Larry Gude
Strung Out
If you are going to say moto I have to disagree...while extremely physically demanding if you are putting the average Mixed Martial Artist professional against the professional MX'er I'm taking the physicallity of the MMA guy everytime.
MMA is #2 behind MX and here is why;
Coordination; it takes more to get a bike around a dirt track than it does to fight. Both hands, both feet, plus balance and an ever changing terrain in addition to opponents. Fighting clearly takes great coordination but, the only variable is the opponent.
For concentration, strength and stamina, MMA is very demanding, obviously. However, you get a break every 5 minutes. And you only go 3-5 rounds. For a moto, you don't get a break for 30 minutes plus two laps. Then, you do another moto. I would argue that MMA takes more peak exertion, by a good bit, but, you do get that break and a great deal of the time, you are preparing for that exertion as opposed to actually expending it.
As for courage, fearlessness, guts and commitment, it obviously takes all four to step into the ring/octagon knowing full well you WILL be getting hit and likely bloodied, may end up with a broken arm, huge welts on your shins, legs, etc or maybe knocked out.
The balls it takes to ride MX riders, to triple, to blitz the whoops, the chaos and mayhem in the first turn, to be, especially in super cross, constantly on the verge of an incredibly nasty crash, the lap after lap physical and mental demand is far superior, in my view, to what it takes to step in against a man who might well beat your ass but ain't likely to toss you about at 40 mph like a rag doll into the face of a step up and, perhaps, have you bike meet you there, or someone elses.
Further, people get carted off of MX/SX tracks pretty regular. The vast majority of MMA fights, both men walk out. Even if you got knocked or chocked out.
More further, your career as a pro racing a dirt bike is measured in years, not decades. If you don't make it by your early 20's, you ain't gonna. If you did make it by your early 20's, you might make it to your early 30's, maybe.
MMA, your best years may well be in your late 20's and into your early 30's.
You have a chance of taking most dirt bike racers and turning them into decent fighters. That is not the case with most fighters. In my view.
All in all, coordination, concentration, strength, stamina, courage, fearlessness, guts and commitment, MMA comes in second place to MX and SX.
In my opinion.