Can physical activity induce excitoxicity and increase the risk of ALS?

Even from the time of the earliest descriptions of ALS, environmental causation was considered possible. For example, Charcot mentioned that a third of his patients considered exposure to cold and damp was responsible, and he singled out one man who had sustained a fractured clavicle a few months before the onset of the disease.1 Trauma, occupational or sports-related physical activity, cigarette smoking, exposure to electromagnetic fields or electric shocks, military service and exposure to environmental lead or organic solvents have all been reported to increase the risk of acquiring ALS.2 3 However, many of these studies are based on small case numbers, or have been criticised on other methodological grounds and, for now, only an association with smoking history, pesticide exposure and dietary factors, especially premorbid fat intake have been consistent, although at a low level …