Could your fitness routine be secretly putting you at risk for a devastating neurological disease? It's a question that might make even the most dedicated athlete pause. Professor Dame Pamela Shaw, a leading neurologist, has observed something quite remarkable: nearly every patient she's encountered with Motor Neurone Disease (MND) has been physically active. This finding flies in the face of the common perception of MND as something that strikes those leading sedentary lives.
Professor Shaw, who directs the Sheffield Institute for Translational Neuroscience (SITraN), a renowned hub for MND research, has personally seen thousands of patients. She notes, "I've never seen a couch potato get motor neurone disease." Instead, she finds that her patients are often highly active – some are even professional athletes, while others simply engage in a lot of sports. They are the kind of individuals you'd describe as "always on the go, always buzzing about."
This observation has sparked a deep interest for Professor Shaw: why are so many physically active people developing MND? It's a complex puzzle, especially since, as she points out, "clearly most athletes don’t develop MND." The current thinking is that it's not just one factor, but rather a combination of an individual's genetic makeup and their lifestyle choices.
SITraN's unique setup, housing both clinical doctors and scientists under one roof, and its close ties with the NIHR Sheffield Biomedical Research Centre, allow for rapid translation of discoveries into patient trials. This "translational approach," as Professor Shaw calls it, is crucial for harnessing scientific advancements to benefit patients and their families.
Motor Neurone Disease affects approximately 1 in 300 people. Alongside Professor Johnathan Cooper Knock, Professor Shaw has made significant strides in understanding the disease's origins. A key discovery points to a link between strenuous exercise and an increased likelihood of developing MND in individuals with a specific genetic mutation known as the C9orf72 gene (or C9 gene). While everyone has two copies of this gene, in the most common genetic form of MND, one copy is altered.
Their research involved surveying a large group of MND patients who carried the C9 gene alteration. They asked about their strenuous physical activity throughout their adult lives and found a compelling correlation: the more strenuous the activity, the earlier the onset of the disease.
Professor Shaw explains this by suggesting that if you have the C9 genetic predisposition, a sedentary lifestyle might not trigger the damage to motor neurones. However, if you have that same genetic makeup and engage in intense physical activity, like being a professional rugby player or a marathon runner, you're essentially stressing your motor system. And this is the part most people miss: if your genetic makeup means your body's stress response isn't robust enough, this prolonged stress can gradually damage motor neurones over time.
But here's where it gets controversial... This theory was strikingly illustrated by a case involving identical twins, both carrying the C9orf72 gene change. One twin was an extreme athlete, training daily and participating in triathlons, and sadly developed MND in his 30s. His identical twin, however, lived a completely sedentary life and remained healthy 12 years later. This stark contrast raises profound questions about the interplay between genetics and lifestyle.
Further intriguing experiments at SITraN, led by Professor Shaw and Dr. Ryan West, have utilized fruit flies. By introducing the human C9 gene into fruit flies and then subjecting them to forced climbing exercises (simulating strenuous activity), they observed a fascinating outcome. While normal fruit flies showed improved lifespan and motor strength with such activity, the C9-modified flies experienced worse outcomes: reduced lifespan, motor strength, and climbing speed. This suggests that in the presence of the C9 gene alteration, exercise might not be beneficial and could, in fact, be detrimental.
Supporting evidence also comes from international studies. The Vasaloppet, a massive cross-country ski race in Sweden, has been the subject of a study comparing elite skiers to the general population. The findings indicate that elite skiers who have competed in the Vasaloppet multiple times have a significantly higher risk of developing MND, whereas those who participate only once do not show this increased risk.
Another area of interest is a study on military personnel in the US, which revealed a four-fold increased risk of developing motor neurone disease (known as ALS there). Professor Shaw believes this is likely linked to the intense physical training undertaken by military members and sees it as a valuable opportunity to further investigate the genetic and environmental factors at play.
Professor Shaw is careful to emphasize that their research is not about discouraging healthy exercise. "We're cautious," she states, "because clearly we don't want to stop people doing healthy exercise which is protective for so many things." The concern, she clarifies, is not about gentle exercise or running twice a week, but rather about "hammering your system."
Ultimately, the path to finding a cure or effective treatments for MND lies in understanding its causes, a mission that dedicated researchers like Professor Shaw and her team at SITraN are tirelessly pursuing.
What are your thoughts on this surprising link between intense exercise and MND? Do you agree with Professor Shaw's interpretation, or do you believe other factors are more significant? Share your opinions in the comments below!
