Common Agonist / Antagonist Muscle Pairs

Muscle work in pairs. When one muscle contracts, its opposite relaxes, and vice versa. That allows the lifting and lowering to happen. (Flexion / Extension). If the opposing muscle does not relax, the action cannot occur, not matter how hard the active muscle contracts.

Opposing muscles are called agonist / antagonist.

Short list of common agonist / antagonist muscle pairs.
  • pectorals / latissimus dorsi
  • anterior / posterior deltoids
  • trapezius / deltoids
  • abdominals / spinal erectors
  • left / right external obliques
  • quadriceps / hamstrings
  • shins / calves
  • biceps / triceps  
  • flexors / extensors forearm

Its important when training, to work both opposing muscles equally, or it increases injury risk. Its common for soccer players to suffer hamstring injury, as the quads are much stronger than the opposing hamstring. Both opposing muscles must be developed fully and worked to failure.