I agree with everyone above. I've been wearing a HRM monitor for 4.5yrs and I log the min/max/mean data in Excel from every run/ride. My max. hasn't changed over the past 4+ years even with a switch in HRMs. For the last year I've been using a PowerTap so I can literally review the entire workout in detail.
According to the formula my max should be 183. I'm literally just getting warmed up at 175-180 bpm. If I don't hit between 198 and 200 on a ride I feel like I'm not working hard enough. I've been consistently hitting 204 on my hard workouts. It's easier on a run but a nice hill and some pushing gets me there as well. I've seen higher (215 to 220bpm) from time to time but I usually can attribute that to interference because it's a spike. It doesn't happen much with the coded PowerTap either.
Short story.. test yourself and establish your own baseline. Don't believe what you read. As long as your a healthy 25yr old and have been exercising regularly you should be OK to push yourself. Listen to your own body and quit when you feel you need to.
PS: I'm no doctor so what do I know anway.