Regular vigorous exercise increases the risk of developing motor neuron disease (MND) in people who are genetically predisposed to the condition, the researchers say.
Scientists at the University of Sheffield found a causal relationship between high-intensity physical activity and the disorder among those already susceptible to the disease.
They believe the work marks an important step towards understanding the link between strenuous exercise, which can contribute to motor neuron damage in certain people, and neurodegenerative disease that affects some 5,000 people in the UK.
“For some time we suspected that exercise was a risk factor for MND, but until now this link was considered controversial,” said Sheffield neurologist Dr. Johnathan Cooper-Knoc. “This study confirms that in some people, frequent strenuous exercise leads to an increased risk of MND.”
The lifetime risk of developing MND is about 1 in 400, but previous studies have suggested that it is six times higher in professional soccer players compared to the general population. Several high-profile British athletes have shared their experience with MND in recent years, including Rob Burrow of the rugby league, Doddie Weir of the rugby union and footballer Stephen Darby.
The Sheffield researchers emphasize that the vast majority of people who engage in vigorous exercise do not develop MND, and that the next step is to develop tests that identify those most at risk.
Writing in the diary EBioMedicine, the scientists describe how they analyzed data from the UK Biobank project, which contains detailed genetic and lifestyle information on half a million people. They found that people with a genetic makeup that made them more prone to strenuous exercise were also more likely to have developed MND.
With vigorous exercise, activity levels changed for many of the genes related to the condition, while individuals with a mutation representing 10% of MND developed the disease earlier if they participated in regular, high-intensity exercise.
“Clearly, most people who engage in strenuous exercise do not develop motor neuron injuries and more work is needed to identify the precise genetic risk factors involved,” said Professor Dame Pamela Shaw, director of the Sheffield Neuroscience Institute.
“The ultimate goal is to identify environmental risk factors that may predispose to MND, to inform disease prevention and lifestyle choices.”
MND, also known as amyotrophic lateral sclerosis, affects the nerves of the brain and spinal cord. As the disease progresses, the messages from the nerves are interrupted and eventually stop reaching the muscles, causing them to stiffen and wear out. The disease can dramatically affect people’s ability to move their limbs, speak, eat, and breathe. While around 10% of cases are inherited, the rest is due to a complex interaction between genes and the environment.
George is Digismak’s reported cum editor with 13 years of experience in Journalism