When I do say a long, around 2 hour zone 2, workout my heart rate drops quite a bit for the same power output as the time increases. I have noticed this more on Zwift free rides where I just ride a route and manually keep my HR in the zone. There is about a 10 BPM drop for the same effort after say 90 minutes or so. Which is a lot because my Zone 2 max is only 117 bpm. Maybe the intensity of the rides change rapidly and my HR doesn’t respond quickly enough but I definitely put out a lot more power with no extra strain on my breathing near the end of the workout. Anyone else experience this.
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Yes I have seen similar but only in very easy z2( almost down in z1) workouts done in Erg mode with a fixed power target. My HR spikes at the start and gradually drops over 10 minutes or so as I warm up and I’m guessing that efficiency is increasing. I see a smaller decrease in HR in the later half of the workout as I realise I need more cooling and turn the fan speed up. If you use intervals.icu have you checked the HR decoupling graph, which can be adjusted to exclude warm up and cool down.
What trainer are you using? Some don’t have thermal compensation and report higher power as they warm up.
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Thanks, I do use ICU so will check that out. Not really a real concern so was just curious. The trainer is a Tacx Neo
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Like @JGreengrass said, it could be a low zone 2 thing. When I ride low Z2 (55%-60%) I have a similar issue, but when I ride in the middle of my Z2 (60%-65%) my HR stays pretty steady. And if I ride a high Z2 (65%-70%+) then the HR will creep up over time and I’ll need to tone it down to keep my HR in the zone.
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