Intensity Factor (IF)
The Intensity Factor (IF) expresses in a single number how hard a session was on average relative to your own threshold. An IF of 1.0 means, roughly: the whole session at threshold level. It is the intensity side of your load, apart from how long you were out.
In Trimetra this is called intensity.
What is the Intensity Factor?
IF sets the average effort of a session against your threshold. Below 0.75 is usually easy endurance, around 0.85–0.95 is hard tempo or threshold work, and above 1.0 you were above your threshold on average — only holdable in short, hard sessions or intervals. That way IF makes sessions of different sports and durations comparable on intensity.
Important: IF on its own says nothing about how much a session cost you. A short, fierce interval and a long, moderate endurance ride can have the same IF while the second lands far harder. Only together with duration does the full load picture emerge — exactly what a score like TSS does.
How is IF determined?
IF leans on your sport-specific threshold anchor. In cycling that is power relative to your FTP; in running, pace relative to your threshold pace; in swimming, pace relative to your CSS. If that output is missing, heart rate relative to your LTHR is a common fallback.
Because everything rests on that anchor, IF stands or falls with a current threshold anchor. If your FTP or threshold pace is out of date, every IF — and every load score that leans on it — comes out systematically too high or too low.
How Trimetra personalises this
Trimetra calculates the intensity of every session sport-specifically on your own anchors and uses it together with duration in your load score. Because the value stands or falls with your anchors, the app actively watches them and suggests adjustments as soon as your data gives reason to.
Frequently asked questions
What is a good intensity factor?
That depends on the goal of the session: below 0.75 fits easy endurance training, around 0.85–0.95 fits solid tempo or threshold work, and above 1.0 only short, hard sessions or intervals. "Good" means: fitting what the training was meant to be.
Why is your IF higher than 1?
Then you averaged above your threshold — normal for a short, sharp session or race. If it happens on long endurance rides, your threshold anchor (FTP or threshold pace) is probably outdated and set too low.
What is the difference between IF and TSS?
IF only measures intensity relative to your threshold, independent of duration. TSS combines intensity and duration into one load score. A short, sharp interval session and a long easy ride can have the same IF but a very different TSS.
Every term at a glance in the full glossary.
TSS, NP, IF, CTL, ATL and TSB are trademarks of Peaksware, LLC (TrainingPeaks). Trimetra is not affiliated with them; this page merely explains the term.