Regular and intense physical exertion increases the risk of developing lateral amyotrophic sclerosis in people genetically predisposed to the disease, although most of them are not even aware of the impending danger. This is the conclusion of a group of scientists from the University of Sheffield – one of the most prestigious and authoritative universities in the UK.
The researchers are not urging anyone to stop exercising, but they hope the data will help identify people at risk. Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease or Lou Gehrig’s disease, is an incurable, progressive neurodegenerative disease. It affects the cells of the spinal cord (motor neurons) responsible for coordinating movement and maintaining muscle tone. As a result, the transmission of impulses from the brain to the muscles is disrupted, resulting in progressive weakness that gradually affects all muscle groups. As more and more motor neurons die, the patient’s movements become difficult, and problems with breathing and speech begin. Death most often occurs as a result of respiratory muscle failure.
ALS is a rare disease that affects only about 0.3% of the population. It is known that the onset and development of the disease are determined by both genetics and adverse factors accumulated throughout life. The link between exercise and disease has long been recognized, but scientists have been unable to understand whether it is causal or whether there are third factors involved. In particular, it is known that Italian soccer players are six times more likely to suffer from ALS than the average. Many other athletes, including former Liverpool defender Stephen Darby and Zenit St. Petersburg midfielder Fernando Ricksen, who died of Charcot’s disease in 2019, have spoken openly about their illness.
“We have concluded that intense physical exertion is indeed a risk factor for the development of BAC,” said one of the study’s authors, Dr. Jonathan Cooper-Noke. “It is no coincidence that the percentage of elite athletes who suffer from this condition is disproportionately high.” Scientists analyzed DNA samples from about half a million people stored in the UK Biobank project. Using a method known as Mendelian randomization, they found that people who are genetically predisposed to intense physical exertion are also more susceptible to BAS disease.
The article published based on the results of the study states that as a result of regular physical training, some genes mutate – and in people with a hereditary predisposition to developing BAS disease, it occurs earlier if they exercise regularly and intensively. The article refers to “regular and vigorous” exercise, which is defined as at least two to three sessions per week that last at least thirty minutes. At the same time, the scientists emphasize that the majority of those who train in this mode do not get sick, and it is still unclear how to identify those at risk. However, based on their work, they hope to create a methodology for early diagnosis and prevention of the disease – similar to the one that already exists for checking football players’ propensity for heart problems.
“We don’t know who is at risk, and we have no intention of telling people who can and can’t exercise. If everyone stops exercising, the harms will outweigh the benefits,” says Dr. Cooper-Nok. “Our study brings us closer to unraveling the link between high levels of physical stress and the onset of BAF in people with a genetic predisposition to the disease,” said Professor Pamela Shaw, Head of the Institute of Neurology in Sheffield.
It is believed that low oxygen levels in the body during intense (anaerobic) exercise cause a phenomenon called oxidative stress in motor neurons, which are among the largest and most active oxygen-consuming cells in our bodies. In genetically susceptible individuals, this leads to damage and death of such motor neurons. Dr. Brian Dicky of the nonprofit Association for Combatting BSA believes the Sheffield colleagues have taken the right direction and that more similar work is needed. Genetic and environmental factors in the development of BAS have been studied independently, he says, and “the strength of this study is that it brings the pieces of the puzzle together.”