Researchers from the University of Sheffield have hailed the study as a significant step forward for understanding the link between high levels of physical activity and the development of the neurodegenerative disease.
A number of high profile British sportsmen, including rugby league's Rob Burrow, rugby union's Doddie Weir and footballer Stephen Darby, have shared their experience of living with MND in recent years.
Despite the findings, the research team stressed on Friday that most people undertaking vigorous exercise do not develop MND and insisted that sport has huge health benefits.
“We have suspected for some time that exercise was a risk factor for MND, but until now this link was considered controversial,” Dr Johnathan Cooper-Knock, one of the study’s authors, said.
“This study confirms that, in some people, frequent strenuous exercise leads to an increase in the risk of MND.
“It is important to stress that we know that most people who undertake vigorous exercise do not develop MND.”
Dr Cooper-Knock added: “The next step is to identify which individuals specifically are at risk of MND if they exercise frequently and intensively; and how much exercise increases that risk.”
Previous research has shown an estimated six-times increased risk of MND in professional footballers, according to the study’s authors.
MND, or amyotrophic lateral sclerosis (ALS), affects the motor neurones in the brain and spinal cord that connect the nervous system and muscles to enable movement of the body.
The disease affects approximately 5,000 people in the UK and the life-time risk of developing the condition is approximately one in 400.
About 10 per cent of MND cases are inherited, but the remaining 90 per cent are caused by complex genetic and environmental interactions which are not well understood.
Dr Cooper-Knock said there was an urgent need to understand the link between these factors to help discover new therapies and preventative strategies for the disease.
The Sheffield team said its research, published in the journal EBioMedicine, would have a significant impact on global efforts to identify which individuals are at risk of MND based on their genetics.
They hope it will help doctors to be able to offer advice to the families of MND patients about the risks associated with exercise habits.
“In recent years, understanding of the genetics of MND has advanced, but there has been little progress in identifying the environmental and lifestyle factors that increase the risk of developing the disease,” Dr Brian Dickie, director of research development at the Motor Neurone Disease Association, said.
“This is, in part, because the genetic and the environmental studies tend to be carried out in isolation by different research teams, so each is only working with part of the jigsaw.”
Dr Dickie added: “We need more robust research like this to get us to a point where we really understand all the factors involved in MND to help the search for more targeted treatments.”
Additional reporting by PA