common injury is going to be like Barbara has, anterior knee pain is one of the most common injuries. People who run, they get a lot of quads contractions and they get anterior knee pain. Whether that's a result of the shoe, again it comes back to biomechanics and form, and the shoe allows them to run with a nice big heel impact on the ground, and basically results in the shock that goes to the knee and requires a certain amount of muscle activity.

WARDENRunning barefoot with proper form, so you don't overstride and you land on your forefoot or mid foot and you allow your heel to come down, you decrease that force or that load and decreases the amount of force that's going through the knee, and you actually run with more knee flexion. And, you know, it has the potential -- no one's really shown this yet, but from a biomechanical standpoint, to decrease overuse knee injuries.

WARDENMy concern with the barefoot and that form is exactly what Barbara says, that you start to feel it in your feet and calves. So running barefoot does put a lot more force and stress through the Achilles tendon and in the feet. And there is some literature coming out now, very premature or very early (unintelligible) that people running in Vibrams and things are getting foot injuries.

WARDENAnd because their feet haven't adapted, they've adapted to wearing a nice big cushioned shoe, and now there's no longer that support there. And again, it just means that you've got to think about how you build up to running, and what Chris says, you know, running on the spot is a great idea, and just see how you get used to it. And I should add to that that in between each running session you need to make sure you stretch your calf muscle and stretch your Achilles' tendon, because that's generally the thing that gets tight when you start running barefoot.

NNAMDIChris, how about running barefoot on a treadmill starting out, or starting to walk barefoot on the treadmill and then moving up to running?

MCDOUGALLWell, you're adding a degree of difficulty. Treadmill is moving, so you have to adapt to that moving surface. Also, treadmills are designed to be kind of buoyant, so it can cover up some of your impacts. I think the thing you want to do is actually practice the behavior that you're trying to perfect. And by practicing that behavior, you want to practice what it feels like to run on a hard surface, so practice it, but just cut out the other variables which would be, you know, moving across the sidewalk.

MCDOUGALLJust do it in place. I think what you'll find very quickly is you'll start to relax, your heel will start to come down, and then when you feel comfortable with it, just move forward.

NNAMDIGot a treadmill story for you. Mike Wardian is going to be awfully busy for the next year. He's got training to do to get ready for the Olympic trials.

WARDIANRight.

NNAMDIBut I understand you recently did a little treadmill training during a Baltimore Orioles game at Camden Yards. And by treadmill training, I mean, did you really run an entire marathon while the game was going on around you?

WARDIANYes. Yes. In the concourse.

NNAMDIAnd apparently from what I heard, the game was going to be a lot shorter than you expected it to be.

WARDIANYeah. Yeah. I guess the average game is about three hours.

NNAMDICorrect.

WARDIANSo at the bottom of the sixth inning I was only at 14 miles because I was expecting to have a little more time. So I cranked the treadmill as fast as it could go, which was only six-minute pace, and was able to finish the -- it was a promotion for the Baltimore Marathon, so I finished at the top of the ninth inning, and it was only because the Angels decided to get some hits.

NNAMDIAnd there were only two outs left when you were finished, right?

WARDIANYeah. I actually finished at the top of the ninth inning, and then the Orioles continued to play poorly, and so it was over very quickly after that.

NNAMDIYeah. And you won the San Francisco Marathon last week. That was your 2:33 time.

WARDIANI think 2:27:06.

NNAMDI2:27 -- see, he remembers everything. 2:27:06.

MCDOUGALLNo baby carriage this time.

WARDIANYeah, exactly, yeah.

MCDOUGALLAnd it's only a five-minute difference. It's crazy.

NNAMDIHere is Amy in Silver Spring, Md. Amy, you're on the air. Go ahead, please.

AMYHey there. Thanks, Kojo. I really don't consider myself an early adapter of any sort of athletic gear, but my husband really quickly and totally became a barefoot runner. To the point that he's actually stopped wearing shoes all together. He works at the FCC, but he wears these shoes that Terra Plana makes that basically look like work shoes and can be folded up and put in his back pocket.

AMYSo I was really slow to give it a try, especially when it's my husband suggesting that I do it. I ran and it really was better. And I don't consider myself a runner. I'm kind of stubborn about these things, but I could just go out and run, and I knew it was time to stop when my form changed. So I wasn't going out in shoes and running until I basically couldn't go anymore and running the risk of really injuring myself.

AMYBut I could tell when my form started to get bad that it was time to stop. And it's just been a really joyful experience. Thanks so much for having this show. I love the book. And I really look forward to actually being a runner for the first time in my life.

NNAMDIAmy, thank you very much for your call, and I'm glad you raised the issue of form, Stuart, because we keep talking about that. What exactly is proper form?

WARDENProper form, if you're looking at running barefoot, is -- the main thing is to not overstride and that's what a lot of people tend to do, particularly with a shoe on. Overstride means taking steps that are too big. You need to take short, almost shuffling steps, and if you focus on that, focus on taking short steps as opposed to large strides, then that generally helps bring a lot of the other form factors in.

WARDENSo taking short steps and landing either on the front of your foot or the mid foot, and letting the heel lower down to the ground. And try and avoid landing on your heel as your first point of contact with the ground. And the main thing is don't over stride and try to run very softly. So try and think about running very softly, and what that means is running with your knees with a little bit more bend in them, a little bit more bend in your hip.

WARDENAnd if you think about those two things, don't take long steps, take short, quick steps, and try to run softly, then that generally helps people think about or keep their form with barefoot running.

NNAMDIAnything you'd like to add to that, Chris?

MCDOUGALLYou know, running is a form of jumping. And so if you jump off your chair, you're gonna want to absorb as much impact as possible, be as light and gentle as possible. And that's basically what you should be focusing on. The goal was not to run barefoot. The goal is to run efficiently and lightly. Barefoot is a really efficient way of achieving that goal because you're getting so much more input.

MCDOUGALLSo that's why I advocate barefoot running is exactly what you're trying to accomplish that Stuart's telling you to do, a good way to figure that out is by going barefoot.

NNAMDIStuart Warden is a professor and director of research at the department of physical therapy at the Indiana University School of Health and Rehabilitation Sciences. Stuart, thank you for joining us.

WARDENThank you very much for having me.

NNAMDIChristopher McDougall is a journalist, author, and barefoot running enthusiast. He's the author of the book "Born To Run: A Hidden Tribe, Super Athletes, and the Greatest Race the World Has Never Seen." Chris, thank you so much for joining us.

MCDOUGALLIt was a great show, thank you.

NNAMDIMike Wardian is a champion long-distance and ultra-distance runner. He's the five-time champion of the National Marathon of Washington, D.C. Thank you so much for joining us, and good luck to you.

WARDIANThank you very much.

NNAMDII'm Kojo Nnamdi.