Computer is on the fritz (by the way, where does that expression come from?) so this post will be short.
I was thinking about joint replacement surgery yesterday--knees and hips--and realized that I do not know a single runner or Ultrarunner who has had such a surgery.
All the artificial joint recipients I know tend to be sedentary or inactive. I need to investigate this further, realizing that correlation does not necessarily mean causation. But it certainly is food for thought.