I believe the exertion restriction is also related to BP, BP is the worst enemy of an aneurysm and we tend to hold our breath when lifting heavy weights or exerting while exercising. I had a 5.2 AAA that was fixed with surgery 4 yeasr ago (open heart) but before the operation my Cardiologist explained to me how incredibly BP goes up with heavy exertion (he told me chest presses and crucnches are some of the worst). I was in very good shape and exercised frequently so I had to slow down significantly before the surgery. I recently found videos by Dr Andy Galpin, it is worth while listening to him, he explains the whole relationship between exertion/holding breath and BP and teaches breathing exercises to learn how to properly breathe.