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Science

Your results, supported by science.

CAROL Bike was developed with leading exercise researchers to deliver the shortest, most effective workouts. Our signature REHIT workout creates the most potent training stimulus with just 2×20-second sprints. It’s scientifically proven to deliver superior health and fitness benefits compared to regular cardio exercise—in 90% less time.

How the REHIT adaptation pathway works

CAROL’s AI-personalization helps you push to your limits during the sprints. Like in a ‘fight or flight’ situation, your muscles are forced to mobilize about 25-30% of muscular glycogen—your emergency energy reserve—releasing key signalling molecules (AMPK and PGC-1a), telling your body it must get fitter and stronger.


You develop more mitochondria, your blood plasma volume increases, and your heart gets stronger. Resulting in increased aerobic and anaerobic capacity.

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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.

Time to thrive

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

Maximum Metabolism

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

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