eli5: how does it work that for every pound of weight you lose, there is a 4 pound stress reduction in your knees?

Question

eli5: how does it work that for every pound of weight you lose, there is a 4 pound stress reduction in your knees?

In: 1542

Answer 1

Place a rock on your foot. That’s how much it weighs. Now drop the rock on your foot. Different experience?

Walking or especially running requires your knees to not just support your body weight but stopping your falling body weight.