I haven't read any Church related materials on this but I would say that MMA is much safer than boxing. You can tap out in MMA much like wrestling whereas in boxing you can sustain serious brain damage from the repeated blows to the head. Their actually starting to find from brain scans that professional football players also sustain substantial brain damage over their career. As far as overall usefulness in combat, I would think mma is probably more worthwhile. I have a problem with modern arena sports in general that have become idols to the masses, but I think MMA would be very useful for those looking to learn how to fight and defend themselves. Its an interesting question.

I guess I would have to turn the question around and ask:  Why would it be immoral?”

Caoimhín

I think it comes down to the severity of risk to health and the to the health of the ones you're fighting weighed against the advantages of practicing the sport.

The best place to look up information on the morality of combat sports would be to read what the saints taught about the medieval tournaments.

I know much of that sort of thing was condemned, especially when many such events were "pickup" fights between groups of knights, often with deadly consequences.

Tele brings up the pertinent question, the morality of exposing oneself to serious bodily injury.  The Church severely condemned duelling, for example, because it was an immoral custom.  But fighting competitions do not attain to such extremes; there are rules that protect the fighters.  Serious injury is rare and such an occasion can be made remote by level of expertise.  

The motive for entering into such an endeavor also factors in to the morality of the activity.  A man consumed with self-love, hatred and the socio-pathic need to inflict harm on others is evidently objectively evil, whereas a man who enters into this sport to help support his family has a laudable motive.  

As to the practical comments on fighting, they usually end up on the ground and if you don't know what to do on the ground you will lose.  Thus, the focus on ground technique.  This is especially true when you end up on your back.  Without training, one panics and loses the ability to engage in the fight.  

I have previous 10 years of experience in Tae Kwon Do/wrestling and enjoy combat arts (I probably would have become a Catholic Knight when Christendom was alive and well).  I have the spirit of a fighter for a just cause, either naturally or supernaturally.  The reason I present this question is because we are in need supplemental income and I possess an skill that could possibly help.  Whether or not I can attain to the status of being a paid fighter is questionable as I am currently out of shape and 35 years old.

The environment wherein these comptetitions takes place is certainly satanic, but I consider any arena sport environment satanic to some degree.  Of course, I consider modern offices as satanic as well, or anywhere unbelievers set up their organizations, so any environment where I may work is less than desireable, but I refuse to concede that one necessarily consents to such evil simply because one works therein.        

As Tele noted, the main question should be whether or not you are putting your health (and even more-so -- your life) at risk. MMA and boxing to me just seem like ways to do damage to your bodies. One could say the same about racing. If you choose to get in a racecar and go 200 mph, then you're doing a very dumb thing regardless of the safety mechanics.

You can tap out in MMA much like wrestling whereas in boxing you can sustain serious brain damage from the repeated blows to the head.

You can sustain blows to the head in MMA, too. Perhaps not to the same extent, but it's very possible. Wrestling is fake, though even that I find to be rather stupid.

Good point.  I don't necessarily like the idea, working out and training takes alot of work and I don't know if I'm that committed.  Maybe it could be a form of penance as well.