Why Running *Isn’t* The Best Way To Get Fit, How The Running Craze HARMED Fitness Enthusiasts & Why Walking Is Essential To Health & Longevity, With Mark Sisson.

Ben Greenfield [00:00:00]: My name is Ben Greenfield, and on this episode of the Boundless Life podcast.

Mark Sisson [00:00:05]: Most people who go out the door, put on their shoes, go outdoor run, they're running at a heart rate that's above their fat max. Their heart rate is too high to be burning fat efficiently, so they're mostly burning glycogen. Their heart rate is too low to be generating any sort of shift in VO2 max, or anaerobic threshold or power. So with this, all you're doing is practicing hurting every day and not getting better. You're not performing better as a result of all of this wasted junk miles that you're doing it at the wrong heart rate. So most people would be so much better off walking a lot more.

Ben Greenfield [00:00:38]: Welcome to the Boundless Life with me, your host, Ben Greenfield. I'm a personal trainer, exercise physiologist, and nutritionist, and I'm passionate about helping you discover unparalleled levels of health, fitness, longevity, and beyond.

Ben Greenfield [00:00:58]: All right, it arrived fresh and new and shiny. Although not so shiny anymore, because, you guys, you're watching the video version, you can see all these pages folded over. This is. Well, it's a book, obviously, but it's a book written by a guy who writes books that I always read no matter what. I don't even ask any questions. He could probably write a book about something I'm barely interested in, like the intersection between cryptocurrency and democracy or something like that. I still read it. The guy is prolific.

Ben Greenfield [00:01:27]: He's an OG in the fitness industry. And this book is called Born to Walk. The author is Mark Sisson. Mark, welcome to the show, man.

Mark Sisson [00:01:36]: Hey, good to see you, Ben. Thanks for having me on.

Ben Greenfield [00:01:38]: Yeah, sometimes. Cause I think I've interviewed you twice in the past. I almost take for granted that everybody should know who you are. And then I'll be sitting on an airplane or whatever, and I'll mention, hey, ever check out that website, Mark's Daily Apple, which I know, I don't think is an operation anymore, or, you know, Mark Sisson, and occasionally I'll get an eyebrow raised. So I know not the entire health industry, or at least all my listeners may not know exactly who you are, but who you are is actually a pretty good introduction to this book because I originally knew he was like the, you know, the hardcore, you know, marathoner, ironman, triathlete, you know, endurance guru. But you're not anymore. And how this book came to be is a big part of that.

Mark Sisson [00:02:23]: Huge. And it's, you know, life is a journey and we learn along the way. And I certainly learned a lot starting at an early age when I was an elite competitor and I got injured and I got beat up by the combination of over training, bad equipment, bad shoes, bad diet. And that really set me on my path to explore human, human health and performance in general, not just among elite athletes, but you know, how can we all be strong and lean and fit and healthy? And that really dictated my process for the next 30 years. This book started out as an anti aging book. And because I'm 71 now, and I.

Ben Greenfield [00:03:07]: Should mention, folks, if you don't follow Mark, he's one of the most ripped, fit 71-year old on the planet.

Mark Sisson [00:03:13]: Well, thanks, I try. And the irony here is that a lot of the stuff I've learned have been you guys call them hacks, I don't like that term. But things I've learned over the years that have allowed me to maintain my health and my fitness and my energy and my muscle mass all at the same time without having to make too many massive sacrifices along the way. Whether those were sacrifices in diet or sacrifices in overtraining and things that I thought I had to do to be, to be, as Ali G would say, well, fit. But no. So the book started out as an anti aging book. But as I got deeper and deeper into the research, I realized, Jesus, like so much of this comes back to walking. Walking being the quintessential human movement.

Mark Sisson [00:03:57]: And the idea that somehow we lose sight of that, we lose track of that. We start thinking that with a sedentary life that we've created for ourselves, that the best way out of this hole is to go run and put on running shoes and go run five miles or six miles. And so many people have embraced running as the sort of the ideal form of exercise for humans. And I go back to, you know, the book Born to Run, which came out, Christopher McDougall wrote that book in I think 2010. And I started to really think about like what? We're not born to run, we're born to walk. We're born as these bipedal animals that populated the face of the planet by walking, by lifting and carrying things, not running with them, but by walking with them. And the idea of 10,000 steps a day. Our ancestors got 16 or 20,000 steps a day.

Mark Sisson [00:04:52]: And they weren't throwing on their shoes and going out for a quick six mile jog. They were walking, they were living their lives. The idea that we are somehow born to run got, I think it's a cultural and anthropological misappropriation of a couple of data points. One of the things that McDougal wrote about in his book Born to Run was this notion of the persistence hunter and that we evolved eating meat with larger brains and the ability to track animals. And it was these evolutionary adaptations we had that allowed us to run after a beast and then stick a spear in it after we outlasted the beast for two hours on the hot plains of Africa. Well, that's not how it works in a persistence hunt. A persistence hunt is sort of like jogging a little bit. Stopping, sniffing, tracking, crouching, hiding, cutting the tail.

Ben Greenfield [00:05:47]: There's videos on YouTube, by the way. You can see how it's done.

Mark Sisson [00:05:49]: Yeah, so it's done to the point that, you know, like my friend Eric Edmeads. Do you know who Eric is?

Ben Greenfield [00:05:56]: Yeah, he's amazing. The wild fit wild diet.

Mark Sisson [00:05:59]: Exactly. Eric, by the way, he took a pair of Peluvas of the Peluva desert boots, my shoes, and he went on a persistence hunt with a hadza. And he said it was no big deal. It's like two hours. Like even a reason.

Ben Greenfield [00:06:12]: That's so funny, by the way, because I wore your toe boots on my last hunt. They're great for stalking as well. You're like whisper quiet.

Mark Sisson [00:06:18]: No, that's one of the things that Eric said was the first time he did it, he did it in clunky running shoes. And the guys in the, in the, in the hunt kept turning around and going, sh. And this time you didn't get that. But we digress. So the idea that we're persistence hunters is, you know, it's a romanticized notion. We're not. We're born to be able to run. Right.

Mark Sisson [00:06:39]: We're born to. By the way, the subtitle of the book was going to be Born to walk and then in parentheses and sprint. But we're not born to run metronomically at 8 or 9 or 10 minute mile pace, day in and day out, day after day, over a lifetime. It's literally antithetical to health.

Ben Greenfield [00:06:58]: Yeah, yeah. You say, by the way, that it might better be described as a walking, sprinting, jogging, hiding, climbing, crawling, collaborating, strategizing hypothesis instead of the born to run hypothesis.

Mark Sisson [00:07:08]: Out of the born to run hypothesis. Exactly. So the fact that our ancestors could do this persistence hunt didn't mean that on their days off, look, they didn't do it every day. Once they killed a beast, the beast lasted for however many days it lasted. They didn't have refrigeration, so they couldn't like go accumulate, you know, new new animal carcasses and pile them up in their storage area. They hunted out of necessity. So every couple of days, maybe every couple of weeks, they'd go on the hunt. Well, they didn't, on their days off, they didn't train for the hunt.

Mark Sisson [00:07:37]: Right. They didn't go, hey, let's go do a quick 10 mile or so, we're ready for the next hunt. No, their life of walking, lifting and sprinting prepared them to be able to run and by the way, not run seven minute miles for two hours chasing an animal, but to be able to run enough to catch up and get to the next set of tracks or sense or whatever was there. So anyway, we quickly dispel the notion of humans as born to run in the book and we talk about look work. We're bipedal. Our bodies literally depend on us walking. We, we not just to locomot, not just to get from one place to another, but our immune system depends on us being able to to move and to put like our lymphatic system requires movement, requires slow, steady movement throughout the day.

Ben Greenfield [00:08:28]: BDNF production, VEGF production. You know, miracle grow for the brain. I can tell you right now, you know, even though I get flacked sometimes for walking like I'm doing right now while I'm talking to you, dude, I feel way more focused, way more energized. My head's in the game way better. I'm getting like 20,000 steps a day. And it's incredible for the neural component as well.

Mark Sisson [00:08:49]: A hundred percent. So people will say, you know, a lot of their best thinking is done while they're walking. You know, they, I would say that people who are in a low mood want to go outside and change their mood walk. You're hungry, you're tempted to reach for the refrigerator because you're on a new keto program or a new carnivore or a new whatever it is, a new way of eating. The quick fix is go out the door and start walking. It immediately starts to mobilize stored fat, you start to burn that fat and you become energized. You lose that craving or that appetite pretty quickly if you do this in the appropriate manner.

Ben Greenfield [00:09:28]: Yeah, you get into some of the fat loss, calorie burn stuff later in the book and, and you know, just to briefly touch on that, we were talking before the show started. I just moved into my new home. This is one of the first podcasts I've done in my new office and for five days we're moving, taking boxes out of the truck, hauling them up and downstairs. Best work I do occasionally. I had the first two nights at the home horrible sleep, and I thought it was because I wanted in a new sleep environment. I slapped the blood glucose monitor on. I was sleeping at like 50 to 60 blood glucose because I was simply burning more calories walking around the house. I didn't do a single workout.

Ben Greenfield [00:10:06]: And it reminds me of a text I got from one of my clients. He's probably listening in right now. And he really wanted to start getting fitter faster and burning more calories. And he said, you know, I think I just need to start running again. I used to run 45 minutes a day. I want to pick up my run again. Because this idea still permeates the fitness world that one of the best ways to increase aerobic fitness quickly is to simply start running. And you dispel that notion pretty well in the book.

Ben Greenfield [00:10:36]: But before we get into maybe some of the biochemistry of why walking might even be superior for running, for things like metabolism and weight management, you have a really fascinating section of the book where you get into what sparks this whole myth, if we want to call that in the first place, this whole endurance running craze. I'd love to hear you get into that a little bit.

Mark Sisson [00:10:57]: Sure. Well, you know, we have like, I don't know, first third of the book is dedicated to sort of the, this, this perfect storm of events that happened that created the running boom that ultimately wound up being extremely disappointing for 95% of people who engaged in it. You know, it's. It's fraught with no weight loss when weight loss was intended. It's fraught with burnout, with high cortisol production, with injuries. I mean, runners get injured at a rate higher than NFL players. So in order to set the stage for all of the reasons that maybe running is not the best choice to achieve robust fitness and longevity, we kind of have to go back to the beginning and understand that as we said out of the gates here, our ancestors didn't of necessity go out and run just for fun. It was not a fun thing to do.

Mark Sisson [00:11:48]: It was a life necessity and only precipitated on the need for more food. When did running really start? Well, you know, you trace it back. Yes, there were Olympic games where there were sprinters and there were javelin throwers. This goes back to, you know, Greco Roman times, but really it's only in the, like the post industrial revolution in the mid-1800s when cross country started. And it started as a pub game. It started as, instead of darts or, you know, trivia in a pub in England or the UK, they would have these hounds and harriers things. They'd rip up little pieces of paper and off would go the rabbits, the hares, and they'd set these trails and the hounds would chase them. And that's where the term harrier came into existence for a cross country runner.

Ben Greenfield [00:12:39]: Wait, I'm assuming that both the harriers and the hounds were human beings and the harriers would just take off running as like a, like a chase. The hounds would have to catch them.

Mark Sisson [00:12:48]: Pub game. And it was for, you know, it was to, it was, it was to see who, you know, instead of playing dart, should be outside, seeing who was the more, you know, robust runner. That morphed into cross country, which the schoolboys in, in public and private schools started doing cross country runs where they'd run, you know, 2K, 5K across country on soft surfaces, with leather shoes, with great leather, with good form. That morphed into somehow somebody said, you know, there was this guy Pheidippides, there was a poem written about him. Apparently he, you know, he ran into Athens after the battle of marathon after running 25 miles to tell the townspeople, rejoice, rejoice, we won. And apparently he dropped dead. We should name a race after him. Let's call it the Marathon.

Mark Sisson [00:13:35]: Because the Pheidippides was too difficult a word to pronounce. So the marathon only came into existence in 1896 with the first Olympic Games. It was 25 miles. By 1908, when the Olympics, that Olympic Games were in London, the queen wanted the race to start at Windsor palace and then finish in the stadium. And in order to make that happen, it had to be 26.2 miles. So that's where the, that's where the distance of the marathon came to be.

Ben Greenfield [00:14:00]: Interesting. I didn't realize that.

Mark Sisson [00:14:03]: This guy didn't really run into Athens to say, rejoice, rejoice, you know, we won, and then drop dead. That was a poetic license of a poet, Robert Browning. What really happened was Pheidippides was an incredibly gifted athlete who ran over a period of four days, ran 306 miles as a courier, as a, as a messenger for the armies to enlist the aid of the Spartans. He ran 153 miles to Sparta, at which point he found out the Spartans were on holiday and they couldn't come assist in the war against the Persians. Give us a couple of days. So we had to turn around and tell, run back and tell the general. So if, if we really want to honor this guy Pheidippides, we have to run 306 miles, which nobody's going to do anyway. So all this stuff is sort of background into how even the concept of humans running long distances came to be.

Mark Sisson [00:14:55]: It was sort of a, a human challenge, a game. It wasn't until the 1970s when it really started to take off and this running boom, as we call it now started to take shape. It started with people like me, self selected skinny people who were ectomorphs with large lung capacity, a tremendous capacity for pain tolerance, who were willing to go out and run 5k on the track or 10k on the track, or maybe a marathon once in a while. So everybody who started running in the 70s, in the late 60s and early 70s, was basically a runner. Nobody who was overweight would have considered putting on shoes and going out and saying, I'm going to go run and burn off some calories. It was completely antithetical to health, to any pursuit of longevity or whatever.

Ben Greenfield [00:15:49]: I'm assuming because back then it was glaringly obvious that you would get injured really quickly doing something like that if you weren't actually, like you said, self selected, built to run.

Mark Sisson [00:15:58]: Yes.

Ben Greenfield [00:15:58]: And also running in what back then were the equivalent of, I think, something you alluded to earlier, you know, very thin, you know, leather sold shoes.

Mark Sisson [00:16:09]: I started running at the age of 13, so in 1966 in Chuck Taylor's, in, you know, just basically basketball shoes. And then I was able to get a hold of some Onitsuka Tigers in the late 60s, early 70s. These were the original running shoes in the United States that Phil Knight, later the Nike founder and CEO, imported from Japan. But even those were a quarter inch thick. And it was to the point where in those early days of true runners, gifted, like people who self selected to be runners, it was the shoes that told you when it was time to stop running for the week. It was the shoes that said, man, I think 50 miles a week is tough enough on your joints, on your foot pads, on your heel pads, on your ankles, on your metatarsals. So it was the shoes that kind of dictated how much mileage you put in.

Ben Greenfield [00:17:03]: Right. Built in safety mechanism kind of.

Mark Sisson [00:17:07]: It forced you to run. You couldn't be a heel striker, oh my God, you'd immediately trash yourself if you were a heel striker. So you had to run with perfect running form and perfect running economy. And even then there was still a limit to which your Achilles could take it. And your feet or your lower limbs could take that amount of pounding.

Ben Greenfield [00:17:28]: Right. And by the way, not to insult your shoe company, Peluva, but I can't jog in them. It's uncomfortable. And really, I could say the same for any minimalist shoe. They totally suck for jogging. Now, sprinting up from the mailbox, which is about the equivalent of the running I do incredible because I have to maintain good form.

Mark Sisson [00:17:46]: Yeah, so exactly. If you can maintain good form and if you know what good running form is, which not many people do and not many people can accomplish, then. Then my Peluvas are good shoes. But we tell people, don't run in these shoes, do everything else in them. And then when it's time to run, put on whatever.

Ben Greenfield [00:18:01]: And when you, when you say don't run, you're talking about the exact form of running we're discussing right now.

Mark Sisson [00:18:05]: Yeah, like I think I've ever had. I mean, I could, I could run in them, I could run trails in them all day long. But you know, I know how to run. I know how to have perfect midfoot strike, et cetera, et cetera. So we're digressing a little bit. So what happened was in the early 70s, Bill Bowerman is now the coach of the Oregon. The men of Oregon, the Oregon Track Club, they're some of the best distance runners in the world. Distance running is starting to become a thing.

Mark Sisson [00:18:29]: Frank Shorter wins the Olympic Gold in 72 in Munich. Running becomes kind of a worldwide phenomenon. At least racing does. Worldwide racing. And so Bowerman and Phil Knight get together and they say, let's make it easier for our guys to put in 90 mile weeks and hundred mile weeks and more. Let's put some cushioning in these shoes so that our skinny ectomorphic, self selected runners with good running form can do more miles without beating themselves up. So that was the original, that was the origin, that was the original idea behind the thick cushion, padded running shoe. Well, now we cut to a few years later, Bowerman has written a book called Jogging because he went to New Zealand and found out there were people in New Zealand that were doing this little thing where they were kind of running, but they were running slow.

Mark Sisson [00:19:18]: And he called it jogging. And people were starting to take on. Ken Cooper writes a book called Aerobics. It transformed the notion of heart health and cardiovascular health.

Ben Greenfield [00:19:30]: I still talk to doctors today who are heavily influenced by that book and still prescribe aerobic fitness as their primary exercise modality.

Mark Sisson [00:19:37]: And even though Cooper sort of backtracked it 10 years later and said, whoa, whoa, whoa, not so much, don't do that much. There's a limit to which the benefits accrue and then they start to drop off and there's a decreasing return after a certain point, which we talk about in the book a lot with, especially with elite runners. So with the combination of now an interest in the running boom, books being written on a aerobic endurance and cardiovascular health, with the notion that now these new shoes would enable anybody to go out and run and not hurt their feet, now on comes an onslaught of the runner boom. It begins in the late 70s. Jim Fix writes a book called the Book of Running. And it becomes this growing ethos that running is the best thing you can do for yourself. And, and there's a certain amount of struggle and suffer embedded into it, which is good for you. And you know, you're supposed to sweat when you get out there.

Mark Sisson [00:20:39]: It's, you know, in contrast to this cushy life that we've otherwise provided for ourselves. So then we see for the next 20 or 30 years an increase in the number of people who are running, a decrease or an increase in the amount of time it takes to finish a marathon. Ben, do you know what the average finish time for a marathon was in this country last year?

Ben Greenfield [00:21:00]: Oh, I'm gonna guess five hours.

Mark Sisson [00:21:04]: Yeah, it was four hours and 30 minutes. That's the average finish time. So it's unbelievable to me. Like when I was running, when they were only runners running, if you couldn't break three hours for a marathon, you didn't even call yourself a runner. It was okay, you called yourself a jogger, but you couldn't call yourself a runner if you were competing in a marathon and couldn't break three hours. So now we get more and more people coming on this bandwagon, shoes getting thicker and thicker, form breaking down, more and more, people getting bigger and bigger and fatter. Just in society, I mean, 70 plus percent of people are overweight now and yet and no decrease in the amount of running injuries. In fact, there's been an increasing amount of running injuries over the years within the running community, those people who call themselves runners.

Mark Sisson [00:21:52]: 50% of runners are injured every year. 25% of all runners are injured right now at any point in time. 25% of people who call themselves a runner are injured. This is a horrible outcome for what is supposed to be a healthy activity.

Ben Greenfield [00:22:07]: Yeah, totally. I mean, you were there, I was there. My wife ran cross country. She was there. You're constantly injured for like what 15 years of Ironman for me, not a single week where there wasn't either IT band or. Or big toe issues or some type of low back problem. Like the chronic repetitive motion and friction from that.

Mark Sisson [00:22:28]: Yes.

Ben Greenfield [00:22:28]: And I was light and I was fit, and I can't imagine doing that like 30 pounds heavier.

Mark Sisson [00:22:33]: No. So, so many people engage in running, they heard it was the best thing you can do. They sign up for a 10k or they sign up for a marathon. They sign up for a training program either online or in person, and they start their process of putting in the miles. Well, one of the biggest issues with most people who run is they run too hard for their capacity for their genetic ability. And the fact that they go out and run three miles, five miles, seven miles, whatever it is, and they sweat a lot, and their, and their tracker says, oh, my God. So such a great job.

Mark Sisson [00:23:08]: You burn 600 calories, you burn 700 calories. Well, typically, people who engage in this activity are doing so to burn off stored body fat. You know, when you want to lose weight, you want to lose body fat. What happens when you start untrained and you don't build up an aerobic base, which is what walking will do for sure for anyone. If you don't build up an aerobic base and you start running, you automatically run at a heart rate that is too high for you to be burning fat. So you're burning mostly glycogen in these runs, and it feels valuable. It feels like you're working your ass off, you're sweating, you come back, you're tired, you're exhausted. You know, you just want to sit there and kind of recover for a while.

Mark Sisson [00:23:49]: But what's happening is you're burning off stored glycogen every time you go out and do this. And what the brain says is, oh, my God, we just. We don't want to tap into body fat stores because we've done this stressful activity. We need. If there's access to food, we need to replace, replenish these glycogen supplies. So typically, people replace their lost glycogen with more carbohydrate. As you and I know, going back since we knew each other from day one, you know, carbohydrate is not an ideal choice for most people who are looking to learn how to burn body fat. And over time, you see people not only not losing weight, you do see their body composition changing, because running is catabolic. Running is catabolic.

Mark Sisson [00:24:31]: It tears muscle tissue down. So over time, somebody, a woman might say, well I'm 155 and I've stayed at 155 for the last year since I've been running. She's lost some muscle mass and she's gained some body fat. Her weight stayed the same but her body composition has changed.

Ben Greenfield [00:24:49]: And possibly a short term, somewhat rewarding decrease in overall weight because glycogen carries up to four times or more its weight in water.

Mark Sisson [00:24:57]: Bingo.

Ben Greenfield [00:24:57]: So you lose water, you lose glycogen, you.

Mark Sisson [00:24:59]: Well and you're going from a sedentary lifestyle which is pro inflammatory in and of itself, you lose maybe, Maybe you lose 4 pounds of systemic inflamed water weight that you carry just from an inflamed lifestyle otherwise. It's not unusual for people to lose 10 pounds, you know, their first four months of running and go, oh my God, it's working. Well, not if you're not burning fat, it's not working. In the book in Born to Walk we talk about what it like some of the metrics we would use to decide if you are acclimated to running. If you, for instance, we use the term the max heart rate or the fat max heart rate or zone two, whatever you want to call it in the book, it's 180 minus your age. So let's just say you're a 40 year old man and you start running. If you're running at snail's pace and your heart rate's above 140, you're not in your fat burning maximum zone, you're not in your fat max zone. You're basically in what we call this no man's land of training.

Mark Sisson [00:25:58]: It feels like you're doing the work but you're only burning glycogen, you're not burning fat. Most people discover when they start this process that they can only stay at or below zone 2 at or below the prescribed fat max heart rate if they're walking. Now walking doesn't mean walking slow. You can walk briskly.

Ben Greenfield [00:26:19]: I mean, and by the way, I use this strategy for Ironman training and would often find myself walking on hills when I first began, just because I would exceed that aerobic threshold if I didn't. Yes, it was a little embarrassing.

Mark Sisson [00:26:35]: Yeah. And by the way, if you're walking hills in an Ironman, you're not going that much slower than if you were running those hills. No.

Ben Greenfield [00:26:43]: Sometimes you're going faster.

Mark Sisson [00:26:44]: Yeah, exactly, exactly. So I don't, you know, I want people to understand that walking is an, is a, an amazingly, it's certainly beneficial. It's quintessential human activity. But there are all variations of walking that you can be doing, all of which accrue to your fitness level. But back to the running thing. Most people who go out the door, put on their shoes, go out the door, run. They're running at a heart rate that's above their fat max, and so they're not. What's happening is they're what we call the black hole of training.

Mark Sisson [00:27:15]: Their heart rate is too high to be burning fat efficiently, so they're mostly burning glycogen. Their heart rate is too low to be generating any sort of shift in VO2 max or anaerobic threshold or speed or power. So it's this. All you're doing is practicing herding every day and not getting better. You're not performing better as a result of all of this wasted junk miles that you're doing at the wrong heart rate. So most people would be so much better off walking a lot more and then sprinting once in a while. And make no mistake, I'm a huge fan of sprinting. Sprinting doesn't have to be on the track.

Mark Sisson [00:27:55]: It doesn't have to be running. It can be rope, pole, it could be rowing machine, it could be bicycle, it could be assault bike, it could be any number of pickleball, ultimate frisbee, any yo. Exactly. Any. Any of these things where you get your heart rate up to a max for anywhere from 10 seconds to 30 seconds. And yeah, that's an. That's an integral part of. Of increasing VO2 max.

Mark Sisson [00:28:17]: But, but the fact that you think you would go out and run four miles a day, every day, six or seven days a week, and somehow improve your running economy to improve your body composition, it doesn't happen. One of the things that you sacrifice in doing that is you sacrifice energy for enjoying the rest of your day, going out and playing ball with your kids, or going on a long walk with your dog, or raking the leaves or whatever other activities that your body wants you to do throughout the day. So many people think, well, I already did my activity, I did my four miles. I'm done with activity for the day. That's not how the body operates at optimal efficiency. The body wants to be moving pretty much throughout the day, which is why what you're doing right now, you're multitasking. I used to call it productive leisure, but you're having a podcast while you're walking on a treadmill. I mean, when I started Primal Kitchen, the food company, I bought everybody in the company a stand up desk and a treadmill.

Mark Sisson [00:29:15]: And it was amazing.

Ben Greenfield [00:29:17]: Yeah, it's incredible. That's why the ketchup tastes so good. So besides the risk of injury, the induced state of hypercortisolemia, the shift from a fat oxidation state to a carboxidation state, or the inability to shift into a fat oxidation state in the first place, you haven't addressed what I think is also, and correct me if I'm wrong here, one of the big stinky elephants in the room, and that is the gut. It seems to be persistently problematic amongst most people who run that they're in this constant uphill battle against their gut. What's going on with that?

Mark Sisson [00:29:54]: Well, you know, different, different strokes for different folks. I think something like 30 or 35% of all elite endurance athletes have gut issues that cause them to, you know, have pre race problems. I was one of those guys, for sure. Interrace problems. I mean, I, in the best marathon I ever ran, I ran 2:16:37 in the National Championships in Saratoga, California, 1980. I had to stop at the 15 mile point and, you know, and not just. And not take a leak, shall we say?

Ben Greenfield [00:30:27]: Yeah, I learned early on, don't give your fellow athletes bear hugs after the race.

Mark Sisson [00:30:31]: Yeah, exactly. And we see, you know, you see the memes on Instagram today about the gal, the triathlete who just said, you know, I just shit my pants. Please don't get me for the. From the waist down. Did you see that one?

Ben Greenfield [00:30:42]: I didn't know it would have been painfully, it would have been painful memory for me because I've had that happen too many times.

Mark Sisson [00:30:51]: Anyway, what's happening? Well, first of all, I mean, the most egregious example, Julie White, who won the Canadian Ironman a bunch of years ago after she finished the race, was rushed to the hospital to have a bowel resection because her, she had been ischemic. Her gut had been ischemic for so long that part of her intestines died. She had like 12 inches of her colon removed. That's an example of, that's a real dramatic example of mind over matter. So she was hurting so bad, but she forced herself to finish. What's going on is when you're running this much or doing this much activity, you are diverting blood flow away from the digestive process to the muscles which are working. So the more the muscles are working and the harder they're working and the higher your heart rate, the less is being allocated to digestion. So a lot of people have issues with digestion in that regard. In my own case, my understanding at the time, which was that carbs were gold and you had to carbo load every day to be able to go back and do it again.

Ben Greenfield [00:31:54]: Gatorade, Sports Science Institute, baby, they put out the best science.

Mark Sisson [00:31:57]: That's it. So I had a pretty heavily grain based, sugar based diet. So my gut was always reeling from whether it was, you know, leaky gut syndrome or just other issues with folded, you know, tightly folded proteins, you know, the gluten, the gliadin or whatever. I had all sorts of issues with the, with the foods that I chose to eat in order to top off my, my glycogen storage because I thought that was necessary to get better as an athlete and to continue to train on a day to day basis. I suffered from that for almost 40 years.

Ben Greenfield [00:32:35]: Yeah, and obviously much of this can be mitigated with colostrum, L-glutamine, KpV, peptide, et cetera. But I think, because some people might be wondering, well, I lift weights, it probably does the same thing. Diverts blood away from my gut. And that's true. But I think the difference is that when we're talking about running, particularly marathoning and beyond, you're eating while you're out there.

Mark Sisson [00:32:55]: Well, you're eating while you're out there and you're also, you're not resting, you're not stopping to rest. You're, you're can, so you're lifting weights. You know, you take 90 seconds in between, you let your heart rate come back down. I mean, even if you're doing a high intensity, you know, session, which I, I talk about in the book, you should only do that once or twice a week anyway. I mean, it's not like I, I, I see all these, you know, cardio bunnies doing, you know, orange theory four days a week and then spin classes the other days.

Ben Greenfield [00:33:20]: That's not high intensity though. Tell people why that is. Tell people why that is not what is actually studied. When you see HIIT in exercise literature versus HIIT on the wall of F45.

Mark Sisson [00:33:30]: Or whatever HIIT is wingate, HIIT is Tabata and not. And by the way, Tabata not, you know, like eight sets of Tabata. Cause you know, you automatically meter out.

Ben Greenfield [00:33:40]: Doing a half hour of Tabata is my warmup.

Mark Sisson [00:33:42]: Yeah, exactly. It's like, that's not Tabata, pal. Yeah, high intensity is high intensity. When I say max all out, I'm talking max all out. And I'm saying don't do it more than once a week, maybe if you're really good at it, twice a week. But for most people, they think they're doing high intensity stuff and they're. Again, they wind up in that black hole, that zone of training that no man's land, where they're not. They're going too hard to be burning fat and they're burning glycogen and they're getting exhausted and they're producing cortisol, but they're not going hard enough to generate either power or explosive power or sustained power or VO2 max increases or anaerobic threshold, any of the high end stuff that elite athletes seek in terms of really measuring improvement and ability to sustain a pace at a high output.

Mark Sisson [00:34:34]: All you're doing is struggling and suffering and practicing to hurt every day without getting better. The example I refer to a lot is, and I know, you know, a lot of these people, we see a lot of Internet influencers and they're like, yeah, I'm a, I'm a marathon influencer and I do six marathons a year. And I'm, you know, I'm, I'm 34 years old and I'm, I can run three, 24. And I'm like, okay, A, I'm not impressed. B, if you're not getting any better after all the training you do, you found the wrong sport.

Ben Greenfield [00:35:07]: It's just, you're so jealous of their number of followers right now. It's.

Mark Sisson [00:35:12]: And they have the followers and I'm like, I'm like, okay, this is, this is like me. If, if Mark Bell said, you know, you know, my bench record is 164 and my squat record is 85 pounds, and I'm a weightlifter. No, you're a dude that goes to the gym and lifts weights, but you're not a weightlifter. And, and I feel the same way, like, if, if, if you are not running at a competitive level, then you're just beating yourself up on a regular basis with no positive outcome, you're certainly not improving your longevity prospects. I guarantee you, if you're doing six marathons a year, averaging, you know, 320 or 340 or four hours or whatever it is, all you're doing is accelerating the aging process in the name of feeling somehow feeling good about what you're doing because it hurt and you got through it and on to the next thing. It's kind of the David Goggins effect, which is, and by the way, you know, great, great example. I mean, David has changed a lot of lives, but the guy beats himself up, you know, relentlessly.

Ben Greenfield [00:36:20]: Yeah, I don't want to get negative or, like, throw people under the bus, but sometimes that. That Navy seal, I'm injured, I'm going to push through no matter what. I'll sleep when I'm dead philosophy, yeah, it's inspirational, but I think it's really not doing people a service. And I'm sure that you've been doing several podcasts leading up to the release of this book, Mark. So I imagine you've gotten this pushback from folks who might say, man, how could you say that about fitness influencers, about people just strapping on their shoes and getting out there and moving, baby, and starting to change their lives. And, yeah, they have the identity of an athlete now and they're running. How could you just throw a bunch of water on that gasoline?

Mark Sisson [00:37:02]: Well, you know, it's. It's not like I said with Goggins. I'm like, he's changed a lot of lives. I'm not going to dispute that. How, you know, how he forces himself through all of that is beyond me. And as an example to the rest of the world, I guess that that's fine, that works as a metaphor, maybe, but not do as I, you know, do as I say, not as I do. On the other hand, you know, a lot of the influencers are, you know, I. What I see is, you know, you gotta put the time in, you gotta struggle, you gotta suffer.

Mark Sisson [00:37:30]: And my. My pushback to their pushback is you don't have to suffer. There's ways to do this that are gonna generate improvement in performance, that are gonna make you healthier, that are gonna keep you from getting injured. Look, I mean, the injury rate among marathon trainers is. It's. It's unbelievable. And much of it is due to the footwear. Much of it is due to the shoes.

Mark Sisson [00:37:49]: So. And yet people are, you know, they're. They're pimping the newest brand of thick, cushioned, whatever fly shoes that they're. That they're training and racing in. And then once they finish, once they've gotten four or five hundred miles in them, they relegate them to walking around town shoes, which is just as bad.

Ben Greenfield [00:38:08]: But you wouldn't have a time and a place where, like, I have a pair of basketball shoes, I'm not on the courts barefoot or with what I'm saying, court shoe, you know, train.

Mark Sisson [00:38:16]: Absolutely. When it's time to go race a marathon, put on your, you know, put.

Ben Greenfield [00:38:19]: On your running shoes or go rock climbing, you're going to have a compressed toe box. Deal with it like there's a time and a place.

Mark Sisson [00:38:24]: Hockey players, I mean, Jesus, nobody's got a more restricted foot than a hockey player, so. But wear your skates because that's what they're for. But when you're spending the rest of your day moving around, put on shoes that allow your feet to become, you know, more mobile and resilient and stronger over time so you're less able, less likely to twist an ankle or whatever. And the same goes for running. You know, so much of what happens to runners as a result of over training and overstressing their bodies. These injuries are repetitive use injuries that could be avoided if they spent some time in the gym. I would suggest that for many of the so called runners, walk more, run less, spend some time in the gym, get stronger, sprint once in a while, but cut your miles way back. If you say, but Mark, I'm a runner and I say, well, what does that mean? Well, to me it means I run five times a week, six times a week, my response would be, what if you ran once a week, six miles and every time you ran that once a week you got faster and faster, faster than every workout you ever do as you accumulate your 30 or 40 miles a week.

Mark Sisson [00:39:29]: Wouldn't that be, would you, you know, would you still not, would you not call yourself a runner then? I mean, the identity, runners having an identity as and what we call an obligate runner, somebody who feels compelled to have to run every day or else their life is incomplete. That's a really.

Ben Greenfield [00:39:46]: My son's talked me into doing a DEKA fit last year and you know, I continued my normal habit of walking 15 to 20,000 steps a day. I put in one running day. It was a circuit, we have a quarter mile circuit at our house. So I just, you know, run almost like a 400 on that circuit. Stop, do one of the DEKA Fit exercises, do that again, about an hour long workout. I did that once a week for the 12 weeks leading up to the race and took top age grouper in the race by walking. Which for you and me, as former endurance junkies know, the top age grouper doesn't say much. But I didn't run that much at all.

Ben Greenfield [00:40:19]: It was once a week.

Mark Sisson [00:40:20]: That's my point. That's my point. I mean, in a book that preceded this called Primal Endurance, which I really first started to develop this notion of spending 85% of your time at zone 2 or less, 80% of your training time, I noted the fact that once I retired from competing and I started coaching professional triathletes and I had to make a living because professional triathletes don't pay that well and I was training ordinary citizens to become fitter. So I spent much of my day walking with my regular clients. Not even jogging, walking, walking, walking, walking, doing light weights, doing maybe some easy stair climbs. And then once a week I'd go to the track and do a track workout and I would jump in some of these elite races that I was traveling around the world with my, my, my pro athletes and I'd enter the age group thing and I'd win my age group same thing. On minimal training. When I say minimal training, it was a lot of low end aerobic base building and then just once in a while doing that high, really high intensity stuff to not only maintain my fitness, but in many cases to improve my fitness.

Mark Sisson [00:41:30]: And then jumping in a race once a month, I jump in a race. I mean, one year, the Desert Princess Duathlon, which was the number one duathlon in the world for years. I finished 11th overall, won my age group by far on this sort of minimalist training with lots and lots and lots of low anaerobic stuff, walking and maybe a little bit of easy jogging. But even the easy jogging was zone two or lower.

Ben Greenfield [00:41:55]: Yeah, running every day sells lots of shoes though.

Mark Sisson [00:41:58]: That's the problem. That's the issue. What's funny is we now have the new shoe company Peluva, and we're talking to a lot of running shoe store owners who will say don't tell anybody, but 85% of our business is walkers. Most of our people who buy our shoes don't run. They're walking. And a lot of them are walking because they're injured and they can't run. But they want to do something. By the way, when you're injured running, what do you do to come back from running to return? You walk.

Ben Greenfield [00:42:26]: I was gonna say. I mean, I used to do those boring shoot me now aqua jogging sessions, but yeah, also walking. Yeah, yeah. So explain this to me. Cause I'm a little bit confused about this part. There's so many longevity enthusiasts and physicians talking about zone two training. You talked about the aerobic threshold, about maintaining a conversational pace. If you were going to use that maffetone style training philosophy.

Ben Greenfield [00:42:53]: But zone two often is still running, would you consider walking to actually be zone two or is it?

Mark Sisson [00:43:00]: So, depending on your fitness, zone one.

Ben Greenfield [00:43:01]: And can you get as fit?

Mark Sisson [00:43:03]: Yeah. So zone two for a Lot of people, people can run in zone two, and if you can run in zone two with good form, then go for it. But what we're saying is, most people, if you do this test and you go out and say, you know, how do I put on a heart monitor? And, you know, I'm trying to stay at or below, not above zone two, you know, what kind of pace is that for most people? Once they break into a trot, once they're running a 13 or a 12 and a half minute mile, which is kind of the cutoff point between walking and brisk walking and running, they exceed that heart rate and they have to drop back to a brisk walk. So if you can maintain a run pace at zone two or below, go for it. As long as you're maintaining good form, because form is part of this, you know, we don't want you to get injured. And good form for me means you're running with a midfoot strike. Your, your biomechanics are such that your, you know, all of your kinetic chain is functioning appropriately. So there's no one part of your kinetic chain that is overburdened because of a lack of input from the bottoms of your, of your feet.

Mark Sisson [00:44:17]: There's a lot of nuance to this. What I do for, like my, my favorite workout, I go to the, I go to the south of France every summer. My favorite workout is a hike that I do. It's about an hour and 20 minutes, and I run part of it, but I, but I, I, I run until I lose form, and then I walk and I walk for five minutes and then I run until I lose form and I walk. And at no point is this ever more than 400 meters that I'm running. And when I say lose form, I get tired, my calf gets tired or whatever. I'm happy to just start walking in. That, to me, is the ideal mix of running and walking.

Mark Sisson [00:44:57]: And that's your Ironman training that you're just referenced. You run a little bit, you walk a little bit, you run a little bit, you walk a little bit.

Ben Greenfield [00:45:06]: That reminds me of my Sunday afternoon Frisbee golf sessions. We run the hills. We do 10 pushups, 10 burpees, or 20 air squats at every hole. I know this is probably near and dear to your heart because your co author, Brad, does speed golf at a very impressive pace with a very impressive score. But that kind of leads me to a little bit more of a practical question for you. And I might have a few of my own to add. But your favorite ways to walk besides just walking, like things that you do during a walk to amp up the intensity or trigger another physiological system. Anything like that?

Mark Sisson [00:45:41]: Yeah, yeah. So I love rucking. Rucking is a great way to add some weight bearing activity to your walk.

Ben Greenfield [00:45:48]: Are you a weighted vest or a backpack guy?

Mark Sisson [00:45:50]: I'm a weighted vest mostly, but I do some rucking. I do a backpack, um, but I'm in Florida, so weighted vest works really well for me. I do a weighted vest. I walk as part of my leg day in the gym. I'll do 12 to 15 minutes backwards at a 15 degree incline on a treadmill with a weight vest on as part of a knees over toes, you know, concept as a warmup for the legs. I skip once in a while. I love, I love skipping. I mean, like skip rope or just.

Ben Greenfield [00:46:25]: No, no, skipping.

Mark Sisson [00:46:25]: Skipping. I mean, I'm a, I'm a, you know, I'm a CIS male, but I still like, I still like skipping. And it's, it's fun to break into it. It's a little bit of a, there's a, there's a little bit of a, a track and field drill aspect to that. Brisk walking.

Ben Greenfield [00:46:43]: Bounding is technically plyometrics.

Mark Sisson [00:46:44]: Correct. I'll. One of my favorite things is go off road. I look for cobblestones because I'm wearing minimalist footwear. I want to feel everything underneath my feet. I will. You know, we call it foot candy. I look for, I look for different, different surfaces to walk on.

Mark Sisson [00:47:02]: One of my favorite workouts I've done in the last year, I was in Kona. And you know how the lava fields of Kona are. They're. They're cooled, the ones near the ocean, but they're so crusty and gnarly and up and down. I spent 45 minutes walking on a lava field one day. It was the best foot workout I've ever had.

Ben Greenfield [00:47:18]: My feet, I've done a lot of hunting out of the base of those volcanoes. And your feet are just toast at the end of the day.

Mark Sisson [00:47:23]: Yeah, but they, but they're toast in a good way, right? Because if you're not running on them, if you're not putting 7x the G forces, just, just landing and responding and pushing off from a different plane or platform or direction or tilt or texture every time. Every footfall strengthens your foot in a good way, you know, versus wearing stiff, thick, cushioned shoes where you can't feel the bottom of what's going on and your brain has to guess on how much to bend the knee. Or do I not even roll the ankle, but do I absorb all of this by bending my knee the wrong way outward? So there's lots of ways to walk. I mean, look, speed walkers in the Olympic Games, they can hit six minute miles. Speed walking.

Ben Greenfield [00:48:06]: I know, my exercise physics professor at University of Idaho, Dennis told me. Here's a speed walker, he took us down on the track once. I just crushed us. Even the shin splints alone. He's talking about heel striking.

Mark Sisson [00:48:15]: Yeah, I know, but that's not heel striking in the same way the running heel striking is. Right. They're planting and rolling, planting on the heel, rolling off. But they're the sort of exception on the walking front. But they're still walking in a way that is biomechanically sound. They plant the heel roll off the big toe. Plant the heel roll off the big toe. That works as a walking gait.

Mark Sisson [00:48:39]: It does not work as a running gait.

Ben Greenfield [00:48:41]: Yeah, I'll throw a few more at you. I want to hear your opinion on these. Playing with your breath when you're walking. I have some of these breath devices. They're almost like a whistle. And you put them in your mouth and you're forced to breathe through your nose and then you breathe out, typically through pursed lips against resistance. So it's almost like you're doing Buteyko breathing or carbon dioxide retention while you're walking. Your heart rate's about 10 beats per minute higher, but you saturate your body with carbon dioxide during that protocol.

Ben Greenfield [00:49:10]: And you're also doing nasal breathing the entire time.

Mark Sisson [00:49:12]: Interesting. Love it. I'm going to try it. Yeah. So I do nasal breathing a lot. I mean, I'm focused on that and I'm focused on pacing. I mean, I'm a counter from day one. So it's two in, two out, three in, two out, whatever the pace is.

Ben Greenfield [00:49:28]: A whole book about that. Running on air.

Mark Sisson [00:49:30]: Yep. Yeah.

Ben Greenfield [00:49:31]: Yeah. Okay, so how about thermal stress? Do you ever do, like, obviously you live in Florida now, so you don't do this, but I'll often do, you know, minimalist clothing, often gloves, hat, wool socks, shoes and walk with thermal stress. Do like a cryotherapy walk.

Mark Sisson [00:49:49]: Yeah. I mean, because I'm in Florida, that happens automatically. So I'm not doing thermal walks as much as I'm doing thermal bike rides. You know, if I'm doing fat bike on the sand on a hot day, like I usually quiet at 11 or 11:30 in the morning. It's like literally the hottest part of the day. Sun's highest. And I love that stuff. And I wear a heart monitor whenever I work out, and I'm usually 10 or 15 beats a minute higher than that same effort would be at room temperature, maybe even higher than that.

Ben Greenfield [00:50:22]: By the way, the heart rate thing, that reminds me, Joe Mercola, back in the day, he was telling me that when he was recovering from a heart issue, he used a very, very expensive hospital machine called enhanced external counter pulsation. It's basically like a compression gear that compresses and it compresses times to the diastolic beat of your heart, allowing for a much, much greater return of blood flow to the heart. And he told me about this device. I got it and used it for a couple of years. Called the Counterpace, it's a chest rates or chest strap. It detects the diastolic phase of your heart and then does a little metronome to adjust your walking cadence. So with each strike of your foot, you're actually pumping blood back to your heart. And it teaches you how to time that.

Ben Greenfield [00:51:05]: It's almost like breath running on steroids.

Mark Sisson [00:51:08]: Yep. No, interesting. I mean, all these things. Look, I think. I think walking has. It's been cast aside. It's been relegated to the trash bin of. Of workout options unnecessarily because people think that everything else they're doing is so much more valuable, especially if they're compressing it into 10 minutes or 15 or 45 minutes, when in fact, walking.

Mark Sisson [00:51:32]: I think we're entering a new phase of walking being recognized as the quintessential human movement and something that there are so many ways in which we can optimize our health through things that you've just talked about. This optimized breathing, this, you know, the cardiac output, you know, vagal tone, hrv, whatever it is you want to talk about. There's so much opportunity here to use walking as the aerobic base, building the foundation of everything else we do. And I'm excited to promote. I'm certainly excited to give runners permission to walk again. Look, I was one of those guys when I was a runner. There's no way I was ever going to walk anywhere. If I had to get from point A to point B, I ran.

Ben Greenfield [00:52:17]: Yeah. Okay. So I would be remiss not to ask you one last thing, because I'm just intrigued by your productivity, your energy, your vitality. I've always looked up to you as a guy who accomplishes a lot in the fitness industry in a very approachable and ethical way. And the routine of high achievers is something that I think often tells you a lot about how you can tap into some of that same success. So I realize your daily routine could take you an hour if you wanted to, but give me. Or give us just like the lightning round overview of what Mark Sisson's day looks like when you pop out of bed in the morning.

Mark Sisson [00:52:55]: I mean, it's, you know, it's more root routine is the right word because I really crave that routine. And if I get off my schedule, I get a little bit, you know, upset, but no, get up, I don't know, 7 o'clock, have a cup of coffee, read. I read two newspapers. I skim two newspapers for what's going on in the world. I actually read physical newspapers.

Ben Greenfield [00:53:16]: What's the newspaper?

Mark Sisson [00:53:17]: Yeah, I know exactly. Then I do probably half an hour worth of puzzles, word puzzles. That's kind of my hobby. Hobby. I get to work, do some email, do some writing, do some calls, break at about 10:30 and do my workout, whatever that is, for the day. Understand that by then I still haven't eaten yet. So I do my workouts, fasted other than the cup of coffee. Some days it's, you know, I do weights twice a week.

Mark Sisson [00:53:46]: That's upper body weights twice a week. I do legs once a week. I do a fat bike once a week. I do stand up paddling once a week. And then I fill in a lot of the gaps with walks. So I'm walking every day. By the way, I just had a hip replaced five weeks into my hip replacement. I'm probably 95% back.

Mark Sisson [00:54:06]: I mean, I'm stunning myself. How I rode 45 minutes on a stationary bike today. Pretty hard, which, it's so funny, pretty hard. I was looking at it, I was in zone two, maybe zone three, level 15 for 45 minutes on a life cycle cranking out what amounts to about, I don't know, 180 watts, which is for a 71 year old guy, isn't bad. And my heart rate's not that high. And I'm doing the work. I stretch a fair amount now. So anyway, so that's my workout.

Mark Sisson [00:54:35]: I break around 12. If I have time to go back and do some stuff before lunch, I do that. I usually have lunch around one. It's usually just a piece of protein with some kind of vegetable around it. Not a big meal, work in the afternoon. I have a lot of podcasts. I do podcasts four or five times a week. More writing, more thinking.

Mark Sisson [00:54:59]: I have meetings, I have team meetings with Peluva a couple times a week and then up until maybe 6 or 6:30. Recently I go down to the sauna and I do a 20 minute sauna. I live in a building where I've got a nice little spa at the bottom of it. Come back, have a cold shower and make some dinner. Dinner's again, usually a large steak with either a salad or some kind of green vegetable, a glass of wine or two, and that's it. Now throughout the course of the day, I'm in the meetings, in the writing. I'm productive in that regard. I'm an idea guy.

Mark Sisson [00:55:41]: I'm a big picture thinker. So I'm working with my team. Whether it's my writing team at Mark's Daily Apple, whether it's the book team with Brad, whether it's Instagram or Twitter, I'm the idea guy. And then I've got great people around me who are able to execute based on these wild ass ideas I have about life or about what we should be making.

Ben Greenfield [00:56:05]: Incredible. I get it. I'm the idea guy, too. Much to the trigger of my team. Sometimes when I'm off travel and I come back having read four business books and all of a sudden the slack channel has 11 new ideas in it. What an incredible day. And folks, he did kick my ass on that fat bike the last time I was in Miami. So caution, if you're ever out there on the fat bike with Mark, you loved it.

Mark Sisson [00:56:25]: But you loved it, right?

Ben Greenfield [00:56:26]: Oh, I love it. Yeah. The book is Born to Walk. All the shownotes are at BenGreenfieldLife.com/BornToWalk. If you grab Mark's book, I can tell you he's got a pretty prolific Amazon library. All of his books are good, but this new one will really change the way that you think about running. Check out his company, Peluva. When you see me with those funky looking toe shoes on, that's the brand I use. Nice wide toe box, good fashion.

Ben Greenfield [00:56:51]: You won't even look dumb when you're skipping. And then finally, even though he's sold the company, Primal Kitchen Foods is pretty much the only ketchup, mayonnaise, mustard, et cetera in the Greenfield pantry. So Mark has created a lot in the industry. Check out all of his goodies and I'll produce some juicy show notes for you at bengreenfieldlife.com/BorntoWalk. Mark, thanks so much, man.

Mark Sisson [00:57:15]: Thank you, Ben. Great to be with you as always.

Ben Greenfield [00:57:17]: It's fun. Once again, all right folks, signing out from Ben Greenfield Life. Thanks for listening.

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