Another term used for threshold test results is “metabolic profile”. It really represents your thresholds and how they relate to each other. The reason it’s called the metabolic profile is because it all links back to how you produce the energy needed for training, by burning fats or carbohydrates. 

Athletes should tailor their training based on their unique metabolic profile. It maps out how you respond across the intensity spectrum. See the Fat, Carbohydrates, and Minute Ventilation chart above, that is a metabolic profile. It contains your thresholds which make up your training zones. But, even more helpful, and the final step in utilizing your thresholds, it shows you which threshold is limiting your overall improvement and in doing so, which threshold you can improve the fastest. 

For example:

• An athlete with a strong Balance Point and VT2 but weak VT1 will be held back at higher intensities by their lack of ability to utilize fats for fuel. This athlete should focus on Zone 2 training, at and below VT1, to first improve their aerobic base before continuing to push their other thresholds higher.

• Conversely, an athlete that has been building their aerobic base diligently and has a strong VT1 may see their performance plateau. This is likely because their VT1 improvement is now being stunted by their Balance Point and they need to focus on that before building their aerobic base further.

• Finally, an athlete that varies their training between their thresholds but never pushes themselves quite hard enough to get to VO2max will absolutely improve but unless they raise their ceiling (VO2max) directly it will feel like trying to add a new floor to your home without first raising the roof.

As you can see by these examples there’s no one perfect training philosophy. Each of us are different and need to focus on different parts of our endurance. Like in so many other fields, knowledge becomes the key to continued success and development so let’s take a look at how to best balance your thresholds for that continued success.

A balanced metabolic profile across most endurance sports looks something like this:

• VT1: 60%-65% of VO2max

• Balance Point: 70%-75% of VO2max

• VT2: 80%-85% of VO2max

If one of your thresholds is below these ranges that means it could be limiting your overall performance and, on a positive note, it’s primed and ready to improve faster than the rest of your thresholds. We recommend testing every 4-8 weeks which gives you enough time to focus on and improve your limiting thresholds before resetting your targets. Once you get all your thresholds within these balanced ranges you are ready to raise your VO2max further.

This process of first improving your thresholds to be in a balanced range and then pushing your VO2max high enough that your thresholds fall out of range again makes sure you’re always progressing, always improving based on your fitness level. Building your fitness is like building a skyscraper: you can’t add floors until the foundation is strong enough. Thresholds are the structural base. VO₂max is the skyline you’re reaching for. And once you go higher, you’ve got to reinforce and expand the base again to support the new height.