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Co-Founder Q&A: The science behind CAROL Bike

From how to lose weight with CAROL, to the best way of integrating strength training with their rides, CAROL’s social community sent us their questions. And who better to answer them, than CAROL CEO and co-founder, Ulrich Dempfle.
CAROL is scientifically researched and proven to improve your fitness and health. Developed in collaboration with leading exercise researchers, to create the most effective, time-efficient workout. Here’s your synopsis of the science.

Q: Why is CAROL different from other bikes?

Reduced Exertion HIIT (REHIT) and AI-personalization make CAROL Bike unique. Developed with leading exercise researchers to give you the shortest, most effective workout.


REHIT is the next-level HIIT workout that gives you double the health benefits, in just 10% of the time. CAROL Bike’s signature REHIT workout can be done in just 5 minutes. And it’s proven to be the most effective cardio.

Q: Is the 5 minute workout enough to lose weight?

With CAROL’s signature 5-minute workout you’ll burn twice as many calories minute-per-minute vs. traditional cardio, thanks to afterburn, which lasts for up to 3 hours after you ride.

Ulrich details new research by ACE (American Council on Exercise) that shows you’ll burn more calories on a 15-minute CAROL Bike ride, than a 30-minute run.

Find out more about how CAROL maximizes your metabolism.

Q: How do you suggest integrating CAROL with strength training?

Gym owners have relayed to Ulrich that their clients do strength training before their CAROL workout, and avoid leg work on CAROL days.

While there is no clear research on integrating CAROL with strength, Ulrich recommends experimenting to find your perfect regimen.

Q: Can I improve my VO2max with CAROL?

VO2max is the main measure of fitness. The higher your VO2max, the fitter and healthier you are.


Ulrich references the scientific study which proved CAROL’s signature REHIT workout can improve your VO2max by 12%, in just 8 weeks.

Q: Can I do REHIT workouts without CAROL?

REHIT was developed by scientists looking for the shortest, most effective and accessible way to exercise. Research proved that REHIT is the fastest way to get fit, but there was a catch: true REHIT was only possible in the lab.

We teamed up with the world’s leading exercise researchers to get REHIT out of the lab—into the real world. CAROL is the only way to safely and effectively recreate REHIT, thanks to AI-personalization and Instant Resistance.

Ulrich suggests the next best thing​​—all-out sprinting on a running track—but this comes with safety risks.

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Ulrich Dempfle

CAROL CEO & Co-Founder

Ulrich co-founded CAROL and partnered with the world’s leading exercise researchers to take REHIT out of the lab. 40 prototypes later, the world’s only REHIT exercise bike was launched.

Ulrich Dempfle

CAROL CEO & Co-Founder

Ulrich co-founded CAROL and partnered with the world’s leading exercise researchers to take REHIT out of the lab. 40 prototypes later, the world’s only REHIT exercise bike was launched.

Get Fitter

Improve your fitness by 12% in just 8 weeks.

Live Younger

Improving your VO2max by 12% is like turning the clock back on your age by 10 years.

Live Healthier

Reduce your risk of type 2 diabetes by 62%—and blood pressure by 5%.

Next-level HIIT

Why Reduced Exertion HIIT (REHIT) is the most effective workout.

Maximum Metabolism

You’ll burn more calories on a 15-minute CAROL ride, than a 30-minute run.

Time to thrive

Make the most of your time with CAROL Bike's short and efficient REHIT workouts.

What is a REHIT workout?

Explore REHIT, the game-changing workout that redefines time-efficient training with just 2x20-second sprints.

Demo: How to do REHIT on CAROL Bike

Explore a hands-on guide to doing REHIT on CAROL Bike, showcasing its efficient, effective workouts tailored for every fitness level.

Boost your brainpower

Get fit, stay sharp: how high-intensity exercise and BDNF benefit your brain.

12 benefits of cycling

Regular cycling can help strengthen your heart and lungs, reduce the risk of certain types of cancer, and more.

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