While my peak power score did increase, something still felt like it was missing. I wondered what fitness trainers like Alex thought about concepts such as REHIT workouts and the CAROL – where time efficiency is the number one priority of the exercise.

“When it comes to exercise and especially weight loss,” she says, “people often want to find a shortcut to reach their goals. This has been proven time and time again not to be the right way to go about it. Exercise should be an integral part of your lifestyle.

“If you hate indoor cycling and find it boring, switching a 45-minute cycling workout to a 9-minute one won’t address the underlying reason why you’re not exercising enough. This is where other forms of HIIT are better than REHIT, as they allow you to play around with different exercises and equipment. A Tabata workout can be varied and utilises equipment such as kettlebells, weighted balls, and even a barbell – whereas REHIT is restricted to a stationary bike.”

Maybe that’s just it. I understand and appreciate the science of CAROL and REHIT, but I’m not in it for time efficiency. I’m not too fussed about increasing my peak power. Since lockdown, I’ve adopted a more holistic approach to fitness. When one of the only reasons we could leave our houses in 2020 was for exercise, I cherished my daily walks and occasional runs in nearby woods. Working out became as much about mental wellbeing as physical health.

To me, a ride on CAROL feels like the equivalent of a meal replacement shake. Sure, from a health and fitness perspective, the science is solid and it’s mighty convenient – but is that necessarily a good thing?

I put this question to Ulrich.

“If somebody enjoys running, he or she should definitely keep running and enjoy it,” he says. “But, for people who would rather spend time with their kids or partner, meditate or just go to a pub to meet friends, CAROL offers a chance to not have to choose between this and getting a good and effective workout done.” I would argue that you can definitely do both.

“On the other hand,” he adds, “we totally recognise that some users want more variety. We are continually adding more features to the bike to offer more choice and versatility. For example, the bike can be used for streaming classess such as Peloton Digital or Apple Fitness+.”

Strength training: “Can the CAROL stationary bike really get me fit in just 9 minutes?”