Antagonist Muscle During a Pushup
The pushup is a foundational exercise for strengthening the upper body. Among the many muscles you work during this movement are the pectorals, the front shoulders and the triceps. These muscles are known as the agonists, and they contract to allow you to do a pushup. Other muscles resist and/or counteract your movements; these are known as antagonists. The purpose of these antagonistic muscles is to allow your joints and limbs to go back to their original positions. They play an equal role to agonists when you try to balance your body.
Pushup Joint Movements
To perform a pushup, you must move your shoulder and your elbow joints. Specifically, you must bend and straighten your arms, and bend and straighten your shoulders in a horizontal direction. To do a pushup, you start with your palms down on the ground, arms straight, torso parallel to the ground and legs straight with your toes on the ground and heels elevated. To initiate the movement, you must bend your shoulders and arms. You do this by relaxing your agonists and contracting your antagonists, which include your rear shoulders, middle trapezius, rhomboids and biceps. Then, to raise your torso back up to the starting position, you must extend your shoulders and arms. To do so, you need to relax your antagonists and contract your agonists, mainly your pecs, front shoulders and triceps.
Your front and rear shoulders are an agonist/antagonist pair. The front muscle is known as the anterior deltoid, the rear as the posterior deltoid. During the pushup, the front deltoid assists when you straighten your shoulders horizontally, while the rear deltoid works to bend your shoulders.
Middle Trapezius and Rhomboids
A lesser movement during the pushup is that of your shoulder blades. During the descending phase of the motion, your shoulder blades move toward each other in the rear direction. This action is done by the middle trapezius and rhomboid muscles of the back, which act as antagonists. In the ascending phase, your shoulder blades move away from one another in the forward direction. Your serratus anterior muscles are responsible for this agonistic movement.
The final main joint movement during the pushup is flexion and extension of your elbows. When you initiate the pushup, you bend your elbows, thus relaxing your agonistic triceps muscles and contracting your antagonistic biceps muscles. The opposite holds true when you straighten your elbows to return to the beginning position. The biceps, which is made up of a short and a long head, also has an agonistic role during the pushup. Specifically, the short head assists the pectorals and anterior deltoids to horizontally straighten your shoulders. Therefore, the biceps short head can be referred to as an agonist during the pushup, while the biceps long can be called an antagonist.
Richard Choueiri is a fitness and nutrition expert and the author of "The Human Statue Workout." He began writing professionally in 2007 and his work has been featured in Bodybuilding.com and "Physique Magazine." Choueiri studied exercise science and nutritional science at Rutgers University. He holds an American College of Sports Medicine CPT, and a National Exercise and Sports Trainers Association CMMACC.