Skull Crushers: The Best Tricep Isolation Exercise
Skull crushers, also called lying tricep extensions, isolate the triceps through a deep stretch that other tricep exercises cannot match. They are the most effective single exercise for building tricep mass.
Proper Form
Lie on a flat bench holding an EZ-bar or dumbbells with arms extended directly above your shoulders.
Keeping your upper arms stationary and perpendicular to the floor, bend at the elbows to lower the weight.
Lower the weight toward your forehead or just behind the crown of your head for a deeper stretch.
Extend your elbows to press the weight back to the starting position, squeezing the triceps at the top.
Keep your elbows pointed at the ceiling throughout; do not let them flare outward.
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Skull Crushers on GLP-1 Medications
Skull crushers target the triceps, which make up two-thirds of your upper arm size. For GLP-1 users wanting to maintain arm size during weight loss, tricep training is actually more important than bicep training for overall arm appearance. As body fat decreases, tricep definition becomes the defining feature of toned-looking arms. Include skull crushers 1-2 times per week for 3 sets of 10-15 reps. Use moderate weight and focus on the stretch at the bottom of each rep, as research suggests that loaded stretching may enhance muscle hypertrophy.
Variations
- 1EZ-bar skull crushers (standard)
- 2Dumbbell skull crushers for independent arm work
- 3Incline skull crushers for a greater stretch on the long head
- 4Cable skull crushers for constant tension
- 5Skull crusher to close-grip press combo for burnout sets
Why Skull Crushers Beat Other Tricep Exercises
The tricep has three heads: long, lateral, and medial. Most tricep exercises primarily target the lateral head. Skull crushers are special because they place the long head of the tricep in a deep stretch when the weight is lowered behind the head. The long head crosses both the elbow and shoulder joints, and it is only fully lengthened when the shoulder is in flexion (arm overhead) and the elbow is bent. This stretched position creates a powerful hypertrophy stimulus that pushdowns and kickbacks cannot replicate.
Protecting Your Elbows
Skull crushers have a reputation for causing elbow pain, but this is almost always due to poor form or excessive weight. Use a controlled tempo: 2-3 seconds down, pause briefly, 1-2 seconds up. Never bounce at the bottom. Lower the bar to behind your head rather than to your forehead, which reduces elbow stress and increases the tricep stretch. If you experience elbow pain, switch to an EZ-bar (the angled grip reduces forearm torque), reduce weight, or substitute with overhead cable extensions.
- Use an EZ-bar to reduce forearm rotation stress
- Lower to behind the head for less elbow stress and more stretch
- Control the eccentric: 2-3 seconds minimum
- Never lock out aggressively; smooth, controlled extension
- Warm up with lighter sets before working weight
Programming Skull Crushers
Skull crushers work best in the 10-15 rep range with moderate weight. They are an accessory exercise and should follow your primary pressing movements (bench press, overhead press, dips). Perform 2-3 sets, 1-2 times per week. Pair them with a bicep curl for an efficient arm superset. For advanced trainees, the skull crusher to close-grip press transition set (do skull crushers to failure, then immediately switch to close-grip bench press for additional reps) is a devastating tricep finisher.
Muscles Worked
Exercise Disclaimer
This content is for informational purposes only and does not replace professional instruction. Consult a qualified trainer or healthcare provider before starting any exercise program. Individual calorie burn varies based on fitness level, intensity, and body composition.
Frequently Asked Questions
Yes, skull crushers are one of the few tricep exercises that effectively target all three heads, with particular emphasis on the long head due to the overhead arm position and deep stretch at the bottom of the movement.
Common causes are too much weight, lowering the bar to the forehead (instead of behind the head), and aggressive lockouts. Switch to an EZ-bar, reduce weight, lower behind the crown of your head, and control the tempo. If pain persists, substitute with overhead cable extensions.
Most men use 40-70 lbs on an EZ-bar; most women use 20-40 lbs. The weight should allow 10-15 controlled reps. This is a technique exercise; using too much weight forces compensatory movements and stresses the elbows.
The EZ-bar is generally preferred because the angled grip reduces stress on the wrists and forearms. Straight bars place the wrists in a fully supinated position under load, which can cause discomfort over time. Dumbbells are another excellent option.
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