A team at the University of Sheffield has uncovered a troubling paradox at the heart of modern health wisdom: vigorous exercise, long celebrated as a cornerstone of wellbeing, may accelerate the onset of motor neurone disease in those whose genes already place them in its shadow. Drawing on the genetic profiles of half a million people, the researchers have not come to condemn movement, but to refine our understanding of who bears the hidden cost of it. The finding is less a warning to the many than a call to find and protect the few.
Intense exercise may raise MND risk in genetically vulnerable people, study finds
Motor neurone disease dramatically reduces lifespan and affects movement, speech, and breathing; approximately 1 in 300 people develop the condition.
If everyone stopped exercising that would do more harm than good
Mark
So this study is saying exercise causes motor neurone disease?
Mimi
Not exactly. It's saying that for people who are genetically predisposed to MND, intense exercise appears to increase their risk. For everyone else, the benefit of exercise almost certainly outweighs any risk.
Luke
But we don't know who the genetically predisposed people are yet, right? That's the whole point—they're calling for screening.
Mimi
Correct. The researchers identified the mechanism, but they can't yet tell you whether you're at risk just by looking at you.
Mark
How confident are they in this finding?
Mimi
They used data from half a million people and a statistical method designed to show causation, not just correlation. That's fairly robust.
Luke
Though Mendelian randomisation has limits. It's a clever technique, but it's not the same as a randomised trial where you actually make people exercise and measure what happens.
Mimi
True. But you can't ethically do that experiment with a disease this serious.
Mark
What happens now?
Mimi
They want to develop screening tests so people at genuine risk can know about it. The hope is precision medicine—tailored advice based on your genetics, not blanket recommendations.
Luke
And in the meantime, people with a family history of MND might want to talk to their doctor before starting a new intense exercise program.
Mimi
That seems wise, yes.
Le Pouls
- A disease that strips away movement, speech, and breath now has a newly confirmed trigger — intense exercise — for those carrying certain genetic vulnerabilities.
- The paradox is acute: the very behaviour prescribed for a longer life may shorten it for an estimated one in 300 people predisposed to MND.
- Researchers used genetic data from 500,000 UK Biobank participants to establish exercise as a causal risk factor, not merely a correlation — a methodological step that sharpens the alarm.
- Athletes like Rob Burrow and Doddie Weir have put a human face on the pattern, lending urgency to what science is only now beginning to explain.
- Scientists are not calling for people to stop exercising — they are racing to build screening tools that can identify who should think twice before they do.
A team at the University of Sheffield has uncovered a troubling paradox at the heart of modern health wisdom: vigorous exercise, long celebrated as a cornerstone of wellbeing, may accelerate the onset of motor neurone disease in those whose genes already place them in its shadow. Drawing on the genetic profiles of half a million people, the researchers have not come to condemn movement, but to refine our understanding of who bears the hidden cost of it. The finding is less a warning to the many than a call to find and protect the few.
Motor neurone disease takes movement, speech, and breath, and it does so without reversal. It touches roughly one in every 300 people. Now researchers at the University of Sheffield have added a disquieting piece to its puzzle: vigorous exercise may raise the risk of developing the condition — but only in those whose genetics already incline them toward it.
The study, published in EBioMedicine, drew on genetic data from 500,000 UK Biobank participants. Using a technique called Mendelian randomisation — which treats genetic variation as a kind of natural experiment — the team found that people with a higher genetic predisposition to MND faced elevated risk when they exercised intensely, defined as more than 15 to 30 minutes of strenuous activity two to three times a week. More strikingly, those carrying the most common MND-linked mutation developed the disease earlier if they exercised strenuously.
Lead researcher Dr Johnathan Cooper-Knock was unambiguous: exercise, he said, is a confirmed risk factor for motor neurone disease. Yet he and his colleagues stopped well short of advising people to stop moving. Without knowing who carries the relevant mutations, a blanket warning would cause far more harm than good. The real ambition is targeted screening — identifying vulnerable individuals so they can make genuinely informed choices.
The link between athletic life and MND has long been observed in figures like Doddie Weir, Rob Burrow, and Stephen Darby, all of whom have spoken openly about their diagnoses. The Sheffield findings offer no simple remedy, only a sharper map of a complicated risk — and a reminder that even our most trusted health instincts contain shadows worth examining.
Motor neurone disease is a condition that steals movement, speech, and breath. It affects roughly one in every 300 people. It is brutal and it is final. Now a team of researchers at the University of Sheffield has found something unsettling: the very thing most of us are told to do for our health—vigorous exercise—may actually increase the risk of developing this disease, but only for people whose genes make them vulnerable to it.
The study, published in EBioMedicine, drew on genetic data from 500,000 people enrolled in the UK Biobank project. The researchers used a statistical technique called Mendelian randomisation, which allowed them to treat the genetic information as if it were an experiment. What they discovered was that people whose DNA carried a higher predisposition to motor neurone disease faced an elevated risk if they engaged in intense physical activity. The researchers defined intense activity as more than 15 to 30 minutes of exercise performed two to three times per week.
The findings went deeper still. Many of the genes already known to increase MND risk altered their behaviour in response to exercise. More strikingly, people who carried the most common mutation linked to the disease developed it at an earlier age if they exercised strenuously. Dr Johnathan Cooper-Knock, one of the lead researchers, was direct about the implications: "We have conclusively said exercise is a risk factor for motor neurone disease," he told the BBC.
Yet the researchers stopped short of telling people to stop exercising. Cooper-Knock acknowledged the paradox plainly: "We don't know who is at risk and we wouldn't go as far as advising who should and shouldn't exercise. If everyone stopped exercising that would do more harm than good." The goal, instead, is to develop screening tools that can identify which people carry the genetic vulnerability, so that those individuals can make informed decisions about their activity levels.
Prof Dame Pamela Shaw, director of the Neuroscience Institute in Sheffield, framed the work as progress toward understanding "the link between high levels of physical activity and the development of MND in certain genetically at-risk groups." The connection between exercise and motor neurone disease has long been observed. A growing number of athletes have been diagnosed with the condition, among them Doddie Weir, Rob Burrow, and Stephen Darby, all of whom have spoken publicly about their illness. Burrow, who revealed his diagnosis in 2019, has recently been shortlisted for a National Television Award for his documentary about living with the disease. The research offers no easy answers, only a clearer picture of a complicated risk—and a reminder that the path to better health is rarely straightforward.
Citations marquantes
We have conclusively said exercise is a risk factor for motor neurone disease— Dr Johnathan Cooper-Knock, University of Sheffield researcher
We don't know who is at risk and we wouldn't go as far as advising who should and shouldn't exercise— Dr Johnathan Cooper-Knock
Envie de l'histoire complète ?
Lire l'original sur Evening Standard ↗
Science & Space