Barbell Lying Triceps Extension Skull Crusher

triceps upper arms barbell

Learn how to do the Barbell Lying Triceps Extension Skull Crusher with proper form and technique. This barbell exercise primarily targets your Triceps, with secondary emphasis on Shoulders.

Barbell Lying Triceps Extension Skull Crusher exercise demonstration showing proper form

How to Do the Barbell Lying Triceps Extension Skull Crusher

Follow these steps to perform the Barbell Lying Triceps Extension Skull Crusher with correct form:

1Lie flat on a bench with your feet flat on the ground and your head at the end of the bench.
2Hold the barbell with an overhand grip, hands shoulder-width apart, and extend your arms straight up over your chest.
3Keeping your upper arms stationary, slowly lower the barbell towards your forehead by bending your elbows.
4Pause for a moment when the barbell is just above your forehead, then extend your arms back up to the starting position.
5Repeat for the desired number of repetitions.

Barbell Lying Triceps Extension Skull Crusher Muscles Worked

Primary

triceps

Secondary

shoulders

Exercise Details

Equipment: barbell
Body Part: upper arms
Category: Main

Muscles & Anatomy

The lying triceps extension — commonly called the skull crusher — is one of the most effective exercises for the triceps brachii's long head, the largest of the three triceps heads. Because the long head originates on the shoulder blade and crosses the shoulder joint, it is fully stretched when the arm is raised overhead or in the extended-back position — exactly the position created when the bar is lowered toward the forehead with the upper arms perpendicular to the floor. The medial and lateral heads (which originate on the humerus) also activate strongly throughout elbow extension, making the skull crusher a complete triceps exercise. The EZ-bar or straight barbell loaded on the eccentric creates significant mechanical tension on the triceps in the stretched position, making skull crushers one of the best exercises for total triceps mass development.

Pro Tips for Better Results

1Lower the bar slightly behind the head — to the forehead or just beyond — rather than directly to the forehead. Lowering behind the head increases the long head's stretch by allowing the upper arms to angle slightly backward, creating more tension in the lengthened position. This small adjustment dramatically increases long head recruitment.
2Keep your upper arms stationary and perpendicular to the floor throughout the entire movement. Any movement of the upper arm changes the exercise. If your elbows are flaring out or your upper arms are rocking back and forth, fix the upper arms in position and move only the forearms. This isolation is what makes the skull crusher specifically effective for triceps.
3Use a slow, controlled 3–4 second eccentric. The skull crusher's greatest risk is a fast, uncontrolled lowering phase that creates elbow joint shear and can drop the bar toward the face. Control the descent completely — this is also where the long head receives its maximum stretched-position loading.

Common Mistakes to Avoid

✗ Letting the elbows flare wide during the lowering phase

Fix: Elbows flaring outward converts the skull crusher into a partial bench press and removes the triceps isolation. Keep your elbows pointed directly at the ceiling throughout — neither flaring out nor pinching inward. If elbows flare, the weight is too heavy for controlled triceps extension and needs to be reduced.

✗ Upper arms rocking backward during the lowering phase

Fix: When the upper arms angle backward excessively as the bar lowers, the front deltoids and lats take over and the triceps are partially unloaded. Keep upper arms strictly perpendicular to the floor — vertical — throughout the movement. Any backward rocking of the upper arms means the weight has exceeded your triceps' capacity.

✗ Lowering to the nose or forehead and missing the long head stretch

Fix: Lowering directly to the forehead keeps the upper arms perfectly vertical but doesn't provide the behind-the-head position that maximally stretches the long head. Allow the upper arms to angle back very slightly — 5–10 degrees behind vertical — as the bar passes the forehead. This creates a more complete long head stretch without excessive shoulder stress.

✗ Bouncing at the bottom and using the stretch reflex to press back up

Fix: Bouncing at the bottom of the skull crusher uses elastic energy from the tendons and ligaments rather than triceps force — and creates extreme elbow joint shear stress at the most vulnerable position. Pause momentarily at the bottom before extending. This eliminates bouncing, increases triceps stimulus, and protects the elbow joint.

How to Program the Barbell Lying Triceps Extension Skull Crusher

Sets & Reps

3–4 sets of 8–15 reps. The skull crusher handles a meaningful load and is effective across both strength (6–10 rep) and hypertrophy (10–15 rep) ranges. Many powerlifters use heavy skull crushers as a primary bench press accessory because the triceps strength developed transfers directly to the lockout portion of the bench press.

Frequency

1–2 times per week. The elbow joint tolerates skull crusher volume well when technique is sound, but the combination of heavy load and the stretched triceps position can accumulate tendon fatigue. Once per week as a primary triceps movement is sufficient; twice per week works for those prioritizing triceps development.

Where to Place It in Your Workout

Perform as the first or second triceps exercise in a session — after any compound pressing work but before isolation pushdowns or overhead extensions. The skull crusher is a compound triceps movement that deserves early placement while the triceps are fresh enough to handle meaningful loads safely.

How to Progress

Add 2.5–5 lbs per week for beginners; monthly for intermediate lifters. The triceps' larger size relative to the biceps allows more consistent progression. When load stalls, use a pause rep protocol — pause 2 seconds at the bottom before extending — for 2–3 weeks before attempting a weight increase. Pauses break through plateaus by eliminating the stretch reflex dependency.

Variations & Alternatives

EZ-Bar Skull Crusher

Use an EZ-bar instead of a straight barbell. The angled grip reduces wrist pronation stress and is more comfortable for most people over heavy sets. The elbow and triceps mechanics are nearly identical. Many lifters find they can focus better on the triceps with the EZ-bar because wrist discomfort doesn't distract from the movement.

Dumbbell Skull Crusher

Perform with two dumbbells instead of a barbell. The independent hand position allows each arm to find its natural range of motion. Eliminates any bilateral compensation and increases stabilizer demand per arm. Typically done with lighter load than a barbell but with potentially greater range of motion at the bottom.

Decline Skull Crusher

Perform on a decline bench set to 15–30 degrees. The decline increases the long head stretch at the bottom of the movement by changing the angle of the upper arm relative to the torso. Slightly more comfortable on the shoulder than flat skull crushers for some people. Often allows a slightly greater range of motion into the stretched position.

Related Exercises

Frequently Asked Questions

What muscles does the Barbell Lying Triceps Extension Skull Crusher work?

The Barbell Lying Triceps Extension Skull Crusher primarily targets your Triceps. Secondary muscles worked include Shoulders. This makes it an effective exercise for developing your upper arms.

What equipment do I need for the Barbell Lying Triceps Extension Skull Crusher?

The Barbell Lying Triceps Extension Skull Crusher requires barbell. Make sure your equipment is properly set up and you have enough space to perform the movement with full range of motion.

How do I perform the Barbell Lying Triceps Extension Skull Crusher with proper form?

Start by lie flat on a bench with your feet flat on the ground and your head at the end of the bench.. Hold the barbell with an overhand grip, hands shoulder-width apart, and extend your arms straight up over your chest. Keeping your upper arms stationary, slowly lower the barbell towards your forehead by bending your elbows. Focus on controlled movement throughout the entire range of motion. See the full step-by-step instructions above for complete form guidance.

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