The End of Cardio? Burn Fat & Boost VO₂ Max in Just 8 Minutes a Week – with REHIT | Ulrich Dempfle : 1275

How does 15 minutes a week of REHIT training compare to 150 minutes of jogging?

95% of Americans don't do enough exercise because lack of time. So then giving a recommendation to spend 5 to 8 hours per week on mild cardio feels slightly misguided to us.

You stay consistent. But what if the way you've been training is the reason you're not seeing results? Ehrlich Denfli isn't just another fitness guy. He's a German trained engineer and an epic sports scientist. And he built something that's shattering everything we thought we knew about cardio. Because real performance, it doesn't take four hours of zone two, it doesn't take 45 minutes of cardio, or 30 or even 10. What if the most powerful workout for your heart just took two 20 second sprints? He's the creator of Carol Bike and his REHIT protocol isn't theory.

Our research is aimed at people who currently are inactive and would like to do more exercise to get healthier, but just don't find time to do this for reduce individuals rewards.

The perfect solution, six times better fitness gains than jogging for an hour a day. A 62% drop in diabetes risk. A 12% VO2 max improvement with a five minute workout. And that correlates to a two year increase in life expectancy. Cyclists shaped it, scientists tested it, AI perfected it. If you run to clear your head, great. But if you exercise to change your body, this interview will change your mindset.

We have really hard scientific data and we saw that doing three short workouts, we achieved a 12% improvement in Beard Max in only eight weeks.

What do you say to people who say there's no way rehit is dominating older cardio methods this much? You don't need more motivation, you need better science. Smaller effort, bigger results. This is the new cardio. You're listening to the Human Upgrade with Dave Asprey.

Maintain it.

Hey, real quick, if you've only been listening on your favorite podcast app, you're missing half the fun. Head on over to my YouTube channel. I'm doing way more over there. Full video podcast episodes, weekly YouTube only videos, and some wild extras you're not.

Going to hear here.

Just search Dave Asprey on YouTube. See you there. Our guest today is Ulrich Demfle, who's CEO and founder of Carol Bike. And this is a really cool biohacking technology. Like I am allergic to this mindset. Well, if you want to die at the normal age, but at least be healthy until you die because longevity is Impossible. You have to do zone two cardio for 12 hours a week. And there's a guy who says he's a longevity doctor who doesn't believe in longevity, who's promoting this. And I'm like, I don't have 12 hours a week to spend on that because I want that time back to do things that actually matter with my life. And if I want to do zone two with a friend or something, that's great. I just fundamentally, I want to get the results in the least possible time. So there was a time in my life where I would do an hour and a half of exercise, including 45 minutes of hard cardio, six days a week. And I never lost any weight on that and it really pissed me off. Even after 18 months and. Or it comes along, it's like, oh, I have this new research, there's three studies now supporting this that show you can increase your VO2 max. VO2 max is a major thing for, for aging and you can do it in 15 minutes a week. And it works six times better than an hour a day of cardio. So that's what we're going to talk about in the episode today is the Carol bike and the technology behind it called Rehit and and Ulrich, how much have you increased your VO2 max using this 15 minutes a week kind of protocol?

Over 50%. So I've actually, I've looked this up again. 12 years ago, when I was 35, I had a VO2 max of 32, which, that's low, but I was, I had three young children, job as a management consultant and didn't focus on that. Today I'm 47 and I have a VO2 max of 53 and I do that literally with 15 minutes a week. So it's, it's 50, 60% increase and it works.

This is so cool. And you're not just an inventor sort of thing. You also sort of helped pioneer AI within the UK National Health Service. Like, like you're a true scientist nerd. And like me just saying, you know what, like, I don't have time for this. I got kids, I got stuff to do. And so I'm, I'm super grateful that you're just poking holes in some of the beliefs and the primary belief is that working harder or struggling or working longer gets results and it doesn't appear to be linear. What is a J shaped curve for exercise and why does it matter?

For most exercise, it is true that if you do more longer or harder, you get better results, but if you trigger or course and pull specific triggers, you can get a much stronger training stimulus much, much faster. And that is essentially you achieve that by ramping up the intensity with which you work out very rapidly, almost instantly from zero to max. And then you only have to hold it for a very short moment. 2 times 20 seconds is enough to get your body to release very powerful signaling molecules like AMTK, PGC1alpha and create and saturate the adaptation pathway that creates that training stimulus. And it's in fact you don't have to do more sprints or longer sprints because it's like flipping a switch. Getting that stimulus once into the system saturates the pathway and you get already maximum benefits.

You said that for most types of exercise that doing more gets you better results. But crossfitters, they get over trained, they get injured. And a lot of the fact 80% of the people who come in to upgrade labs, we're measuring all these biological parameters, they do not need more exercise, they need more recovery. And so it feels like even for strength training, the speed of exhaustion is more important than the volume of work. Are you seeing that pattern as well?

Oh, absolutely. That's true in cardio where you can do an exercise like reheat reduced exertion, high intensity interval training, 2/20 all out sprints. And you can achieve the same thing with strength training where if you have AI controlled resistance, like mechanized resistance, that delivers exactly the maximum force that you can basically move at that point in time, you can also get a much better result in a much shorter period of time. But the thing is you need to have access to that technology and understand the training methodologies and then you can basically create this alternative stimulus. But if you're say you do moderate intensity training, you go jogging or. So then generally speaking it's true that if you put more time into that, you get better results. And for things like sewing tool, yeah, you do have to work out quite long because otherwise you just don't create the training stimulus at all.

That is a valid point. If you're jogging, you're wearing out your knees and your ankles and all that. 80% of people who start running quit in the first year because they get injured anyway. But it is gonna take a long time to get enough stimulus to have any effect. But the results of the stimulus are very small because even like an hour a day, in eight weeks you're gonna improve by about 2% if you're doing a normal spin class kind of thing. But if you're doing re hit on Carol, you're getting a 12% improvement in your VO2 max in like 15 minutes versus several hours. So when guys like say, Peter Attia are out there going, like, you have to do Zone two for two hours a day and then, you know, ruck something or whatever his latest over training regimen is, what do you say to the Zone two zealots?

What we tell them is, one, if you have a lot of time and you enjoy it, yes, by all means, it's fine.

So if you're a masochist, like you moved to Berlin or something. Okay, I gotcha.

Don't. That's all right. I mean, to be honest, if you like in summer, I love hiking with my family. I guess I stay in Zone two. That's. That's a valid thing.

Yeah, that's for fun. That's different, right?

Absolutely. But what we say is, yes, Zone two has some evidence behind it, and if you do it right and if you do it in the proposed quantity. So like 60 to 90 minutes per sessions, three to five times a week. So, yes, you will see some improvement in your mitochondrial density, you will see improvement in your mitochondrial efficiency. But should that be the top priority and the basic recommendation for a broad audience? No, we disagree wholeheartedly to that. That is something that trickled out of athletes, like big elite athlete training into the mainstream with actually very little scientific evidence. Especially some of the recommendations that I've given don't have much scientific evidence. And it has picked up some traction. It seems to have become fashionable. Many people seem to buy into that. I wonder how many people really do it, because there's just. I think most people will run into time constraints eventually. 95% of Americans don't do enough exercise because lack of time. So then giving a recommendation to spend what, like five to eight hours per week on mild cardio feels slightly misguided to us.

Wow. I, I couldn't agree more. It. It's that you could be. If you had 10 hours a week to exercise and to become a better human being, you have to allocate some of this to meditation. Or you could do meditation plus breath work, which works faster. And there's my newest book, Heavily Meditated, that's all that stuff. And on the exercise front, if you look at smarter, not harder, I write about your work. I write about reheat in there, like for exercise. So if you only have 10 hours or you're like a lot of people, you have two hours a week, and that's gotta be everything. So do you want to take a cold Shower or do you want to do cryotherapy? You want to do cryotherapy because it's faster, right? And then do you want to do all of your time on zone two and then, oh, I guess I'll just hire a babysitter while I do the rest of it. Or do you want to just do re hit on a carol bike? I think you have kind of a moral obligation to say, if my goal was this, let's get there quickly so I can do more important things in the world. What do you do with the time you save?

Oh, I mean first I can do other types of exercise which are necessary and effective. So that's strength training, mobility training. And then as you said, like there's so much more that you can do, like meditate, like spending time with your loved ones. And for me, so our bike, and I think it should be. This is slightly ironic that I advocate a little bit against Zone 2 because Caro Bike is probably the best tool to do Zone two because we have the coolest technology to help you find exactly the right intensity for Zone two. So if you wanted to be Zone two and you can listen to a cool podcast or watch your favorite show on that, then it's a great addition to it. Yeah, so I don't want to poo poo it all together. It's just most people don't have spare time. There's intense competition for our time. There's this trillion dollar companies that compete for our time and our attention. So therefore, just saying, well, you have to do it all seems unrealistic. And in all fairness, the big proponents, I think they all say no, you have to do Zone two, you have to do Zone five, you have to do it all. So they recognize that Zone 2 alone is not enough. In fact, for anybody who's under some misconception there, there's good data that shows if you only did zone two at government guidelines level of 150 minutes per week, that 40%, 40% of people would just not see an increase in their cardiovascular respiratory fitness in their VO2 max at all. So therefore, you have to listen carefully to what people say and you hear, yes, you have to do Zone two and Zone five. And we say there's it's other way around. Start with the most efficient training as your base. Make that your base. Then do strength, then do mobility, do something for your mind, do something for your social connections, make sure you get enough sleep so there's enough else you ought to be doing. And then if you have still more time and to really enjoy it, then yes, by all means, in Zone two and do it in the most effective and efficient way possible. And we help people with that too, but it's, it's somewhere later down the line. List of priorities.

I'm with you there. If you are a pro athlete or you have unlimited time and you love it, you do a bunch of Zone two. I would just say re have so much more evidence behind it. In fact, you should do reheat and then you could do some Zone two if you really wanted to. I don't know if you've ever looked into these things, but there's a substance I wrote about in Superhuman that's banned by the International Olympic Committee, which means we know that it works. And it's called GW 501516 or Carterine. That raises PGC1 Alpha and increases mitochondrial density. So I'd rather do REHIT plus something like Carterine and get the mitochondrial density. That would have cost me like eight hours a week of Zone two. So I'm like, guys, pick up some heavy stuff. Learn functional movement in the time you save on this because REHT frees up so much. And then you can have the VO2 Max that you want. Hey, real quick, if you've only been listening on your favorite podcast app, you're missing half the fun. Head on over to my YouTube channel. I'm doing way more over there. Full video podcast episodes, weekly YouTube only videos, and some wild extras you're not going to hear here. Just search Dave Asprey on YouTube.

See you there.

I have a question for you. Because you pioneered this, you've done heavy duty research on REHT and built it into the Carol AI capability set. What do I do if I'm on the road? There's no upgrade labs where you can, you can do re hit with Carol. But like, can I go to a park and do it? What's the closest way I could come to what you're talking about if I don't have your tech?

Yeah, sure. So there's a few things that I wouldn't do. Yeah, I wouldn't do it on a treadmill, I wouldn't do it on a rower. I wouldn't do it on. And it's very difficult on a regular exercise bike, to be honest. And treadmill broa is just the injury risk would be too high if you're good to run. If your joints can cope with sprinting and you have a hill, then hill sprints, for example, are a very effective tool where you can also increase the intensity quite swiftly. So the rapid increase from zero to max is important and where you can achieve really all out intensity. So that would be an alternative that probably works quite well. But there's a few caveats. First, can your joints handle it? Is there maybe a trip hazard? And most people have slight inhibition being seen in public going all out. So carrier bikes are not only in the leading fire hacking facilities like upgrade labs, but also some offices have it because it's so quick, most people don't sweat. You can do it in your lunch break. And what we've seen is if the bike is in a, in a public area, it just gets much less usage than if it is in a secluded private area where you can go all out and, and not you'll somehow. Yeah, funny about yourself. And I think the same thing happens if you run outside. Most people just don't want to go, especially if they don't look like, you know, an athlete yet. But they, they want to get there, go all out in public. So that, that's one the other thing if you have access to an air bike like an assault bike or something like that. So if your gym has something like that, you could try. So those are bikes where you can also increase intensity quite quickly. It's not perfect because it has essentially just one gear. So it might be optimal for a, you know, your 35 year old CrossFit athlete, but it's almost certainly not perfect for somebody who's 60, 65, 70 and with Carabyte because we have 255 years and AI controlled braking mechanism and algorithms that tailored and personalize it to we can every single time provide a optimal workout for basically every age and fitness level. And my mom, who's 81, she can do it three times a week and her workouts look different than mine. But for her it's an optimal workout and she can do it. And so yes, there are some different options. Our bike is very, very optimized for it.

I haven't found anything better and that's why it's a part of our tech stack at Upgrade Labs. Tell me more about the specific benefits of what you can do with Carol. How does 15 minutes a week of REHIT training compare to 150 minutes of jogging? Give me the hard numbers.

Yeah, sure. And so there we have really hard scientific data like a randomized controlled peer written academic trial. And we saw that through doing at least three short workouts a week, the Renit student would achieve a 12% improvement in VL2 max in only eight weeks. And as you said, VO2 max is a really, really critical, maybe the most important health marker. There's a very substantial improvement. And if you then continue further, so you see about 20% improvement on average over 20 weeks and the progress continues, for me, it was over 50% in the first year. The control group that spent like six times as much time, even more time on moderate intensity training, so they did five times a week, 30 minutes jogging, they also saw an improvement, so they saw an improvement of about 6% in VO2 max. But if you. And so it's very clear exercise is good for you. I don't want to be any misconceptions about that. Exercise is good for you, but they have to spend a lot more time and got around half the cardio respiratory fitness benefit. And that's one big part of the story. Other big part of the story is around metabolic health. So you can measure a basket of indicators like your blood sugar levels, cholesterol, HDL and so on, and then compute your risk of developing metabolic diseases. And with the rehit group, in that eight week period, they saw a 62% risk reduction.

62% risk reduction in 50 minutes a week?

Absolutely.

That's actually a greater risk reduction than you get from brushing your teeth.

Yeah, it's a very good thing to do. It's a shame that not everybody does it yet, but we're working on that. The other group also saw a substantial risk reduction. They got something like 27% risk reduction. So again, exercise is really good. If you don't do exercise yet, do something. And if you love zone two training, by all means do zone two training. But if you want to get like maximum benefits in minimum time and the most efficient exercise for your cardio, for your metabolic health, then something like, we hit this.

That is just incredibly cool. I mean, we can, we can transform our time. And so if you're on the road and you go to a hotel, they don't have, you know, an assault bike or anything like that. What if you skip for a week or what if you, you only do it once a week? How many times a week do you have to do rehit in order to get results?

Yeah. So for the cardio respiratory, for the VO2 max benefit, two times a week is actually enough. That's what the latest research shows, or metabolic health, that the effect is slightly shorter lip, there's a more acute effect. Three times a week is better. So our recommendation is three times a week or if you pan just every other day and every other Day is pretty much what I do. And then there is obviously this is how exercise works. There is a detraining effect and that's why it's so important that you have something that you can stick to and not just say oh I'm going to do a big effort and spend now 10 hours a week and then get in shape and then you run out of time and reality catches up with you. Because detraining effect tends to be as fast as the training effect. So you can achieve like the body responds wonderfully to stimulus and to exercise. It's really magic. But it also means unfortunately if you stop, you detrain. Now I had human experimentation on myself. I broke my collarbone skin around Christmas and had like a two months break on the bike and I did see a reduction in my VO2 maximum because I couldn't do terribly much in terms of cardio exercise or strength training. And I saw maybe a 15% reduction in that time. But I caught that arc really fast again and got back to yeah, a really, yeah like a high level for my age and I think very high YouTube max overall. So it's, it's really important that you find something you can do and you can stick to.

Okay. So it just doesn't have to be that hard. That gets you out of the way. And these are things you can get at home with a carol bike. You can come and do an upgrade labs as part of your membership. You can stack this on. What are the other most surprising benefits you found from Rehit that just you would not have predicted?

There's actually quite a long list of benefits and I think again it is just reflective of how important exercise is and then it's really encouraging to see that you can get those benefits in a really short period of time. So beyond, so the headline is VO2 max metabolic health. Beyond that it has good impact on your leg strength. So in that eight weeks you will also see on average an increase in 15% of your leg strength, also measured in one rep max of a, of a squat because the forces are that you exert, even those sprints are so high they're relevant for strength training to the next thing is I'm absolutely convinced I haven't seen much data on that but just with greater metabolic flexibility and greater insulin sensitivity that weight management becomes easier. So we, we, we hesitate to promise to people, oh, you better just lose weight like a miracle. Because nutrition is just the number one thing for weight loss. Yeah, it's, it's your top priority is what you eat, how much you Eat and but exercise is if it helps me to gain metabolic flexibility, gain good insulin sensitivity. It just makes weight management so much easier because we can go for periods without eat. You can fast for example without starving your brain because you actually have access to, you know, in the energy you carry around in your, your fat cells. And then there's, there's a bunch of other things. There's rebook for your circadian rhythm. If you do it at the same time after you get up helps to set that if you have problems sleeping. High intensity exercise has been shown to to offset some of the damaging effect of lack of sleep. So even even one night lack of sleep paralyzed insulin resistance like temporary insulin resistance and high intensity training helps to to offset that you get in terms of brain health. You can get with high intensity exercise much higher BDNF release than with regular exercise. So BDNF helps.

How much more BDNF comes from reheat versus normal exercise? BDNF is really important because it makes your brain more neuroplastic.

Correct, Correct. And so there, there was a recent study out of New Zealand that has shown four to five times higher BDNF rooms and they Whoa, okay.

Five times more BDNF from using rehab versus zone two. I think you just punched zone two in the nuts.

Is that, that, that was specifically. That was a hit program that was not specifically rehit. But I think it's quite easy to presume and surmise that that applies to rehab because we have mimics in many ways. It takes hit to the next level. So you get hit benefits in a very very compressed way. So yes, no, that's. It's very very rewarding in a way and fascinating like how so little effort can have so many like such a long list of benefits. Another thing is. So this is again research more done on HIT more broadly is around anxiety and depression that exercise and specifically high intensity exercise is as effective or more effective than psychotherapy or medication in managing anxiety and depression. So there's a, a long list of benefits. I think most of it is just a testament for exercise being so important and so beneficial and then achieves to capture those benefits in an incredibly short amount of time. And so you can basically tap into that long list of benefits in a very, very efficient way.

What's the difference between 22nd and 10 seconds Exercise intervals during reheat?

20 seconds are our kind of main GOTO protocol has most researched and and has been basically titrated to being the minimum effective dose of getting the full Benefits of rehec and 20 seconds, it, it doesn't sound like terribly much but if you've done 220 seconds all out split will notice like the first 10 seconds feel actually really easy, then the next 5 seconds feel a bit harder. But the last 5 seconds are actually quite hard. The beauty is you always see the light at the end of the tunnel and psychologically it's quite easy to push through. But nevertheless for some people it is too hard and then 10 seconds is a much, much easier way of doing so. It feels it's not half as hard, it's like a 10 or so in terms of how hard it feels and it still offers meaningful benefits. And so where we saw the 12% improvement in VO2 max over ink weeks with the 22nd protocol, I think it was 4 to 5% improvement of the 10 second protocol. So it's a, you know there comes then a trade off where less is less. But if that's what helps you get started and that's what allows you to do it, then it's a wonderful way to get it in. And it's also like a good energizer. So if you want to do it in a workplace and you just need to have freshen up a little bit and once you get crisp and sharp again, that's a wonderful way without kind of getting heavily out of breath and just really to get that quick boost.

In energy that's just incredible. It almost sounds too good to be true. What do you say to people who say there's no way REHT is dominating older cardio methods this much?

So try it, try it. The threshold's not that high. I'm sure you offer. Some people can go to upgrade labs and try and see for themselves. In fact we offer. So if you, we don't have showrooms, it's, that's not something we offer. We sell our bikes directly to customers. But if you purchase a bike we offer a 100 day, what we call risk free trial which means you can you get your Herald bike and then you have 100 days to see whether it's effective, whether it works for you, whether you like it and whether you can stick to it. And if it isn't, then we just take it back. Yeah, we'd like to know why you don't. But it's good boss to learn. Yeah, didn't like the color. Okay, but we can think about that for our next version of whether they want to have a white bike or so. But we're not going to haggle or so no, we just get a full refund and we pick up the bike. And we can only offer that because for most people it works really well. It delivers amazing results. They like it and they can stick to it. That's, that's why we're able to upper. Like, I don't think there's anybody else who gives you a hundred day risk free home trial.

It's kind of ridiculous because within 100 days most fitness devices become clothing racks. It just happens. And you're saying if it becomes a clothing rack because you just don't use it, send it back. And I've never heard of that before.

Yeah, we pick it up. Exactly. To pick it up you have to take your clothes off, but we're happy to pick it up. So no, we're that confident in our bike and we have by now thousands and tens of thousands of riders and millions of rides. And we see the improvement. We see it in our data. It mirrors what is achieved in clinical trials. And so yes, we're by now really very confident that this is real.

I have no doubt about it. I mean I, I've written about it in the books. I've built it into our tech stack at Upgrade Labs where people can come in and you, you can come in, you can try out the bike and you can even measure other physiological things using other tech there to see what's changing in your body. So guys, if you're in one of the nine cities that have an Upgrade labs, you should swing by and check it out. And if you're not, you can pick up a Carol bike or come visit. We're happy to do it. It's upgrade labs.com if you want to find a, there's one near you and it's Carol bike.com, right?

That's right, yes.

All right, it's carolbike.com you can use Code Dave, which usually works on places and they have a special deal. They'll give you at least a hundred dollars off. And if there's any better special anywhere, they'll just automatically give you the best pricing. So if you're interested in saving a whole bunch of time, this is way more important than an electric toothbrush. It's kind of ridiculous what it does. The one area that really does deserve more attention in the world's diet has to do with mitochondrial effectiveness or insulin sensitivity, which is a measure of that. What does rehit do for insulin sensitivity versus zone 2 or other types of cardio?

Here's actually a little bit of debate and evidence that points in different directions. So the Zone 2 proponents and some research points towards greater Benefits from Zone 2 if you do it for all those many hours in terms of mitochondrial density. So how many mitochondria you have, how large they are, and high intensity training like rehip seems to be more attractive in increasing mitochondrial efficiency. So how well your mitochondria work. And so that kind of makes an argument to say, well if you have all the time in the world, you might as well do both and use one to develop as many and as large mitochondria as possible, use the other to make them as efficient, efficient as possible. Now some of the scientists that we work with, I know don't necessarily agree with those findings and say no, you get, with VHIT, you get really strong PGC1 Alpha activation. And there's actually not much reason to believe that Zone 2 training was better at improving mitochondrial density. But that's this. And really if you look through the literature, there's kind of, yeah, there's a discourse and I think current state of the art would be if you want to do it all, you do it both. If you want maximum results with minimum time, then you do something like REHIT and you have like know that you get fantastic results in terms of year two maxim movement and, and improvements in mitochondrial health and mitochondrial efficiency. And I think that will be the right advice for the big majority of people.

Very well said. And I like your, your level headedness about Zone two and that if you're willing to put in all the time, it does have additional marginal benefits. It's benefits that I know how to get with supplements anyway. But it's not that it's zero benefits, it's just the benefit per minute is just so low. That's why it, I find it just kind of sad when people are just, just going out and pushing this because like you're not seeing your kids, you're not doing other things.

So yeah, I think it's quite good to understand where this current hype of Zone two, that's at least how we understand where it came from.

Well, where, where did the world get this Zone 2 fetish?

So if you look at really elite athletes, Tour de France cyclists who do this for a living, they're professionals, they train 25 to 35 hours per week and you just cannot do more than five to seven hours at high intensity each week. If you did more at high intensity, you would clearly be over training. It would be counterproductive. So once these top athletes have five to seven hours at high intensity in their workout schedule, they fill up the rest of the time with low intensity work. And that means another 20 hours or so of low intensity work. And that's where recommendations like we should do 80% zone 2, 20% zone 5 come from. Because, well, if like the to the frost winner does that as his exercise program, then it must be good for everybody. But that's just so that split 80% zone 2 versus 20% zone 5. So to the best of my knowledge, and the researchers who work with just does not have scientific evidence. It's yes, elite athletes do that, but whether it's good for, you know, the masses out there, that's less clear. Even strong advocates like Professor San Milan are really clear that high intensity training is critical. So I can quote him pretty much directly as saying kind of high intensity glycolytic training is essential. And it is where the magic happens. So it's not that they say, oh, you only have to do zone two at all. So they're very clear you have to do high intensity work as well. It's just then somehow it led to, I think, quite wrong advice that zone two should be your base. And like this 80, 20 split should be good for everybody when it's good for ev athletes.

I feel like Zone two has become the new low fat. Like everyone believes it based on a study, but it's more like, oh, if it works really well for a Formula one driver, it's what you should do. So you have a bunch of people swapping their tires out every time they come home from work for new tires because they could be worn out and doing all this crazy 100 octane fuel, none of which your Camry needs, right? So unless you are a really ultra elite athlete, then maybe there's a case for this because you're getting paid to go do that, that Zone two time like that, that is what your primary focus is. For the rest of us, we want to live a very long time. We want to look good, we want to feel good, we want to have lots of energy, wanna have mitochondrial density, all that stuff. So I think rehab is so much more powerful. It's not just twice as good, it's like 10 times as good as the type of exercise people are doing. But what I want to know is how much better is rehit than hiit? Because I've recommended, you know, do five one minute sprints with a minute or two of calming down between them as being more effective for years. And then I switched to recommending, re hit in my last book. But what's the delta between old style hit and re hit.

So the delta comes down to first time and how doable it is. So.

Okay, that's accurate.

You get good results with it, no question. Yeah. So again, that's on the Carol bike, like the Norwegian protocol. 4 times 4 minutes in 5 in zone 5 with 3 minute rest periods in between. Has a ton of research, highly effective. It's just, it takes half an hour. You're absolutely sweat, sweat, wrenched. And it is really hard. It's really hard mentally because the rate of perceived exertion is very, very high. And so, yeah, I would again argue that the Carol bike is probably the best tool to do that if you want to do it. And we want to give people the best tool for what they want to do.

It is a versatile tool and that there's a heart rate monitor built in, there's an AI system watching what you're doing. It can guide what you're doing. It's an all encompassing thing. And it does have a Zone 2 setting on the Carol bike. I just have never turned it on because I value my life. But like you're saying, everything is so quantified that compared to just using a peloton or something, it's not even the same universe in terms of the feedback and the data. So I'm just a big believer in effectiveness on something like this. There's something else that happens, Ulrich, when you combine cold plunges and you combine saunas and you combine any other emotional or physiological stresses, maybe fasting, intermittent fasting. Each of these increases the amount of stress on the system. And it's good stress until it becomes bad stress. Right. And the stress handling systems become overwhelmed. And that's why a lot of the tech that I work with is around recovering from stress so that you can handle more of it. But the population that hits the stress wall first is usually perimenopausal women. And that's because their DHEA and pregnenolone and progesterone levels have tanks and those are anti stress hormones. So cortisol is higher, adrenaline is often higher without the corresponding hormones of youthfulness and resilience. So for perimenopausal women, why would rehit work better than hit or zone two?

As you say the and we hit you. It's reduced exertion, high intensity interval training. So you get this, the training stimulus with a very, very short, very intense, but very short amount of stress and with the overall level of exertion is very low. And so that is just especially for women Perimon cortical women beneficial because, well, long zone two, long cardio training, things that traditionally would have been done would have all those other, you know, unwanted effects, high cortisol and some arguably even catabolic and, and kind of making it even harder to maintain and, and build muscle mass. And so having cardio covered with a like reduced exertion hit program is just incredibly beneficial. And then you can focus on like other things that become really important in that, for that group and resistance training. So I would very much. Female listeners, like before you do zone two, please make sure you have done resistance and strength training because it's just so much more important for you.

It's a beautiful picture. You're saying, all right, your ability to manage stress of all forms is likely a little bit compromised in perimenopause or frankly in andropause for men as well, we have similar problems, but not as dramatic of a decline. We do get andropause. So during that time you want to provide enough stimulus to stay healthy so that you don't get insulin resistance, which is going to take down everything else and is going to make you old. So what's the right dose in order to do it? And if you do rehed, which provides less overall stress on the body but strong adaptation, you have enough energy left to pick up some heavy things or do some planks so you don't get the lack of bone density and all of a sudden you don't have the weight gain that comes from perimenopause because you didn't get insulin resistant and you didn't overwhelm your stress handling systems. And you might want to do some things like take DHE and pregnenolone and hormone replacement and all so that it's less of an issue. That's a different biohack. That's pure longevity. But most women I know who are in perimenopause have no desire to go do zone two training all the time, nor do they have time.

Right.

So that's out the window. And if they were to try and do Norwegian protocol high intensity interval training, it's going to overwhelm the system. Right. So what's left? Well, REIT is manageable.

Right.

And then even if they were to lift one time a week on top of rehit, the lifting is going to take what, about a half hour and REIT's going to take 15 minutes. So now you're like 45 minutes total per week, but that's three five minute carol sessions and one half hour let's pick up some heavy stuff or at least do squats. And they can be squats in the kitchen while you're blending something if you want to. I've seen that work just fine. Right. It's manageable.

Right.

And for most of us, including me when I was really fat, it feels like there's this insurmountable amount of work you have to go do at a time when, you know, for me my adrenals were blown out, my testosterone was lower than my mom and I'm like, I, I'm willing to go to the gym, but it's taking everything I've got and I'm not changing because I was already depleted. So I feel like this is a way out of the kind of the, the trap that happens around middle age where, you know, I can't exercise the way I did when I was 25.

Right.

Because it doesn't work.

Right.

Even if I do put that amount of energy out, I don't feel the way I did back then. And you can get that back and I certainly have. But for most people it's not there. So this is the path forward as far as I can tell. I'm not trying to sell Carol to anyone. What I am trying to sell is the advice from Smarter, Not Harder, which is my last book, not heavily meditated. My next one, I'm just. Guys, there's so many ways to get the signal in without breaking yourself. And I take it personally because I did break myself when I was 26 and I'm going to the gym 90 minutes a day, like it was ridiculous. What advice would you have for someone who's 19 who's interested in doing rehab?

They can. Absolutely they can. So we have, in fact we don't have a lower age limit for the bike. So we do kind of our times and conditions that delayed. If you're a child, you have to do it under adult supervision, but you can start doing rehit as soon as you're tall enough. Use the bike. So for a 19 year old, absolutely you can. And if I look at my kids circuit, two 16 year olds, they use the bike not necessarily because they need it to get their, their cardio fitness in because they don't have other time but to help them complete in their sport. So we're wearing Europe soccer players and, and at a fairly competitive level to get training sessions in additional training sessions that don't stress the body, body further. So if they have two matches, three training sessions with a team or so, then they do some additional training. Sessions kind of in their off days almost to get additional stimulus that doesn't again, doesn't break them and doesn't create unnecessary stress rather than beyond what they, what they get already through their other training.

I'm pretty passionate about this. I guess people, people can tell. I look at how much of my life I spend doing things that weren't very effective from an exercise perspective. And it's at least two years of full time work. Like I would have rather had the salary and the same results. And that's why I get all excited about it. There are other things though that, that are a part of how you built Carol. You didn't just look at Rehit. There's some AI components that I think are critical to us continuing to do exercise. How do you use AI to make exercise easier With Carol, it's a critical.

Part for us to personalize and optimize the workouts and to actually get to be able to replicate the benefit that have been demonstrated in a lab in real life. So when we, when we first came across in 2012, we just heard about it, but. And I got myself a normal exercise bike. Was very disappointed that I couldn't replicate what scientists did in the lab. And that was because they had a second person operating the bike for you, applying the right resistance at the right time. And that's just impractical for normal people. And what we can do because we have the data, therefore we have the data from tens of thousands of users, millions of rides. We can run sophisticated algorithms and they get better and better reinforcement learning algorithms over the data to identify what an optimal ride looks like and not just engineering terms, but for somebody exactly like you. And then dial the resistance very quickly to that optimal level of resistance that helps you to, to get to your maximum intensity to, to hit your peak power and keep the, the workout effective, efficient, optimal for you as you get better and stronger. Or what happened with me, which you, if you have an injury and you, you lose some fitness as well or whatever life caught up with you and you had to take a break to then very quickly find again your optimum, create a lighter workout for you to then build up your strength and your condition again. And that's where we can use AI because we have the data and that's really what sets us apart because nobody else has that, even the scientists we work with. Usual academic study is, you know, eight weeks, 12 weeks, has 40, 50 participants or so. So you're talking about hundreds of workouts. We have millions and thereby can develop more things on the back of that. And there's, there's cool stuff coming. So for, for the people who want to do Zone two, because one, one difficulty with the Zone two is what's the right level of intensity. We hear all sorts of suggestions. Oh, like should be able to talk but not sing or should be uncomfortable and so on. Even if you are, we have access to that, of course. But if you use like gas analyzers or so to measure your respiratory exchange rate, it's all a bit unpractical and not that precise. So you're, if you, if you want to really. Okay, there are people who want to do Zone two and they want to do it optimally. So a very cool new thing that is coming is looking at heart rate variability in real time. And yeah, not looking at, only at heart rate variability, but looking at the complexity. So that's like higher orders, those. You have heart rate, heart rate variability and then the complexity of your heart rate variability. And by analyzing the complexity of your heart rate variability, you can quite reliably find that optimal point where you're switching from fat metabolism to carb and glucose metabolism. And so that, that's something that will. So I'll, let's put a timeline within the next three months. We'll have that available on our bikes, certainly. So if, if you are so. And there are, there are some people who make their. You must know some professional biohackers.

Oh, well, most professional biohackers don't want to do Zone two because they have things like, you know, stuff to do. But professional athletes I'm friends with do want to do that.

Exactly right, Exactly. And for example, if you're, if you're competing and you can't take those banned substances and you want to do it all and you have the time, then we can help them with that, like, new analysis, compelling new research, and we can implement it on their mind to make it optimal for them. So there's lots of cool things that can be done once you have a ton of data and the algorithms get more and more powerful. And having the data is then just such a big asset to develop new stuff.

What you said about heart rate variability just warms my heart. Many years ago, I was an Advisor to the HeartMath Institute and I brought them into the quantified self and biohacking movement. And Roland McCready has been a friend now for almost 20 years who's the head of research and development and has shown this incredible, like, symphony of mathematical beauty that's in your EKG tracings from the heart. And it's a lot more than the spacing between your heartbeat or how frequent it is. And because you have so much data, you can dig in on that in a way that's unprecedented. And I fully believe that if you did want to do zone two or just rehet, there's a unique personal dose that changes every single day based on all kinds of hidden variables, including how well you slept, whether you had a glass of beer last night, did you eat a bunch of carbs or not, how much lactate you have all these things, and you're going to be able to get that straight from the body and in real time, provide exactly that. So if I was going to do zone two or rehet, I would want to do it with ultra personalization. And that's why we built you guys in to upgrade labs, to be honest. And we do the same thing with muscle building with a different system, and all of our systems we're integrating into our master data system. Because I just want to do what works right. And I cannot wait to see that. You might even convince me to try some zone too, because it'll be personalized for me. And at least if I'm going to waste two hours of my life, I might as well waste it with the.

Ultimate efficiency to get results, because that's the other thing. Then if you do it too low, then it's like complete waste of time. Get nothing. If it's too high, then they say, like, oh, but now you, you went into carb metabolism and it doesn't count anymore.

You nailed it. That's exactly, exactly what happens. Oh, my gosh. I, I didn't realize you were coming up with that. That, that genuinely makes me happy. Let's talk about this. Why do most people quit their workouts?

That's a great question. So, like, if you, if you survey people, the number one answer is lack of time. And I think secondary answer is something like boredom. And you can, you can. Then there's different approaches to it. Like some people, and they're, they're, they're all valid, and I would say whatever works best. And so some people try to make it really fun and have, like, super soundtracks and very attractive celebrity instructors that work out with you in front of you on a big screen and so on. And other people like us try to make it very, very efficient and will just help you get it done in minimal time. And maybe there's, you know, many people out there. For some people, the music and the very attractive instructor, it means the thing that helps them get it done and wonderful. Yeah. So, so, no, in seriousness, the number one thing for exercise is adherence. So the best workout does nothing for you if you don't do it. So adherence is the number one. So if you found something that works for you and that you enjoy and that you can stick to, that's beautiful. If it's on true with a podcast, that's great. Yeah. But if you, like many the majority of the American population, then lack of time will play a big role. And yeah, attention, your attention is a very precious commodity that people compete very hard for. And there's great, great companies that are very important, very efficient at stealing the attention in some ways. Yeah. And so like we're not going to be more exciting and, than TikTok and Instagram and kind of, not more kind of instant gratification and satisfaction. So we felt we had to go down a different path and just help people get the benefits in as little time as possible.

Not having enough time is very, very meaningful. I deal with it too, and I'm pretty darn optimized. So I, I feel like we don't have enough time to go through everything that we could talk about because you've gone so deep on all the science. But there is one more topic I want to go in on. If you have another couple minutes, can you talk to me about lactate and how important that is and what it does in exercise?

Lactate actually if you switch from hat metabolism to glucose and glycolytic workout, you just break the glycogen molecules down and a very important metabolic product of that process is lactate. And on the one hand it creates then a threshold for how hard and how long you can work. So for athletes, improving their lack tolerance and the ability to clear lactate in their mitochondria is really important for competitive performance. But lactate is thought to have also a bunch of positive effects. So when it comes to for example, your mental health, as far as I understand, lactate is transported to the brain and placed there really important role in your, in your neurotransmitter household and is an important factor in the production of serotonin. And so while yes, the stuff that makes your legs burn, it also helps you kind of feel happy after workout and improved your, your mood and has a number of positive kind of results. And I don't want to call them side effect, but effect.

I think lactate is, is not it. It's not respected enough as, as being both good for you and bad for you. And it's a complex thing to manage. One of the technologies I use that modulates lactate is blood flow restriction bands. So you put things on your arms or legs or both and they restrict some blood flow which causes an increase in lactate and then when you take them off you get a surge of lactate that's good for your brain and your metabolism. Can I use blood flow restriction bands with the curl bike?

So I know people who do and I very clearly bore some of the workouts as entirely possible. Now for WI hit and just how our bike is built and how our also our algorithms work. It wouldn't be our first choice for wiihit. So there's. If you want to do some of the lower intensity workouts with blood blow restriction bands. Absolutely. So if you especially if you had like say an injury or something that limits how much force like can we. Even if it's so short it can really go all out, then I think blood pill restriction bands are entirely. Yeah. Like. Like good thing to use. And also to use with the bike for revit specifically. Maybe you could actually if you did it all the time then maybe that would work. I wouldn't do like sometimes with. Sometimes without that. That would seem a wrong choice.

Interesting. Okay, so consistent use of blood flow restriction and probably not necessary. It seems like you're better off to do your re hit session because it only takes five minutes and then put on your blood flow restriction bands and you can read all about this in Smarter, not harder. I go through that tech. You can put those on and then lift some weights or just go for a walk. There's good studies about walking.

Yes, correct. So. So blood flow restriction has good evidence behind it. It's a good thing to do especially if you can't go through for whatever physiological like if something stops you from going like up to really high forces. Also it's strength training if you. If you can't super heavy and to get a very, very efficient effective stimulus via like just going to your maximum weight. Blood flow restriction bands are a very good way to get a very effective training stimulus with just lower weight and lower load.

That makes good sense. So you don't need to combine the two. Have you heard of interval walking training?

I haven't. Tell me about it.

I came across some Japanese research and I just posted about it and the summary was twice the benefits of 10,000 steps a day and it takes 30 minutes a day. And it reminded me of your work and they found four times the improvement in blood pressure from 10,000 steps a day a reduction of stroke risk by 40%. An improvement in sleep efficiency by 12%. This is 30 minutes a day. Okay, just reht takes five minutes a day and is different than this but it's similar thinking and here's what you do. You walk really slowly for three minutes like with your dog and then you walk fast for three minutes. Kind of like zone two, walking for three minutes, you know, where you're almost out of breath. And then you repeat that five times. Walk slow for three, walk fast for three. And that outperformed 10,000 steps a day, which is a made up number. Anyway it that was invented also by Japanese researchers in the 1950s trying to sell pedometers like the first fitness tracker ever made up 10,000 steps a day. And to this day your Fitbit still tells you to do it and it's nonsense. I know I was CTO of the first company to get heart rate from the wrist. I went into that history and so what are your comments on the this crazy intermittent, whatever you want to call it, interval walking training. The idea is rest intense, rest intense. And it's getting better results than the old way of walking. It feels like it's the same algorithm you're applying to intensity but just to walking.

My, you know, obviously not fully informed but instant reaction would be that it's entirely plausible and that I think brave exercise and hit. It's been shown quite conclusively that alternating higher lower intensity periods is more effective than just steady state. So I think it's entirely plausible. I've not read the research myself yet, but I think this would make very good sense and I wouldn't be surprised if that were beautiful.

I'm, I'm really impressed with your physiological knowledge and your level of biohacker cred nerdiness and this dedication to just finding out what works, especially using the data you have. That's very precious. Find out what works not for everyone because let's face it, the 70 year old man and the 16 year old woman, or girl, whatever you want to call her and my daughter's 17. I haven't figured that one out yet. But whatever that difference is, it's so broad that you can't make anything up that's going to apply. So let's measure and let's customize and personalize and let's do it effectively and efficiently. So I just think that's the only future that makes sense for humans when we're going to go force ourselves exercise. So thanks for being at the very cutting edge with your work at Carol Ulrich, appreciate you.

Thanks to you also for, I mean, just creating this movement and getting awareness to all the like, really exciting new things that that are being developed. It's very necessary.

It's an exciting time. And guys, carolbike.com use code Dave and you can do this and you'll save so much time in the first hundred days that it pays for itself if you have a decent hourly wage, like it's that big of a savings. So I'm a big fan of doing that. Or come into Upgrade Labs, become a member, and we'll do all the other stuff that stacks along with this. Either way, you win. So anyway, full respect and I can't wait to see you at the Biohacking conference in Austin May 28th. You'll have tons of Carols there for people to try, right?

Exactly that. Yes. So that's another way how you can try the Carol Bike and we'd love to see you there, of course.

All right, guys, biohackingconference.com, the original conference and you can actually meet Ulrich and all the other inventors of the cool tech that's there when you come and hang out with yours truly as well. We'll see you on the next episode. See you next time on the Human Upgrade Podcast.

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