Just for surviving after two failed kidney transplants and living long beyond the prognosis of six months he was given at age 20, Shad Ireland was already a something of a walking improbability.
The 37-year-old living with no working kidneys has taken his status as a medical marvel much further, though, performing physical feats most normally healthy people wouldn't even dream of, despite spending most of his life on dialysis.
"For me to be on dialysis for 27 years, for me to do two triathlons, has really got the medical community scratching their heads," Ireland said. "If you asked any doctor, if you told them about me, they would say it's impossible."
Last week Ireland took his determination 4,639 miles. He biked from California to the steps of the U.S. Capitol Building to draw attention to the 500,000 people with kidney failure currently living on dialysis.
More importantly, however, Ireland said, he biked across the country to get the attention of the millions of Americans whose obesity, high blood pressure or diabetes put them at risk for kidney failure.
To make it across the country, Ireland had to schedule four-hour long dialysis sessions every Monday, Wednesday and Friday to clean the toxins out of his blood that a healthy kidney would have rid him of. Doctors say kidney disease makes conditioning for any physical task much more difficult.
"When I said I was going to do an Ironman triathlon, my biceps were the size of quarters. I went to a gym. I had no idea what I was getting into: I couldn't walk two minutes on a treadmill, I couldn't pick up 10 pounds," Ireland said. "Within a year I was able to gain 42 pounds of muscle."
Like the other 500,000 people in the United States living with kidney failure, Ireland had a body that was ravaged by dialysis and his disease. Many dialysis patients are unable to work, they may suffer from bone loss and end up in a wheelchair, and 15 percent to 20 percent of people on dialysis die every year.
"Healthy kidneys remove these things (toxins) every second of every day, so there is very little accumulation and the concentration of these chemicals in the blood stays within a very tight range," said Dr. Alicia Neu, a professor at Johns Hopkins University School of Medicine in Baltimore.
"Many of these substances can affect physical strength, endurance, memory, sleep habits, etc.," said Neu. "Many patients can and should remain physically active on dialysis. They may need to work harder and certainly have more to overcome to achieve the level of activity of those who have normal kidney function."
Ireland's physical feat might seem impossible to many, but doctors want their dialysis patients to think the opposite.
"No it's not impossible -- it's fantastic," said Dr. Robert Stanton, the chief of nephrology at Joslin Diabetes Center in Boston.
"The idea of trying to get people to exercise has been talked about for years," said Stanton, who is also a professor of medicine at Harvard Medical School. "Look, there is no reason that you have to be sitting around and feeling ill. If you get up and moving you can really take charge of your life."
Stanton explained that the benefits of exercise -- such as lower blood pressure and increased bone strength -- often counteract the secondary health conditions caused by kidney disease.
"But most patients find it tiring or draining after dialysis," he said.