Comment by doytch

This is a gross simplification on both accounts.

US Army veterans do have a higher rate of arthritis but their days are quite different from the "run 3-5 days a week" that most people think of when talking about recreational runners.

And the pacemaker comment stood out so I did a bit of digging and found a study [1] you might be referring to. Again, the effects were strong only in the heavy-duty-exercisers/pro/semi-pro cross-country skiier group. Additionally, this didn't offset the gains to cardiovascular or mortality risk - that group was still "healthier."

[1] https://pubmed.ncbi.nlm.nih.gov/39101218/