Why load differs from TrainingPeaks or Intervals.icu

Platforms compute load from your FTP, threshold HR, max HR and resting HR, and it’s easy to end up with different values on each. Yours are in Settings → Performance.

With the same FTP, Shape, TrainingPeaks and Intervals.icu produce the same TSS for the same ride.

Here the models legitimately differ. Shape uses HRSS, the TRIMP-based model Intervals.icu also uses. It works from your heart rate reserve, so a fit athlete with a low resting HR gets less credit for an easy spin than the raw bpm suggests. TrainingPeaks’ hrTSS only looks at heart rate relative to threshold.

Both agree that an hour at threshold is 100. Below threshold HRSS falls off faster, so easy HR-only sessions read noticeably lower in Shape than in TrainingPeaks. That’s by design: we think heart rate reserve is the more individualized read. Hard sessions and anything with power match closely.

Intervals.icu uses moving time rather than total time, so it can run slightly lower on rides with stops.