I think what your after is called an antagonistic pair of muscles, for example the bicep and the tricep. When the bicep is contracting the tricep relaxes and when the tricep is contracting the bicep relaxes.
Muscle does not only work when it relaxes it also works when your stressed because muscle helps your body relax from that stress.. You may not know what I'm talking about but its true!
The bicep muscle. The tricep contracts to straighten the arm as the bicep relaxes.
Relaxes
contract
The muscles can only pull, not push. So, to move a limb, one muscle relaxes while the other muscle pulls.
The muscles can only pull, not push. So, to move a limb, one muscle relaxes while the other muscle pulls.
the smooth muscle
gdg
antagonist.
It Contracts
relaxes
It relaxes