If you did not know your heart rate or power threshold at the time of sign up, you may have added an estimated value based on your age (for heart rate) or a combination of factors used to estimate power threshold. These numbers are meant to provide a good starting to point when you begin training in Stages Link, but should be updated once you're able to perform a threshold test.
If you're planning on using training plans, a threshold test will be added into your training plan in order to accurately input zones for your workouts. If you are not yet ready to begin a training plan, a threshold test can be added to your calendar at any time by clicking the workouts pop up on the right hand side of the calendar and searching for "Test - 20min" and dragging it to the next available day that you will have time to perform the test.
If upload ride files before taking your threshold test and find that your threshold heart rate or threshold power has changed drastically, see our other topic on how to update files that are uploaded with the wrong threshold.