Carol exercise bike review – delivers the same cardio benefit of a 45-minute run in an 8-minute ride

The whole “I don’t have time for exercise” excuse will not work anymore. That’s because you can get the same cardio benefits that come from a moderately paced 45-minute jog in less than 8 minutes with the new AI-powered CAROL exercise bike.

It sounds too good to be true, but peer-reviewed studies confirm it. CAROL operates on the “minimum effective dose” theory of exercise, which is thought to be two 20-second sprints at a high pace by the researchers who created the protocol. This rapidly depletes your glycogen muscles and, in principle, allows your body to become more responsive to insulin and to burn fat over time for energy.

  • Amazingly powerful bike that takes less than 10 minutes per session and just three sessions per week for a successful cardio workout, customizable workouts that change as you get fitter, easy to setup and shift as required.

  • Expensive, and not a good health tool for people who aren’t in good shape.


This innovative concept comes down to two key concepts: science and only be summed up as 40 seconds.

The principle is that the exercise bike guides you, personalized to each rider, through a short workout. CAR.O.L stands for Cardiovascular Optimisation Logic, the program that the bike uses each time you ride to calibrate the resistance. The bicycle turns up the resistance as you get fitter, functioning like a kind of automatic personal trainer.

The science first

Your body breaks down some of the nutrients into glucose sugar when you eat food, particularly anything carb-rich, and stores most of it as glycogen in your muscles. In basic terms, glycogen is muscle power, which is what the muscles use when you lift, jog, or sprint (or do pretty much anything, really).

The more glycogen you have at the ready, the more you can exercise (aka, the more you’re in shape). And burning up as much of it as you can during daily workout sessions is the way to get more glycogen.

Serious exercise helps your muscles grow physically bigger by fixing the tiny tears formed in their fibers and prompting your body to store more of that muscle fuel at the ready. There are two basic types of this type of intense exercise: a long, continuous duration of exercise, or a short and intense period.

The CAROL bike hopes that your body will have experienced a fundamental improvement after a few months of using the bike daily (three to four days a week). Its goal is to make your body adapt to rapid depletion of glycogen and become more successful in turning to another source of energy once glycogen runs low. The other source of energy? Yeah. Fat.

Carol exercise bike review Carol bike review

Setting up and using the Carol exercise bike

For eight weeks, I tested CAR.O.L and completed 32 rides during that period, averaging four a week, slightly more than the three a week recommended.

The bike is straightforward and easy to use. CAR.O.L measures your baseline fitness and an acceptable level of resistance for the first six drives, after which you can start to monitor your results in the app.

The trip will not really be that hard the first time you use the CAROL bike, nor will it be the second, third, fourth, fifth, or sixth time. Ride seven is where things are starting to get serious. At that point, the bike (more accurately, the machine inside) has ample information to set the optimal heart rate for warm-up, vigorous exercise, recovery, and cooling down. It utilizes this to create a workout that is tailored to be as demanding and effective as possible.

As well as a free ride mode, there are four pre-set workouts to choose from, enabling you to manually set the length and difficulty as you would on a regular exercise bike.

Eight minutes and 40 seconds is the intense workout environment, consisting of two 20-second sprints punctuated by two to three minutes of warm-up, rest and warm-down. It’s a slick experience, because the software does this for you, you never have to alter the resistance.

When you reach the sprints, until the resistance kicks in and slows you down, the screen turns red for three seconds-your cue to start pedalling as hard as you can. During the sprints, the aim is to power through and sustain the velocity as much as possible, resulting in muscle exhaustion. Twenty seconds can sound fast, but trust me, when your muscles are functioning at AI-determined full strength, it certainly feels longer.

The Carol exercise bike has a few music choices and a visualization track built-in that has you sprinting away from a tiger with a sabre-tooth. It helped me to get my sprint pace up, aside from initial skepticism, although I think I would tire of listening to the same music every day.

Here’s how to break down the main eight-and-a-half-minute workout:

  • Warm-up: 2 minutes
  • All-out sprint: 20 seconds
  • Recovery: 3 minutes
  • All-out sprint: 20 seconds
  • Cooldown: 3 minutes

CAROL bike app

Using different metrics, the CAROL bike app monitors your progress, including your Octane Score (how many heartbeats are necessary to generate the total power you produce during a ride) and your Peak Power (the power you generate for the resistance level set for you).

My Octane Performance had increased by 9 percent and my Peak Strength by 25 percent after eight weeks. Your heart rate or calories burned are not monitored by the app, but my Fitbit showed that my resting heart rate fell from 63 to 60 on average and my sleep score improved marginally. My weight has been the same all along.

As a result of using the bike, I would not say that I felt radically different, but it was an energetic and pleasant way to start my morning. It was nice to know that I was at least ready for some exercise on very busy days, and with less than nine minutes needed, there was no excuse not to do so.

And it is. Eight reasonably quick minutes of pedaling, and two 20-second intervals of the most challenging time imaginable on a bike. It also tells you exactly what to do, whether it’s to pedal harder and faster, or when it’s time to back down, and even when to take a big breath, through on-screen prompts.

For a few months, do that three or four days a week and you may just be in the best shape of your life. That’s the brand’s target, at least. Tailored HIIT (high-intensity interval training) exercises, such as the 15-minute Fat Burn or a longer 30-minute program if you have the time, are also available.

A few nitpicks

The CAROL bike does have one flaw: the exercise is almost too hard. That is the point, I understand (and this is likely an unpopular opinion). The bike saves time and helps you to get in a decent workout even when you’re pressed for time, but I prefer a long run or an hour-long gym class. As a result, being able to get on and off the bike in under 10 minutes makes it less appealing to me rather than more appealing.

On the other hand, if I want a longer workout session to clear my mind and enjoy an extended period of activity, I can simply go for a run or go for a long bike ride.

Another downside is that the bike isn’t exactly affordable, costing up to $3000. This puts it in the same price range as other interactive stationary bikes like Peloton or NordicTrack, so it’s not shocking if you’re looking for anything like the CAROL exercise bike.

How to get fit fast with CAROL exercise bike

As a culture, we’re always on the lookout for new methods to exercise and improve our health.

Artificial intelligence (AI) has already impacted everyday activities such as shopping, social networking, and self-driving cars in other parts of our lives, but it hasn’t yet made its way into the mainstream fitness industry…until now.

CAROL is the fitness of the future.

What distinguishes CAROL exercise bike from the competition?

CAROL is nothing short of a game-changer. It’s an AI-powered workout bike that can help you achieve your health objectives more quickly and in a scientifically precise manner.

Prior to CAROL, using AI to precisely adapt workout programs depending on the rider’s fitness demands was only possible in a scientific laboratory.

You may now benefit from laboratory-like fitness gains at home, due to CAROL. A lab would require an AI expert, specialized software, and pricey gear. CAROL does everything.

But don’t just take our word for it. “CAROL exercise bike is the only system that accurately replicates my study outside of the laboratory,” says Dr. Niels Vollaard, professor of Health and Exercise Science at Stirling University.

CAROL is not only a smaller version of the big lab cycle, but it’s also a quarter of the price.

How does CAROL get you in shape quickly?

CAROL’s self-learning algorithms adjust the resistance level in every session as you gain fitter and stronger throughout your first six sessions (called ‘calibration rides’).

CAROL exercise bike provides riders the degree of resistance required to attain maximum intensity, unlike any other indoor training bike on the market. Supra-maximal resistance must be customized to the rider’s objectives, demands, and physiology, which is impossible to do on standard cycles.

The most valuable investment in your health

CAROL exercise bike helps you lose weight and get in shape faster.

In one research, fitness improvements from CAROL exercise bike intensive and fat-burning rides were compared to standard training. For eight weeks, 28 men and women did either CAROL exercises three to four days a week or 30-minutes of moderate-intensity treadmill activity five days a week. The findings revealed that:

CAROL bike workouts are more efficient in terms of time. The total amount of time spent on regular workouts each week was 150 minutes. CAROL exercises were just 40 minutes long. That’s just about a quarter of the time commitment.

In comparison to the typical, moderate-intensity group, the CAROL group had an almost two-fold increase in fitness (12.3%). (6.9 percent )

So, if you want to be in better shape faster, go with CAROL exercise bike.

Carol exercise bike review

New 5-minute REHIT workout

Since the release of the CAROL bike in 2018, it has been able to get the health and fitness advantages of a 45-minute run in just 8 minutes 40 seconds.

This brief, effective cardio workout is based on peer-reviewed scientific research into a time-efficient alternative to regular exercise known as low effort high-intensity interval training (REHIT).

Four years later, the most recent CAROL bike upgrade allows you to reap the health advantages of REHIT in just 5 minutes. That’s right, the most efficient and effective cardio workout just became much more efficient!

How does REHIT work?

The physiological underpinning of REHIT is that high-intensity exercise causes your body to go into fight or flight mode, resulting in a 100-fold increase in energy needs. After all, your body has no concept that you’re sprinting on an AI-assisted exercise bike rather than fleeing a predator.

Because your body has no clue how long you’ll be sprinting, your muscles mobilize substantially more glycogen (stored sugar) than is necessary for two brief sprints. This quick loss of energy reserves triggers physiological changes that make you fitter and stronger. After all, you might need to run even faster and further next time to avoid the ‘predator.’

Delve deeper into the science of muscle glycogen depletion

CAROL bike is the only exercise bike that provides genuine REHIT because its AI personalizes your exercises to ensure you always reach your personal maximum intensity. Dr Niels Vollaard, a health and exercise science in sport researcher at the University of Stirling, puts it another way:

“CAROL exercise bike is the only system that accurately duplicates my research outside of the labs.” This scientific exercise cannot be performed on a standard bike because to the supra-maximal resistance necessary, which must also be customized to each individual’s physiology.”

The science  behind the new 5-minute REHIT workout on the CAROL bike

This is the structure of the REHIT protocol utilized in CAROL’s initial 8-minute 40-second Intense ride:

2 minutes of warm-up

1 – 20 seconds sprint

3 minutes of recovery

2 x 20 second sprint

3 minutes of cooling down

The physiological effects of REHIT can be traced back to the maximal effort sprint periods, according to research. That got us thinking: could the non-sprint periods be cut in half without compromising the overall health and fitness benefits?

“The health and fitness benefits of REHIT are activated by two 20-second maximal intensity sprints,” Dr Vollaard said when asked about the question. The length of the warm-up has no bearing on the efficiency of REHIT.”

Thus far, so good. But what about rest periods in between sprints? “In order to get the maximum health and fitness advantages of REHIT, your recovery time between sprints must be sufficient to allow for a powerful second sprint.”

How long is “long enough”? It is all up to you. It’s best to wait until you’ve caught your breath, but you may do it whenever you’re ready.

The cooldown timer stays at three minutes. “It’s vital for blood pressure to equalize again after the race,” says Ulrich Dempfle, CEO and co-founder of CAROL. According to research, mild pedaling accomplishes this faster than simply sitting or standing. This is due to the fact that keeping the muscles active aids in pumping blood back to the heart and hastening the clearance of ‘waste’ products from the muscle, so minimizing the imbalance between the concentration of such particles inside and outside the muscle cell.”

To conclude, the health advantages of REHIT are found in the sprints at maximal effort. And, although cooldown is necessary to ensure your body returns to normal before getting off the bike, warm-up time has no bearing, and recovery phase duration is unique to you.

Should you purchase CAROL exercise bike?

Yeah, as long as you assume you’ll really need it. Don’t bother if it’ll sit there untouched one week, rode four times the next, and then untouched for a month. You know yourself, so be truthful – the whole plan relies on your dedication. That said, if you can spare nine minutes three times a week, go for it.

What are your alternatives?

This is a unique system given the amazing efficiency of the workout but there are other HIIT bikes out there that will give comparable results if you’re willing to spend a bit more time. A BlueFin bike is a fine alternative, especially if you like the idea of riding with others in a class.

If you want the same intense workout but don’t like stationary biking, a smart rower like Hydrow or Ergatta will build personalized workouts based on your health and goals, and row machines are a fantastic way to get a full-body workout.

Carol exercise bike review

Carol exercise bike review

The bottom line of CAROL exercise bike

CAROL manages to transform exercise into something akin to popping a pill – fast, easy, and relatively painless – while still providing the minimum effective dose needed for cardiovascular health, according to some studies. In some ways, it’s the fitness equivalent to drinking Huel: a reasonable choice for those who don’t have the time or desire to exercise, but unlikely to bring much value to those who do, but unlikely to add much extra value for people who like to exercise and already fit in several workouts each week.

The Carol bike’s main drawback is its cost, which is higher even than a Peloton.

I enjoyed using CAROL exercise bike and was pleased with the results, particularly since they were accomplished with just a half-hour of exercise per week that didn’t even make me sweat. I’ve never had a workout as effective as the one offered by this bike. It’s an awesome workout that’s impressively successful for your legs and cardiovascular system, despite the fact that it doesn’t do much for your upper muscle groups or heart.

If you’re looking for an interactive stationary bike that offers a wholly different approach to what’s currently available, CAROL delivers.

What does Carol bike workout stand for?

Why you should buy a Bluefin Fitness Tour 5.0 Exercise Bike? Our Review

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