How much can you lift in one arm ? Lets say 10 kilograms. Does this amount qualify your arm's muscle power ?No. Your bisceps is much stronger. The figure shows how this muscle works. It is attached close to the fulcrum to the lever that the bone of your forearm represents. The load you are lifting acts on the other end of this live lever. The distance between the load and the fulcrum , that is the joint, is almost eight times the distance between the biceps and the fulcrum. This means that if you are lifting a load of 10 kg, your biceps is exerting eight times the power , and consequently could lift 80 kg.
It would be no exaggerating to say that everyone is much stronger that he is, or rather that one’s muscles are more powerful than what we can really do with them. Is it a an expedient arrangement ? Not at all. By the “golden rule” of mechanics : whatever we lose in power we gain in displacement. Here you gain in speedyour arm moves 8 times faster than it’s muscles do. The muscular arrangement of animals help them to move more quickly, which is more important than strength to survive . Otherwise, it would move in snail’s speed.