Knuckle conditioning is a two-edged sword in martial arts.  On the one hand hard knuckles and a conditioned fist make for a much more powerful punch in a streetfight and make it less likely you'll break your hand or sprain your wrist. On the other hand it increases the risk of arthritis and non-functional hands as you get older.  What should martial artists do? If you're interested in more information like this then check out the 3 free self defense PDFs I have available at http://selfdefensetutorials.com/get-free-self-defense-tips-by-email/