Gee, what do you think? Although precautions are taken, you're doing things human beings were not designed to do. That's why Hollywood A-listers are happy to step aside and let you take the chances so they don't have to worry about busting up their pretty little faces.
You'll be in peak physical condition and you'll have a team of people watching out for you, but that doesn't negate the fact that you're doing some perilous stuff. At least there will be a top-notch medical staff on set. And, if you do take a tough spill, all of the director's medics and all the director's aides should be able to put you together again.