Skull Crushers: How to Perform & Muscles Worked

May 04, 2026 5 min read

Skull crushers are one of the best triceps isolation exercises for building stronger, fuller arms. They can be done with a straight bar, EZ bar, or dumbbells, and each version has its own benefits depending on your goals, comfort, and training style.

What Are Skull Crushers?

Skull crushers, also called lying triceps extensions, are a horizontal elbow-extension movement performed while lying on a bench. The exercise is called “skull crushers” because the weight is lowered toward the head or forehead area, although in proper form it should be controlled and safe. They are a staple triceps exercise for both strength and hypertrophy training.

The movement is simple, but highly effective. By keeping the upper arms relatively still and extending only at the elbows, you place direct tension on the triceps through a large range of motion.

Muscles Worked during Skull Crushers

Skull crushers primarily target the triceps brachii, which has three heads.

Triceps heads worked

Long head: This is the largest head of the triceps and plays a major role in arm size. Because it crosses the shoulder joint, it is especially challenged when the arms are positioned slightly behind the head or when the exercise is done on an incline.
Lateral head: This is the outer head of the triceps and contributes to the “horseshoe” look of the upper arm.
Medial head: This deeper head helps with elbow extension and supports overall triceps strength and stability.

Secondary muscles involved

Anterior deltoids: Help stabilize the shoulder joint.
Pectoralis major: Assists slightly in controlling the lowering and pressing phases.
Forearm flexors and grip muscles: Help maintain control of the bar or dumbbells.
Core muscles: Stabilise the body on the bench.

The main benefit of skull crushers is that they isolate the triceps more directly than pressing exercises, making them excellent for arm development and assistance work for bench press strength.

How to Perform Skull Crushers

Set up:

Lie flat on a bench with your feet planted firmly on the floor.
Hold your chosen implement directly above your chest with your elbows extended.
Keep your wrists stacked and your upper arms mostly vertical or slightly angled back.

Execution

Bend only at the elbows and lower the weight slowly toward your forehead or slightly behind the head.
Keep your upper arms as still as possible.
Lower until you feel a strong triceps stretch without losing control.
Extend the elbows to return the weight to the starting position.
Repeat for controlled reps.

Form cues

Keep your elbows pointed forward or slightly inward.
Avoid flaring the elbows excessively.
Use a slow lowering phase.
Don’t let the shoulders take over the movement.
Stop short of any pain in the elbows or shoulders.

A good training range is typically 8 to 15 reps, depending on whether the goal is strength, hypertrophy, or joint-friendly volume.

Skull Crushers -Barbell vs EZ Bar vs Dumbbells

Different equipment changes the feel, loading potential, and joint comfort of skull crushers.

Straight bar / barbell skull crushers

The straight bar version is the most traditional and usually the easiest to progressively overload. Because both hands are fixed on one implement, it creates a very stable movement pattern. The downside is that the fixed wrist position can be less comfortable for some lifters, especially if wrist or elbow mobility is limited.

EZ bar skull crushers

The EZ bar is often the best middle ground. The angled grips reduce wrist strain for many people and usually feel more natural at the elbows. It still allows good loading, which makes it a popular choice for lifters who want a balance of comfort and performance.

Dumbbell skull crushers

Dumbbells give each arm more freedom to move naturally. This can help reduce stress on the wrists and elbows and may also highlight strength imbalances between sides. Dumbbells usually require more control, but they often feel smoother and more joint-friendly.

Here’s how each version compares:-

Variation	Main Benefits	Main Drawbacks	Best For
Straight bar / barbell	Easy to load heavily, stable bar path, strong overload potential	Can be harder on wrists and elbows, less forgiving on joint comfort	Lifters focused on strength and progressive overload
EZ bar	More wrist-friendly, often easier on elbows, still allows solid loading	Slightly less fixed than a straight bar, not as much freedom as dumbbells	Most lifters, especially those wanting a balance of comfort and load
Dumbbells	Independent arm work, natural wrist path, greater range of motion, often easier on joints	Harder to stabilize, usually less load than bar variations	Beginners, lifters with joint irritation, and those wanting unilateral control

Benefits of Each Variation

Barbell benefits

Best for heavy loading.
Simple progression.
Stable and predictable path.
Good for advanced lifters seeking strength-focused overload.

EZ bar benefits

More comfortable grip.
Usually easier on the elbows and wrists.
Great compromise between load and comfort.
Very popular for regular triceps hypertrophy work.

Dumbbell benefits

Natural arm and wrist movement.
Greater freedom of motion.
Helps reduce left-right strength imbalances.
Often preferred by lifters with cranky elbows.

Common Skull Crusher Variations

There are several useful ways to modify skull crushers to suit different goals and training levels.

Flat bench skull crushers - This is the standard version and a great all-round choice for triceps size and strength.

Incline skull crushers - Performing the movement on an incline bench places the arms in a more stretched position and often increases emphasis on the long head of the triceps.

Decline skull crushers - A decline setup changes the angle of resistance and may feel easier on the shoulders for some lifters.

Behind-the-head skull crushers - Lowering the weight slightly behind the head increases the stretch on the triceps, especially the long head. This is a strong hypertrophy variation, but it requires good control.

Single-arm dumbbell skull crushers - These are useful for improving symmetry and focusing on one arm at a time. They can also help lifters find a more comfortable path.

Neutral-grip dumbbell skull crushers - Using a neutral grip can feel more natural on the elbows and wrists, especially for lifters who struggle with straight-bar versions.

Cable skull crushers - Cable versions provide constant tension through the whole range of motion and are often easier on the joints. They are a great option for higher-rep work.

Skull Crushers Programming Tips

Skull crushers work well after compound pressing movements such as bench press or overhead press. They are best used as an accessory lift rather than your main strength movement.

A solid approach is:

3 to 4 sets.
8 to 12 reps for size.
6 to 8 reps for strength-focused work.
10 to 15 reps if you want more joint-friendly volume and control.
If elbow discomfort appears, reduce load, slow the tempo, shorten the range slightly, or switch to an EZ bar, dumbbells, or cables.

Skull Crushers Conclusion

Skull crushers are a highly effective triceps exercise that can be performed with a straight bar, EZ bar, or dumbbells. The straight bar is best for heavy loading, the EZ bar is usually the most joint-friendly compromise, and dumbbells offer the most natural movement and unilateral control. With the right variation and good form, skull crushers can become one of the most productive exercises in your arm training routine.