Is the Skullcrusher (Triceps Extension)exercise to build muscle, lose fat?

Skullcrusher (Lying Triceps Extension) – Triceps Isolation Exercise

The skullcrusher is a highly effective triceps isolation exercise performed lying on a bench. It places strong emphasis on triceps development, especially due to the deep stretch and long range of motion, making it excellent for building size and strength in the back of the arms.

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Advantages Compared to Other Triceps Exercises

Maximum triceps isolation

This movement strongly targets the triceps with minimal assistance from other muscle groups.

Strong stretch position

The exercise places the triceps under a deep stretch, which is highly effective for muscle growth.

Easy progressive overload

Weight and repetitions can be increased gradually, making it suitable for long-term strength progression.

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Muscles Worked

Primary muscle

• Triceps brachii (especially the long head)

Secondary muscles

• Anterior deltoid (shoulder stabilization)
• Forearm muscles (grip and control)

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How to Perform the Skullcrusher Correctly

Starting position

Lie on a flat bench and hold a barbell, EZ bar, or dumbbells with arms fully extended above your chest.

Elbow position

Keep elbows fixed and pointing forward. Do not let them flare out.

Lowering phase

Slowly bend your elbows and lower the weight toward your forehead or slightly behind your head.

Bottom position

Pause when the triceps are fully stretched, maintaining control.

Pressing phase

Extend your arms back to the starting position and actively squeeze the triceps.

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Breathing Pattern

• Inhale while lowering the weight
• Exhale while extending the arms

Range of Motion

• Full extension at the top
• Deep controlled stretch at the bottom
• Smooth, controlled movement without momentum

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Variations and Difficulty Levels

Beginner

• Dumbbells (lighter load)
• Controlled tempo with reduced weight

Advanced

• EZ bar variation
• Slow eccentric phase (lowering)
• Overhead angle variation for increased stretch

Other variations

• Cable skullcrusher
• Incline bench skullcrusher

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When to Use This Exercise

• Mid or end of triceps training sessions
• As a secondary movement after compound pressing exercises
• For hypertrophy-focused arm training

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Alternative Exercises

• Triceps pushdown (cable)
• Dips
• Overhead triceps extension

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Recommended Sets, Reps, and Rest Time

• Sets: 3–4
• Reps: 8–12
• Rest: 45–90 seconds

Sample Triceps Workout

• Close-grip bench press – 4 × 6–8
• Skullcrusher – 3 × 10
• Cable triceps pushdown – 3 × 12

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Common Mistakes and How to Avoid Them

Elbows flaring out

Keep elbows locked in position to maintain triceps focus.

Using shoulders instead of triceps

Isolate the elbow joint and avoid shoulder-driven movement.

Too much weight

Excess load increases joint stress and reduces muscle activation.

Short range of motion

Lower the weight fully to maximize stretch and growth stimulus.

The skullcrusher is one of the most effective triceps-building exercises, especially for developing thickness and size in the upper arm when performed with proper control and full range of motion.

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