# What is TSS and IF?

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### What is TSS?

Training Stress Score: ROUVY uses several physiological metrics to quantify the training stress of a particular workout or portion of a workout.

Training Stress Score. In ROUVY software, this is an indicator of how hard a workout is.

The formula for TSS is:

TSS = [(s x NP x IF) / (FTP x 3,600)] x 100

Where “s” is workout duration in seconds, “NP” is normalized power (or pace in running), “IF” is intensity factor, “FTP ” is functional threshold power (or pace in running), and “3,600” is the number of seconds in an hour.

NP Normalize Power: An estimate of the power that a rider can maintain for the same physiological “cost,” if their power output is perfectly constant, rather than variable. Let’s say that is kind of average Power from one of your Training sessions.

TSS points are non-transferable. It means if you have 150 TSS of 160 TSS points that are needed for the current level and you finish an activity that has the value of 100 TSS points, only 10 will count.

### What is IF?

IF Intensity Factor: The ratio of normalized power to the rider’s threshold power. IF = NP/FTP. And Power (W) is calculated as estimated power based on the user's heart rate.

Note: NP, IF and TSS are trademarks of Peaksware, LLC and are used with permission. Learn more at www.trainingpeaks.com.