http://www.nytimes.com/2010/04/01/health/01parkinsons.html?hpw

The man had had Parkinson’s disease for 10 years, and it had
progressed until he was severely affected. Parkinson’s, a neurological disorder
in which some of the brain cells that control movement die, had made him unable
to walk. He trembled and could walk only a few steps before falling. He froze in
place, his feet feeling as if they were bolted to the floor.

But the man told Dr. Bloem something amazing: he said he was a regular exerciser
— a cyclist, in fact — something that should not be possible for patients at his
stage of the disease, Dr. Bloem thought.

“He said, ‘Just yesterday I rode my bicycle for 10 kilometers’ — six miles,” Dr.
Bloem said. “He said he rides his bicycle for miles and miles every day.”

Thanks to Tom. No foolin'. Watch the video.