Dumbbell Skull Crusher: Muscles Worked, How To Do and Form

The Dumbbell Skull crusher, also known as lying triceps extension, is an isolation exercise that works the triceps brachii muscle.

The name “skull crusher” derives from the exercise mechanics of bringing the weight down to your skull from an overhead position.

Dumbbell skull crushers are a great way to build strength and size in the triceps. They can also help improve your performance in other exercises, such as the bench press and overhead press. It has been used by bodybuilders and strength athletes for decades.

There are many other variations of dumbbell skull crusher that you can do to maximize muscle stimulation.

• One Arm Dumbbell Skull Crusher
• Incline Dumbbell Skull Crusher
• Decline Dumbbell Skull Crusher

You can also do it with various grips, including neutral, pronated, or supinated.

Dumbbell Skull Crusher Muscles Worked

• Dumbbell skull crushers primarily work the triceps brachii.
• The forearm muscles, specifically the brachialis, brachioradialis, and forearm flexor muscles, act as stabilizers during dumbbell skull crushers, helping to maintain control and stability.
• In addition to targeting the tricep, the skull crushers work several synergist and stabilizer muscles: the pectoralis major, anterior deltoid, Lats, and biceps brachii.

How To Do Dumbbell Skull Crusher

1. Lie down on a flat bench or the floor with your feet firmly planted on the ground.
2. Keep your head, upper back, and buttocks on the bench.
3. Hold a dumbbell in each hand and rest them on your legs.
4. Now, raise the dumbbells above your chest with your palms facing each other. The dumbbells should be shoulder-width apart.
5. Keep your upper arms stationary and slowly lower the dumbbells towards your head by bending your elbows. The motion should be like lowering a heavy object towards your forehead.
6. Pause for a moment when the dumbbells are just above your forehead.
7. Then push them back up to the starting position by extending your elbows.
8. Perform 3–4 sets of 8–12 repetitions.

Know More: 10 Best Dumbbell Tricep Exercises For Building Bigger Arms

Tips For Proper Form

• Avoid flaring your elbows out to the sides; keep them pointed towards the ceiling instead.
• Focus on squeezing your triceps at the movement’s top for maximum contraction.
• Avoid using excessive momentum or swinging the weights.
• Keep your arms parallel to the ground while doing the exercise.
• Avoid lowering the weight too close to your face or forehead. This can put too much strain on the elbows and increase the risk of getting hurt.
• The entire movement should be performed slowly and with control, especially when the weight is moving behind the head.
• Focus on your breathing. Exhale as you lift the weight back up, and inhale as you lower it down towards your forehead.
• Keep your shoulders and upper arms fixed. All the movement should be in your elbows.
• Prevent your elbows from flaring out to maintain proper form.
• There are many variations of dumbbell skull crushers, so try a few different ones to find the ones that work best for you.
• Dumbbell skull crushers are just one exercise for the triceps. Do other exercises, such as tricep pushdowns, dips, and overhead tricep extensions, to target the muscles from different angles and ensure balanced tricep development.
• Select sets and rep ranges for muscle growth and hypertrophy, as given below.

Goal	Sets	Reps	Rest Between Sets
Muscle Growth	3 to 4	8 to 12 reps	60 to 90 seconds
Endurance	3 to 4	15 to 20 reps	30 to 45 seconds

Dumbbell Skull Crusher Variations

You can do a skull crusher with dumbbells in many ways by changing the bench and grip positions.

• If you are new to performing dumbbell skull crusher, you may want to apply a few modifications to make the exercise easier. One way to counter this problem is to use a lighter weight. Another way is to perform a skull crusher with a single arm.
• If you want a more advanced variation to stimulate different muscle fibers in the tricep, try Incline and decline dumbbell skull crushers.

1. Incline Dumbbell Skull Crusher

The incline dumbbell Skull crusher, also known as an Incline tricep extension, helps build muscle and strength in all three tricep heads.

The incline position allows for a deeper triceps stretch during the eccentric (lowering) phase and a more intense contraction during the concentric (lifting) phase.

Adding incline skull crushers to your tricep workout routine can help you strengthen and overcome plateaus.

How To Do

1. Grab a dumbbell in each hand and lie against an incline bench, face up, with your feet firmly planted on the floor.
2. Extend your arms over your shoulders with your palms facing each other.
3. Keep your upper arms fixed, with your elbows close to your head.
4. Then, slowly lower the dumbbells behind your head.
5. Hold this position for a while, then raise your arms to where you started.
6. Do not use excessively heavyweight, as this is dangerous for your elbows.

2. Decline Dumbbell Skull Crusher

The decline dumbbell skull crushers are a variation of the lying dumbbell tricep extension that slightly declines the movement. It is more effective for two reasons: the use of a neutral grip and the location of the shoulders.

This triceps workout increases the range of motion, allowing you to get a greater stretch on the tricep at the bottom of the movement.

How To Do

1. Grab a dumbbell in each hand and lie against a decline bench with your feet firmly on the pads.
2. Extend your arms over your shoulders with your palms facing each other, and then slowly lower the dumbbells behind your head by bending your elbows.
3. Hold this position for a count. Then, in a controlled motion, raise your arms back up to the starting position.
4. At the top of the movement, do not lock out your elbows.

3. Single Arm Dumbbell Skull Crusher

The single-arm skull crusher is a variation of the traditional dumbbell skull crusher, where you do it with just one arm at a time.

It helps you isolate each arm and allows you to focus better on the contraction and extension of the triceps, leading to a stronger mind-muscle connection.

How To Do

1. Hold a dumbbell in one hand while lying on a bench with your feet planted.
2. Raise the dumbbell above your chest with your palm facing inward and your arm extended fully.
3. Lower the weight towards your head slowly. Keep your upper arm still.
4. When the weight is near your head, stop for a moment and lift your arm back to where you started.
5. Complete the desired repetitions on one arm before switching to the other.
6. Make sure both arms are given equal attention and effort.

References

1. Boehler B, Porcari JP, Kline D, Hendrix R, Foster C, Anders M. ACE-sponsored research: Best triceps exercises. American Council on Exercise.
2. Alves D, Matta T, Oliveira L. Effect of shoulder position on triceps brachii heads activity in dumbbell elbow extension exercises. J Spors Med Phys Fitn. 2017;58(9):1247-52. doi:10.23736/s0022-4707.17.06849-9