Skull Crushers

What skull crushers actually train

The triceps has three heads, and they do not all do the same job. The lateral and medial heads cross only the elbow. The long head crosses the shoulder as well, which means its length depends on where your upper arm is, not just on how bent your elbow is.

Kholinne and colleagues examined the distinct roles of each head in elbow extension and found the heads contribute differently depending on position and demand. That distinction is the entire reason skull crushers are worth programming rather than just doing more pushdowns.

Maeo and colleagues compared elbow extension training performed with the shoulder flexed, so the long head was stretched, against training with the arm by the side. Long head hypertrophy was substantially greater in the stretched position. Skull crushers sit partway along that spectrum. A pushdown trains the long head in a shortened position. An overhead extension trains it fully stretched. A skull crusher, especially one lowered behind the head rather than to the forehead, lands closer to the overhead end than most people realise.

That is the case for keeping them. Pressing trains the triceps heavily but always with the arm at the side. If the long head is the head you want to develop, arm position is the variable that matters.

Setting up and executing

Lie flat on a bench with the feet planted and press an EZ bar or straight bar up over your chest. Take a grip roughly shoulder width with the palms facing your feet.

Now tilt the upper arms slightly back so they point a little behind vertical rather than straight up. This is the small setup detail that keeps tension on the triceps at the top instead of letting the bar stack over the elbow where the load disappears.

Set the shoulder blades into the bench and brace the abs. Bend the elbows to lower the bar, keeping the upper arms exactly where you put them. The elbows stay roughly shoulder width.

Guide the bar towards your forehead, or better, to just behind the top of your head. Lower until you feel a clear stretch along the back of the upper arm. Then extend the elbows and drive the bar back, stopping just short of a hard lockout.

Two seconds down, controlled up. Every rep.

The mistakes that cost you the most

Moving the upper arms is the fault that changes the exercise entirely. If the elbows drift forward as you extend, you have turned a triceps isolation movement into a close grip press, and the chest and shoulders have quietly taken a share of the work. The upper arms are a fixed hinge. Only the forearms move.

Flaring the elbows out wide shortens the lever, which feels easier and is easier, and it adds strain to a joint that does not need it. Keep them in.

Stopping the bar too high is the most common way people leave results on the table. Lowering only to eye level skips the stretched position, and the stretched position is where the long head advantage lives. Pallares and colleagues found full range training generally produced better adaptations than partial range work, and on this exercise the deep portion is the part that distinguishes it from a pushdown.

Going too heavy is a specific problem here because the elbow is a small joint under a long lever. Aching elbows the day after a skull crusher session almost always means load, not technique.

Dropping the bar towards your face and catching it near the bottom is both the reason for the name and a waste of the most productive half of the rep.

Sets, reps and rest by goal

Moderate reps suit this best. Very low rep skull crushers put a lot of stress on the elbow for very little extra benefit.

For muscle gain, three to four sets of eight to twelve with about seventy five seconds of rest. For strength work, three sets of six to ten with two minutes, though triceps strength is usually better trained with close grip pressing. In a fat loss phase, three sets of twelve to fifteen with a minute of rest.

Schoenfeld and colleagues found a dose response between weekly sets and hypertrophy, so what matters is the total triceps work across the week, of which pressing already contributes a substantial share. Refalo and colleagues found that stopping a rep or two short of failure produces comparable hypertrophy to training to failure, which is particularly welcome on an exercise where the failed rep involves a loaded bar above your face.

Where it fits in your split

Skull crushers go after pressing, never before. Fatiguing the triceps first will cost you far more on the bench press than the skull crushers gain you.

On push, pull and legs they belong on push day as the main triceps movement once the chest and shoulder work is done. On an upper and lower split they sit in the accessory block. On a bro split they open the triceps portion of arm day.

Two triceps exercises a week is plenty for most people if you press regularly. Pair a skull crusher or overhead extension, which loads the long head at length, with a pushdown, which loads the elbow extensors in a shortened position, and you have covered the muscle properly.

Variations worth knowing

The EZ bar version is the default. The angled grip lets the wrists sit at a more natural angle, and most people find it noticeably more comfortable than a straight bar.

Dumbbells give each arm its own path with a neutral grip. If the bar version irritates your elbows, try this before abandoning the exercise.

Lowering behind the head rather than to the forehead is the upgrade worth building towards. More stretch on the long head, and based on the Maeo findings, more of the specific adaptation you want.

Incline skull crushers sit the arms further behind the torso for the same reason, at the cost of a slightly fiddly setup.

The cable version keeps tension at lockout, where a bar gives you almost none, because the line of pull no longer runs straight down through your elbow at the top.

And overhead extensions are the closest relative. Same principle, more shoulder flexion, more stretch. Rotating between them across a training block is more sensible than arguing about which is better.

What the evidence says

The most directly useful finding is Maeo and colleagues, who found substantially greater long head hypertrophy when elbow extension training was performed with the shoulder flexed rather than with the arm by the side. The long head is the largest of the three heads, so how you train it drives a lot of overall triceps development. That single finding is the best argument available for programming a stretched-position triceps exercise rather than three variations of pushdown.

Kholinne and colleagues describe the differing roles of the three heads in elbow extension, which supports the general principle that head-specific training is a real thing rather than bodybuilding folklore.

Pallares and colleagues on range of motion supports lowering the bar deep rather than stopping short, and Schoenfeld and colleagues and Roig and colleagues both found modest advantages for eccentric-emphasised training, which is the reason for the two second descent.

Vigotsky and colleagues, as ever, are the caution. Electromyography comparisons between triceps exercises are widely quoted and do not establish which produces more growth. The Maeo study is more valuable than a dozen activation papers precisely because it measured muscle size after a training period rather than signal amplitude during a session.

Common questions

Should I lower to my forehead or behind my head?

Behind the head, if your shoulders and elbows allow it. It puts the long head under more stretch, and the stretched position is where the training effect for that head is largest. Start at the forehead if the movement is new to you and work backwards as your control improves.

Do skull crushers hurt your elbows?

They can, and the usual cause is too much weight, elbows flaring wide, or a straight bar forcing the wrists into an awkward position. Switch to an EZ bar or dumbbells, drop the load, keep the elbows in, and the problem usually resolves. Persistent pain is worth getting looked at rather than working around.

Are skull crushers better than pushdowns?

For the long head, almost certainly, because the arm position stretches it. For the lateral and medial heads, they are roughly equivalent. The sensible programme runs one of each rather than choosing.

Can I do them with dumbbells?

Yes, and for many people it is the better version. A neutral grip and two independent weights let each elbow find a path it tolerates. The only cost is that loading progresses in bigger jumps than with a bar.

How heavy should I go?

Light enough that the upper arms stay still and the descent takes about two seconds. If your elbows drift forward, if the bar drops rather than lowers, or if your elbows ache the following day, take weight off. Progress on this exercise comes from reps and range far more than from load.