The organizers of the Boston marathon once did a study in an attempt to reduce the number of deaths that occur during the race. They found that about 1 in 50,000 people who attempt a marathon die during the process. This may sound like a fairly low risk; but with huge events this works out to a death every couple years. In fact this is one reason event organizers limit the field; so they don’t have deaths every year. They then debated requiring doctor supervised physicals that included a stress test. In the end it turned out that stress testing kills about 1 in 20,000 so by putting in the new rule they would be killing several more people each year. The idea was dropped.

I find it funny that just doing it is safer than getting tested to find out if it’s ok.