Experts in Parkinson's disease are baffled by the case of a man who shakes so badly from his condition he cannot walk, but is able to ride a bicycle with ease.
The case is described in the New England Journal of Medicine, which included videos of the 58-year-old patient before and after he rides the bicycle.
In the first video, the strong tremors in his legs and arms make him barely able to shuffle down a hallway. At one point, his feet seem locked in place, described as gait freezing; later, his tremors cause him to collapse to the floor.
In the second video, the man is helped with mounting a bike, is given a push, and then cycles through a parking lot. He makes a U-turn, cycles back and then hops off the bike. The minute he does, the tremors in his legs return.
Dr. Bastiaan R. Bloem, of the Radboud University Nijmegen Medical Center in the Netherlands, who describes the patient in the journal, told The New York Times that in all in his years of caring for patients with Parkinson's disease, he had never met a patient who could cycle before.
The patient had had Parkinson's disease for 10 years. The disease, in which brain cells that control movement die off, had left him severely affected. Yet he said he regularly cycled for exercise.
After seeing that patient, Dr. Bloem asked 20 other severely affected Parkinson's patients about riding bicycles and it turned out, all of them could do it.
It's unclear why patients who cannot stop their tremors enough to walk can suddenly ride bicycles. Bloem calls it "kinesia paradoxica."
"This striking kinesia paradoxica may be explained by the bicycle's rotating pedals, which may act as an external pacing cue," Bloem suggests in the NEJM piece.
"Alternatively, the motor-control mechanisms involved in gait as compared with other activities engaging the legs, such as cycling, could be affected differentially in Parkinson's disease."
Previous research has shown that some people with Parkinson's can run, walk and do complex movements for a few minutes if they are given appropriate signals, such as with music or visual cues. Bloem says that until now, it was not known that patients with Parkinson's could ride bikes.
In Canada, Dr. Bin Hu of the Movement Disorders and Therapeutic Brain Stimulation Program at the University of Calgary has also studied kinesia paradoxica and how some Parkinson's patients are able to dance without Parkinson's symptoms.
Bloem adds that cycling may offer a good way to help some Parkinson's patients who have severe freezing of gait to exercise, and to give them an opportunity to be symptom-free for a short while.
