What Does the Antagonist Muscle Do?

Coordination requires cooperation between skeletal muscles. For every muscular action there must be an equivalent reaction. Your muscles often work in pairs in order to produce a smooth and controlled motion. Within the muscle pairings there are separate groupings known as the agonist muscle and the antagonist muscle.

  1. Role of the Agonist Muscle

    • An agonist muscle is the muscle responsible for creating the primary movement. A normal range of motion is created through the contraction of the muscle. For example; when flexing the elbow, the primary muscle, or agonist, would be the biceps.

    Role of the Antagonist Muscle

    • An antagonist muscle creates the opposite motion of the agonist. It is the job of the antagonist muscle to return the limb to its initial position. Building on the example of elbow flexion, the triceps would be the antagonist muscle, as it extends the elbow. The coordinated contraction and relaxation of the skeletal muscles are what allow you to sit upright, bend over, walk and run.

    Additional Muscle Pairings

    • The combination of agonist and antagonist muscles is essential for normal function. In your lower extremities, the quadriceps and hamstrings represent an agonist and antagonist pairing. At your core your abdominals and lower-back muscles illustrate an agonist and antagonist pairing. In the upper body, the muscles of the chest and upper back demonstrate an agonist and antagonist relationship.

    Importance of Training

    • In order to maintain the strength and coordination of each muscle pairing, it's important to train both muscle groups equally. For example, after doing a chest press exercise, complete a rowing exercise. Another example would be the hamstring curl; following completion of the curl do a quadriceps press exercise. For every pushing or pressing exercise you complete, do a pulling exercise. Injury can occur when one of the muscle groups in the pairing overpowers the other; the weaker muscle is unable to control its corresponding function with complementary force.