https://pmc.ncbi.nlm.nih.gov/articles/PMC10151186/
I personally believe that exercise is overwhelmingly beneficial and exercise every day, but there is evidence that athletes have slightly increased risk of ALS (though this may be related to something other than exercise itself, eg maybe the fields on which sports teams play have harmful chemicals, higher head injury rates, etc)
Didn't they link it to pesticide use at golf courses ?
Like most things, there’s a U-shaped curve to the benefits and downsides of exercise.
Exercise creates a lot of oxidative stress, and after a while or too much exercise your body can’t handle the oxidative stress and that’s where things start going wrong.