July 20, 2009 -- Neuroscientist Jay Alberts is an avid cyclist, but he never expected to make any medical discoveries on his bike.
He did just that on a 50-mile ride across Iowa with his tandem bike partner, fellow neurologist Dr. David Heydrick, who has the movement disorder known as Parkinson's disease.
After the bike trip, Heydrick noticed that his handwriting dramatically improved.
In a video they shot before the ride, Heydrick's hand shook wildly, but afterward, it was steady.
In Alberts' mind, the mysterious side effect of the bike ride held an intriguing medical possibility that motor control in the arms could improve even if it was the legs that were exercising.
"It suggested that there was some change in the central nervous system or the brain function," Alberts told "Good Morning America." "What we were thinking was, maybe we have found a method of exercise here that actually is treating the disease rather than just treating some of the symptoms."
To find out, Alberts started a small trial at the Cleveland Clinic in Cleveland, Ohio, to test whether eight weeks of forced exercise on a tandem bike could improve the symptoms of Parkinson's disease. Forced exercise requires the patient to peddle faster than they would voluntarily.
"What we found was there was a 35 percent improvement in motor functioning for those patients who did the forced exercise compared to the voluntary exercise," Alberts said.
According to Alberts, the improvement lasted, although dwindled, for four weeks after the patients stopped biking.
Current Parkinson's medications generally control only motor functions for a few hours, much less days. Patient Sally Terrell said all the exercise was worth it.
"I noticed that after continued exercise that I have a calmer right side," Terrell said.
Scientists: Exercise Could Be Overriding Nervous System
Researchers think the forced exercise works because making people peddle harder may be overdriving the central nervous system, triggering the release of some chemicals that may improve motor function.
"Maybe we can turn back the clock and improve motor function to earlier levels of diagnosis," Alberts said.
Following the study, Alberts contacted Dr. Micheal Phillips for a brain scan study, comparing the brain of a Parkinson's patient on medication for the disease and one who has exercised. In each, the same brain regions were activated.
"You know, the hope is that you have an alternative way to treat your Parkinson's disease," Phillips said. "This is really cool stuff."
Terrell was so convinced of the workout's effectiveness that she has continued to exercise to battle the disease.
"I have seen the results, and I'm looking forward to keeping this disease at bay as best I can," she said.
Dance companies are getting involved in fighting the disease as well. The Mark Morris Dance Group in New York City offers classes for people suffering with Parkinson's, saying that it improves flexibility and instills confidence.
Scientists said it would take more studies to conclude if exercise actually slowed down the progression of Parkinson's and whether it could complement or even replace medication.