EP 1274
1274. The End of Cardio? Burn Fat & Boost VO? Max in Just 8 Minutes a Week – with REHIT | Ulrich Dempfle
In this episode of The Human Upgrade, Dave Asprey sits down with Ulrich Dempfle—German-trained engineer, sports scientist, and co-founder of CAROL Bike—to explore a radical idea: everything we’ve been told about cardio might be wrong.
Together, they expose how outdated fitness advice and time-wasting workouts have failed most people, and reveal the cutting-edge science behind REHIT (Reduced Exertion High-Intensity Training)—a revolutionary 5-minute protocol that delivers maximum benefits in minimum time. From VO? max and insulin sensitivity to metabolic flexibility and brain performance, this conversation flips the script on traditional exercise and introduces a powerful, personalized approach for modern life.
If you’re tired of long workouts with little return—or you’ve been told you “just need to move more”—this episode will reset your understanding of cardio and give you the tools to train smarter, not longer.
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In this Episode of The Human Upgrade™...
You’ve probably heard of HIIT—but have you heard of “REHIT?” This isn’t just another workout trend…it’s a new science-backed way to train with maximum efficiency and zero wasted time. If you’re still jogging, you’re wasting hours for minimal results.
In this episode of The Human Upgrade, Dave Asprey sits down with Ulrich Dempfle, German-trained engineer and co-founder of CAROL Bike, to dismantle outdated cardio advice and introduce the 5-minute protocol that’s obliterating fitness myths.
Forget the treadmill grind. REHIT (Reduced Exertion High-Intensity Training) exercising delivers:
- 12% VO? max increase
- 6x the fitness gains of daily jogging
- 62% drop in diabetes risk
- 5x more BDNF for brain power
—all with just 8 minutes of effort per week.
But was it? Ulrich unpacks the hard data, crushes the Zone 2 obsession, and shows how a brand-new way of exercising is giving explosive results—no matter your age or fitness level.
What You’ll Learn in This Episode:
- Why Zone 2 cardio is outdated advice for most people
- The science of REHIT and how 2 sprints beat 2-hour workouts
- The shocking data on VO? max, insulin sensitivity, and lifespan
- How CAROL uses AI to personalize exercise for any age or ability
- Why most people fail at fitness—and how to fix it
- The real role of lactate, BDNF, and HRV in recovery and resilience
- How perimenopausal women benefit more from REHIT than HIIT or jogging
- Why adherence—not intensity—is the #1 predictor of results
- What to do when you’re traveling or don’t have access to the tech
“For most people, cardio should be about efficiency—not tradition.”
Ulrich Dempfle
- 00:00 Introduction to REHIT Training
Kickoff to the 5-minute cardio protocol shaking up fitness norms.
- 00:24 Meet Ulrich Dempfle: The Mind Behind CAROL Bike
Engineer, scientist, and REHIT pioneer joins the conversation.
- 00:51 The Science and Benefits of REHIT
How REHIT boosts VO? max, burns fat, and cuts disease risk fast.
- 01:44 Comparing Traditional Cardio to REHIT
Why jogging for hours can’t compete with 2 sprints.
- 02:32 Dave Asprey’s Personal Fitness Journey
Why hours of cardio failed him—and what finally worked.
- 03:43 The Efficiency of REHIT Training
15 minutes a week. Better results. Backed by science.
- 05:03 Practical Applications and Accessibility of REHIT
How anyone—at home, in office, or gym—can do this.
- 08:22 Addressing Common Concerns and Misconceptions
Debunking the “too good to be true” narrative.
- 11:25 The Future of Fitness: REHIT and Beyond
Tech, recovery, and rethinking the role of exercise.
- 18:29 Scientific Validation and Real-World Results
Clinical proof of REHIT’s effects on performance and health.
- 31:53 Clinical Trials and Tech Integration
CAROL’s evolution through lab data and AI feedback loops.
- 32:06 Upgrade Labs and CAROL Bike
Where to try it in person—and why it’s a core tech.
- 33:00 Mitochondrial Effectiveness and Insulin Sensitivity
How REHIT improves energy, fat-burning, and aging markers.
- 36:05 Zone Two Training vs. High-Intensity Training
The real ROI comparison—and why REHIT wins.
- 42:02 REHIT for Perimenopausal Women
Why this protocol is ideal for hormonal and metabolic shifts.
- 48:18 AI and Personalized Exercise
How CAROL adapts your workout with real-time precision.
- 57:52 Lactate and Exercise Benefits
The surprising brain, mood, and metabolic boost from lactate.
- 01:01:48 Interval Walking Training
How slow-fast walking outperforms 10,000 steps a day.
- 01:04:01 Conclusion and Future Insights
The next frontier in personalized, efficient, and effective fitness.
Resources:
- Dave Asprey’s New Book – Heavily Meditated: https://daveasprey.com/heavily-meditated/
- CAROL Bike Website and use code ‘DAVE’ for a discount – https://carolbike.com/
- CAROL Bike Instagram – https://www.instagram.com/thecarolbike/?hl=en
- 2025 Biohacking Conference: https://biohackingconference.com/2025
- Danger Coffee: https://dangercoffee.com
- Dave Asprey’s Website: https://daveasprey.com
- Dave Asprey’s Linktree: https://linktr.ee/daveasprey
- Upgrade Collective – Join The Human Upgrade Podcast Live: https://www.ourupgradecollective.com
- Own an Upgrade Labs: https://ownanupgradelabs.com
- Upgrade Labs: https://upgradelabs.com
- 40 Years of Zen – Neurofeedback Training for Advanced Cognitive Enhancement: https://40yearsofzen.com
Enjoy the show!
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