Brendan Marrocco sits at a table in the occupational therapy room and, with the help of his teeth, straps the exercise hooks to his wrists.
His new flesh-and-blood hands are not yet strong enough to grip the pull-up bar, so the hooks must do for now.
He slides out of his wheelchair, walks a few steps on the stumps of his legs and looks up at the bar.
"I have to prepare myself to do this," he says. He reaches up, latches the wrist hooks to the bar and curses. "I'm so not ready right now."
His occupational therapist, Joe Butkus, who is watching, says: "You got it. This is easy."
Then the retired Army sergeant, who has no legs and has transplanted arms joined with plates and screws, begins.
One, two, three . . .
"Yeahhh," Butkus says.
Four, five, six . . .
Marrocco's belly tattoo peeks from under his black polo shirt.
Seven, eight, nine . . .
With a grunt and a grimace, he stops at 10, unhooks from the bar and tears off the straps with his teeth.
"Awesome job," Butkus says.
It has been 18 months since Marrocco, 27, of Staten Island, N.Y., underwent a rare double arm transplant at Johns Hopkins Hospital in Baltimore.
He had lost both legs and parts of both arms to a makeshift bomb in Iraq on Easter Sunday 2009.
At the time of his injury, he was the first service member from the wars in Iraq and Afghanistan to survive the loss of four limbs.
He then became the first service member to receive a double arm transplant and still is one of only seven people in the United States who have successfully undergone the procedure.
He spent several months recovering in Baltimore and last year moved to Walter Reed National Military Medical Center in Bethesda, Md., for intensive rehabilitation.
"I feel great," he said as he sat in Walter Reed's occupational and physical therapy complex.
"Arms feel great," he said. "I can't complain about anything with the arms, really."
He can do pull-ups, push-ups and drive a car. His left arm, which had been amputated below the elbow, is progressing faster than the right arm, which he lost above the elbow.
But his wrists are still thin. And his hands are a work in progress. He has some dexterity in his left hand and can sign his name. He used to be right-handed. "Not so much anymore," he said.
He has limited use of his right hand. The fingers are in the position of a slightly closed fist — a phenomenon called "clawing," his chief doctor said.
But his therapy includes wearing spring-loaded splints on his fingers that work to keep the hand open.
You can see where the transplanted limbs were attached because the donor arm's skin tone seems slightly darker than Marrocco's, and one of Marrocco's old arm tattoos is now cut short.
The new arms had a surprising benefit. They gave him better balance when he walked on his prosthetic legs. Before the transplant, he often fell while using his artificial legs. Since the transplant, he has not fallen at all, he said.
Now he must be patient. With the muscle, skin, bone and blood vessels connected, he must wait for his body's nerves to grow into the transplanted arms.
The new arms will not return to 100 percent function, his doctors have said, but similar patients get enough dexterity to do such things as tie their shoes and use chopsticks.
Meanwhile, he must keep the other parts of both arms strong and flexible.
This requires constant occupational therapy. Exercises, dexterity drills, wearing the finger splints and special elastic tape, and stretching his fingers.
In addition, he undergoes hours of physical therapy to help him get back on his prosthetic legs, which he said he had essentially stopped using three years ago.
"I got to admit, it does suck at times," Marrocco said.
"Has to be done," he said. "It doesn't matter how tired or hung over you are."
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His injuries were horrific. In addition to the loss of his limbs, Marrocco's face and neck bear the scars of the blast that came when the armored truck he was driving hit an explosive device. His left eye is healing from a cornea transplant he had in February.
And at times, he wishes things were different.
"I wish ... they were the way they were before," he said, "but it's not possible."
"You ... try to forget about a lot and kind of stay in the present," he said, "just continue to push through all that."
He is mostly bothered by his limitations in walking.
"It takes so much effort," he said. His leg amputations are so high up the limbs that he has little leverage to move the artificial legs.
"You have a little bit of leg trying to support the prosthetic, and they're pretty heavy," he said. "So it takes a whole lot of effort and energy to just kind of get around the (exercise) track once. It's extremely tiring."
"Besides that, I think I'm managing it pretty well," he said.
Meanwhile, Marrocco has been accomplishing other goals.
He was able to handle a cellphone within two months. And, as a huge NASCAR fan and student of automobile mechanics, he was overjoyed to be able to drive again, with hand controls, in December.
He had not driven a car in more than four years.
"Last time I drove, before this, was when I got blown up," he said.