My girlfriend and I like to guess where other tourists we see on the streets are from and one of the most obvious indicators for Americans is that as soon as they hit 40-50 there’s a high chance they're either limping or using a cane or similar.
My theory used to be that a lot of them played high-impact sports such as (American) football or basketball in their youths and consequently ruined their knees. But honestly not being used to walking might also contribute