How to do skull crushers the right way: The dos and don’ts you need to know

Skull crushers is an intriguing name for an exercise, but don’t let that put you off. This is a killer move for swelling your triceps, which are the muscles on the back of your arms with three attachment points at one end. I’ll admit I was conflicted when I first heard about this exercise because I was both a little intimidated and pumped at the same time. This move can generate serious results, but I’ve learned the key is to master your form so you can perform this move as safely and effectively as possible.

Read on to learn how to do skull crushers and the benefits, FAQs, variations, and more.

What are skull crushers?

Skull crushers are a version of a triceps extension where you’re lying down on your back on a bench. They might be called lying triceps extensions. You typically perform skull crushers with a barbell or you can use two dumbbells. The name comes from the mechanics of the move, where you bring the weights down to your skull from overhead.

What are the benefits of skull crushers?

The skull crusher is a variation of the triceps extension, which is undoubtedly one of the best exercises for isolating your triceps. The primary function of your three-headed triceps muscles in the back of your upper arms is to extend your elbow. Adding skull crushers to your routine can significantly add mass to your triceps, boost muscle power, and improve function.

One interesting study shows that targeted triceps exercises like skull crushers can increase bench press strength. In other words, getting stronger triceps by doing moves like skull crushers will improve your ability to perform other exercises like the bench press.

Here are some additional benefits of skull crushers:

• Get better at activities like football, baseball, and other sports that involve throwing. 
• Build a more well-rounded upper body by including skull crushers and moves like bicep curls in your routine.
• Improve your ability to perform your everyday functional tasks, such as pushing the grocery cart.
• Add mass to your triceps.
• Bodybuilders commonly use this move to build upper body mass and power.

What are the muscles worked?

Your triceps work with the anterior deltoids in your shoulders and the pectoral muscles in your chest to help you push the weight up and control the weight as you lower down back to the starting position. Not only do skull crushers supercharge your triceps, but they also strengthen your forearm extensors and engage your brachialis and brachioradialis. 

Research shows skull crushers are a better way to activate your triceps’ medial head than other exercises like standing triceps extensions.

How to do skull crushers

How to do a skull crusher:

1. Lie on a bench with your body supported by the bench, except for your lower legs. Your feet should be planted on the floor for stability.
2. Grip a dumbbell or barbell with both hands and your palms facing up toward the ceiling. Hold the weight up overhead without fully locking your elbows. 
3. Bend your elbows to carefully lower the weight down toward the top of your head.
4. Hold the position for a few seconds.
5. Lift the weight back to the starting position with control.
6. Repeat until you complete the set.
7. Aim for 2 to 4 sets of 8 to 10 reps.

How to make skull crushers more or less challenging

Make it a little easier

Choose the bar instead of the dumbbells, and go with a lighter weight if you’re a beginner and you want to work on mastering your form. You could also try the lying cable skull crusher using cable resistance, which keeps constant tension on your triceps throughout the move.

Increase the difficulty

Dumbbells are more challenging because you have to keep your elbows in and gain control over the weight. You can also heighten the challenge by using dumbbells and an incline bench. A slight incline further stretches your triceps and hits the muscle from different angles.

The most common mistakes to avoid when doing skull crushers

These are the most common mistakes to avoid when doing skull crushers so you can get the most out of this exercise.

Uncontrolled descent

Learn to control your dumbbells while descending. Slowing down the movement can increase the stimulation of your triceps and shoulders. Rushing increases your risk of injuries and compromises your form.

Bad form

The perfect form for skull crushers is to keep your elbows and wrists not too close or far apart — they should be shoulder-width apart. Avoid flaring your elbows, which can lead to shoulder injuries and diminish the effectiveness of this move.

Excess weight

You should avoid going too heavy or too light when doing skull crushers. Reps between 10 and 20 are OK; doing less may not get you the desired results, and doing too much could cause injuries and muscle fatigue.

Locking your arms

Avoid locking your arms, which takes away some of the benefits and diminishes triceps engagement.

Lowering the weight toward your face

Do not lower the weight toward your forehead or your face; instead, the weight should go just behind your head. Make sure you aren’t hitting the back of your head with the dumbbells.

Tips for proper form

The following top tips will help you fine-tune your technique:

• Keep your elbows tucked in.
• Start with a few reps and work your way up to performing three full sets of 6 to 12 reps.
• If you’re using barbells, you can use a spotter if you need to.
• Focus on control rather than speed and momentum.
• Engage your shoulders and keep your shoulder joints stable.
• Keep a firm grip and your wrists straight.
• Keep your spine neutral as you lower the weight down.
• Avoid arching your back, and make sure you’re lying flat on the bench.

Top variations to try

Once you’ve conquered the skull crusher, you can try other variations, such as:

• Barbell skull crushers
• Dumbbell skull crushers
• Incline lying triceps extensions (using an incline bench)
• Resistance band skull crushers
• Overhead triceps push-aways

Different variations and positioning of your elbows emphasize different parts of your triceps. Bodybuilders and influencers like Nick Wright and Matt Ogus choose variations based on which muscles they specifically want to target for well-rounded, powerful upper arms and boulder shoulders.

FAQs

Should skull crushers go to your forehead or behind your head?

Despite the name, you don’t want to be crushing your skull or risking coming too close to your forehead. Aim for behind your head for proper form and to perform the exercise safely and effectively. 

Do you keep your elbows in or out for skull crushers?

Keep your elbows tucked in when you’re performing this move, and use your shoulder joints to help stabilize your upper body.

Where should you feel skull crushers?

You’ll feel this exercise working your triceps in the back of your upper arms the most, particularly the long head of your triceps muscles, but all three heads will get a good workout. You’ll also strengthen other muscles, including your shoulder deltoids, pectoral chest muscles, and forearm extensors.

How often should you do skull crushers for results?

Consistency is key regardless of what you’re trying to achieve and your routine. Include skull crushers in your workout routine at least twice a week to see some results over time. If you can work your way up to doing them once every couple of days, that’s even better. 

Do skull crushers target your abs, too?

While you engage your core to brace yourself, skull crushers don’t fire up your abs enough to be considered an ab exercise.

What’s the best triceps exercise?

There isn’t one single winner of all the triceps exercises, and including a variety in your routine is optimal. That being said, the skull crusher is definitely on the elite list for supercharging your triceps.

Can you do skull crushers every day?

You can challenge yourself to do skull crushers daily, but most fitness trainers and professionals recommend leaving at least one day between sessions to give your muscles time to rest and recover. 

How to include skull crushers in your workout routine

You can add this exercise to your arms sesh, upper body training, or push-day to target those triceps. When you want to grow your triceps and enhance your muscular endurance, aim for three sets of 20 reps with a moderate weight. If you’re going for strength, you can aim for 4 to 6 sets of 4 to 6 reps with a heavier weight.

If you’re a beginner, start with a lighter weight until you feel more comfortable powering through this unique exercise. Focus on control and proper form to reduce your risk of injury and maximize your outcome.