Near the end of the paper: Though the risk rise (26% higher) is low in individuals with a history of vigorous physical activity, there is a five-fold morta

Near the end of the paper: Though the risk rise (26% higher) is low in individuals with a history of vigorous physical activity, there is a five-fold mortality rate increase in professional athletes (39). Vigorous physical activity likely increases glutamate excitotoxicity and oxidative stress, hastening neurodegeneration in individuals with a genetic predisposition for the development of ALS (38). Therefore, while the impact of marathon running in well trained individuals is null, for those with ALS genetic risk, disease vulnerable motor areas are impacted more on otherwise physiological myelin expenditure (e.g., corticospinal tract), as myelin itself and myelin-producing oligodendrocytes are also vulnerable to glutamate excitotoxicity as well (40).