Moderate or vigorous exercise may lower the risk of ALS, a fatal disease, for men but not women, new research finds.

The study, published Wednesday in Neurology, the medical journal of the American Academy of Neurology, followed 373,696 Norwegian people for about 27 years.

Participants recorded their physical activity, ranging from sedentary to moderate to intense. During the follow-up period, 504 people developed ALS.

Adjusting for lifestyle factors that can affect the risk of ALS, like smoking and body weight, researchers found that male participants who reported moderate levels of physical activity had a 29% lower risk of ALS while high levels of physical activity meant a 41% lower risk.

The study only found an association between physical activity and the risk of ALS in male, not female participants.

Researchers also analyzed participants’ resting heart rates, an indicator of overall fitness, finding that those with the lowest rates had a 32% reduced risk of ALS compared to participants with higher rates.

Study author Dr. Anders Myhre Vaage, of Akershus University Hospital in Norway, notes that the diagnosis of ALS in high-profile athletes has spurred the thinking that strenuous physical activity is an environmental risk factor that leads to the development and early onset of the disease.

One study found that NFL players are four times more likely to develop and die from ALS than the general adult male population.

Research has also shown that ALS risk genes are activated by exercise, adding to the growing debate about the relationship between physical activity and ALS.

“There have been conflicting findings on levels of physical activity, fitness and ALS risk,” Myhre Vaage said. “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.”

What is ALS?

ALS, also referred to as Lou Gehrig’s disease, for the Hall of Fame baseball player who died of it in 1941, is a progressive neurodegenerative disease. With ALS, the nerve cells that control muscle function deteriorate, and patients gradually become unable to walk, move, eat, speak and breathe, leading to partial or total paralysis and death.

There is no known cure for ALS — the average life expectancy after diagnosis is two to five years.

Myhre Vaage hopes the study’s findings lead to more research on ALS risk factors.

“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 they may be protective against the disease,” he said. “Future studies of the connection between ALS and exercise are needed to consider sex differences and higher or professional athlete physical activity levels.”

Other research suggests that the type of physical activity is an important factor in mitigating ALS risk. For example, one study proposed that golfing and gardening put men at three times greater risk of developing ALS.

That study found that golfers and gardeners are especially prone because of frequent exposure to pesticides, which prior research has tied to the disease’s development.

Famous people who have been diagnosed with ALS

According to the ALS Association, someone dies from ALS and someone is diagnosed with it every 90 minutes — and celebrities are not immune to its punishing effects.

Footballer Dwight Clark and physicist, cosmologist and author Stephen Hawking have lost their battles with the disease, while singer Roberta Flack, sportswriter Sarah Langs and former Chicago Bears football player Steve McMichael are still fighting.