WHAT’S YOUR GO-TO arm day exercise? There’s a good chance your answer is the dumbbell biceps curl. That’s a great answer—we’ve talked at length about the move and how valuable it can be for your training plan—but it’s not a complete pick if you want to make the most of your workout.
If your goal is to build balanced arm muscle and strength, you’ll want to pair your biceps work with a complimentary triceps movement. One of the best choices to do that is the skull crusher.
Muscles Worked By the Skull Crusher
The skull crusher is all about the triceps. The three-headed muscle, located on the back side of your arm, is the biggest muscle on the limb, making it an essential point of focus if you want to grow those guns. The name of the movement comes from the slightly precarious position you put yourself in to pull it off, isolating the muscles and moving the weight up and down directly above your head.
That might make you nervous that you’ll wind up in a #gymfails compilation if you make one wrong move. But as long as you work to use the proper form with a load that you can handle, there’s no danger here.
Benefits of the Skull Crusher
The best triceps exercises put you in a good position to make use of the muscles’ primary function: extension of the elbows. There are few better (or tougher sounding) moves to do this than the skull crusher. If you work with proper form, you’ll isolate the muscles so that you’re focused on only elbow extension. This will make your triceps stronger—which is essential for compound pushing exercises like the bench press—and spur muscle growth, too.
The exercise is also fairly adaptable to the gear you have on hand. You can use dumbbells, a standard barbell, EZ bars, or other implements to do skull crushers. You’ll also need a bench, although you can perform the exercise prone on the ground, too.
How to Do the Skull Crusher
Follow the directions from Men’s Health Fitness director Ebenezer Samuel, C.S.C.S., to better understand how to do the skull crusher the right way every time. The version we’re going to focus on here is using the EZ bar.
- Start by lying back on the bench. Don’t arch your back—drive your shoulder blades into the bench, squeeze your abs and glutes, and keep your feet flat on the floor.
- Press the weight straight up above your chest. Your upper arm should be just past 90 degrees, at a 91 or 92 degree angle. Keep your wrists strong and a tight grip on the bar.
- Lower the weight slowly down to an inch above your forehead, moving only at the elbows. Don’t allow your shoulders to shift forward; keep your upper arm still.
- Drive the weight back up (again moving only at the elbows), squeezing your triceps at the top.
Keep these more detailed form tips from Samuel in mind during your skull crusher sets.
No Arch
Eb says: Maintain a sturdy body position: Feet flat on the floor, squeezing your glutes, and keep your core active so that you’re not arching your back on the bench. I know, I know; we always say you shouldn’t arch your back, but it’s more important to get the most out of the skull crusher. You want, at minimum a perpendicular upper arm angle relative to your torso; anything less than that, and your arm action misses the point of the skull crusher. If you arch your back, it’s harder to find that proper angle.
Shoulder Position
Eb says: Once you have the bar over your head, drive your shoulders aggressively into the bench and maintain a little bit of tension in your mid-back. Then lean your upper arms back just slightly. Typically, you’ll see people aim to keep their upper arms perpendicular to the floor; I want you to be at a 91- or 92-degree angle instead. That slight shift places more tension on the triceps when you straighten your arms and prevents the straight-armed position from being a position of rest. Now you need to fully flex your triceps to maintain straight arms.
Elbows Tight
Eb says: As you lower the weight, work to keep your elbows in. Your elbows and wrists should both be shoulder-width apart; not closer or farther apart. It’s common for people to let their elbows flare out as they’re doing skull crushers; avoid this. That’s a good way to injure your shoulders and it also takes emphasis off your triceps, diminishing the effectiveness of the move.
One Lever Only
Eb says: Once you’ve gotten into this position, lower the bar to your head, moving only at the elbow joint. It’s tempting to let your upper arms roll back as you lower the bar toward your forehead, then shift your upper arms forward as you drive the weight back up, but that takes emphasis off your triceps and gets your lats involved. You’re aiming to move only at the elbows, maximizing the work your tris have to do.
How to Add the Skull Crusher to Your Workouts
Start by adding the skull crusher to your arm day or upper body workouts one or twice a week, performing four sets of 10 to 12 reps. As you gain strength you can add weight and drop down to the six to eight rep range.
Want to master even more moves? Check out our entire Form Check series.
Brett Williams, NASM
Brett Williams, a senior editor at Men’s Health, is a NASM-CPT certified trainer and former pro football player and tech reporter. You can find his work elsewhere at Mashable, Thrillist, and other outlets.
