Agonist muscles and antagonist muscles refer to muscles that cause or inhibit a movement.
Explanation:
Agonist muscles cause a movement to occur through their own activation.[4] For example, the triceps brachii contracts, producing a shortening contraction, during the up phase of a push-up (elbow extension). During the down phase of a push-up, the same triceps brachii actively controls elbow flexion while producing a lengthening contraction. It is still the agonist, because while resisting gravity during relaxing, the triceps brachii continues to be the prime mover, or controller, of the joint action. Agonists are also interchangeably referred to as "prime movers," since they are the muscles considered primarily responsible for generating or controlling a specific movement.
