113. Why Isn't Everyone Getting Fit in 5 Minutes? with Ulrich Dempfle

Why Isn't Everyone Doing This? with Emily Fletcher

Emily Fletcher

Education

4.9 • 529 Ratings

🗓️ 10 March 2026

⏱️ 56 minutes

🔗️ Recording | iTunes | RSS

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Summary

What if the reason you're not exercising isn't laziness — it's that no one told you it could take five minutes? In this episode of Why Isn't Everyone Doing This?, Emily sits down with Ulrich Dempfle, mechanical engineer and co-founder of Carol Bike, to explore a form of exercise most people have never heard of — and that science says is the most efficient workout on the planet. Ulrich introduces ReHIT — Reduced Exertion High Intensity Interval Training — a five-minute workout with just two 20-second all-out sprints that has been clinically shown to produce a 12% improvement in VO2 max in just eight weeks with only two to three sessions per week. He breaks down why VO2 max is the single most important health marker for longevity, why low cardiorespiratory fitness causes more preventable deaths than smoking, diabetes, and obesity combined, and why the "no pain, no gain" belief is keeping most people from getting healthy at all. Emily connects the science to her own experience — linking the fight-or-flight spike of a sprint to hormesis, mitochondrial biogenesis, and heart rate variability — and why intentional, acute stress is the perfect complement to the chronic stress release she's spent 17 years teaching through meditation. In this episode, they explore: What ReHIT is and why it outperforms traditional cardio for VO2 max improvement The biological pathway that makes two 20-second sprints more powerful than an hour of zone 2 Why 40% of people see zero VO2 improvement from zone 2 training alone How sprint training supports hormonal health in perimenopause and beyond How to combine ReHIT with strength training for a complete weekly routine Why breathing in the recovery period may be the most important part of the workout What changes on the planet when everyone gets fit in five minutes Key Moments: 00:00 — The statistic that changes everything: fitness vs. smoking, diabetes & obesity combined 07:00 — What is ReHIT? The paradox of reduced exertion and high intensity, explained 14:43 — VO2 max: the strongest predictor of life expectancy you're probably not tracking 19:07 — The fight-or-flight connection and why this is "good stress" 22:54 — Clinical results: 12% VO2 improvement in 8 weeks, 20% in 20 weeks 26:01 — The biological pathway: glycogen → AMPK → PGC-1 alpha → mitochondria 33:40 — Hormones, perimenopause & why long endurance cardio can work against you 44:52 — Why breathing in recovery might be the most powerful part of the ride 53:00 — What changes on the planet when everyone gets fit in five minutes 🚴 Try Carol Bike — 100-Day Risk-Free Trial: Carol Bike is backed by peer-reviewed clinical research and a full 100-day risk-free guarantee. Get the best deal with the code ZIVA at carolbike.com 🔗 MORE FROM EMILY & ZIVA: Join Ziva Magic: zivameditation.com/pages/zivamagic Learn Ziva Meditation: preview.zivameditation.com Free masterclass: learn.zivameditation.com Get 15% off with promo code WHYTHIS: whythis.zivameditation.com Follow us on Instagram: @zivameditation 🔗 MORE FROM EMILY & ZIVA: Join Ziva Magic: zivameditation.com/pages/zivamagic Learn Ziva Meditation: preview.zivameditation.com Free masterclass: learn.zivameditation.com Get 15% off with promo code WHYTHIS: whythis.zivameditation.com Follow us on Instagram: @zivameditation

Transcript

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0:00.0	Low cardiorespiratory fitness leads to more avoidable deaths than smoking, diabetes and obesity combined.
0:09.0	Lack of time is the number one barrier why people don't exercise.
0:14.0	We've been trained and we've grown up to believe that exercise is something that needs to be long and hard and you have to sweat.
0:23.6	So a rehab workout is really, really short.
0:26.6	It can be done in as little as five minutes and you only work hard for two 20-second sprints.
0:33.6	So you create a huge spike in energy demand.
0:36.6	In some ways, you simulate a fight or flight situation.
0:39.3	It's probably the highest ROI return on the time you invest into exercise.
0:44.3	On average, you can expect, and we see this in our users,
0:48.3	to achieve a 12% improvement in VO2 max, over an eight-weeks weeks period with only two to three workouts per week.
0:58.0	What do you think would be different on the planet if everyone was getting fit in five minutes?
1:05.0	We'd be it.
1:07.0	Sweet friends, it's Emily, and I want to welcome you to why isn't everyone doing this.
1:12.9	Now, my guest today is Ulrich Demple.
1:14.9	He's the founder of Carol Bike.
1:17.0	He's a mechanical engineer turned health innovator who is genuinely asking the question,
1:22.4	why isn't everyone getting fit in five minutes?
1:25.9	Now, I know that sounds like a tall claim, but this episode is for
1:28.8	you if you want to take care of your body and your heart, but you feel like you simply do not
1:33.6	have the time. And yes, I'm talking to my single mama's out there and my folks who work from
1:37.8	home. So if your schedule is full, your nervous system is already juggling so much, and the
1:42.8	idea of spending hours a week exercising
	...

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