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Get defined and impressive arms with the dumbbell lying tricep extension

Most men covet strong, defined and athletic arms that appear carved out of granite. But almost all of them fail to realise the results they want. A big reason why is they make basic mistakes when training their triceps. Use my dumbbell lying tricep extension advice to finally pack on the muscular size and strength to your arms that will transform your triceps, says New Body Plan editorial director Joe Warner

Want bigger arms? Then you need to dedicate as much training time to your triceps as you do to your biceps. Sure, doing your dumbbell biceps curls and EZ bar curls and cable curls will add upper arm size and definition. But focusing on your mirror muscles to the exclusion of your triceps will severely limit your gains.

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Your triceps do get worked during all upper-body pressing compound lifts. These include the barbell bench press, the Smith machine bench press, and all types of shoulder press, whether that’s the barbell overhead press, the Smith machine shoulder press, or the shoulder press machine.

But to fully maximise the size, strength and definition of the triceps, or any muscle group for that matter, you need to isolate it.

That simply means you exercise it without the involvement or support of any other muscle or muscle group. Even in a triceps-dominant exercise such as the triceps dip or close-grip bench press the shoulders and chest muscle in on the act. So to maximise your upper arm development you must regularly do exercises that test the triceps in isolation.

Here’s how to do the dumbbell lying triceps extension the right way to sculpt the big, strong and impressive arms you want!

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What is the dumbbell lying tricep extension?

The dumbbell lying tricep extension is a very popular triceps-focused isolation exercise. The move is also known the skullcrusher (keep reading to find out why!).

Along with other triceps-specific moves, such as the cable rope pressdown, the dumbbell lying tricep extension should be a regular part of any muscle-building training plan to build bigger, stronger and defined arms.

What muscles does the dumbbell lying tricep extension work?

The dumbbell lying tricep extension works the triceps, the muscle group on the back of the upper arm.

The triceps are actually a three-headed muscle. Its proper name is triceps brachii, which is Latin for “three-headed muscle of the arm”. The three heads, or parts, of the triceps are called the medial, lateral and long heads. The primarily role of the triceps is to extend the elbow joint to straighten the arm. But it is also involved in addicting the arm and extending the shoulder.

The triceps works antagonistically (opposingly) with the biceps (biceps brachii, Latin for the “two-headed muscle of the arm”), which is primarily responsible for flexing the elbow joint to bend the arm. It is also involved in shoulder flexion and abduction, and forearm supination (rotation).

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Why are dumbbell lying tricep extensions also known as skullcrushers?

For the very simple reason that you don’t want to lose control of the weights when they’re directly about your head. The movement pattern of the dumbbell lying tricep extension lowers the weights down from over your chest to just above your forehead. From there you press the weights back up.

If you lower the weights down too quickly you risk hitting yourself in the face. Or if you select a weight that’s too heavy you may get stuck with the weights directly above your head.

It’s for these reasons the lying dumbbell tricep extension is also known as the skullcrushers. And why you should always use a lighter weight and prioritise perfect form. Go too heavy and the risks far outweigh the rewards.

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When should I do dumbbell lying triceps extensions?

Don’t make the mistake of doing dumbbell lying tricep extensions at the end of your workout like you would with almost all other isolation exercises.

In most cases isolation lifts are best done at the tail-end of your session. Why? Because they’re a very safe way to fully fatigue as many muscle fibres as possible to make them grow back bigger and stronger.

This is true for most arms exercises, including the dumbbell bicep curl, the dumbbell hammer curl, or the cable tricep pushdown.

While these lifts can be done relatively safely to failure (if your muscles can’t complete a just drop the dumbbells or cable handles), if you reach failure on a lying triceps extension you risk dropping the weights on your head. Hence the move’s other name of the skullcrusher!

The dumbbell lying triceps extension is therefore best done in the middle of a chest and triceps workout, or a push session, or on a dedicated arms training day, once the triceps are fully warmed up but before they’re approaching fatigue.

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How do I do the dumbbell lying tricep extension?

Lie on a flat bench holding a dumbbell in each hand with a palms-facing grip and straight arms directly above your chest.
Look at the position of your elbows and lock them into place.
Your elbows shouldn’t move forwards, backwards or to the sides once the set starts.
The only part of your body that should move once the set starts are your forearms. If you can’t do the move without your elbows moving the weight is too heavy.
Keeping your head and neck in a neutral position and your elbows pointing at the ceiling, bend your arms and slowly lower the weights down in a smooth arc towards the top of your head.
Pause for a second in this bottom position then press the back up powerfully, without your elbows moving, to the start position.
That’s one rep. Do three sets of eight to 12 reps, resting 60-120 seconds between sets.

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What other equipment can I use to do the dumbbell lying tricep extension?

Dumbbells are the most common bit of weight-training kit used to do the lying tricep extension but you can also use an EZ bar.

This type of bar means you don’t work each arm individually, but that means you can likely lift more weight, and it provides a more comfortable grip position to reduce strain on your wrist, elbow or shoulders joints.

You can also do the move using a cable machine with a double rope or straight-bar handle attached to the low pulley. However, getting into the start position requires some skill. So it’s best if you’re new to the move to start with dumbbells or an EZ bar.

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