I usually tell people that Boxing is probably the most demanding sport. However, on further consideration, I would imagine certain forms of mountain climbing are pretty dam challenging. Just something to think about.
I've got no time for MMA, but I do think it is generally more damaging for the sportsmen involved. It's savage and barbaric. ****ing brutal, man, but strangely also quite homoerotic
MMA is definitely tougher than boxing. Don't they use 4 or 6 oz gloves? And in MMA you risk having your arm yanked out of your socket. Plus knees, kicks, bodyslams, etc.. MMA is still for ***s, though.
Boxing has all the mental components of being tough, and then the physical of the punch that could take your head off. Chess is not a sport either. Boxing is the toughest. The skill level involved to be at the top combined with all the toughness, discipline, dedication, and just the demanding physical nature. You could say recently Chavez Jr sort of dispels that notion, but look at his face afterwards. It's tough and skills required to be great takes incredible ability and dedication to hone.
Boxing is tougher because you have less ways to win.The rules were created to be the physical most demandant and the thoughest fight possible, in equal terms.You are always in punching distance (wich is the distance with more KO percentage in MMA), and having to punch and defend punches during 12 rounds.Also receiving a lot of punches. A boxing match syntetize the most technical and demandant aspects of MMA, is harder to punch a guy when he is standing and can couterpunch you, than when he is with his back on the floor.Boxing is a chess match, timming and sense of space and distance all the time, in mma if you are afraid of getting hit you can lay of on a fence, or offer the neck for a submission and tap.In boxing is no easy way out.And of course boxing is proved the combat sport that more pulmonar VO requires and that produces more lactic acid in the bodie. At the end of a MMA match is a drink of gatorade and a new T-shirt, meanwhile in boxing often both participants go to the hospital, even the winner of the match.You can't usually say that in the case of the mayority of sports, even the thouger ones.