So my gym just got a rowing machine and I gave it a shot for the first time today. This thing had to have been made in like 1982 because it had these old ass atari looking graphics. Anyways, I rowed for 20minutes (the highest you could go) and put it up to level 9 (the highest it could go), and my heart rate stayed right around 65%. I was expecting this thing to kick my ass but it really didn't, as far as exhertion goes I felt like it was the equivalent of jogging.
I thought about rowing faster but it had this thing on there that said "desired strokes per minute" and if I got above it it would start flashing till I got it back down.
So this is my question: is there something I'm doing wrong with this thing or can I make it more difficult (put a rucksack with weights on) or something like that? Contrary to most guys on here I'm a cardio freak, a distance runner (10k) and I sprained my ankle recently so I'm trying out new things. My gym has one of the tread-walls which I really enjoy but it just doesn't get my heart rate up enough. Any advice?