It's good show biz, but I cringe when I see them slamming their joints (esp. knees and ankles) on hard surfaces such as concrete and asphalt while wearing shoes that don't seem to absorb shocks.

I bet an orthopedist would advise them to modify their act.

Long ago, I went to a podiatrist because my heels hurt, and he told me, "Years of walking on concrete have turned your Achilles tendon into a steel cable, and now it's pulling on your other muscles." If mere walking does that, what does that energetic dancing do?