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Synergist Muscles: Definition and Examples

What Is a Synergist Muscle?

A synergist muscle assists an agonist (a prime mover muscle) during an activity. It can produce force to support the movement and promote stability. Synergist muscles help make movement more fluid, increase power and strength output, and reduce instability. For example, the bicep is the agonist during a bicep curl, but the brachialis and brachioradialis assist with the motion and are synergists.

Synergist vs. Agonist Muscles (+Examples)

To better understand the role of synergist muscles, we must first look at agonists.

An agonist muscle is the prime mover during a specific activity. It produces the most force and is mainly responsible for creating the necessary movement at a joint. For example, the quadricep is the agonist during a squat because it produces most of the force to create movement.

Synergist muscles assist the prime mover in some way, such as helping increase power output or promoting stability and reducing the risk of unwanted movement.

To use the squat as an example again, synergist muscles would be calves, glutes, adductors, abs, spinal erectors, and, yes, even the hamstrings. These muscles assist the quadriceps by directly producing force for a more powerful squat (as with the glutes) or promoting stability (as with the erector spinae).

The hamstrings are an antagonist to the quads (having opposing functions). However, they serve more of a synergistic role during squats, as they promote knee stability and help with hip extension.

Synergist Muscle Examples

Here are some synergist muscle examples for popular movements:

  • Bench press – synergists: triceps, anterior delts, and serratus anterior
  • Squat – synergists: calves, hamstrings, adductors, glutes, and spinal erectors
  • Pull-up – synergists: biceps, brachialis, brachioradialis, infraspinatus, and teres major
  • Shoulder press – synergists: triceps, upper chest, and serratus anterior


1. What is an example of a synergist muscle?

An example of a synergist is the serratus anterior during a bench press. The chest is the prime mover, and the serratus anterior assists by stabilizing the scapula, allowing for a more powerful press.

2. What is a pair of synergist muscles?

A pair of synergists consists of two muscles simultaneously assisting a prime mover. For example, the anterior deltoids and triceps are a pair of synergists that help the chest during a bench press.

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