all the muscle filaments move away from each other
depends on which muscle but the opposite muscle sometimes contracts aswell to stabalize the joint some relaxes ...
muscles relaxes
The bicep muscle. The tricep contracts to straighten the arm as the bicep relaxes.
One group of muscles contracts, and the other group extends. As an arm moves down, the bicep muscle (the one that faces the front side of the body and goes from the shoulder to the elbow) relaxes. When the muscle relaxes, it goes from being contracted to elongated. This relaxation happens at the same time that the tricep muscle (the one that faces the backside of the body and goes from the shoulder to the elbow) contracts. This happens because the human body's skeletal muscles have what can be considered compliments. I say this to mean that when a muscle relaxes, there is a muscle that contracts simultaneously. Therefore, they move antagonistically to each other. This is to serve the purpose of creating specific movements that help assist in locomotion. On the molecular level of what happens when a muscle contracts and relaxes, the actin and myosin filaments in muscle fiber overlap to contract and separate to relax.
Relaxes
contract
the smooth muscle
gdg
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.
antagonist.
relaxes
It Contracts