Aren't you kind of presuming these people would not have injuries if they had chosen the non-academic vocation they're most likely qualified for?

Any sustained outdoor work like landscaping, roofing, and plumbing is brutal on the body in the long-term. Even the salty old kitchen workers I've met eventually start falling to bits.

Star athletes are also inculcated with a conscientiousness around health and fitness that desk jockeys and eggheads don't have the benefits of.