What are Synergist Muscles?

Muscle Pump-elderly man with big muscles in the gym


Synergist muscles assist the prime movers, stabilizers, and fixators during an exercise by contributing additional support, force, and targeted muscle activation.


  • Every exercise involves multiple synergist muscles working together even if targeting a specific muscle group.
  • Synergists fix joints in place, control accessory motions, and transfer force to the prime movers acting as helpers.
  • Identifying synergists allows for full activation and tension during lifts – don’t just think of prime movers.
  • Weaker synergists can limit your strength capacity on big lifts. Train them directly or with assistance exercises.


  • Hamstrings and glutes aiding quadriceps during the squat.
  • Upper back muscles stabilizing the core and shoulders on bench press.

Related Terms

  • Prime mover muscles, stabilization, isolated exercises, compound exercises

Common Questions

  • How do I learn which muscles are synergists? Analyze exercises biomechanically to identify joint motions and muscle roles.
  • Should I train synergists directly? Yes, strengthening them boosts compound lift performance by plugging weak links.

Do Not Confuse With

  • Antagonist muscle pairs – Muscles performing opposite actions that counter each other.
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