Exercise and Physical Fitness Correlate with a Lower Risk of Amyotrophic Lateral Sclerosis
The cause of amyotrophic lateral sclerosis (ALS) is presently unclear despite a wealth of data. It may have many distinct possible causes that progress to converge on a phenotype of maladaptive neuroinflammation at motor neurons and other locations. ALS tends to emerge in later life, but lacking good insight into its causes makes it unclear as to exactly how the processes of aging may contribute to its onset. Certainly, greater neuroinflammation is a feature of aging, and so any condition that involves localized inflammatory reactions may be theorized to be worse or more likely to occur in later life.
ALS is a rare, progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. People with ALS lose the ability to initiate and control muscle movement, which often leads to total paralysis and death. The average life span after diagnosis is two to five years. Researchers looked at 373,696 people in Norway with an average age of 41. They were followed for an average of 27 years. Of the total participants, 504 people developed ALS. Of those who developed ALS, 59% were male participants.
Participants recorded their level of physical activity for the past year into one of four categories: 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; or participation in hard training or sports competitions regularly, several times a week. Due to few participants with the highest level of physical activity, researchers combined the third and fourth categories into one high activity group.
Researchers found that of the 41,898 male participants that had the highest level of physical activity, 63 developed ALS; of the 76,769 male participants with the intermediate level of physical activity, 131 developed ALS; and of the 29,468 male participants with the lowest level of physical activity, 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. Researchers also looked at resting heart rate. Men in the lowest of four categories of resting heart rate, which indicates good physical fitness, had a 32% reduced risk of ALS compared to those with higher resting heart rates.