The legs support the parts of your body which are above them. The
lowest parts of your legs (near your feet) support the most weight. The
upper parts of your legs support less because they do not have to
support the lower parts of your legs.
Within the leg, most of the weight is carried by the bones. In
fact, the bones have more force on them than just your weight (and even
more than the impact forces involved in walking). This comes about
because muscles only operate by contracting -- they pull but do not
push. All pushes come from the bones. When you walk, muscles on either
side of the leg pull on tendons to turn, say, your feet so you push
forwards with your toes. Your leg stays the same length even though
your muscles are contracting because the bones push in the opposite
direction.
The strongest muscles in the body are in the buttocks. So the
upper leg bones may even have more force on them than the lower ones
when you walk, or better yet, when you climb stairs (but maybe not when
you are just standing).
Tom
(published on 10/22/2007)
