I don't know if this is boast-worthy. It wasn't that challenging to my lungs, or my heart, or my muscles. The only discomfort was a numbness in my legs and buttocks. It was like they were asleep, despite my rowing the entire 30 minutes. At 12 minutes in, the numbness began. At 18 minutes in, I thought about getting off just for a minute to regain feeling. But, my pace was on target for a new PR and I didn't want to sacrifice it. I figured I'd live, albeit uncomfortably for the next 12 minutes. At 6 minutes left, I just about talked myself into quitting, but then I thought better of it. I'd suffered this long.
This was with bubble wrap, under the cushion I bought direct from Concept2! I think I may need to gain some fat in my backside, because I never got this numb when I was heavier. (but, I'd never spent over 10 minutes on the rower when I was heavier, either)
Suffice it to say, I stuck with it. My goal was to get over 8013,(my old Personal Best) which I did. I had initially set a goal of 1:53 pace, but except for when the numbness crept in, 1:50 was tolerable. I figured it would get more intolerable in the later part, which it did, and I might need the time cushion.
I had hoped to increase my speed as the row continued, as I find I do better after I'm profusely sweating. (bones and muscles take a while longer to warm up than I like to give them before I started) And I did, but that tingly feeling isn't conducive to speed.
Still, for a 52 year old guy, I ranked #46 verified, so either not many others can stomach sitting on the C2 that long, or I did pretty good.