What Is the Triceps' Antagonist?

Man flexing muscles

An antagonist is usually thought of as an adversary who fights with or competes against you. In terms of muscle tissue, the antagonist does act in opposition, but not in a fighting way. The joints of your body move when the agonist muscles and antagonist muscles counteract.


The triceps are three headed muscles located on the backs of the upper arms. One of the muscle fibers begins on your shoulder blade. The second muscle fiber begins on the top of your upper arm bone. The third head starts on the lower portion of your upper arm bone. The three heads connect and attach just below the elbow on the back of your lower arm bone. When the triceps contract, or shorten, the elbow extends and your arm straightens. The triceps are considered the agonist muscle group when you perform exercises specifically for this muscle group, such as overhead arm extensions.


An antagonist muscle produces the exact opposite movement of the agonist muscle. The body contains many opposing muscle groups. For example, the antagonist of the triceps is a muscle group that flexes the elbow and bends your arm. The biceps counteract the movement by the triceps. Another agonist and antagonist muscle group is the front of your upper thigh, the quadriceps, that extend your leg, and the back of your upper thigh, the hamstrings, that flex your leg.


The biceps are two headed muscles located on the front of your upper arms. The biceps begin above your shoulder and end on your lower arm bone. When the elbow flexes, the biceps shorten or contract. The biceps are the antagonist of the triceps as this flexion is the direct opposite action of a triceps extension.

Muscle Balance

The muscles help keep the body aligned. If the agonist is stronger than the antagonist, muscle imbalances occur which leads to stress on the agonist muscle. Muscle stress leads to muscle strains, muscle pulls or tendon inflammations. You can workout to equally strengthen both the agonist and antagonist muscles. Include arm extension exercises to strengthen your triceps. Use movements such as overhead extensions, behind the body arm kickbacks and bodyweight dips. For the antagonist, include bicep strengthening arm curl exercises. Dumbbell bicep curls with your palms facing up, facing in and facing down strengthen the entire bicep muscle group.