Very good question and i do not have the answer. I know that parachutists are still traveling pretty fast when they hit the ground, and they are trained to do that. They practice it. Is there any similar training going on for PWP: and more than just written advice: is there any actual physical training going on to teach us to react quickly and instinctively to protect ourselves when we go down, either from loss of balance or from stumbling? The statistics on the number of PWP hospitalized with bone fractures are quite horrendous; I don't remember the stats off-hand; but a lot of money could be saved and misery avoided if there is any practical way of teaching us how to hit the deck without getting hit by the deck.