Biohacker's Blueprint guide: Discover 8 hacks for optimal fitness. DOWNLOAD NOW.

Less pain, more gain: Redefining the rules of exercise

Supramaximal sprint interval training (SIT) with just 2x20-second sprints effectively improves cardiovascular fitness, challenging the "more is better" mindset.

Breaking the assumption that more exercise yields greater results, high-intensity interval training (HIIT) has revolutionized fitness by delivering exceptional health benefits in less time compared to traditional aerobic exercises.

Research has revealed that significant improvements in cardiovascular fitness can be achieved with just a few high-intensity sprints in a specific form of HIIT – supramaximal sprint interval training (SIT). Questioning the notion of “more exercise leads to better results.”

The significance of cardiovascular fitness​

Improving cardiovascular fitness, measured by maximal oxygen uptake (VO2max), is one of the most impactful things we can do for our health. The higher your VO2max, the fitter and healthier you are.


In addition to boosting performance, research shows that high VO2max can increase longevity along with additional health benefits. In fact, improving your VO2max by just 12% is like turning your body clock back 10 years.

Studies show that having a high VO2max leads you to live longer and improve your health.​

The power of SIT

Supramaximal sprint interval training (SIT) involves short bursts of maximum effort activity followed by a longer rest period. This form of training has been found to be highly effective in improving VO2max, especially for individuals with lower baseline VO2max.



In fact, a meta-analysis of 34 studies and 38 trials reveals the impact of SIT on VO2max improvement. The analysis confirms that performing SIT results in a significant overall improvement in VO2max, but found a surprising twist when the number of sprint repetitions increased.



Performing more sprint repetitions did not enhance the improvement in VO2max—in fact, it reduced the effect. Findings showed that performing just 2x maximal 20-second sprints was very effective in improving VO2max. But then, for every extra sprint completed, the improvement in fitness is reduced by around 5%. This may seem like a small amount, but it quickly adds up. By the time you’ve done 7 sprints you’ve already lost 25% of the possible improvement.



This groundbreaking research suggests that SIT protocols with fewer sprint repetitions, such as the 2-sprint protocol, can effectively boost VO2max while providing incredibly time-efficient interventions. These findings indicate that as little as 10 minutes of exercise can yield significant health and fitness benefits. It’s a revolutionary approach that challenges the long-held belief that extensive workouts are necessary for optimal results.

The CAROL Bike advantage​

Developed alongside leading exercise researchers, CAROL Bike delivers the shortest, most effective workouts. Its signature Reduced Exertion HIIT (REHIT) ride adopts the SIT approach with just 2×20-second sprints provides the optimal cardio workout. No need for excessive training—just 2 sprints provide a powerful training stimulus.

CAROL Bike delivers the shortest, most effective workouts—backed by science.

Just 2x20-second sprints can effectively boost VO2max while providing incredibly time-efficient interventions.

Looking ahead

Further research is needed to fully understand the mechanisms underlying these findings and explore the impact of SIT. One possible reason could be that participants might not exert maximal effort in initial sprints if they anticipate additional repetitions, as discussed in our article on how to make exercise a habit.


Exercise remains integral for improving fitness and reducing chronic disease risk. However, research suggests that the amount of exercise required may be less than commonly assumed.

CAROL Bike embraces this concept, giving you the shortest, most effective workouts—AI-personalized for any age and fitness level. So you can get maximum health and fitness benefits in the shortest amount of time.

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 these workouts, or the science behind CAROL Bike, 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.

Maximum Metabolism

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

Time to thrive

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

What is a REHIT workout?

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

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.

Boost your brainpower

Get fit, stay sharp: how high-intensity exercise and BDNF benefit your brain.

12 benefits of cycling

Regular cycling can help strengthen your heart and lungs, reduce the risk of certain types of cancer, and more.

Scroll to Top