Ulrich from Carol Bike Explains the 5-Minute Cardio Protocol That Adds Years | DSH #1807

Summary

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Digital Social Hour Ep. #1807 Summary

Guest: Ulrich (Co-Founder, Carol Bike)
Host: Sean Kelly
Date: February 4, 2026
Main Theme:
Exploring the science and impact of the 5-Minute Cardio Protocol (Reduced Exertion High-Intensity Training, or REHIT) with Ulrich from Carol Bike—how ultra-efficient, science-backed sprint workouts can profoundly boost fitness, longevity, and health for even the busiest people.

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Episode Overview

Sean Kelly interviews Ulrich from Carol Bike at the A4M Longevity Fest. The conversation centers on the Carol Bike’s science-based, minimalist approach to cardiovascular exercise—offering profound health and longevity benefits in just a handful of minutes per week. Ulrich dives deep into the REHIT protocol, the data supporting its effectiveness, how it compares to competitors like Peloton, and why short, ultra-intense exercise might be the paradigm shift modern busy people need.

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Key Discussion Points & Insights

The Carol Bike and the Magic of Short, Intense Workouts

• Carol Bike vs. Peloton

  • Traditional bikes (like Peloton) focus on entertainment, community, and long rides with celebrity instructors, whereas Carol Bike is centered on the shortest, most efficient, and science-backed cardio workouts (REHIT).
  • Ulrich:

    "Peloton is about entertainment, celebrity instructors, great music soundtracks. Carol Bike is about the shortest, most efficient science backed workouts." [00:50] "If you want to improve your VO2 max, your metabolic health, and you want to do it in the minimum time possible, then we are for you." [01:15]

• What is REHIT?

  • Reduced Exertion, High-Intensity Interval Training: Scientifically developed and validated to deliver maximum cardiovascular benefit in the least time.
  • The core workout: just two all-out, 20-second sprints per session—workouts can be as short as five minutes, including warmup, recovery, and cool-down.
  • Ulrich:

    "A workout can be done in as little as five minutes. You only have to work hard for two 20-second sprints." [02:04]

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Why VO2 Max and Longevity Matter

• VO2 Max is the single strongest physiological predictor of life expectancy.
  • A 10% improvement can equate to two more years of healthy life.
  • Average VO2 max declines 10% per decade after age 30—REHIT can reverse a decade of decline in only 6–8 weeks.
  • Sean:

    "A 12% improvement is roughly equivalent to being up to 10 years younger." [05:30]

  • Ulrich:

    "Most people with a 10% improvement in VO2 max would gain two years of healthy life expectancy." [00:00 / 06:37] "So in six to eight weeks you can offset that by more than a decade." [06:37]

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Consistency & Adherence: The Real Challenge

• Time as the Biggest Barrier
  • Most people neglect exercise due to "lack of time," not laziness.
• Workouts must be easy to stick to
  • Even the best protocol loses efficacy if not maintained—detraining occurs rapidly if you stop.
  • Having the bike at home, ready, and frictionless makes a difference.
  • Ulrich:

    "You really do have to stick to it. So you get those improvements very rapidly. Six to eight weeks...but if you don't stick to it, the detraining effect is similarly fast." [07:26]
    "Everyone's got five minutes, no matter who you are." [08:44 Host / 08:46 Ulrich]
    "The bike is set up to be as frictionless as possible...All you have to do is, when you’re told, pedal hard for two 20-second sprints." [08:46]

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The Science Behind the Protocol

• Peak Intensity > Duration
  • Carol’s sprints force you to push all-out, simulating “emergency” physical scenarios (run for your life!).
  • This method mobilizes muscle glycogen and key signaling molecules, triggering the body’s “master regulator” for mitochondrial growth (PGC1alpha), increasing your capacity to process oxygen.
  • Ulrich:

    “The intensity levels are orders of magnitude smaller [in HIIT or Peloton workouts]. So the level of peak power… are three, four times higher than what you do in a HIIT workout in a Peloton.” [09:32] “The training stimulus is created through the level of intensity, not the time. And so that is really… there’s very good scientific data now.” [13:33]

• Two Sprints Is Optimal
  • Scientific literature (e.g., McMaster University, Canada) confirms two sprints is enough and more is not better—longer or more sprints may deliver less benefit due to self-pacing.
  • Sean:

    "Really? … it has worse effects if you do it more." [12:52]

  • Ulrich:

    "It's very clear that you don't get more benefits. The data...suggests that you get less benefits." [12:56/13:05] "Once you know, you have to do 4, 5, 6 sprint intervals...you don't go all out, you pace yourself." [13:05]

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Professional Athletes & Broader Adoption

• Elite athletes: All serious endurance athletes incorporate high-intensity work for maximal results—“Vigorous intensity is where the magic happens.” [14:50]

Real-World Use and Growth

• Launched in late 2018/early 2019, with version 2 in 2022.
• Present in biohacking centers (Upgrade Labs, Smart Fit Method), but most users keep the bike at home for ease and habit formation.
• Ulrich:

  “It’s almost as positioned between my bed and the bathroom ... I can just do it every other day without having to think about it—becomes second nature and then you get good adherence rates.” [16:50–17:20]

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Tracking Results

• The bike provides rich metrics, an at-home VO2 max test, and a fitness score to help users track improvements and "see the results" within a few weeks or months.
• Ulrich:

  "You get a rich basket of metrics where you can track with every ride your progress... You can test your VO2 max even without a breath analyzer." [19:25]

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Risk-Free Trial and Pricing

• Industry-leading 100-day “risk free trial”—full refund if not satisfied.
• List price: $2,795 (promotional discounts possible).
• Ulrich:

  "We can do that because we know by now that people like our bike and that they see the results." [20:30]

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Standout Quotes & Memorable Moments

• On longevity and efficiency:

  "You save a ton of time every week because you have to spend way less time on cardio exercise. But then you gain like two years." —Ulrich [00:00 / 06:37]

• On real-world barriers:

  "Time is really the most valuable thing. And there's trillion dollar companies that are competing for our time, for our attention." —Ulrich [02:05]

• On adherence:

  "You need an exercise you can do whatever the weather...that fits into normal people's lives." —Ulrich [07:26]

• On science:

  “The training stimulus is created through the level of intensity, not the time.” —Ulrich [13:33]

• On challenging convention:

  "If you tell people, 'two 20 seconds is all you need,' there's a lot of skepticism, but the science is there...the improvement is not subtle." —Ulrich [15:48]

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Timestamps for Key Segments

• [00:00] – Introduction to VO2 max benefits and longevity
• [01:00] – Carol Bike vs. Peloton: Focus and philosophy
• [02:04] – What is REHIT? and the 5-minute workout explained
• [03:31] – Science: Two sprints and physiological impact
• [05:30] – Real-world impact: What 12% VO2 max gain means
• [06:37] – Aging, VO2 max, and rapid offset through REHIT
• [07:26] – Importance of adherence and frictionless exercise
• [09:32] – Peak intensity vs. “normal” HIIT workouts
• [12:53] – Why more is not better; scientific basis
• [13:33] – Physiology: Glycogen, AMP, PGC1alpha, and mitochondria
• [14:50] – Serious athletes and high-intensity training
• [15:39] – Market launch and overcoming skepticism
• [16:50] – Home use and workout adherence
• [19:25] – Tracking progress and measuring gains
• [20:28] – Risk-free trial, pricing, and closing remarks

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Episode Tone and Feel

Ulrich comes off as passionate yet pragmatic—grounded in science but appreciative of the skepticism many listeners may have. The tone is encouraging, motivational, and direct, with a no-nonsense approach to health and a focus on enabling everyone, regardless of schedule, to access serious health benefits.
Sean Kelly keeps the conversation lively, relatable, and occasionally incredulous—playing the everyman interested in fast, achievable solutions.

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This summary provides a comprehensive roadmap to the episode’s science-backed revelations on time-efficient cardio and longevity, key scientific concepts, and real-life applicability for anyone curious about maximizing health with minimal time.

Transcript

[Ulrich]

Most people with a 10% improvement in VO2 max would gain two years of healthy life expectancy. So that's. You save a ton of time every week because you have to spend way less time on cardio exercise. But then you gain like two years. Wow.

[Host]

Just from eight weeks of biking, you gain two years.

[Ulrich]

Yeah. I mean there's something. Exercise is wonderful. Foreign.

[Host]

Guys, we're at a 4M longevity fest. We got Ulrich here from Carol Bike. It's a bike company. And getting to know you today. We just met, so thanks for coming on, man.

[Ulrich]

Thank you.

[Host]

Yeah, I'd love to learn more about the bike. And I actually own a Peloton, so I'd be curious what the main difference in your opinion would be.

[Ulrich]

I mean, there's a ton. It's completely different. I would say the only thing that it has in common is that it's a bike with a screen, but noteware. Peloton is about entertainment, celebrity instructors, great music soundtracks. Carol Bike is about the shortest, most efficient science backed workouts. So we're all about results. If you want to improve your VO2 max, if you want to improve your metabolic health and you want to do it in the minimum time possible, then we are for you. So Carol Bike is actually very versatile. It can do many things and you can do peloton rides on it too. Because it's not a locked ecosystem, you can have multiple apps on it. But the reason why people get a CARO bike is to do what's called rehit. That's reduced exertion, high intensity interval training. That's a scientifically developed and validated workout that basically gets you fittest fastest and is the minimum effective dose of cardio exercise.

[Host]

Sign me up.

[Ulrich]

Yeah, and the deeper thing is VO2 max. Your cardio fitness is really super important. It's the strongest correlate to life expectancy. It's probably the most important physiological marker that you have. And if you ask people why they don't exercise and why they neglect something so important, the number one reason is always lack of time. So that's every scientific survey shows, why do you not exercise? People say this lack of time and some people say, well, it's about laziness and so on, but time is really the most valuable thing. And there's trillion dollar companies that are competing for our time, for our attention. And so we believe people when they say that they don't exercise because they don't have time. And so we've developed a product, a bike that makes this, these rehab workouts as simple and as easy as possible to allow people to in. So a workout can be done in as little as five minutes. You only have to work hard for two 20 second sprints.

[Host]

That's it.

[Ulrich]

Yeah. The rest is just a gentle warm up recovery and cool. So it's two 20 second sprints. That's all you have to do to trigger a really profound training stimulus and improve your Cardiovascular Fitness, your VO2 max and your metabolic health dramatically. You do that two to three times per week and then you've got the vast. So then you've basically taken care of your cardio exercise. And so in those two 20 second sprints you do work hard. So those are not easy. There's the all out sprints and the bike is basically optimized to help you hit maximum power, maximum intensity and make that as easy and as frictionless as possible. But if you do that, yeah, you don't have to spend hours to get in great cardio shape and to do really something very profound for your health, for your longevity and general well being.

[Host]

Yeah, very profound. I mean it's been shown in published studies to increase, increase VO2 max by around 12% in eight weeks.

[Ulrich]

That's right, yes. And it doesn't stop there. So the most scientific studies, and this is by now a very well researched workout protocol, most scientific studies run like eight to 12 weeks, some up to 20 weeks and the improvement goes further. Of course at some point it tapers off, but we see from our users if you do this for six months, if you do it for a year, you can get improvements of over 30%, 30, 40, 50%. Yes. It depends obviously where your starting point is. If you're a super trained athlete, the marginal gains are lower, but most of us are not. Most of us live sedentary lifestyles and so you will make dramatic improvements really quickly.

[Host]

And just to put that into perspective, for people watching, a 12% improvement is roughly equivalent to being up to 10 years younger.

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[Ulrich]

That's correct, yes. So from the age of 30, our VO2 max on average decreases by 10% per decade. So in six to eight weeks you can offset that by. By more than a decade. Wow. And it's. Yeah, very profound. The, the other thing that's to. To put it into context. So most people with a 10% improvement in V2 max would gain two years of healthy life expectancy. So that's you. You save a ton of time every week because you have to spend way less time on cardio exercise. But then you gain like two years.

[Host]

Wow. Just from eight weeks of biking, you gain two years.

[Ulrich]

Yeah. I mean, there's something. Exercise is wonderful. Exercise is.

[Host]

If you enjoy it, it's wonderful. You know what I mean?

[Ulrich]

I meant in the sense of the. The benefits are really very substantial, very significant. However, there's a catch to it. You really do have to stick to it. So you get those improvements very rapidly. Six to eight weeks, 10 weeks. But if you don't stick to it, the detraining effect is similarly fast. So you have to find something that you can stick to. Absolutely, yes. You need an exercise that you can do whatever the weather. And that's, I think, another reason to have something that's really short and that fits into normal people's lives. Because if your motivation is nice soundtracks and celebratory instructors, that's great if that keeps you doing it. But then if you get into a busy stretch or so and you drop off, that's no good. So you need something that really. That you can do whatever happens, two to three times a week. And with Rehit on a CARO bike, you have a tool like a fallback option even, that allows you to keep working out even when life gets busy.

[Host]

Yeah, yeah. Everyone's got five minutes, no matter who you are.

[Ulrich]

Yeah, exactly. And the whole bike is set up to be as frictionless as possible. So you log in and the bike basically does everything for you. You're coached through the workout, it sets your optimal resistance at the optimal time, it adjusts as you get fitter, and basically all you have to do is when. When you're told to pedal hard for two 20 second sprints. So this, this taking away mental load and making it as easy as possible is also a big thing in our opinion.

[Host]

Yeah, this is very achievable. I feel like for me, like I do the hit workout on peloton because I don't want to be biking for an hour personally. And the hit is like 20 minutes.

[Ulrich]

That's right. And it's good. Interval training is definitely effective and a good thing. And we know that because people do use also do do peloton classes on our bikes. The intensity levels are order of magnitude smaller. So the level of peak power that you reach in those two 20 second sprints are like three, four times higher than what you do in a hiit workout in a peloton. Yeah, exactly. And that's also the secret what makes this so effective. So you go momentarily, you push to your limits and that creates just a different training stimulus that gets to the same endpoint as long endurance exercise, but, but just much, much faster. So what we do is we simulate or when you're on the bike is what you do. You simulate an emergency situation like as if you had to run for your life or fight for your life. And the energy demand in your legs goes up by about a factor of 100. So really dramatic energy crisis, if you want to call it that way. And it forces your muscles to engage all the fastest acting energy systems. So that's your glycogen system. So first phosphocreatine for about 10 seconds and then your glycogen system and you release about 25 to 30% of the glycogen. So that's a storage form of sugar in your thighs. And the important thing, so what triggers the training stimulus is just that you mobilize the glycogen because bound to the glycogen is a certain signaling molecules, amp that get released and mobilized with the glycogen activated to AMPK and then downstream activate another important signaling molecule called PGC1alpha. That's your body's master regulator for mitochondrial biogenesis. Mitochondria are the parts in your cells, like the powerhouses in your cells, that help you metabolize oxygen. And with that signaling molecule, you tell your body that it has to grow more and larger mitochondria and thereby you're able to process and burn more oxygen. And that's then what increases your VO2 max, your ability. So that's your maximum ability to metabolize oxygen and increases your metabolic, your cardiovascular fitness. And with those short sprints you can trigger the stimulus literally in seconds. So 2/20, this has been scientifically validated that 2/20 is enough to trigger that. And it's not only that, it's enough. This is. That gets really insane. If you wanted to do more or longer sprints, you don't actually get more benefits.

[Host]

Really?

[Ulrich]

Yeah. That's a crazy.

[Host]

That's crazy.

[Ulrich]

You actually get. So it's very clear that you don't get more benefits. And then the data is indicative, suggests that you get less benefits.

[Host]

No way.

[Ulrich]

Yes. And so here, these are complex biological processes and I'm a mechanical engineer, but we work with the leading researchers in this field and what they presume, their hypothesis is that once you know, you have to do 4, 5, 6 sprint intervals and they're like 40, 60, 80, like a minute long, you don't go all out, you pace yourself.

[Host]

So.

[Ulrich]

Your body or your mind somehow pulls back and says, I have to somehow get through this. Whereas with two 20 second sprints, it's really so short that you can push to your limit. And here the training stimulus gets created through the level of intensity, not the time you to maintain that. And so that is really. Yeah. And there's very good scientific data now. So McMaster's university in Canada, they're probably the leading university in that field. They've just published a very, very solid study again on this. The science is solid.

[Host]

That's fascinating. I can't believe it has worse effects if you do it more.

[Ulrich]

Yeah, I mean, it's. And that's. So that part is slightly where I say that's a assumption, a hypothesis. What we do know is the effectiveness. So we know very well, if you put this in, this is what you get out on average, of course, like, everybody's a little bit different, but on average that is thoroughly established.

[Host]

It does make me wonder, like about marathon runners or people that bike features 50, 100 miles, like, at what point is it diminishing returns?

[Ulrich]

So I mean, first, there are no serious endurance athletes that don't also do interval training and high intensity training. So it's very clear. So there's this whole. Some people are very passionate about zone 2 and lower intensity workouts that have also some benefits. But even the leading proponents of that are very clear that vigorous intensity is where the magic happens. That is where you get the most profound improvements. And so, yeah, even like every serious endurance, endurance athlete will also engage in high intensity, vigorous training because that's where you get like the biggest training stimulus that makes sense.

[Host]

How long have you guys had the product released to the market.

[Ulrich]

So we launched this in late 2018, early 2019, second version came out in 22.

[Host]

Got it. It's relatively new.

[Ulrich]

It's relatively new. And so there is a. We have our work cut out because we're obviously challenging a lot of conventional beliefs or long held beliefs. And if you tell people, oh, two, 20 seconds is all you need. There's a lot of skepticism, but the science is there and it's actually something you can experience. So once you try the workout, you will understand that it's effective. Once you try it for six weeks, eight weeks, the improvement is not subtle. So that's profound. You will definitely notice it. So yes, we have to educate. And there's really something about challenging long held beliefs and overcoming skepticism that we're working and that's great to be able to talk about it.

[Host]

Are you in any gyms yet?

[Ulrich]

So we are in not the big box gyms, but biohacking facilities. So if you for example, upgrade labs or Smart Fit method or exercise coach. So those are facilities that are not your standard big box stores but where you come in with a specific program. And yes, in those we are. And we're spreading and expanding so you'll see us in more places. But no, most people actually have their bike at home because when it comes to making it frictionless. So this is incredibly important for me is that I have a bike at home and it's almost as positioned between my bed and the bathroom. So so I. And then I can just do it every other day without having to think about. Becomes second nature. And then you get good adherence rates. So that's there. There's a real benefit of having it at home so. Because you will need something that you can stick to.

[Host]

Yeah, makes sense. Because you would spend longer driving to the gym to use than you would be on it.

[Ulrich]

Exactly, exactly that.

[Host]

So if you just wake up and it's right in your room, 20 seconds like you said, right?

[Ulrich]

Yeah, exactly.

[Host]

Sure. And quick. That's cool, man. I can't wait to try it.

[Ulrich]

Yeah.

[Host]

Excited. I'm going to try it for six weeks, two days a week. I'll commit that on the show right now.

[Ulrich]

Nice.

[Host]

And then I'll. I'll message you how I feel after.

[Ulrich]

Good.

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[Host]

There'S a way to measure my results before and after.

[Ulrich]

Absolutely. So first the bike. Because it's a computer controlled bike, AI controlled, it optimizes your resistance automatically. You get a rich basket of metrics where you can track with every ride your progress. So you get your fitness score. You can also do at the beginning and after a while then like a VO2 max test. So there's, there's a range of. The bike is very versatile, it's very capable, can do many things. What people use it Most for like 70, 80% of the workouts on the bike are for this rehit workout. But there's a broad range of other things and amongst them also a whole variety of fitness tests. And you can test your VO2 max even without a breath analyzer on the bike. Yes.

[Host]

That's cool. I'll definitely play around with that. Well, Ulrich, this was great. We'll link the website if people want to buy one. Maybe a little code too?

[Ulrich]

Yeah, absolutely.

[Host]

Anything else you want to close off with?

[Ulrich]

Well, one thing we have probably an industry leading returns policy. We call it risk free trial. So if you purchase a bike, you have 100 days to see whether you like it, whether you can stick to it and whether it's effective for you. If it's not, then you can just call us, we pick the bike up and you get a refund. We can do that because we know by now that people like our bike and that they see the results. Therefore it's a relatively risk free way to try it.

[Host]

That's great. Thanks for doing that, honestly. Because people I'm sure are skeptical. It is.

[Ulrich]

Yeah, exactly.

[Host]

Hefty price.

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How much is it?

[Ulrich]

So it's 2795.

[Host]

Okay.

[Ulrich]

And we, we from time to time do promotions here at A4M. I'm sure there's a. And we. We. I'm sure we can. We'll have a nice discount code for you.

[Host]

Nice. Perfect. Check them out, guys. And if you don't like it, just return it.

[Ulrich]

So, thanks.

[Host]

See you guys. Peace.

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I hope you guys are enjoying the show. Please don't forget to like and subscribe. It helps the show a lot with the algorithm.

[Host]

Thank you.