Powerful or Endurant: calculate your endurance index to progress!

In long-distance sports (triathlon, trail, marathon, cyclosport events, etc.), VO2max*, MAP** or MAS*** are often referred to as essential references for endurance performance. These references that may be of interest for training are only one piece of the puzzle and cannot explain the endurance performance as a whole.

Indeed, athletes with an identical MAP or MAS do not necessarily have the same performance on a long-duration event. It would be too simple because it would be enough to have the MAP/MAS of the athletes before a race to be able to establish the ranking. In the reality of the field, we know that performance is much more complex! In other words, the MAP or MAS are insufficient indicators to determine athletes’ performance in long-term events.

The Endurance Index, the central index of endurance performance

Having a high MAP or MAS is good, but if you are not able to maintain a high % of this value over a long period of time, your performance will not meet your expectations. This is the whole principle of endurance that we will discuss in detail!

Endurance can be defined as an athlete’s ability to maintain a high intensity while minimizing its decrease as the duration of effort increases. An athlete with a high level of endurance will thus be able to achieve better performance than an athlete with higher MAP/MAS values but with low endurance.

To assess your endurance we have developed the endurance index which corresponds to the ratio between:

Indoor bike

  • Your best performance on 20′ and your best performance on 5′.

Flat outdoor bike

  • Your best performance on 20′ and your best performance on 5′.
  • Or your best performance on 60′ and your best performance on 20′.

Uphill outdoor cycling

  • Your best performance on 20′ and your best performance on 5′.

Indoor running

  • Your best performance on 20′ and your best performance on 5′.

Flat outdoor running

  • Your best performance on 20′ and your best performance on 5′.
  • Or your best performance on 45′ and your best performance on 20′.

Uphill outdoor running

  • Your best performance on 20′ and your best performance on 5′.

Each athlete therefore has his or her own endurance index, which is expressed differently according to the context of the exercise (indoor vs outdoor, flat vs uphill) and the duration of the effort.

Indeed, powerful athletes will often have a better performance over 5′ while endurance athletes will have a lower decrease in intensity with the extension of the duration of effort. For example, a rider may have a high endurance index on the flat while in a uphill he will have a low endurance index and conversely for the climber who will have a high endurance index in uphill and low endurance index on the flat.

The Endurance Index is a training-related individual approach that helps to determine your endurance profile and guide you in choosing your training sessions based on your strengths and weaknesses.

The optimal endurance index:

  • Ratio 20′ / 5′: between 85 and 89.9%.
  • Ratio 60′ / 20′: between 92 and 97%.

Let’s take some concrete examples to understand how the endurance index works

Some athletes may have balanced profiles. Here is an illustration with the ratios 20’/5′ and 60’/20′ of the same athlete.

For this type of athlete, because of his endurance index, a mixed work between critical intensity (Z2) and high intensity (Z3) can be interesting to progress and pass an additional level.


On the other hand, other athletes may have unbalanced profiles with an optimal 20’/5′ ratio and a 60’/20′ ratio with a low endurance index. Example below for the same athlete.

For this athlete profile, training can be directed towards work at critical intensity over a prolonged period in order to improve mechanical performance and help him to maintain a high intensity over a long period of time.


Caution! A low or high endurance index may also indicate that performances are not representative of the reality and that it would be appropriate to update them.

On this example, we see that the best performance over 5′ is very close to the best performance over 20′. It is therefore certainly advisable to carry out a 5′ performance test to ensure that the endurance index is consistent. If this is consistent, the orientation of the training can focus on high-intensity work in Z3.

In this example, the athlete who has performed his performance tests on a home trainer at maximum intensity shows a strong lack of endurance. In his case, it will be a question of working with intervals in Z2 of a duration >8′ to help him maintaining a high intensity over a long period. When the ratio 20’/5′ is in favour of 5′ then it will be appropriate for the athlete to use the RPE (the rate of the perceived exertion) to define his effort intensities because they will often be low in regards of the break in the curve intensity-time.


How to use the Endurance Index feature?

Go to the “Performance profile” page and then go to the “Endurance index” tab.

You will have the choice to calculate your endurance index according to the discipline (cycling or running), the context (indoor, outdoor flat, outdoor ascent) and the date on which your best performances have been achieved.

To help you use this feature properly, we have placed various tips that you can discover by clicking on the ”?”.

Depending on your endurance index, chosen discipline and context, you will then obtain a 4-week training program that has been specially designed to allow you to progress on your weak point. You can also choose whether you are “trained” or “very trained” to get sessions with more or less volume at high intensity. Then click on “schedule these sessions” to integrate them into your training calendar, and drag-drop them.


Special case of triathlon

Triathlon is a special discipline because you can have a low endurance index in indoor cycling, moderate in outdoor cycling and high in flat outdoor running.

You cannot reasonably perform HIT sessions in every conditions. We have therefore created a short tutorial to guide you through the layout.


You now have all the keys to build your program over 4 weeks in order to progress on your weak point(s).

We wish you a good training with this new Premium feature – available on the WEB App – and we hope it will meet your expectations.

To subscribe to the Premium package click on this link if you already have a GUTAÏ account => https://apps.gutai.training/athlete/payment/profile or create your account by clicking on this link => https://apps.gutai.training/login

(*) maximum volume of oxygen that can be used at the muscular level during exercise

(**) best power over 5′.

(***) best speed over 5′.