Maintaining an active lifestyle with moderate physical activity and fitness may reduce the risk of amyotrophic lateral sclerosis (ALS) in men, a study revealed.

ALS is a rare neurodegenerative disease that impairs muscle movement, potentially leading to paralysis and death. It is caused by the progressive degeneration of nerve cells in the brain and spinal cord.

Several observational studies have noted an increased risk of ALS among professional athletes, raising concerns that physical activity could elevate the risk.

"The diagnosis of prominent athletes with ALS at young ages has sparked the uncomfortable idea that higher physical activity could be tied to developing ALS. There have been conflicting findings on levels of physical activity, fitness, and ALS risk. Our study found that for men, living a more active lifestyle could be linked to a reduced risk of ALS more than 30 years later," said the author of the latest study, Dr. Anders Myhre Vaage, from Akershus University Hospital in Norway.

To analyze the risk, the research team evaluated 373,696 participants who were followed up for an average of 27 years. The participants were residents of Norway, with an average age of 41. Out of the total participants, 504 individuals developed ALS and among them, 59% were male.

The physical activity of the participants was recorded for a year, and they were divided into four categories based on their activity levels: sedentary; a minimum of four hours per week of walking or cycling; a minimum of four hours per week of recreational sports or heavy gardening; and regular participation in intense training or sports competitions several times a week.

The third and fourth groups were eventually combined into one " high activity group" since there were only a few participants.

The analysis showed that among the 41,898 men with the highest level of physical activity, 63 developed ALS. Out of the 76,769 men with moderate activity levels, 131 developed ALS, and among the 29,468 men with the lowest activity levels, 68 developed ALS.

"After adjusting for other factors that could affect the risk of ALS, such as smoking and body mass index, researchers found that for male participants, when compared to those with the lowest level of physical activity, those with moderate levels of physical activity had a 29% lower risk of ALS and those with high levels of physical activity had a 41% lower risk of ALS," the news release stated.

Researchers also examined resting heart rate. Men in the lowest of four resting heart rate categories, indicating good physical fitness, had a 32% lower risk of ALS compared to those with higher resting heart rates.

"Our findings show that, for men, not only do moderate to high levels of physical activity and fitness not increase the risk of ALS, but that it may be protective against the disease. Future studies of the connection between ALS and exercise are needed to consider sex differences and higher or professional athlete physical activity levels," Myhre Vaage said.

However, a limitation of the study is that the physical activity questionnaire was administered only once, which may not accurately reflect exercise levels over the nearly 30-year duration of the study.

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