Exercise Physiology
Our third language uses the science of exercise physiology. When it comes to better understanding training zones, the most important concept from exercise physiology is the integrated nature of our energy systems.
There are three energy systems that power exercise. The ATP-PCr, glycolytic, and oxidative.
The ATP-PCr and glycolytic are referred to as “anaerobic” because they are able to produce energy without oxygen. The oxidative energy system is considered “aerobic” since oxygen is a requirement to produce energy.
In this comparison image, you can see how the contribution of the energy systems varies based on the intensity and duration of the effort.
The shorter and more intense an effort, the greater the contribution from the ATP-PCr and glycolytic systems. The longer or less intense, the greater the contribution from the oxidative system.


Understanding a few basics of exercise physiology certainly isn’t a requirement to train effectively. Still, it can be helpful in generating a more broad understanding of why workouts are programmed and designed in a specific fashion.
If you put all three languages together, this is how they may look in graphical form.

Before we introduce each training zone in detail, a quick detour to highlight the value of being more intentional about the data displayed on your bike computer.
You can learn more about customizing your cycling computer ride screens by clicking on page five.