2 min read

Next-level HIIT

CAROL’s the only bike with REHIT, the next-level HIIT workout that gives you double the health benefits, in just 10% of the time.


Reduced Exertion HIIT (REHIT) was developed by scientists looking for the shortest, most effective and accessible way to exercise.

REHIT creates the most potent training stimulus with just 2x20-second sprints. It’s scientifically proven to deliver double the health and fitness benefits compared to normal exercise—in just 10% of the time.

CAROL’s AI-personalization and Instant Resistance help 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—which releases key signaling molecules (AMPK and PGC-1a), telling your body to get fitter and stronger.

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

Previously REHIT was only possible in a lab setting. But we teamed up with the world's leading exercise researchers to get REHIT into the real world. And 40 prototypes later, CAROL Bike—the world’s only home REHIT exercise bike—was launched.

“CAROL is the only bike that accurately replicates REHIT outside of the labs. This scientific exercise cannot be done on a regular bike because it requires the supra-maximal resistance tailored to each person’s physiology.”

Dr. Niels Vollaard

PhD, Exercise Physiology Researcher, University of Stirling

Read the full study here.