NTL is a measure of fitness—not performance ability. It is important to understand that fitness and performance ability are not the same, even though many people use these terms interchangeably.
Fitness vs Performance Ability
Fitness is your capacity to sustain a specific training load without undue fatigue, with ample energy to meet the demands of your daily routine, and while maintaining a state of good health and well-being.
Performance ability metrics describe your ability to produce individual “best effort” outcomes in a specific discipline whether they are done racing or during training. Examples are an FTP test or other assessment, stamina metrics, or your current 10k run time.
Understanding Your NTL
Your NTL needs to be high enough to allow you to safely complete the training necessary to improve your performance ability. As your performance ability increases, higher and higher NTL may need to be reached to support additional training required to sustain performance gains.
However, unnecessarily increasing your NTL or maintaining an unnecessarily high NTL, will likely come at the expense of performance gains and with increased injury risk.
The rate at which your NTL can be safely increased depends on many factors such as your current NTL, age, body composition, health, and genetics (see Physiogenomix™).
Increases in your NTL represent increases in your ability to maintain a higher training load which may or may not be associated with increased performance.
Many athletes not using Optimized Training™ frequently make the costly mistake of working to increase their training load (“fitness”) with the belief that their performance will also increase.
Performance increases are much more related to how you train rather than how much you train.
Maintaining a high NTL for a long period of time or changing your NTL is done purposefully with careful analysis of the costs and benefits and not with the assumption that higher NTL automatically leads to better health or performance.