Extension
Extension is the anatomical movement that increases the angle between two body segments. Opposite of flexion.
Extension - Opening the joint angle
Definition
Extension is an anatomical movement that increases the angle between two body segments at a joint. It is the opposite of flexion, which decreases that angle.
💡 Simple way to remember: extension = "extending" the limb (straightening it). Flexion = "folding" it.
Examples of extension
- Knee extension: straightening the leg (leg extension on machine)
- Elbow extension: triceps push (lockout in bench press)
- Hip extension: pushing the leg backward (hip thrust, deadlift)
- Spinal extension: arching back (back extension exercise)
- Wrist extension: bending hand backward
Main extensor muscles
| Joint | Main extensors |
|---|---|
| Knee | Quadriceps |
| Hip | Glutes, hamstrings |
| Elbow | Triceps brachii |
| Spine | Erector spinae, multifidus |
| Shoulder | Posterior deltoid, lats |
Best exercises for extensors
Knee extension (quads)
- ✅ Squat, leg press, leg extension, lunges
Hip extension (glutes / hamstrings)
- ✅ Hip thrust, deadlift, Romanian deadlift, glute bridge
Elbow extension (triceps)
- ✅ Bench press, dips, skull crusher, triceps pushdown
Spinal extension
- ✅ Back extension, good morning, deadlift
Extension and athletic performance
Most powerful explosive movements rely heavily on extension:
- Triple extension: simultaneous extension of hips, knees, and ankles. The basis of all jumps, sprints, and Olympic lifts.
- Hip extension = sprint speed, jump height
- Spinal extension = lifting strength and core stability
⚠️ Hyperextension (going beyond the normal range) is risky for the spine and can cause injuries (lumbar disc, facet joints).
Common mistakes
- ❌ Confusing extension (open angle) with flexion (close angle)
- ❌ Forcing hyperextension on the lumbar spine
- ❌ Neglecting hip extension (one of the keys to performance)
- ❌ Locking out joints under heavy load
Key takeaways
Extension = opening the joint angle. Essential for explosive performance, locomotion, and posture. Train extensors deliberately (quads, glutes, triceps, lower back). Triple extension is the foundation of athleticism.
Termes associés
The concentric phase is the shortening phase of the muscle under tension: the active phase where you lift the load.
Closing joint movement that decreases the angle between two segments. Engages biceps, hamstrings or abdominals.
An isometric contraction is a contraction where the muscle produces tension without changing length. Strengthens key positions.
Range of motion (ROM) is the full extent of a movement. Working through full ROM maximizes muscle growth and strength gains.
