I can’t say anything more about SciAm’s interview on the science of Batman. The article speaks for itself:
What’s a realistic training regimen?
I didn’t give a training manual in my book, but he’d want to do specialized weight training to build up an ability to work at a really high rate for maybe 30 seconds to a minute (the maximum time period associated with his fights). One of the early comics shows him holding an enormous weight over his head. That’s not the right kind of adaptation toward punching and kicking. He’s got to make sure he’s doing all the skill training at the same time so that he’s actually using the (physical) adaptations he’s slowly gaining. In conventional martial arts, when people take weapons training, you’re doing a kind of power-strength training.
What effects would all that training have on Bruce Wayne’s body?
I looked up what DC Comics and some other books said (about Batman’s physique). I settled on the estimate that Bruce Wayne started off at about six-foot-two and 185 pounds. I gave him a body fat of 20 percent (slightly below average) and a body mass index of 26. Let’s say after 10 or 15 years, after he’s become the Batman, he’s weighing about 210 pounds and has a body fat of 10 percent. He’s probably gained 40 pounds of muscle. His bones will actually be more dense, kind of the opposite of osteoporosis.
Are we talking freakishly dense bones?
The percentage change is actually quite small—maybe 10 percent. In judo, where people do a lot of grappling and throwing, you’re going to have more density in the long bones of the trunk. In karate and other martial arts where they’re doing a lot of kicking, there’s going to be a lot higher density in the legs. Muay Thai (kickboxing) is a great example. They’re always doing these low shin kicks. They try to condition the body by kicking progressively harder objects and for longer.
Lots more at the link.