@mickywickyftw I don’t see how ZS adds anything that you don’t get with HR anyway. For me it is just too inaccurate. I wanted to know how ZS actually performs and analyzed 150 runs and rides that I all did as Suunto recommends for ZS. While the mean reported thresholds over all workouts come very close to my actual thresholds, the standard deviation is at 9 bpms for the aerobic and at 7 bpm for the anaerobic threshold. So therefore on normal runs or rides, I get fluctuations of up to ±9 and ±6 bpm respectively and I never know when it is accurate or not. I had workouts where ZS told me that I am pushing way too hard but my HR was as usual and I was able to do the workout/race exactly as planned. I also had it the other way around. If I would have listened to ZS, I would have had a lot of destroyed workouts or races. From years of racing and training, I know that my HR never differs more than ±2 bpm at the anaerobic threshold and ±4 at the aerobic threshold if I am not completely destroyed or sick. So therefore HR and pace in combination with RPE is way more reliable. At least for me.
