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The complete guide to CAROL Bike workouts

CAROL Bike revolutionizes home fitness with 20+ diverse, science-backed workouts, including the time-efficient REHIT series and calorie-torching Fat Burn sessions. Tailored for all fitness levels, these AI-personalized routines maximize results in minimal time, redefining home exercise efficiency.

In the quest for peak health and fitness, time is often the biggest challenge. CAROL Bike addresses this by offering a variety of scientifically-proven workouts, each tailored to maximize fitness gains in minimal time. Developed in collaboration with top exercise researchers like Dr. Niels Vollaard and Prof. Lance Dalleck, CAROL Bike’s AI-personalized workouts learn to push you to your limit, so every second matters. Let’s explore the diverse workout range that makes CAROL Bike a game-changer in home fitness.

Diverse workout options on CAROL Bike

Here our co-founder introduces the workouts available on CAROL Bike.

CAROL offers a range of 20+ science-backed workouts, continuously evolving with new research. Here’s a breakdown of what you can expect from CAROL Bike workouts:

Revolutionary REHIT workouts

An insight from our co-founder into our signature REHIT workouts.

CAROL Bike’s flagship is its range of REHIT (Reduced Exertion HIIT) rides. These workouts are the pinnacle of time-efficient training, delivering maximum fitness benefits in minimal time. They are the shortest, most effective cardio—that can be done in just 5 minutes. The REHIT rides are scientifically validated and inform the AI-personalization of all other workouts.


The key with REHIT is that you go all out during the sprints. If you find the signature Intense workout too hard, build your fitness first with the alternative REHIT rides.

REHIT Intense (2x20-second sprints)

This is CAROL’s signature ride. In just 5 to 8:40 minutes, it involves 2×20-second sprints with a low-intensity warm-up and cooldown. This workout is proven to improve cardio fitness by 12% and reduce type 2 diabetes risk by 62% in just 8 weeks.

REHIT Intermediate (2x15-second sprints)

A slightly less intense version, delivering around 70% of the fitness benefits of the Intense variant in a more manageable package. The duration of REHIT Intermediate is 4:50 – 8:30 minutes, depending on the length of your warm up and recovery.

REHIT Intermediate (3x15-second sprints)

Similar benefits to the Intense version but with a lighter workout feel, making it suitable for those seeking a balance between challenge and manageability. Despite having a larger overall sprint volume than REHIT Intense (45 vs 40 seconds) and eliciting a similar physiological stress (peak heart rate), and therefore also presumed training stimulus, the 3×15-second REHIT Intermediate workout might be a great choice for you if 2×20-second sprints feel too tough and 2×15-second sprints not challenging enough. The duration is 6:05 – 10:45 minutes, depending on the length of your warm up and recovery.

REHIT Energizer (2x10-second sprints)

Offers a substantially easier option, but still delivers around 40% of the Intense workout’s fitness benefits. The duration is 4:40 – 8:20 minutes, depending on the length of your warm up and recovery.

REHIT Energizer (3x10-second sprints)

Presumed to deliver similar fitness benefits as REHIT Intermediate but in a much lighter workout. This workout might be a great choice for you if 2×15-second sprints feel too tough and 2×10-second sprints not challenging enough. The duration is 5:50 – 11:30 minutes, depending on the length of your warm up and recovery.

These workouts, while varying in intensity and duration, are all designed to maximize your fitness gains with minimal time commitment, ensuring adherence and sustainability. While 5 seconds sounds like a really marginal difference, it can actually make a world of difference.  Where 2×20-second sprints could be a bit challenging, 2×15-second sprints may feel much less taxing, and 2×10-second sprints feel easy and energizing—and this is confirmed by the emotional response data we gather from our users. While the REHIT Energizer with 2×10-second sprints, for example, is of course less effective than REHIT Intense with 2×20-second sprints, ultimately adherence is everything.

Fat Burn series: HIIT reinvented

Discover why these rides should be your go-to workouts for weight loss.

These sessions, which are much closer to traditional HIIT on an exercise bike, focus on shorter sprints but more repetitions. Ranging from 10 to 25 minutes, these workouts consist of multiple 8-second sprints and are scientifically proven to burn twice as many calories as moderate-intensity exercise—making them ideal for those targeting fat loss. The resistance level is linked to your personal, optimized resistance set through the REHIT workouts.


If fat loss is indeed your main objective and you are seeking workouts at home to lose weight, we recommend adding 1—3 Fat Burn rides to your baseline of 2 REHIT rides per week.

Fat Burn 30

Consisting of 30×8-second sprints, this workout is a 10 to 15-minute session focused on burning calories efficiently.

Fat Burn 45

With 45×8-second sprints, this 14 to 20-minute workout ups the ante for those seeking a more intense calorie-burning session.

Fat Burn 60

The most challenging of the series, featuring 60×8-second sprints over 17 to 25 minutes, offering the highest calorie burn.

Free and Custom rides: Flexibility at its finest

Discover the flexibility of CAROL Bike with our Free and Custom rides.

For those who prefer a more traditional workout experience, CAROL offers Free and Custom rides, allowing for a conventional exercise bike feel with direct resistance control or power output targets. This includes:

Free Ride

Use CAROL like a conventional exercise bike with direct resistance control. 

Constant Power Model

Similar to Free Ride, however instead of controlling the resistance yourself, you choose a target power output and the bike will adjust the resistance accordingly, so that you produce a constant power regardless of your pedal speed. 

Zone-Based Training

This mode allows you to train within specific power and heart rate zones, a method that has recently gained significant popularity. You have the option to either let the bike automatically control the resistance to maintain your desired zone, or you can manually adjust the resistance while monitoring which zone you’re in. This feature makes CAROL an ideal platform for those who prefer structured zone-based training, especially focusing on Zones 2 and 5.

Sprint Interval Training

These include: 

    • 10×6-Second Sprints: Perfect for those who prefer short but intense bursts of activity. 
    • 3×20-Second Sprints: Ideal for those seeking a higher challenge level. 
    • 30×4-Second Sprints: Offers a unique blend of intensity in a compact timeframe.

Each of these workouts is backed by solid scientific research, providing effective alternatives to the standard REHIT rides. Whether you’re looking for a heightened challenge or prefer maximum intensity over shorter durations, these additional options on CAROL Bike cater to a wide range of fitness needs and preferences.

Fitness Tests: Measuring your progress

Easily and effectively track your progress and performance—here’s how.

At the core of CAROL Bike’s innovative approach is the inclusion of comprehensive Fitness Tests, designed to provide an accurate assessment of your aerobic fitness levels. Each REHIT ride on the bike gives you a Fitness Score, offering a precise way to track your progress. These scores are based on your performance during the anaerobic sprints, focusing on how quickly your heart rate escalates and recovers. 


However, the Fitness Tests on CAROL Bike delve deeper, evaluating your aerobic exercise capabilities. These tests help you determine three key metrics:

Functional Threshold Power (FTP)

This is the highest power you can maintain consistently for an hour. While it’s challenging to measure directly, CAROL Bike simplifies this by estimating your FTP based on either a 20-minute continuous effort or two 8-minute sessions. 

Maximum Aerobic Power

Measured through the Ramp Tests, where the bike increases the resistance gradually, pushing you to your limits over a period of 7-15 minutes. This method mirrors laboratory protocols for determining VO2max.

Estimated VO2max

The latest feature is the submaximal VO2max  test, which is relatively easy to perform. After warming up, you cycle for 6 minutes at a specific power level set by the bike, allowing it to estimate your VO2max and FTP based on your heart rate response.

These metrics are vital, especially if you’re following a Zone 2 and Zone 5 training approach, as they define your power zones. Although challenging, these Fitness Tests are integral to understanding your aerobic fitness and setting precise training goals. 


Moreover, for those seeking detailed fitness tracking, some commercial CAROL Bike users couple the Ramp Test with a gas analyzer for an exact VO2max measurement. This level of precision makes CAROL Bike not just a tool for fitness enthusiasts but also a valuable asset for professional settings.

Third-party integrations: Versatility at its best

Explore the wide range of third-party apps compatible with CAROL Bike.

CAROL Bike stands out not just for its specialization in REHIT workouts but also for its remarkable versatility. It seamlessly integrates with a host of popular third-party apps, expanding its utility and appeal to a broader audience. Whether you’re looking to combine fitness with entertainment or seeking a more interactive cycling experience, CAROL has you covered. 


For those who enjoy entertainment while working out, CAROL Bike is compatible with favorite streaming platforms like Netflix, Disney+, YouTube, and various news channels. You can easily adjust the resistance or target power while watching, using the overlaid controls on the bike’s screen. 


For a more immersive cycling experience, CAROL Bike works effortlessly with Peloton Digital. This app can be installed directly from the Google Playstore, allowing you to participate in a wide range of Peloton’s renowned cycling classes. 


Cycling enthusiasts will appreciate CAROL Bike’s compatibility with popular cycling apps such as Zwift, Kinomap, and Rouvy. In Zwift’s ERG mode (target power mode), the app takes full control, adjusting the bike’s resistance automatically. Alternatively, in Zwift’s SIM mode, the resistance changes in response to the virtual terrain’s gradient, offering a realistic cycling experience right from your home. You can even virtually shift gears to suit the changing landscapes of your chosen route in Zwift. 


This extensive range of third-party app integrations highlights CAROL Bike’s adaptability. It’s an ideal feature, especially in households where multiple individuals with varying fitness interests and goals use the bike. CAROL Bike successfully combines the rigor of specialized workouts with the flexibility and enjoyment of interactive and entertaining cycling experiences.

Workout recommendations: Tailoring your fitness journey

Get direct advice from our co-founder on how to tailor your regime for your personal goals.

With CAROL, your fitness routine is personalized. Whether your goal is improving cardiorespiratory fitness, weight management, or endurance, CAROL has a workout for you. 


Navigating CAROL Bike’s extensive workout options raises the question: How do you tailor an optimal workout program to suit your needs? The key to crafting the perfect exercise regimen lies in 2 essential questions: How much time can you dedicate to cardio each week, and what are your fitness goals?

Time-efficient workouts with REHIT

For those with limited time or a preference for shorter cardio sessions, REHIT emerges as the ideal choice. These workouts, which can be as brief as 5 minutes, should ideally be performed 2 or 3 times a week. If your focus is primarily on enhancing cardio-respiratory fitness, 2x REHIT rides weekly are generally sufficient according to recent studies. To achieve comprehensive metabolic health benefits, 3x weekly sessions are advisable. Even daily REHIT rides are beneficial and pose no drawbacks. 


So, with your base covered with REHIT, consider your goals:

Weight management

For those focusing on weight management, integrating 1 to 3 Fat Burn rides each week is ideal. These intense HIIT sessions are not only challenging but also remarkably effective, burning twice the calories of standard exercises in the same amount of time. 


If you’re aiming for enhanced longevity and have more time to dedicate, adding 2 to 3 extended sessions weekly, each lasting 60 to 90 minutes at a lower intensity in Zone 2, is beneficial. Zone 2 training, endorsed by health experts like Dr. Peter Attia and Prof. Andrew Huberman, has become increasingly popular for its profound health benefits. CAROL Bike facilitates this with its versatile Zone 2 training options, both in free ride mode and through compatibility with various third-party streaming and cycling apps.

Fitness tracking

For those keen on detailed fitness tracking and quantification, engaging in the Fitness Tests available on CAROL Bike periodically can provide valuable insights. And if your priority is to stay entertained while staying active, you can join group cycling classes through Peloton Digital, or enjoy your favorite shows on platforms like YouTube, Netflix, or Disney+ during your ride.


Remember, a well-rounded exercise program should include not only cardio and endurance training but also incorporate strength and mobility exercises for comprehensive fitness.

A fitness revolution at home

Whether you’re an avid fitness enthusiast or someone squeezing in workouts between busy schedules, CAROL offers scientifically proven, effective workouts that fit into your life effortlessly. It’s not just about exercise; it’s about optimizing your time and effort for the best possible results. With CAROL, witness a paradigm shift in home workouts, where every minute counts, and every workout moves you closer to your health goals.


Explore the ultimate CAROL Bike resource: Uncover everything from how CAROL Bike helps build fitness habits, to exclusive revelations about the unique design and CAROL’s fitness-transforming capabilities.

Got a question? Let's book a call.

All our experts have MSCs in Exercise Science, and they’re here to answer your questions. Whether it’s about the science behind CAROL Bike, or general fitness advice, whatever’s on your mind—we’re here for you.

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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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.

What is a REHIT workout?

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

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