Edit - Just realised the title might be a little on the alarmist side.....sorry....
I was on one of those ski machines yesterday, one with a built in heart rate sensor. Toward the end of a very strenuous workout I thought I'd check to see how I was doing....turns out my heart was doing 190 bpm....after 30 secs it was down to 178. Even so, isn't 190 a little high?
I know those machines aren't hugely accurate, but even with a 10% margin for error, that's still pretty high, right?