system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: How do parkourists not break their ankles?

I just saw a video of some guys jumping off extremely tall buildings onto concrete, no rolling afterwards.  How do their ankles not just snap?
gpt
They are young, flexible, and lucky.

There are some ways to fall more gracefully than others, but at the end of day, you have to remember you're watching an edited video that was chosen to be posted.

Those people may have broken bones many, many times and not bother to post those videos.