Muscle that supports the work of the agonist and facilitates the completion of the task goal. Synergist muscles include muscles that contribute to the joint moment of the agonist and/or stabilize the origin of the agonist muscle to enable efficient movement during the task. This “functional” or “biomechanical” definition should not be confused with “muscle synergies” (also called modules or motor primitives). Muscle synergies are coordinated activations of a group of muscles.

The energy required to move an electric charge between two points in an electric field, measured in Volt. EMG is typically measured in µV or mV.