Thread: how muscle force work

If muscle works with force on joint and joint works with exact force on muscle how can muscle drag much heavier weight than itself

biomechanics.byu.edu/exsc365%28hunter%29/images/armfreebody.gif (I would post picture showing muscle forces directly but forum doesn't let me)

The muscle force is simply greater than the force of gravity on your arm + the weight.

I think what you are really asking is how the structure of muscles can exert more force than it's own weight.

Well weight is really a relative thing, the same mass of muscle would weigh less on a small mass such as the moon.

It would also be able to lift more mass, but not more weight.


So I think the answer to your question is the proportion of gravity to the force your muscles can generate.

If we were on a very dense planet then your arm would weigh more, and even if the ball weighed the same (less mass) the muscle would now not be lifting more weight than itself.

Even though the weight of the barbell is the same.

It would be more correct to say a muscle applies a force to a tendon that transers that force to a bone which causes a movement at a joint. Muscles contract because muscle cells have fibers that cause the cell to shorten.

Originally Posted by Sealeaf

It would be more correct to say a muscle applies a force to a tendon that transers that force to a bone which causes a movement at a joint. Muscles contract because muscle cells have fibers that cause the cell to shorten.

Thanks for the explanation of muscle contraction.



So if you get "stronger" do these cells get stronger or do there just get more cells.

Also how could more cells = more force if they only shrink.

If they shrink all in the same direction, meaning one end of the cell doesn't go in then I could see how the collection of force would add up.

But if they were all just shrinking I don't see how more cells would make greater contraction force