The short version:a skullcrusher is a lying triceps extension. You lie back on a bench, hold an EZ bar or a pair of dumbbells over your chest with your arms straight, then bend only at the elbows to lower the weight toward your forehead or just behind your head - and press it back up. Your upper arms stay pointed at the ceiling the whole time. It is one of the best moves there is for building the triceps, the muscle that makes up most of the back of your arm, and you can do it at home with almost nothing. The catch is that it rewards a light weight and a slow, controlled tempo, so we'll spend most of this guide on how to keep your elbows happy while you train.
What a skullcrusher actually trains
Your triceps make up roughly two-thirds of your upper arm, so if you want bigger, stronger arms, the triceps matter more than the biceps most people think of first. Pressing movements like the dumbbell bench press already work the triceps, but they share the load with your chest and shoulders. The skullcrusher isolates the triceps almost completely, because your shoulder stays still and the only joint doing the work is your elbow. That focused stretch and contraction is why it builds the arm so well.
It pairs neatly with the overhead tricep extension, which is essentially the same idea done sitting or standing with your arms overhead. Between the two, the skullcrusher hits the triceps from a slightly different angle and tends to feel a touch more stable because you are lying down and supported by the bench. Many home lifters rotate between them to keep the muscle challenged and the elbows fresh.
EZ bar or dumbbells - and why not a straight bar
The most comfortable tools for this move are an EZ bar or a pair of dumbbells, and there is a good reason both beat a straight barbell here. A straight bar forces your palms to face fully away from you and locks your wrists in a flat, pronated position. Under a triceps stretch that angle puts real strain on the wrists and the inside of the elbow. An EZ bar - the wavy curl bar - has angled grips that let your hands turn slightly inward, which lines your wrists up more naturally and takes the pinch away. If you want the full comparison, our EZ bar vs. straight barbell guide walks through it, and how to choose an EZ bar helps you pick one.
Dumbbells go one step further: because each hand moves on its own, you can rotate your palms to face each other (a neutral grip), which is usually the gentlest position of all for the wrist and elbow. They also stop your stronger arm from carrying the weaker one, so both triceps get trained evenly. If you already own a pair of adjustable dumbbells, you have everything you need to start today - no extra bar required.
How to do a skullcrusher, step by step
Set a flat bench and pick a light weight - lighter than you think - then follow these steps:
- Lie back and set the start. Lie flat on the bench with your feet planted on the floor. Press the EZ bar or dumbbells up so your arms are straight and the weight is over your upper chest or shoulders, not directly over your face.
- Point your elbows up. Tuck your elbows in so your upper arms point roughly at the ceiling, angled just slightly back toward your head. This is the position they will hold for the entire set - fixed, not swinging.
- Lower with the elbows only. Bend at the elbows and lower the weight in a smooth arc toward your forehead, or take it a little further back toward the top of your head. Keep your upper arms still; only your forearms move.
- Feel the stretch, then reverse. Lower until you feel a strong stretch in the back of your arms without any elbow pain. Pause for a beat under control - no bouncing off the bottom.
- Press back to straight.Extend your elbows to drive the weight back up to the start position, squeezing your triceps hard at the top. Stop just short of fully locking out to keep tension on the muscle. That's one rep.
Breathe in as you lower, breathe out as you press up, and keep the whole movement slow and deliberate. A good target is a two-to-three second descent - that control is what protects your elbows and what actually builds the muscle. Warm up your elbows and shoulders first with a light set or two; our warm-up guide covers a simple routine.
This is general guidance from a home-gym enthusiast, not a certified trainer, and it isn't medical advice - if a movement causes pain, stop and check with a professional.
The mistakes beginners make
The first and biggest is going too heavy. The triceps are a small muscle and the skullcrusher exposes them in a long stretch, so a weight that feels easy for a press will feel wrong here. If the bar speeds up on the way down or you have to heave it back up, you are too heavy - drop the load and earn it back with clean reps.
The second is letting your elbows flare out. When the weight gets tough, people let their elbows drift wide to recruit the chest and shoulders. That takes the work off the triceps and stresses the elbow joint. Keep your elbows tucked and pointing up throughout. The third is moving your shoulders - swinging your upper arms back and forth turns the exercise into a clumsy pullover and robs the triceps of tension. Pin your upper arms in place and let only your forearms move. Finally, bouncing out of the bottom uses momentum instead of muscle and is the fastest way to an achy elbow; pause and press smoothly instead.
How to program it and progress
The skullcrusher is an accessory, or finishing, movement - not the star of your session. Do your big presses first, then add 2 to 3 sets of 10 to 15 reps of skullcrushers toward the end of an upper-body or push day. Higher reps with lighter weight suit the triceps well and keep the elbows comfortable. It sits naturally alongside the dumbbell fly and overhead tricep extension as bench-based isolation work.
To keep getting stronger, add weight only when you can complete all your reps with clean, pain-free form - which is exactly where adjustable dumbbells or a loadable EZ bar shine, because you can climb in small steps rather than big jumps. Our progressive overload guide explains how to make those gradual increases, and reps and sets for beginners covers how to structure the whole session.
Simple variations once you're comfortable
Once the basic lying skullcrusher feels solid, a few small tweaks keep the triceps challenged and let you hunt for the version that treats your elbows best. The easiest change is where you lower the weight: aiming for your forehead keeps the triceps under tension the whole time, while taking the bar back past the top of your head - toward the bench behind you - opens a bigger stretch and usually feels friendlier on the joint. Try both light and keep whichever gives a strong triceps feeling without any pinch.
You can also change the tool. Swapping between an EZ bar and dumbbells from week to week gives your wrists a break and hits the muscle slightly differently, and dumbbells let you fix a strength imbalance because each arm has to do its own work. Some lifters set the bench to a slight incline, which shifts the angle of the stretch - a small change that can feel fresh once the flat version gets routine. None of these are essential; the plain flat skullcrusher with a light load will build your arms for a long time on its own.
A last word on staying pain-free: the triceps recover quickly, but the elbow tendons that this move stresses do not, so more is not better. If your elbows start to nag, back off the weight, cut the volume, or rotate to the overhead tricep extensionfor a few weeks before returning. Training around a cranky joint beats training through it every time, and the arms you're building are a long game, not a one-week sprint.
The bottom line
The skullcrusher is one of the best triceps builders you can do at home, and the whole game is control. Lie back, point your elbows up, lower the weight slowly toward your forehead or behind your head, and press it back - all with your upper arms held still. Use an EZ bar or dumbbells to keep your wrists happy, start lighter than feels necessary, and add weight only when your form earns it. Do that, and you'll grow the back of your arms without the sore elbows that scare beginners off. All it takes to start is a bench and one adjustable weight you can already load light.