Interesting I rowed more than 13 years on national level up to u21 and never had any back problems until I hit a car cycling and fracturing my t6. I also don't know of any of my former friends who developed back pain. I actually always put this done to having very good core strength from rowing.

In contrast or my cycling friends (which I took up after) have back problems, in particular the ones who started when young.

Mind you this was more than 20 years ago so maybe the training regime has changed.