I'm not sure what to think about my max heart rate now, because I'm only 23 and about 6 months ago I had a VO2 max test and my max heart rate came out at 173bpm, although in racing since then I've seen it go to 176bpm which has been maintained around there for up to 10min. I've never seen it any higher. I've got a VO2 max test complete with skinfolds an blood lactate levels scheduled for tomorrow, so I'll see how it goes. One sports scientist has told me that your max heart rate only matters so far as determining your training zones, and if you use it for this correctly it doesn't matter whether your max is 170 or 200, because using these correct zones you will get results from your training.