Just chatting to my niece the other day and she mentioned she would like to learn a Martial Art. I suggested Tai Chi that I learned for many years to help manage my arthritis. Now I never learnt how to use it as a Martial Art but my teacher most certainly had. Some demoes he gave were quite scary. He demoed some Pa_Kua strikes on a watermelon - the outside was not affected much - but the inside was mush. I thought - god what would happen if you were hit by that. I even got a book on Pa-Kua just to see what it was about and found some master declared a virtual one man war on the Japanese during WW2 and was very effective. My niece however refused to accept this and wants to learn Karate. My issue is, having bad arthritis myself what the long term impact on her joints would be. It may take longer to learn Tai Chi or Pa-Kua (evidently they are related though - my teacher always suggested you learn both) as a martial art but I think the long term heath benefits may be better.