Parkinson's patients may be able to reduce their symptoms by emulating British cycle hero Bradley Wiggins, new research claims.
Scientists saw that cycling led to greater connectivity between brain regions linked to the disease. But research found that vigorous "forced" pedalling was key to the changes, which were associated with improvements in co-ordination and balance.
The US research lends support to anecdotal evidence of cycling alleviating Parkinson's symptoms.
The debilitating disease, which affects motor regions of the brain, causes shaking, rigidity and slow movement.
Neuroscientist Dr Jay Alberts conducted the study after riding a tandem bicycle across Iowa with a patient to raise awareness of the disease.
Ride 'improved condition'
He noticed that his companion's condition improved after the ride.
"The finding was serendipitous," said Dr Alberts, from the Cleveland Clinic Lerner Research Institute. "I was pedalling faster than her, which forced her to pedal faster.
"She had improvements in her upper extremity function, so we started to look at the possible mechanism behind this improved function."
Dr Alberts led a team of scientists who carried out brains scans on 26 Parkinson's patients using a technique called functional connectivity magnetic resonance imaging (fcMRI).
The patients had to undergo sessions on exercise cycles three times a week for two months. Some pedalled at their own pace, while others were forced to cycle faster by motors fitted to their bikes.
FcMRI flags up the functional connectivity of different brain regions by measuring changes in blood flow.
The scans showed that faster cycling boosted nerve connections between the primary motor cortex and thalamus. Signalling between these two regions is vital to co-ordinated movement, and impaired in Parkinson's patients.
The findings were presented today at the annual meeting of the Radiological Society of North America in Chicago.
Researcher Chintan Shah, also from the Cleveland Clinic, said: "The results show that forced-rate bicycle exercise is an effective, low-cost therapy for Parkinson's disease."
The scientists are now studying how patients fare with exercise bikes in their homes. They also want to see whether other forms of exercise such as swimming and rowing have similar benefits.
Changes after vigorous cycling
Dr Kieran Breen, director of research and innovation at the charity Parkinson's UK, said: "This new research adds to the growing body of knowledge which suggests that cycling may be beneficial for people with Parkinson's.
"In this new study, the researchers found that people who cycle vigorously three times a week, saw improvements in their co-ordination and balance - areas which suffer badly once Parkinson's begins to advance.
"Although this sounds like a simple way to reduce some of the symptoms of Parkinson's, it is important to remember that the level of exercise undertaken by those in this study was high. This level of activity would simply be beyond the physical capabilities of some people living with the condition."
"While it is too soon to encourage people with Parkinson's to get on their bikes three times a week on the basis of this study, we do know that exercise can be beneficial.
"A regular exercise routine can help those with the condition to not only improve their general fitness but can also help to improve movement and balance as well as other symptoms of the condition such as anxiety and depression."