Comments by "LancesArmorStriking" (@LancesArmorStriking) on "Does Running Really Ruin Your Knees?" video.

Bit of an extreme case... Your tendons will thicken to accomodate your running, but cartilage just doesn't. After it wears away, you're just grinding bone on bone, hopefully I don't need to explain why that would stop you from running (and in the past, dying). Our bodies only evolved to withstand as much activity as was necessary to keep the human tribe alive and reproducing— that's about 50-60 years, at which point anything can happen to your body. Shitty knees is one of those things, our bodies aren't meant to be perfect they're just meant to work within their environment.
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