Skull Crushers: A Complete Guide

Quick Intro

Skull Crushers, also called the Lying Tricep Extension, is an isolation strength exercise performed by lying on a bench and lowering a barbell or EZ bar toward the forehead by bending only at the elbow, then extending back to lockout. It’s a dedicated triceps builder, using a barbell as the main equipment.

Equipment Needed

Skull Crushers needs a Barbell, the one required piece of equipment. A straight barbell is the standard implement here, though many lifters reach for an EZ Bar instead, since its cambered grip is easier on the wrists through the full range.

Why Skull Crushers Matters

Bending and straightening the elbow while the upper arms stay fixed overhead isolates the back of the upper arm (triceps brachii) almost by itself, with no other muscle group sharing meaningful load through the rep. Muscular strength is the main demand, the payoff of loading a single muscle group through its full range with no other joint sharing the work. Endurance comes with it, from holding a fixed upper-arm position for a full set.

When to Do It

Skull Crushers works well as an accessory movement after the day’s heavier pressing work, once the shoulders and chest have already done the bulk of the pushing and the triceps are ready for direct, isolated attention. Two to three sessions a week, with enough recovery time between hard sets, lets the tendon around the elbow adapt alongside the muscle.

Anyone with elbow tendon irritation or a history of tricep strain should approach this lift cautiously, since the stretched bottom position loads the tendon directly. Starting with a light bar and a shorter range of motion is a reasonable way to test how the elbow responds before adding weight.

Getting Ready

A few minutes of easy upper body movement, like arm circles or light band pull-aparts, raises blood flow to the shoulders and elbows before any loading begins. A few reps of the empty bar, focused purely on keeping the upper arms still, rehearse the exact path the bar needs to travel.

Once the bar is loaded, one or two light warm-up sets let the elbow tendons adjust to the stretch at the bottom before the first hard set.

Step-by-Step Instructions

1. The setup. Lie on a flat bench holding the bar with a shoulder-width grip, arms extended straight up over the shoulders.

2. The lower. Bend only at the elbow, lowering the bar toward the forehead or just behind it, keeping the upper arms vertical the whole way down.

3. The stretch. Let the bar travel until a clear stretch is felt through the triceps, without letting the elbows flare out to the sides.

4. The extension. Straighten the elbows to press the bar back to the starting position, keeping the upper arms fixed throughout.

How Many, How Often

Skull Crushers is dosed by reps, sets and the weight on the bar, with the working weight chosen relative to how well the upper arms stay still through a full set.

Keeping the upper arms vertical throughout the rep matters more here than the weight on the bar, since elbows that drift forward or back quietly turn this into a partial press, not a true tricep isolation movement.

Modifications and Variations

Skull Crushers has one easier entry point and one compound alternative.

For an easier entry point using one arm and a longer lever, Overhead Tricep Extension presses a single dumbbell overhead rather than lowering a barbell across the face, removing some of the setup complexity this exercise demands.

As an alternative built around a compound press, Close Grip Bench Press presses a barbell from the chest with a narrow grip, sharing the same triceps emphasis while adding chest and shoulder involvement on top of it.

Progression path: Overhead Tricep Extension as an easier entry point → Skull Crushers, with Close Grip Bench Press as a parallel alternative for a compound-movement version of the same emphasis.

Common Mistakes to Avoid

Letting the elbows flare out or drift during the lower. It’s the reason this exercise earns its name the hard way: elbows that travel back toward the face instead of staying fixed overhead put the bar on a collision course with the forehead. Keeping the upper arms vertical throughout the descent keeps the bar traveling safely past the head.

Bouncing the bar out of the bottom stretch. Using momentum to rebound out of the deepest part of the range trades triceps tension for a quick, uncontrolled reversal that also stresses the elbow tendon. Pausing briefly at the bottom before extending back up keeps the tension on the muscle where it belongs.

Using too much weight for the range this exercise demands. Because the triceps work alone here with no help from the chest or shoulders, a weight chosen for a compound press is almost always too heavy. Dropping the weight enough to keep the upper arms still is worth more than chasing a bigger number.

After Your Set

This lift barely raises the heart rate, so a minute of easy shoulder rolls is enough before stretching begins. Reaching one arm overhead and bending the elbow to drop the hand behind the head, then gently pulling the elbow with the other hand, stretches the triceps that just did the entire set of work. Switching sides after a few breaths keeps both arms evenly released.

Going Deeper

Skull Crushers usually sits as an accessory movement after a heavier pressing exercise, giving the triceps direct, isolated attention once the bigger muscle groups have already been trained. Pairing it later in a session with a biceps isolation exercise gives the upper arm balanced development on both sides of the elbow.

Progress here tends to stall on elbow drift, not raw strength: as the weight increases, it becomes tempting to let the elbows creep backward to make the lockout easier, which quietly turns the exercise into a different, less effective movement. Filming a set from the side, or asking a training partner to watch the elbow position, tends to catch this faster than trying to feel it from the inside.

Someone new to this lift generally learns to keep the upper arms still within the first few sessions, and works up to a weight that challenges the triceps for a full set somewhere in the four to eight week range, though elbow tendon adaptation is usually the limiting factor, not raw muscle strength.

How to Know You’re Improving

1. Upper arms that stay vertical and still from the first rep to the last
2. A controlled, paused bottom position
3. A working weight that has grown while the elbow position stays clean
4. A full stretch felt through the triceps at the bottom of every rep

Upper arms that hold their position through the whole set, not the number on the bar, is what marks progress here.

Muscles Worked

• Triceps Brachii (the back of the upper arm, worked in isolation with the upper arms held still and vertical)

FAQ

Why is it called Skull Crushers? The name comes from the bar’s path directly toward the forehead if the elbows drift back during the lower (see Common Mistakes above). Keeping the upper arms vertical the entire time is what keeps the bar traveling safely past the head.

Should I use a straight bar or an EZ bar? An EZ Bar’s cambered grip is easier on the wrists through this exercise’s full range and is a common substitute, even though a straight barbell is the standard implement here (see Equipment Needed above). Either works for training the triceps.

Why do my elbows hurt after this exercise? This usually means either the weight is too heavy for a pure isolation movement or the bottom stretch is being reached too quickly without control (see Common Mistakes above). Reducing the weight and controlling the descent fully tends to resolve it.

Can I do this with dumbbells instead of a barbell? Yes, holding a single dumbbell in each hand or one dumbbell with both hands works the same muscle through a similar path, and Overhead Tricep Extension uses a related single-arm dumbbell setup as an easier alternative.