How to Do Skull Crushers (Lying Tricep Extensions)

Getting your arms looking right is about more than just pumping up your biceps. Big biceps are great, they make you look powerful, and they’re the easiest thing to show off when you get back from the gym, sure, but if you want real pythons you’re going to have to work on your tricep too. If you give attention to both halves of your upper arms you’re going to have some serious girth much faster than you could have ever imagined. So, if you want some truly thick pipes then the skull crusher, or lying tricep extension is the way to go. 

Your Triceps and You

Your triceps are the muscles that lie opposite of your biceps on your arms. They do pretty much the opposite of everything your biceps do, and without them, your arms would be basically useless.

Triceps, or the triceps brachii, get their name from their shape and locations. Their Latin name literally means they’re a three-headed muscle in your upper arm. The longest head extends from the scapula, something it shares with your biceps and runs all the way down to your ulna. The lateral and medial heads (the two shorter heads of your triceps muscle) originate above and below the radial groove of your humerus and meet the long head of your triceps down in the ulna. 

Your triceps are the unsung heroes of your arms. Their primary function is acting as an extensor muscle. Extensors are the muscles you use to “open up” a joint, so to speak. Your elbow is the joint in question here, so these muscles are what you use to extend your arms. Any time you reach for something, or when you put your weights back down after a set of curls, you have your triceps to thank for allowing your arms to reverse the work your biceps have done. They’re not just responsible for their obvious function, though. Your triceps are also engaged when you’re making motions that require fine control.

When you’re writing or typing, or really anything else that asks for still hands and fine finger control, your triceps are there fixing your elbow in place so you can keep your hands steady, allowing your forearms space and time to engage your hands and fingers in all of the complex movements they’re known for.

This stabilizing effect isn’t restricted to fine motor skills. When you’re making explosive movements to generate a lot of force the lateral head of your triceps kicks into gear, and when you’re making low force precise muscles, you’ll be using the medial fascicle.

Have you ever wondered why your bench press gets better after you’ve worked on your triceps? The explosive lifting motion you make to get the bar up off of your chest uses your triceps just as much as your chest. Lowering the weights back down requires your triceps as well. You really can’t avoid using your triceps, regardless of how much you think they’re involved in an exercise. 

The fact that they’re so involved in so many of the movements you make throughout your day in and outside of the gym means you really should be taking the time to beef up your triceps. Isolation of your triceps isn’t terribly tricky, but some exercises are better than others. This is how we’ve arrived at skull crushers. Skull crushers, when you do them right, are phenomenal for your triceps. You’re going to be able to put a lot of tension and weight on them, and that’s a formula for incredible growth.

Maximum Crushing

When you’re setting out to build muscle, it’s important to know that there’s more to it than just exercising. Your diet and allowing your muscles time to rest are two of the most important ingredients in a swole soup.

Growing your muscles is a process called muscular hypertrophy. You’re putting your muscles through the wringer to make your body wake up and increase the size of your individual muscle cells. Every time you break them down, your body wants to build them back stronger. Your body wants to rise to the occasion just as much as you do, but you need to help it along. 

Working out your muscles is only the first step. When you go to the gym, work as hard as you reasonably can without hurting yourself. What you’re really doing here is breaking down your muscle fibers a little bit. Pushing past your limits is literally what’s going on during those last few reps.

When you push yourself that far, your body wants to fix the damage, just like fixing a small cut or building a callus. That’s where the hypertrophy comes in. The word hypertrophy refers to any time your body increases the size of your cells. So, when you’re building muscle you’re building bigger fibers one cell at a time. These bigger muscle fibers are better suited to larger loads by virtue of their size and increased efficiency.

When they increase in size they also increase in storage capacity, meaning it’s easier for your muscles to draw energy towards themselves and do their work. 

All of this is great, you’ll look better, feel better, and lift better, but that won’t happen without allowing your muscles time to rest. Rest days are the second piece of the puzzle. If you’re in the gym every single day of the week putting the exact same muscle group in the forge every single day, then you’re never going to reach your goals. Rest days are how your body reallocates resources to your muscles. When you give a muscle group a day off, you’re allowing your muscles the time they need to grow and better serve you in the gym. 

Rest days don’t have to be couch days. You can work in some cardio to up your general blood flow and muscle oxygenation, or you can take some time to stretch. Muscles are rigid by nature, so you’ll want to take some time to stretch if you’re focused on building muscle. Stiff muscles and overloaded tendons are how you get hurt in the gym. Loosen yourself up with stretches to encourage flexibility and blood flow.

Rest days can also be days you spend in the gym. Just switch up your routine to avoid muscle groups you’ve worked out previously, and you’ll still be making progress towards bigger better muscles.

The final piece of this equation is going to be your nutrition. Your muscles are essentially protein and water. Keep yourself hydrated and fed well. Protein supplements will make this easier. You’re going to need a lot of it if you’re in the gym all week. You can get this from your diet by checking your nutrition facts and all of that, but sometimes, you’ll just need a little boost.

Protein powders are a simple way to make sure you’re getting the nutrients you need without having to fuss with the contents of your food. You’re also going to want to make sure you’re not taking in more energy than you’re expanding. Fat cells come from unused energy. Your body hates wasting resources, so don’t make it hold onto anything extra. Keep your body active by pushing yourself in the gym, and eating a balanced diet, and you’ll be rid of your fat stores, building muscle, and looking shredded.

Getting Warm and Fuzzy

Before you do any exercise, you should always make sure you’re warmed up. Isolation exercises tend to work you into tricky positions and the focus on a single muscle group may tempt you into overworking yourself. To minimize your chances of injury and maximize your output, you should get some stretches and light warm-ups in.

A simple tricep stretch will have you reaching for the sky. Bend your arm at the elbow, reach behind your back, and use your opposite arm to gently push on your elbow for a few seconds at a time. Limber up your triceps so you’re not going into this exercise with rigid unyielding muscles. You don’t want to fail out early with this weight above your head.

If you’re into more active warm-ups then you could do some simple arm rotations. This will get your shoulders into the mix as well. Extend your arms, and hold them both out to your sides. make tiny forward and backward circles. This is great for getting all of the heads of your delts up out of bed, and keeping your arms extended parallel to the floor is a great way to get your triceps revved up.

Let’s Crush Some Skulls

Skull crushers are a great isolation exercise for your triceps. They engage your triceps in all of the work they love to do. You start your arms in a fully flexed position, allowing your triceps to do what they do best, and extend your arms out above your body.

Skull crushers ask you to lie down on a bench, so you’ll be working against gravity the entire time, maintaining tension on your muscles throughout the entire lift. You also need an explosive motion to get the weights moving initially, something that the smaller heads of your triceps love to do. Even while lowering the weights back to the starting position your triceps will be engaged in keeping your arms stable. The only thing scarier than the name is the results.

If you’re ready to get your skull crushing on, here’s how you pull them off with perfect form:

• Find a flat bench and a barbell
• Lie down on your back
• Grab the barbell with your arms about shoulder-width apart with an overhand grip and start with your arms extended up above your body
• Lower the weight, bending at the elbows, past the top of your head, the weight should be in line with the crown of your head or the top of the bench if you can manage it
• Reverse that motion until your arms are almost straight, don’t lock your elbows, try keeping tension on your muscles the entire time
• Repeat this lowering and raising motion for about 10 to 12 reps per set

Skull Crushing Variants

Varying the skull crusher is pretty simple.

Adjusting the bench or your grip will bring different parts of your triceps into the spotlight.

• You can do your skull crushers on an inclined bench. This will move your center of gravity and engage the long head of your triceps a bit more. The long head is engaged most in generating sustained force and working your shoulders and elbows together. The adjusted angle of your body will add that tension by moving where you’re holding the weight in relation to your shoulders and force you to sustain tension while keeping the weight and your arms above you for the duration of the exercise.
• Using a decline bench will also engage one head of your triceps a bit more than the others. The decline of the bench will put the onus on your lateral head. The lateral head is used most with explosive high-intensity force. Getting the weight up above you from the declined position is going to have you digging deep, and your lateral head will come to tag you out of trouble.

Tricep Tricks

Gravity: When you’re doing your skull crushers, an easy way to ensure you’re getting the most work out of your muscles is the angle of your arms. If you keep your upper arms perfectly perpendicular to your body, you’re going to be robbing yourself of the opportunity to lift the maximum amount of weight. When you’re lifting the weight to a point directly above your body you’re allowing the force of gravity and the force of your body to create a relatively neutral point above you. 

Try holding a weight straight up above you, you can probably keep it up there for a long time, but if you move your arms at an angle, you’ll have a harder time holding those weights. Always make sure you’re keeping your upper arms at an angle throughout the skull crushers to maximize the resistance you’re encountering so you’re not wasting time and energy.

Weights: Figure out the right weights for you. You can do skull crushers with any sort of weights, the benefits are all different, but if you take the time to work out what works best with your anatomy you’re going to have a much easier time keeping skull crushers in your workout rotations. 

If using a barbell is hurting your wrists by forcing them to rotate inwards more than you’re comfortable with, then try an EZ curl bar or a single dumbbell held perpendicular to the ground. The bent shape will fit the anatomy of your body a bit better, and allow you to more comfortably lift the weights. The single dumbbell will allow for a more natural close grip.

If you feel like imbalances in tricep growth are creeping in, then consider using a pair of dumbbells. Using a dumbbell in each hand will force you to utilize the full strength of both arms without granting you the opportunity to use your dominant hand to compensate for the side that’s lagging behind. Using separate dumbbells will also force you to work more on your stability, engaging your core, and all three heads of your triceps. Remember that your triceps aren’t just responsible for extension, but elbow stability as well. You’ll be lifting a lighter weight, but the trade-off is worth it.

Cables will allow you to put even more tension on your triceps the entire time. You won’t be able to escape from the force of your weights even if your form starts to suffer. You can also change the handle for your cable machine to the ropes. If you use the ropes you can hold the weight in the most comfortable position, and add some extra challenge to your skull crushers by supinating your hands at the apex of your lift. That twist makes a world of difference. 

Isolation: keep an eye on proper form, if you engage your upper arms too much, you’re most likely going to be bringing your deltoids into this exercise. Skull crushers are supposed to be utilizing your triceps more than anything else. If you’re having trouble isolating your triceps, think about using your elbows as a fulcrum, because that’s where they connect and exert their force. If you need more practice with isolating your triceps, try doing some warm-up triceps exercises before you lie down to do your skull crushers.

Crushing It

Skull crushers are one of the most effective exercises for your triceps. They’re a happy place for your triceps, and they yield excellent results. Lying on your back and positioning your arms at a slight angle will allow you to put an immense amount of tension on your triceps allowing them to do everything they do the best. Small adjustments to your form and the weights you use will keep your wrists and elbows happy, opening the Gates of Gains, and giving you the thick pistons you need to pump more iron.