Batman is the most down-to-earth of all the superheroes. He has no special powers from being born on a distant world or bitten by a radioactive spider. All that protects him from the Joker and other Gotham City villains are his wits and a physique shaped by years of training—combined with the vast fortune to reach his maximum potential and augment himself with Batmobiles, Batcables and other Bat-goodies, of course. In the 2005 blockbuster Batman Begins, vengeful Bruce Wayne (played by Christian Bale) hones his killer instincts in the streets for seven years before landing himself in a Bhutanese prison, where he falls in with the mysterious League of Shadows, who teach him the way of the ninja. The Dark Knight, the next movie in the Batman franchise, opens in theaters Friday. To investigate whether someone like Bruce Wayne could physically transform himself into a one-man wrecking crew, ScientificAmerican.com turned to E. Paul Zehr, associate professor of kinesiology and neuroscience at the University of Victoria in British Columbia and a 26-year practitioner of Chito-Ryu karate-do. Zehr's book, Becoming Batman: The Possibility of a Superhero (The Johns Hopkins University Press), due out in October, tackles our very question. An edited transcript of the conversation follows.

What have comic books and movies told us about Batman's physical abilities?

There's a quote from Neal Adams, the great Batman illustrator, who said Batman would win, place or show in every event in the Olympics. Probably if I were Batman's handler, I'd put him in the decathlon. Although Batman is shown in the comics as being the fastest and the strongest and all these other things, in reality you can't actually be all of that at once. To be Batman properly, what you really need to do is be exceptionally good at many different things. It's when you take all the pieces and put them together that you get the Batman.

What's most plausible about portrayals of Batman's skills?

You could train somebody to be a tremendous athlete and to have a significant martial arts background, and also to use some of the gear that he has, which requires a lot of physical prowess. Most of what you see there is feasible to the extent that somebody could be trained to that extreme. We're seeing that kind of thing in less than a month in the Olympics.

What's less realistic?

A great example is in the movies where Batman is fighting multiple opponents and all of a sudden he's taking on 10 people. If you just estimate how fast somebody could punch and kick, and how many times you could hit one person in a second, you wind up with numbers like five or six. This doesn't mean you could fight four or five people. But it's also hard for four or five people to simultaneously attack somebody, because they get in each other's way. More realistic is a couple of attackers.

How long would Bruce Wayne have to train to become Batman?

In some of the timelines you see in the comics, the backstory is he goes away for five years—some it's three to five years, or eight years, or 12 years. In terms of the physical changes (strength and conditioning), that's happening fairly quickly. We're talking three to five years. In terms of the physical skills to be able to defend himself against all these opponents all the time, I would benchmark that at 10 to 12 years. Probably the most reality-based representation of Batman and his training was in Batman Begins.

Why such a long training time?

Batman can't really afford to lose. Losing means death—or at least not being able to be Batman anymore. But another benchmark is having enough skill and experience to defend himself without killing anyone. Because that's part of his credo. It would be much easier to fight somebody if you could incapacitate them with extreme force. Punching somebody in the throat could be a lethal blow. That's pretty easy to do.

But if you're thinking about something that doesn't result in lethal force, that's more tricky. It's really hard for people to get their heads around, I think. To be that good, to not actually lethally injure anyone, requires an extremely high level of skill that would take maybe 15 to 18 years to accumulate.

Where does that number of 15 to 18 years come from?

That comes from my own training in martial arts and seeing how long it takes people to respond to simple situations—let alone the complexities of smoke bombs going off and people having big Batsuits on. No matter how much training you have, when we're subjected to a lot of psychological stress, we make a bunch more mistakes. The police talk about this when they use things called reality-based training. It takes years and years and years and years to have the poise to be able to perform when somebody is attacking you for real.

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.

What about his reaction speed?

There is evidence that experts in something like football or hockey have an improved ability to perceive movement in time. In the book I use the example of Steve Nash throwing the ball, even though he can't see where the receiver of the pass is going to be. Experts are able to extract more information faster than others. It's almost like their nervous systems become more efficient.

How would Batman get enough rest?

The difficulty for Batman is he's going to be trying to sleep during the day. He's going to be really tired, actually, unless he can shift himself over to just being up at night. If he were just a nocturnal guy, he would actually be a lot healthier and have a lot better sleep than if he were doing what he does now, which is getting some light here and there. That's going to mess up his sleep patterns and duration of sleep.

Wouldn't fighting Gotham's thugs every night take its toll?

The biggest unreal part of the way Batman's portrayed is the nature of his injuries. Most of the time, in the comics and in the movies, even when he wins, he usually winds up taking a pretty good beating. There's a real failure to show the cumulative effect of that. The next day he's shown out there doing the same thing again. He'd likely be quite tired and injured.

Is there any indication in the comics of how long Batman's career lasts?

The comics are really vague on this, of course. In Frank Miller's The Dark Knight Returns, he deliberately shows an aging Batman coming back after he's retired, and he highlights him being tired and weaker. Somewhere around age 50 to 55, he should probably retire. His performance is going down. He's always facing younger adversaries. That is well at the end of when he's going to be able to defend himself and be able to not have to deal that lethal force. This was actually shown in an animated series called Batman Beyond.

Oh right. It's the future; Batman is old and he trains a kid to replace him.

You're familiar with that one? What we learn is that Batman, when he was older but before he retired, actually picked up a gun against a thug because he had to. His skills had let him down so that he wasn't able to defend himself without harming another person. So that's when he decided to retire.

How would all those beat-downs have affected his longevity?

Keeping in mind that being Batman means never losing: If you look at consecutive events where professional fighters have to defend their titles—Muhammad Ali, George Foreman, Ultimate Fighters—the longest period you're going to find is about two to three years. That dovetails nicely with the average career for NFL running backs. It's about three years. (That's the statistic I got from the NFL Players Association Web site.) The point is, it's not very long. It's really hard to become Batman in the first place, and it's hard to maintain it when you get there.

There's research suggesting that concussions might cause depression in NFL players. Could that be one reason why the Dark Knight is so brooding?

I went through a lot of comics and graphic novels and I only found a couple of examples where some of those blows to Batman's head had the effect of something like a concussion. Whereas in reality, that would be a very likely outcome. He's able to offset some of the physical damage to his head because of the cowl—it works a bit like a helmet. But these things would definitely add up. Since they don't admit that he has concussions, you can't really ascribe repeated concussions as the reason why he's brooding.

Do you think Batman would take steroids to heal faster?

No. There is one comic where he did go on steroids. He went a little crazy and he went off them again.

How many of us do you think could become a Batman?

If you found the percentage of billionaires and multiply that by the percentage of people who become Olympic decathletes, you could probably get a close estimate. The really important thing is just how much a human being really can do. There's such a huge range of performance and ability you can tap into.