Hi
I have been rowing on the erg for about 6 months, getting 350Km

. I am now in my 4th week of the UK site 2km training plan. I can maintain 2.05 - 2.10 splits and 19-22 stroke rates at my AT2 zone (up to 45 minutes, have not tried more), with not that bad power curves (at least they look like
spanish gumdrops or haystacks). My
problem is that I have developed
now a mild lower back pain (only when I wake up in the moning) I've never had before. I can not identify any new other changes in my activity (I keep riding my motorcycle 1 hour a day, I stopped skating 2 months ago due to adductor strain, and my work is still 6 hours a day at a computer desk)
From the many posts I have read about technique, splits, stroke rate and HBR, my diagnostic is that due to my better efficiency and pushing unstrapped mostly with the legs, the weak link is now the trunk. My problem is that if I take it easier and concentrate on technique (even more!) I dont even enter AT2 zone, something I need for the training I am looking for.
This is on top to my real training zones being higher than those calculated with the 220-age rule that I am using, since I can row in the theoretical oxygen transport zone for 20 minutes

. I do have a slow beating, quick recovering heart, but I am afraid of doing a max heart rate test for fear of back injury... but I digress
Any suggestions? (sorry for the long post)