That's what Irish motivational speaker Mark Pollock says when he agrees to a proposal or signs off of a conversation. But for Pollock, who's been blind for 16 years and paralyzed from the waist down since 2010, "good stuff" doesn't even begin to capture his feelings about being "Iron ElectriRx Man" in a robotics lab at UCLA.
In the spring of 2014, Pollock became the first subject in an experiment that set out to meld electrical stimulation therapy with a robotic exoskeleton that in effect walks for paralyzed patients. The study's aim: to help those with spinal cord injuries learn to walk again.
A fall from a second-story window caused Pollock's catastrophic spinal cord injury in 2010, and doctors told him any return of sensation or function below his waist was out of the question. Pollock took the news with the same combination of acceptance and defiance that led him to participate in endurance trials and adventure races across some of Earth's harshest terrain, including the South Pole.
He would learn to make a meaningful life using a wheelchair. But he also resolved to "keep the paralyzed bits in good enough shape that I'd be ready for any innovation that came down the track," he said.
When Pollock first arrived at UCLA, he had nearly four years of aggressive rehabilitation under his belt and had mastered the use of a battery-powered bionic suit, called an Ekso. The sensors and motors on the robotic exoskeleton are programmed to detect how much "help" a patient is capable of giving, and then to do the rest of the stepping.
Pollock's injury was so extensive — broken bones had nicked and pierced his spinal cord in two places — that he was, essentially, a passenger in the Ekso.
That was about to change. In the lab of V. Reggie Edgerton, a neuromuscular researcher at UCLA, therapists attached electrical patches to the skin over Pollock's spinal cord. Over the course of a week, he got five hours of electrical stimulation.
After that, when Pollock strapped on the Ekso, "it felt like I was moving up to the 'sport' version of the device," he said.
His heart rate increased. He felt perspiration burst from his brow. And he felt another sensation he had missed for four years: tension in his legs, which turned to tingling as his limbs "joined in with the movement" of the Ekso, he said.
He could walk up to his fiancee and hug her. He could engage others from an active, standing position. The tension in his hips eased. His legs felt looser, and his digestion improved.
"It felt, like, right," said Pollock, who has since returned to his native Dublin, continues his rehabilitation with the Ekso and serves on the Christopher and Dana Reeve Foundation. "It felt like it used to feel."
Edgerton, who described Pollock's case last week in Milan, Italy, at a meeting of the world's largest international society of biomedical engineers, said the electrical stimulation to the spinal cord appears to reawaken neurons there. Once abuzz, those spinal neurons seem to recognize sensations sent up by the moving lower limbs and respond by ordering muscles to pitch in to aid the movement.
Even if the brain is out of the loop, the spinal cord appears to retain some of the "automaticity" that allows people with full motor function to initiate and make movements with little to no conscious effort, Edgerton said.
"After the injury there's a lot of functional capability that remains," Edgerton said. "But it has to do some relearning" — a process that appears to get a jump-start from electrical stimulation, he added.
By providing the legs with a natural stepping movement, the Ekso essentially reminds the spinal cord what walking "feels" like. And as the spinal cord responds by initiating muscle movement, the Ekso's sensors and motors adjust to provide less stepping power.
Challenged to do more, the reawakened spinal cord neurons may continue to relearn their old ways — to a point.
"We think the future in robotics and rehabilitation is that the device will assist but will not completely take over," Edgerton said. "The robot will do less and less and the subject will do more and more."
Whether that process leads a paralyzed patient to walk again depends on the extent and location of the spinal cord injury, Edgerton said. "If they practice and regain 50% of control, that's highly significant," he said.
The work on Pollock's case was published by the IEEE Engineering in Medicine and Biology Society.