This is a set of three values that Xert uses to measure your fitness.  It is represented by: Threshold Power (TP),  High Intensity Energy (HIE) and Peak Power (PP). Xert performs extraction on all activities that contain power data to obtain that activity’s fitness signature.  When changes in your Fitness Signature are detected from previous activity, you’ll get a Fitness Breakthrough.

The three fitness values are used to calculate MPA interactively on your activities.  Your fitness signature is shown at the bottom of the page on each Activity Details page:


Your fitness signature can also be used to calculate a power-duration curve.  In principle, your Fitness Signature establishes your ability to perform during steady-state or variable intensity power.


Your Fitness Signature is a foundational aspect of the Xert system.