Dumbbell Skull Crusher

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Beginner

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A dumbbell isolation exercise performed lying supine that targets the triceps, particularly the long head, to build hypertrophy and arm size.

About Exercise

Equipment

Dumbbells, Flat Bench

Difficulty

2/5 • Beginner

Primary Muscle Groups

Triceps

Accessory Muscles

Shoulders

Popularity Score

Goals

Hypertrophy

Strength

Training Style

Bodybuilding

Setup Requirements

Requires Rack

Requires Bench

Yes

Requires Spotter

Space Needed

Medium

Noise Level

Low

Muscle Breakdown

View Muscle Map

Triceps

10/10

Long Head, Lateral Head

Shoulders

2/10

Anterior Delts

Programming

Typical Rep Range

8-15 reps

Rest Between Sets

60-120 seconds

How to Perform

Lie flat on a bench, holding a dumbbell in each hand above your chest with a neutral grip and fully extended arms. Ensure your feet are stable on the floor.

Maintaining vertical upper arms, slowly bend your elbows to lower the dumbbells towards your temples.
Stop when the forearms are parallel to the floor or the dumbbells are near your ears.
Contract the triceps to forcefully extend the elbows, pressing the dumbbells back to the starting position.
Fully lock out the elbows and squeeze the triceps at the top of the movement.

Coaching Tips

Form Cues

Keep upper arms fixed.
Elbows slightly tucked.
Full tricep squeeze.
Control the descent.

Breathing

Inhale as you lower the weight (eccentric phase); exhale sharply as you extend your arms (concentric phase) and maintain core bracing.

Tempo

3-0-1

Range of Motion

Lower the dumbbells until the forearms are slightly past parallel to the bench or when a deep stretch is felt in the triceps long head.

Safety

Safety Notes

Avoid aggressively locking out the elbows at the top.
Use a manageable weight to protect elbow joint integrity.
Stop if acute elbow pain occurs.

Spotting

The spotter stands behind the bench and supports the dumbbells near the wrists/forearms during the movement, assisting the final lockout if necessary.