Tried zone2 for a month, something unxepected happenend

[iain]

My anaerobic max is currently 10.9WMin (360w@33); but my cardio can't keep up with more than ~4.5WMin for 45min+ sessions.

My cardio has always been my limiting factor when exercising; whether running/swimming/cycling/hill walking; there always hits a point when I just can't deliver the oxygen required, the lactic builds and the HR keeps rising - I'm not finding it difficult to sustain from an effort perspective.

I find that it is the absolute power that determines the cardio load, yes it is harder to pull the same pace at low rating, but the difference is less than increasing the power. That is one of the main reasons for doing rows at lower ratings (as well as allowing concentration on technique). While my technique leaves a lot to be desired, I am sure that you could increase that significantly from improved technique (stronger position at the catch, breaking arms later, making sure handle moves as far as the seat etc.). I see that as more of an issue than the low rating at this stage. The other point is that it is "unnatural" to push as hard as is required. Every stroke is like a squat with much higher effort than in more continuous sports. You then get a mini rest every stroke!