The way training zones are determined and used hasn’t changed for decades, as if nothing happened in sport science lately. It’s time to throw them out of the window and start creating training zones that actually matter. Let’s start right away.

Infographic - Why you should stop using FTP or anaerobic threshold (AT)


Currently, most coaches create training zones based on…

  • A percentage of anaerobic threshold or FTP (Functional Threshold Power)
  • A certain lactate value
  • A certain personal best expressed in pace/speed
  • Maximum heart rate

For example, a typical endurance heart rate training zone could be between 70% – 80% of maximum heart rate. A VO2max training zone could be between 105% – 120% of anaerobic threshold / FTP.

Let’s quickly look at the most important reason why you should not use these kind of training zones.

This is best explained with an example. Let’s use the VO2max training zone based on a percentage of anaerobic threshold / FTP (for some known as training zone 5).

The thing is: at a training intensity of 120% of FTP, one athlete can be 10% below his/her VO2max intensity while another athlete can be 10% above his/her VO2max intensity. In other words, the relationship between FTP and VO2max is not a fixed relation that can be expressed in a percentage. It differs per individual:

Athlete A

  • 120% FTP
  • 90% VO2max power

Athlete B

  • 120% FTP
  • 110% VO2max power

In this example, it becomes clear that athlete A and B will have a different training stimulus on the aerobic energy system when they both ride at the same percentage of FTP. So if you want to create a VO2max interval in which the athlete exercises at an intensity close to the VO2max power, the intensity should not be based on a percentage of FTP / anaerobic threshold.

A VO2max training zone based on %FTP is just an example of how you should not plan training. Other examples could be: a FatMax training zone based on a lactate concentration; a VLamax training zone based on pace/speed; an endurance training zone based on a percentage of maximum heart rate.

It only takes a small step to improve those training zones.


Now that we’ve seen how we should not create training zones, it’s easy to understand how we should. Simply use the master metric (the physiological value that is used to calculate the intensity) that is related to your training goal:

Do you want to create VO2max intervals? Base the training zone intensity on a percentage of VO2max.

Do you want to create intervals in which the athlete burns a lot of fat? Base the training zone intensity on (a percentage of) FatMax.

Do you want to create a training zone that elicits a high energy contribution from the anaerobic energy system? Base the training zone intensity on a percentage of anaerobic energy contribution.

Last example: do you want to create an endurance training zone that your athlete can sustain? Base the training zone intensity on a carbohydrate combustion rate of (e.g.) 60 grams per hour.

In other words, describe training zones based on the master metric that you want to focus on, instead of some unrelated parameter. To be clear: you still want the unit of intensity (reference) to be in speed, pace or power.

FatMax training zone
Here’s an example of how INSCYD coaches are already used to working with training zones based on a master metric. For instance: the intensity of the FatMax training zone (zone 4) is based on... FatMax.

Since the INSCYD software provides you with many master metrics after performing an exercise test, it’s easy to create your own training zones based on a master metric of your choice. But wait, there is more! Even if you want to stick to your current training zone…


Having training zones based on master metrics is great, but do you really know what actually happens in the body of your athlete when exercising at that intensity? Now you can!

With the INSCYD Training Zone Builder, you can add additional information. For instance, when you create a FatMax training zone (like the famous training zone 2) based on the actual FatMax intensity, you may also want to know:

  • The fat combustion in grams per hour: how much fat is my athlete actually burning?
  • The carbohydrate combustion in grams per hour: how much should your athlete fuel to maintain this intensity for a longer amount of time?
  • The total energy expenditure in kcal per hour: how much energy will this training cost and how much should your athlete refuel to maintain (or modify) body composition?
  • The percentage of VO2max at this intensity: how much does your athlete trigger the aerobic energy system?
INSCYD Training Zones
Example FatMax training zone based on [90% - 100%] FatMax intensity, with additional metrics at steady state. VO2max training zone based on [90 – 110%] VO2max-power, with additional values after 180s.

The training zones and additional output metrics are all based on the metabolic profiles of one athlete. Therefore they are highly individual.

Here’s a video example of how easily you can create such a training zone:

For training zones that do not cause a steady state, like VO2max intervals, you may want to add:

  • Lactate concentration after 200 meters (swimming zone)
  • Aerobic energy contribution after 1 km (running zone)
  • Carbohydrates burned after 20 minutes (cycling zone)

This enables coaches to know exactly how much impact a training session has on the athlete. Even before the training is executed.

Ready for a step-by-step guide to start creating these kind of training zones? Check out this article: INSCYD launches a revolutionary training zone builder. Current INSCYD users can also use our help center.

Watch the Training Zone Builder webinars

There are 2 webinars available in which Sebastian Weber talks about training zones and the INSCYD Training Zone Builder. You can now watch both webinar recordings for free. Click the button to see a summary of the topics we covered and start watching the webinar.


  • Do you know what your goal is of spending time in a certain training zone? If so, are you using the right master metric to determine the intensity? Evaluate your current training zones and make sure you base your zones on the right master metric.
  • What additional information would be useful? Information that… confirms that you are working in the right training zone to reach the goal; makes sure the athlete is capable of performing the training; makes sure the athlete is capable of performing the rest of the training plan.

With the INSCYD Training Zone Builder, it’s up to you which training zone you create. From recovery zones to high exercise intensity zones: the possibilities are endless. Read more about the Training Zone Builder in this article or plan a demo with our local partnership manager to talk about your specific needs.

For coaches and labs

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Don’t let your athletes settle for anything less than their absolute best. Book a Free Demo with INSCYD today and experience firsthand how you can elevate your coaching game.



Athletes why train with generic plans when you can have a program tailored to your unique physiology? INSCYD is the key to unlocking your full potential. Find your dedicated INSCYD coach or lab here. 

Already have a coach? Experience INSCYD in action with your coach and redefine your training approach.

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