For what it worth there is a 96year old man "Lao Houtou" who comes to our patch every-so-often to do PH with us and he can throw most of us around easily. He pretty much uses brush knee all the time in various guises. His power is very difficult to detect until it is too late. He started studying Wu (Hao) taiji when he was 60 before that he studied Chang Quan (Long Fist) for many years. One of his young friends is a 91 year old Long fist master. Of course people are respectful of him as he is the oldest person i have ever met (also the fastest walker i have met) but people still try and compete with him to a certain degree, ie they don't just let him do things, he has to make it happen as it were. I have to get some photos of him while i can, but he looks like he could live forever.