Prime Mover (Muscle)
Prime Mover: The muscle that can produce the most force for a joint action. Generally, this is the muscle that will generate the most force during a joint action when exerting force against an external load. For example, the gluteus maximus is the prime mover of hip extension during exercises like the Ultimate Glute Bridge , lateral lunge , deadlift , or squat .
- Synonym: Agonist, although this term may be used for any muscle responsible for a joint action.
- Related: The synergists are all the muscles that cause a joint action but are not the prime mover.
- Opposite: The antagonists would be all of the muscles that perform the opposite joint action.
- Special Note: The prime mover, as defined above, may or may not be the most active muscle for a joint action during activities of daily living. For example, the gluteus maximus is the most powerful hip extensor and, therefore, the prime mover; however, the hamstrings are likely the most active hip extensors during low-level activities like walking or standing.
For additional information, including a video lecture:
Functional Roles of Muscles Glossary Terms:
Articles listing all of the muscles by functional role for each joint action:
- Kinesiology of the Shoulder and Scapula
- Kinesiology of the Elbow
- Kinesiology of the Trunk
- Kinesiology of the Hip
- Kinesiology of the Knee
- Kinesiology of the Ankle
List of Prime Movers by Joint Action
Shoulder (Glenohumeral Joint)
- Flexion: Anterior Deltoid
- Extension: Posterior Deltoid
- Abduction: Middle Deltoid
- Adduction: Latissimus Dorsi
- Internal Rotation: Subscapularis
- External Rotation: Infraspinatus
- Horizontal Abduction: Posterior Deltoid
- Horizontal Adduction: Pectoralis Major
2. Elbow (Humeroulnar Joint)
- Flexion: Biceps Brachii, Brachialis, Brachioradialis
- Extension: Triceps Brachii, Anconeus
3. Hip
- Flexion: Iliopsoas
- Extension: Gluteus Maximus
- Abduction: Gluteus Medius
- Adduction: Adductor Longus
- Internal Rotation: Gluteus Minimus
- External Rotation: Gluteus Maximus
- Horizontal Abduction: Piriformis
- Horizontal Adduction: Adductors
4. Knee
- Flexion: Biceps femoris
- Extension: Quadriceps
- Internal Rotation (of flexed knee): Semitendinosus and Semimembranosus
- External Rotation (of flexed knee): Biceps Femoris
5. Ankle (Talocrural Joint)
- Plantarflexion: Soleus
- Dorsiflexion: Tibialis Anterior
- Eversion: Fibularis Muscles
- Inversion: Tibialis Posterior
6. Spine (Lumbar Spine)
- Flexion: Rectus Abdominis
- Extension: Erector Spinae (Spinalis, Longissimus, Iliocostalis)
- Lateral Flexion: External Obliques, Quadratus Lumborum, Erector Spinae (unilaterally)
- Rotation: External Obliques