Skull Crusher

The skull crusher is a arms movement that works the ['triceps']. Two things decide whether it produces results: the load relative to your one-rep maximum, and the number of hard sets per week. For strength, three to five sets of one to five repetitions at 85 per cent or more of your one-rep max is the classic prescription; for muscle size, three to four sets of six to twelve repetitions at 65 to 80 per cent, taken close to failure; for endurance, two to three sets of fifteen or more at under 65 per cent. Ten to twenty hard sets per muscle group per week is the range most training research converges on, and progression comes from adding a little weight or a repetition rather than from changing the exercise. The calculator below estimates your one-rep max from a set you have actually completed, which is the number every percentage above refers to.

Skull Crusher Strength Standards (kg)

Body Weight	Novice	Intermediate	Advanced	Elite
120 kg	10	25	45	70
130 kg	10	25	45	75
140 kg	15	30	50	80
150 kg	15	35	55	85
160 kg	20	35	55	90
170 kg	20	40	60	95
180 kg	25	45	65	100
190 kg	25	45	70	105
200 kg	25	50	70	110
210 kg	30	50	75	115
220 kg	30	55	80	120

How to Perform the Skull Crusher

Lie on a flat bench holding an EZ-bar or straight barbell with a narrow grip, arms extended straight above your chest. Keeping your upper arms stationary and perpendicular to the floor, bend at the elbows to lower the bar toward your forehead or just behind the top of your head. When your forearms are just past parallel to the floor, reverse the motion and extend your arms back to the starting position by contracting the triceps.

Muscle Activation

The skull crusher is one of the most effective isolation exercises for the triceps because it trains the long head through a stretched position, which is critical for complete tricep development. All three heads of the triceps, the long head, lateral head, and medial head, contribute to elbow extension during this movement. Lowering the bar behind the head rather than to the forehead increases the stretch on the long head.

Common Mistakes

Flaring the elbows out wide, which reduces tricep isolation and can stress the elbows.
Moving the upper arms during the exercise, which turns it into a close-grip press rather than an isolation movement.
Lowering the bar directly to the forehead rather than slightly behind the head, which limits the stretch on the long head.
Using too much weight and compensating with momentum or shoulder movement.

Variations

Dumbbell skull crushers allow independent arm movement. Incline skull crushers increase the stretch on the long head. Cable skull crushers provide constant tension. Overhead tricep extensions, while not technically skull crushers, train the triceps in a similar stretched position and are an excellent alternative.

Programming Tips

Perform 3-4 sets of 10-15 reps, 1-2 times per week. Start with lighter weights to protect the elbow joints and gradually increase loading. Skull crushers pair well with bicep exercises in superset fashion. If you experience elbow pain, try using an EZ-bar or dumbbells for a more joint-friendly grip angle.

Frequently Asked Questions

Skull crushers can cause elbow discomfort if performed with excessive weight or poor form. Use a controlled tempo, avoid locking out aggressively, and use an EZ-bar to reduce wrist and elbow stress. In practice, the skull crusher loads the triceps and needs barbell; an intermediate lifter of average bodyweight handles about 40 lbs, so judge your own numbers against that rather than against a gym record.

Lowering the bar slightly behind the top of your head provides a greater stretch on the long head of the triceps, which is generally preferred for hypertrophy. The forehead version is also acceptable. In practice, the skull crusher loads the triceps and needs barbell; an intermediate lifter of average bodyweight handles about 40 lbs, so judge your own numbers against that rather than against a gym record.

An EZ-bar is the most popular choice as it reduces wrist and elbow strain. A straight barbell also works but may cause more joint discomfort for some lifters. Dumbbells are another option. In practice, the skull crusher loads the triceps and needs barbell; an intermediate lifter of average bodyweight handles about 40 lbs, so judge your own numbers against that rather than against a gym record.

Use a weight that allows 10-15 controlled reps. Skull crushers are not a strength exercise; focus on the stretch and contraction rather than maximizing weight. In practice, the skull crusher loads the triceps and needs barbell; an intermediate lifter of average bodyweight handles about 40 lbs, so judge your own numbers against that rather than against a gym record.

Related Exercises

Progressing on the skull crusher

Progression on a barbell movement for the arms follows the same logic whatever the exercise: add a little load or one repetition once the last set stops being hard, and change nothing else. A barbell allows increments of 2.5 kg at the smallest, which on an upper-body lift can be a jump of five per cent; micro-plates of 0.5 or 1.25 kg are what keep a bench press or a press moving once the easy gains are over.

Stalling is normal and usually means one of three things: total weekly volume for the arms has drifted too low, recovery is short because sleep or calories are, or the load has been pushed while form quietly deteriorated. Filming a set from the side settles the third question faster than any cue. Ten to twenty hard sets per muscle group per week is the range most training research converges on, and a stall at the bottom of that range is a volume problem rather than a programme problem.

Common mistakes on arms work

Arm work is where momentum creeps in first, because the loads are small enough to swing. Keeping the upper arm still and the torso motionless makes a lighter weight harder, which is the point. Full extension at the bottom matters more than the number of repetitions.

Where the skull crusher fits in a week depends on how demanding it is rather than on the muscle it trains. A movement using a barbell across the arms is best placed while you are fresh if it is heavy and technical, and late in the session if it is a single joint. Two sessions a week touching the same muscle group beat one for most people, because protein synthesis after a session returns to baseline within about forty-eight hours, and a muscle trained once a week spends five of those days doing nothing.

Across all of them, the same two rules apply. Warm up with the movement itself at progressively heavier loads rather than with general cardio, and leave one repetition in reserve on all but the last set: training to failure on every set raises fatigue considerably without adding much to the result.

Skull Crusher 1RM Calculator