This article will teach you about the intensity of workouts and how to manipulate this variable.
Intensity Factor (IF)® Defined
The Intensity Factor of a ride is defined as how intense/difficult the ride is. An IF of 1.0 is equal to an all out, one hour effort. An IF of .7 means the rider will be working at 70% of their all out pace for the hour. This is a quick way to gauge how hard your workout will be.
How does IF display on screen?
Notice the green line labeled as "Actual" in the key. This green line also indicates the IF of your ride in comparison to the IF of the prescribed workout. If the green line lays directly atop the course profile (as it does in the screenshot below), that indicates the workout will be completed at the prescribed IF.
How to change the Intensity of a Workout
First, open the workout. Then, find the box in the lower left-hand corner of the screen that allows you to adjust the workout's intensity (screenshot below). This tool allows you change the IF of the workout while keeping the workout's intervals the same.
Note that the course profile of the ride below has the same intervals, but a higher IF and higher power.
How will the course profile and green IF line display during the ride and on my Career page?
If you change the IF of a workout, the course profile will adjust accordingly and an inflated or deflated course will display for the duration of your ride. After you complete your ride, the workout will display on your Career page in its original form. However, the green "Actual" or IF line will display the intensity of the workout that you did. The screenshot below is an example of what a ride with a manipulated IF looks like on your Career page (without the power data).
What do I do as I become stronger?
Changing the IF can be an interesting change of pace to a favorite ride, but this feature should not be used as a substitute for changing your FTP as you get stronger. Update your FTP rather than increasing the IF of rides. This way, your TSS numbers will be more accurate.