High-Intensity Interval Training, or HIIT is a popular training method among  athletes, including cyclists and runners, who want to make the most of their training time. In this article, we bring you the top 5 HIIT workouts for endurance athletes and guide you on choosing the training methods that suit your needs the best.

By Loek Vossen

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Understanding HIIT Training

HIIT, the acronym for High-Intensity Interval Training, encompasses various training methods that alternate between high-intensity exercises and recovery periods. By allowing recovery in between high-intensity efforts, HIIT lets you spend more time at elevated intensities, making it an effective strategy for enhancing endurance.

In the context of intensity training, HIIT is a counterpart to continuous endurance training. A typical HIIT workout session lasts less than an hour, Often even much shorter as we will see with some of our example HIIT workouts.

The high-intensity aspect of HIIT is not strictly defined. It makes sense to include all intensities above steady-state, which are by definition not possible to maintain for a long time.

Some differentiate between HIIT vs SIT (sprint intensity training). When comparing HIIT to SIT, HIIT is about near maximal or submaximal efforts, where SIT insinuates maximal or all-out intervals. In this article we will not differentiate between HIIT and SIT.

Lastly, it’s good to mention the subtle difference between high-intensity interval training vs high-intensity intermittent training (both HIIT):


  • Interval training uses low intensities to recover from the high intensities
  • Intermittent training uses complete stops (full rest) to recover from high intensities.

However, most of the time – as in this article – the specific type of HIIT becomes clear when talking about the workout itself.

For a succinct explanation of interval training and how to effectively implement it in workout regimen, we’ve prepared a short video. This clip offers an overview of the key principles of interval training and gives you a taste of how to leverage it for fitness goals. Watch the brief video below:

If you found the quick explainer helpful and want to dive deeper into the science and physiology behind interval training, we have an extensive webinar for you. This comprehensive session, presented by an expert, provides in-depth understanding of creating effective interval training programs based on an individual’s physiology. It also thoroughly discusses the different aspects of interval training, such as intensity, duration of on and off phases, and how these factors influence the overall training outcome.

So far the theory, let’s dive into practice!

Are Longer or Shorter Intervals Better for HIIT?

According to a recent study, shorter intervals are better than long intervals. At least in elite cyclists.

However, as a coach or athlete, you understand that this statement needs some nuance. You first need to know the physical demands of your goal and your current metabolic profile, before you even know what to improve.

Only once you know what to work on, you can decide on the best training method to do so.

To decide whether longer or shorter intervals will work best for you, here are a few steps to consider:

  1. Understand the physiological demands of your goal
  2. Get to know your current metabolic profile
  3. Compare your goal with your current profile and learn what to work on
  4. Decide whether longer or shorter intervals make more sense, using this article
  5. Implement the intervals in your training program
  6. Track whether these intervals work for you, by performing regular performance tests.

Whether you prefer a lab test with spirometry, a field test with lactate samples, a remote test based on power (cycling) or GPS (running) only, a self-made test or a combination of these tests, INSCYD can do it.

INSCYD offers a comprehensive suite of tools to design effective and individual HIIT workouts tailored to your athletes’ unique metabolic profiles and goals. 

As a coach or lab, book a free consultation in your own language with our INSCYD Expert today. Discover how we can help enhance your athletes’ performance.

Let’s have a look at the 5 most iconic HIIT workouts, starting with short intervals and slowly working towards longer intervals.

Tabat intervals are popular among many athletes, from runners to cyclists to strength athletes in the weightroom. Due to the popularity and the application in all kinds of sports, the exact training protocol has blurred over time.

The original Tabata workout – created by Dr. Izumi Tabata – takes less than 4 minutes. It consists of 7-8 near all-out intervals of 20 seconds, with 10 seconds rest between each interval. That’s it.

Example original Tabata interval workout
Example original Tabata interval workout: 8x20s at 170% VO2max, 10s recovery in between intervals.

It’s probably the shortest HIIT training you’ve ever seen, but its effectiveness was already shown in the first scientific publication in 1996. If you want to boost both your VO2max and your anaerobic power in no-time, Tabata’s should be on your list.

Learn more about the practical application of Tabata intervals and their scientifically proven benefits in our Tabata article.

2. 40-20’s: A HIIT Workout

40/20’s and 30/30’s are named after their work-to-rest ratio: 40 seconds ON, 20 seconds OFF. Recent scientific research showed that these short HIIT intervals induce superior training adaptations in elite cyclists, compared with long intervals lasting 5 minutes.

Contrary to the Tabata workout, 40-20 intervals don’t have a set in stone workout protocol. As a result, you need to decide on the intensities, number of intervals and sets yourself. 

In our full 40-20s Intervals article, we’ll talk more about the best work-to-rest ratio for interval training.

Example 40-20s interval workout
Example 40-20s interval workout: sets of 10x40s at 120% anaerobic threshold, 20s recovery in between intervals.

After only 9 HIIT sessions of 30s ON 15s OFF (similar 2:1 work to rest ratio as 40/20 intervals), elite cyclists significantly increased their:

  • VO2max from 73.3 ml/min/kg to 75.5 ml/min/kg
  • Mean power output during the last minute of the incremental VO2max test from 460 to 476 watts
  • 20-minute power (FTP) from 343 to 358 watts

Learn whether you should do similar HIIT intervals in your training via our full 40-20’s article.

3.VO2max Intervals: Increasing Your Aerobic Power

VO2max intervals are designed to – drum roll – increase your VO2max (aerobic power). Although there are numerous ways to increase your aerobic power, as we’ve already seen with Tabata’s and 40-20’s, VO2max intervals typically last about 5 minutes.

Example VO2max interval workout
Example VO2max interval workout: 4x5min. at 100% VO2max power, 5 minutes recovery in between intervals.

Since there are all kinds of VO2max intervals that increase VO2max, it can be hard to choose which is best for you. To answer this question, you should know what other training adaptations you would like to have too. For instance: would you like to increase or decrease your anaerobic energy contribution, besides increasing VO2max?

Learn how to choose your personal, most effective VO2max interval intensity, regardless of the sport you are in. Receive guide with a video that explains you how to determine the VO2max interval intensity.

While VO2max is traditionally measured in a lab setting, there are ways to calculate and measure VO2max outside the lab.

Learn about the ideal interval duration for VO2max intervals, depending on your specific goal. Read our comprehensive guide about science, benefits and workout of VO2max intervals.

4.Over–Under Intervals: An Alternative to Steady (Threshold) Intervals

Over-under intervals are an alternative to steady (threshold) intervals. They alternate intervals above anaerobic threshold (AT) with intervals below AT, without recovery in between. The idea is to accumulate lactate during the “over”, and clear lactate during the “under”.

Example Over-Under interval workout
Example Over-Under interval workout: 2 sets of 4x2min. at 105% AT, 4x1min. at 95% AT. 5 minutes recovery in between intervals.

Many beneficial training adaptations have been attributed to over-under HIIT intervals. Think improvements in: lactate tolerance, lactate clearance, lactate shuttling, lactate buffering. Don’t use your FTP value when creating over-unders.

Understanding how power is composed can be beneficial for your training. We have a comprehensive article on how power is composed, which can help you better understand the dynamics of power in endurance sports and how to leverage it in your training.

In our full guide about over-unders, we talk more about whether this is true. We also share mistake and practical steps on how to create over-under interval workouts, because it’s easy to mess up this workout with intensities that are too easy or too hard. Spoiler: don’t use your FTP value when creating over-under intervals workout.

5.Peak and fade (pre loaded) intervals

Last but not least, HIIT intervals that elite cyclists call their secret training. Peak and fade intervals start at a high intensity and gradually become more doable. They can range from Wingate-like 30-second intervals to pre loaded intervals that can easily take more than 10 minutes. As a result, the training adaptation can differ a lot between these HIIT workouts.

Example of pre loaded peak and fade intervals
Example of pre loaded peak and fade intervals: 3 sets of 20s near all-out, 8min at 100% AT. 5 minutes recovery in between intervals.

In the full peak and fade article, we cover the benefits of different peak and fade intervals.

Last but not least, HIIT intervals that elite cyclists call their secret training. Peak and fade intervals start at a high intensity and gradually become more doable. They can range from Wingate-like 30-second intervals to pre loaded intervals that can easily take more than 10 minutes. As a result, the training adaptation can differ a lot between these HIIT workouts.

Maximize HIIT Workouts

As we’ve explored various HIIT workouts, it’s clear that understanding an athlete’s unique physiological profile is crucial for tailoring effective training programs. This is where INSCYD – platform for physiological performance analysis, can be a game-changer.

INSCYD provides a comprehensive analysis of your athlete’s performance metrics, helping you tailor your HIIT workouts for optimal results.

Moreover, INSCYD’s unique feature of performance projection can predict how improvements can impact an athlete’s future performance. This can guide coaches in focusing on the most impactful areas during training.

If you’re a coach, lab or an athlete looking to take your training to the next level, consider leveraging INSCYD’s advanced features. It’s not just about training harder; it’s about training smarter.

HIIT training: wrap up

With these 5 iconic HIIT workouts you can directly start training. If you first want to learn more about the physiological background of these workouts, we highly recommend reading the more in-depth articles, using the buttons above.

If you truly want to become a HIIT expert, it’s important to understand the fundamentals of how your body generates energy via our 3 energy systems. Once you understand these fundamentals, you immediately know what type of HIIT workout works best for achieving your goals.

Our comprehensive education platform bridges the gap between complex sports science and its real-world application, providing practical, science-based education for athletes and coaches at different levels.

With a vast library of in-depth sports science courses led by industry experts, INSCYD College simplifies complex sports science concepts and translates them into actionable insights. Plus, our unique business growth courses and certification opportunities can help coaches enhance their career development and grow their businesses.

Master the fundamentals via our education course: Muscular Energy Metabolism

Join INSCYD College today and start translating science into actual performance enhancements.


What is an example of high intensity interval training?

An example of high intensity interval training is Tabata intervals or 30-30 Billat intervals. These intervals are short and high in intensity. 

Is a 20 minute HIIT workout enough?

Yes, a 20 minute HIIT workout is enough to increase VO2max and anaerobic capacity. There are even 4 minute HIIT workouts that are scientifically proven to improve sports performance. These workouts help amateurs to become fit, and even increase performance of elite athletes, when added to their training program. Of course the training adaptation differs per person, depending on your current training status (among others).

What is considered high-intensity workout?

A high-intensity workout is considered to consist of intervals that are so high in intensity that you’re not able to maintain them for a long time. These high-intensity intervals are alternated with recovery. This enables you to do multiple HIIT intervals. 

How long should high intensity intervals be?

High intensity intervals should be between 10 seconds and 5 minutes long. Of course you can use shorter or longer intervals, for instance during an over-under interval. If your intervals are too long though, it’s impossible to perform them at a high intensity.

What is the difference between HIIT and high intensity?

There is no difference between HIIT and high intensity, since the abbreviation HIIT stands for high intensity interval training. So yes, high intensity is the same as HIIT. 


Long vs short intervals

Rønnestad, B. R., Hansen, J., Nygaard, H., & Lundby, C. (2020). Superior performance improvements in elite cyclists following short-interval vs effort-matched long-interval training. Scandinavian journal of medicine & science in sports, 30(5), 849–857. [LINK

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