Researchers say that regular vigorous exercise increases the risk of motor neuron disease (MND) in people who are genetically predisposed to the condition.
Scientist at Sheffield University found a causal relationship between high-intensity physical activity and impairment among those already at risk for disease.
They believe this work is a major step towards understanding the link between intense exercise, which can cause motor nerve injury in some people, and neurodegenerative diseases, which affect around 5,000 people in the UK.
“We have suspected for some time that exercise is a risk factor for MND, but until now this association was considered controversial,” said Dr. Jonathan Cooper-Knock, neurologist in Sheffield. “This study confirms that in some people, repetitive strenuous exercise increases the risk of MND.”
The lifetime risk of developing MND is about 1 in 400, but previous research has shown that it is six times greater in professional soccer players than in the general population. A number of prominent British athletes have shared their experiences 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 their next step is to develop tests that identify those most at risk.
Writing in magazines EBioMedicineThe scientists described how they analyzed data from the UK Biobank project, which contains detailed information on the genes and lifestyle of half a million people. They found that people who had a genetic makeup that made them more likely to engage in vigorous exercise were also more likely to develop MND.
With vigorous exercise, the activity levels of several genes associated with the condition are altered, whereas individuals with mutations representing 10% of MND develop the disease earlier if they participate in regular high-intensity exercise.
Professor Dame Pamela Shaw, Director of the Institute of Neuroscience at Sheffield, said: “It is clear that most people who engage in vigorous exercise do not develop motor nerve injuries and more work is needed to identify the exact genetic risk factors involved.”
“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 in the brain and spinal cord. As the disease progresses, messages from the nerves are interrupted and eventually stop reaching the muscles, causing the muscles to stiffen and be wasted. The disease can significantly impair people’s ability to move their limbs, speak, eat and breathe. While about 10% of cases are inherited, the remainder are caused by complex interactions between genes and the environment.
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