Apple Watches and iPhones measure stability when walking. https://support.apple.com/en-us/HT212503 https://support.apple.com/en-us/HT212503 Flat surfaces and s

Apple Watches and iPhones measure stability when walking. https://support.apple.com/en-us/HT212503 https://support.apple.com/en-us/HT212503 Flat surfaces and shoes, IMHO, reduce the amount of work it takes to stay balanced and thus makes it easier to fall. If you’re walking on uneven ground and need to be careful where and how you step your balance and the amount of attention you pay to it improve quickly.