Got a query about potential overestimated TSS for heart rate only rides. On Tues I did a very steady commute (15 minutes approximately) and was calculated at ~27 TSS @116bpm (no power). Later on, I did a harder effort on the turbo for the same time, 315w @160bpm and got a TSS of 26.
TSS for power is calculated in the standard way and 26 for a almost 100% intensity 15m is what you would expect as 1h at 100% is 100 TSS.
For HR there isn’t a standard way to do it (that I know of anyway) and Intervals.icu has 3 models: Average HR, time in zones and HRSS (normalised TRIMP) as used by Elevate. You are currently using “time in zones” which does tend to overestimate very low HR efforts. I suggest changing to HRSS in /settings as it is more robust. I made it the default for new users a while ago.
You can see the model in use on the activity HR page.
It also seems to me like the TSS for the easy efforts are too low.
When doing a zone 1 ride, I got 12 TSS per hour while the HRSS is around 42 and on training peaks it also states 30 TSS for a high zone 1 ride in the table and the slowest easiest effort on RPE 1 is 20 TSS per hour.
Hi, I realized my heart rate zones was a little different but even after I reset it, the estimated load on HR was 40. There is just too much of a difference compared to the calculated TSS.
Hmm yes. I think its probably best to change to HRSS. The “time in zones” model works well for my data but thats just one data point. HRSS is probably a bit more robust.
After changing to HRSS the load was 17, which sounds a bit better and a recent 2h51 easy ride I did with HR only had a load of 130 and has gone down to 72. It sounds a little bit on the low side to me definitely more acurate.
In a recent hard 4h ride, my TSS was 283 and the HRSS was 267, so that is quite close to each other. Will see how I can tweak my heart rate zones for closer matching.
Edit: I see the zones have no effect, just HR max and resting HR
