In the blockbuster movie Avatar, lead character Jake Sully, a paralyzed military veteran, wakes up in a virtual body to find that he can stand and run and dig his toes into the earth, which he does with animated abandon.

"This is great," Sully says as he disconnects himself from medical equipment and stumbles out of a laboratory.

It is great - and not just for Jake.

The ability to create a cyber version of yourself has been embraced by people with disabilities stemming from arthritis, cerebral palsy, multiple sclerosis, mental illness, and other debilitating conditions. They log on to virtual worlds, Second Life chief among them, to do things they cannot, or are afraid to, do in real life.

Can't go places without a wheelchair? In Second Life, you not only can walk, you can fly. Is your speech slurred? In Second Life, text chats can let out your inner Shakespeare.

Forget for a minute what you can't do. In virtual worlds, it's all about what you can.

"I'm building a house on Second Life right now," says James Parcher, 85, of West Philadelphia, whose avatar is named Huber Grantly. "For an old guy like me, I can't get around very well with the arthritis problems I have. On Second Life, you're young again."

Second Life, which launched in 2003, bills itself as "a free 3D virtual world where users can socialize, connect, and create using free voice and text chat." More than one million members log into it monthly.

Like everyone in Second Life, disabled players first create an avatar to represent themselves. They can be true to their appearance, or be a buff and beautiful version of themselves. Whatever shape their avatar takes, the person behind it often forms an attachment.

"People identify in a very intense way with their avatars," says Sherry Turkle, professor of social studies of science and technology at the Massachusetts Institute of Technology and director of the Initiative on Technology and Self.

Not that using Second Life allows a person to completely detach, of course - it may, in fact, emphasize their health condition. Disabled players often need adaptive equipment to use a computer.

At West Philadelphia's Inglis House, which offers services and housing to people with severe disabilities, the computer lab is stocked with such gadgets and is filled with residents using computers for writing, playing games, and sending e-mails.

Using a computer at all is a triumph of tenacity and technology for Inglis' severely disabled residents.

Standing in front of one computer, Dawn Waller, coordinator of Inglis' computer lab, demonstrates by making a large virtual keyboard appear on a monitor. Then she holds up a big button that can be mounted on a movable metal arm. The arm, in turn, attaches to a wheelchair and is positioned near the part of the body the person can move, maybe his head or her lower jaw.

The button then remotely operates the virtual keyboard - but it takes four clicks to type a single character.

Another device operates a mouse cursor by tracking the movement of a self-adhesive dot most often placed on a user's forehead.

"What they do with our keyboard and mouse takes a significantly longer amount of time for them," Waller says.

Inglis officials started a pilot project at the beginning of this year to see if residents and day-program participants could benefit from Second Life, especially by taking continuing education classes from schools with a presence in the virtual world. But pilot group members, she says, were more interested in the mobility of their able-bodied avatars and the abilities that came with it.

All but two of 10 people in that pilot project have quit - too hard for too little return.

Even one of the remaining participants, Inglis resident Stu Sanderson, 55, who was born with cerebral palsy, plans to stop soon.

"It's too hard," he says, with Waller helping to translate the words he labors to say. Still, Sanderson demonstrates how he controls his Second Life avatar, Stu Mint.

For him, the mouse button on the metal arm is attached to the back of his wheelchair and positioned behind his left ear. He concentrates intensely, jerking his head against the button until his dark-haired, athletic avatar is walking along a boardwalk in Virtual Ability island.

Virtual Ability, a nonprofit group based in Colorado, was founded by Alice Krueger, 60, who was diagnosed with multiple sclerosis 10 years ago. Her group's mission is to help the disabled use Second Life, and the island is tailored to welcome disabled players, with tutorials and areas to practice manipulating your avatar.

The island even abides by the Americans With Disabilities Act, which celebrated its 20th anniversary Monday. Walkways, for example, are wide enough to accommodate virtual wheelchairs.

Virtual sandwich boards advertise the ALS Association, the Arthritis Foundation, and the Autism Society. The U.S. Army is partnering with Krueger to use the virtual world as a place where military veterans who are amputees can get peer-to-peer counseling.

But people with disabilities, says Krueger, don't necessarily join Second Life to get health information.

"They come in to have fun," she says.

That socialization is what made Sanderson stick with Second Life this long.

His fondest memory may be when he and Waller both logged on to Second Life. He wanted to dance, so Waller and he teleported to a hall - and they began to waltz.

"There were tears running down my face as I experienced a dance, something in my wildest dreams I never thought I would do. It was like teleporting out of my physical body and literally sliding and gliding," Sanderson, a poet, wrote about the experience.

"The avatar becomes a psychological and emotional extension of one's sense of self," says John Suler, a psychology professor at New Jersey's Rider University who studies the psychology of cyberspace and has written a book on the subject.

"Some people even report that they can feel physical sensations through the experiences of their avatar," he says.

They also use the camouflage of avatars to overcome inhibitions and fears.

Turkle, the Massachusetts Institute of Technology professor, tells the story of a woman who got a prosthetic leg as the result of an accident.

"She wanted to resume a sexual life, but found it very awkward. She created an avatar with a prosthetic leg and began having virtual 'affairs.' In this safe context, she practiced explaining her situation to her lovers, taking the prosthetic off in their presence, and having virtual sex," says Turkle.

There are pitfalls, too.

"The thing to watch out for, for the disabled and for all of us, is the balance between the real and virtual," she says. "The danger is that life on the screen can begin to seem better, simpler, less of a hassle than the rest of life."

A person may make less effort to go out, or may feel low when the computer is off and their health is the same.

That may all be true, but Sanderson has another reason he's leaving the virtual world: "I like Facebook."

Contact staff writer Carolyn Davis at 215-854-4214 or cdavis@phillynews.com.