Skull Crushers | Your Favourite Tricep Extension

Skull Crushers might sound bad for your health, conjuring images of, well, a crushed skull, headaches, or at least an exercise that will involve your head. They are in fact the tricep extension workout that you’ve been looking for. They involve supporting your back (commonly lying on your back) with your upper arms perpendicular to the floor while you extend from your elbow with weights in your hands.

Skull Crusher Form

Before we get into technique and top tips, let’s take a look at everything you need to know about the muscles you’re trying to develop.

Your triceps brachii is the large part of your upper arm between your elbow and shoulder. The triceps brachii has three heads (lateral, medial, long). The lateral head of the triceps is found on the outer side of the humerus. The medial head of the triceps is found in the middle of the back portion of the upper arm. The long head of the triceps is the largest part of your triceps and is found running down the back of your arm.

Pushing and extension exercises are the best to tone and strengthen your triceps, but varying the inclination and method of these actions can target the different tricep heads.

weights on rack


So Where Should You Begin?

Your upper arms need to be at a right angle to the floor, or the bench that you are using. It will be tempting to move to put other muscles to work when lifting, especially if the weight is too heavy for you. This is incorrect; you should begin with a lightweight to master your technique and ensure that you only extend from beneath your elbow (your forearms). In other words, you need to keep your upper arms still.

You also need to keep your elbows tight to your body to make sure that your triceps take the weight. If your arms flail or spread wide this could share the brunt of the weight and mean the full amount isn’t taken by your triceps.

Avoid being rigid, but do your best to keep them still and certainly keep them at the same angle. The risk here is that you may use other muscles to take the weight and incidentally get a shoulder workout instead of a tricep session.

Your movements should be steady and purposeful to avoid injury and to alight as many muscle fibres as you can.

Don’t ‘lock-out’ your arms at the top of the extension. This will mean that you maintain the tension on your triceps rather than resting and putting the strain on your elbows.

Skull Crushers Variations

Dumbbell Skull Crusher

Dumbbell variations to any kind of lift are divisive in opinion. On the one hand, they mean that you can’t lift as much as you would with “shared-weight” equipment such as a bar or machine. The major advantage is that each arm works individually so that your stronger arm doesn’t take the lead. This means it is good for posture and symmetry. Another great advantage to dumbbells is that you can vary your grip to work different tricep heads, for example by using a hammer hold as opposed to supinated palms.

For a similar effect and range, but with the added luxury of lifting heavier weights, you might consider using cables if they are available to you.

gym wear

Barbell Skull Crusher

Your limitations with a barbell are the angle of projection and the fact you may very well crush your skull with you lose control. The advantage is that you will spread the weight and so can lift a greater volume. Our advice: if you’re going to use a bar, make it a Z bar and keep your skull uncrushed, the way you like it.

Should you use fixed machine options? They aren’t necessarily detrimental to your progress and can certainly help you to develop your strength, but for symmetry and a natural range of movement, free weights are always advisable.

Incline Skull Crusher

This is where Skull Crushers can get interesting. By adjusting the inclination of the angle, instead of performing from a right angle position, you can place more of the strain on the tricep long head. Again, because of the extra strain, you may want to lower the weight to ensure you have your technique down as the incline will definitely make the lift harder. Second to this, you might even consider a declined starting position on a decline bench.


Take Home Message

While most presses will put your triceps to work, they will not necessarily isolate the muscles in a way you would like in order to build them. Think about your biceps and those vanity curls – Skull Crushers, in a way, are the tricep equivalent.

They are diverse too. By altering the equipment and angle of the lift, you can target different parts of your triceps and opt for heavy lifts or independent arm extensions with the likes of dumbbells so that both arms get an even workout.

Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you’re concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

Amy Golby

Amy Golby

Personal Trainer & Exercise Nutritionist

Amy has been a sportswoman for over 18 years playing rugby and netball up to a national level, she has been a qualified personal trainer for 5 years and further her nutritional knowledge with a diploma in sports and exercise nutrition as well a psychology degree. She has been training in a gym and weightlifting for over 10 years and continues to learn and improve her training in order to reach her goals. She believes in both the physical and mental advantages of sport and fitness as well as a balanced diet and lifestyle. Amy has created programs around sport and fitness for Red Bull, Look magazine, Spartan UK, as well as Mental Movement UK around how fitness can help improve your mental health. In her spare time, Amy enjoys playing sport, socialising with friends, and fuelling her shopping addiction to gym wear. She can be found here -

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